Iii-nitride light-emitting devices with one or more resonance reflectors and reflective engineered growth templates for such devices, and methods

This application claims interests under 35 USC 119 (e) of the following US provisional patent application. This US provisional patent application is the US provisional patent application No. 60 / 835,934 (Filing date: August 6, 2006, title of invention: "III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE REFLECTORS AND REFLECTIVE ENGINEERED GROWTH". TEMPLATES FOR SUCH DEVICES, AND METHODS, by RJ Jorgenson ) and US Provisional Patent Application No. 60 / 821,588 (Filing date: August 7, 2006, Title of invention: III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH DEVICES, AND METHODS, by RJ Jorgenson ). Both of the above provisional patent applications are incorporated herein by reference.

The present invention relates to a semiconductor light emitting device.

References are cited throughout this application. The disclosure of each of these documents shall be incorporated by reference in its entirety.

A light emitting diode (LED) is a semiconductor device that generates light from electrical excitation, in which electrons and holes combine and disappear, resulting in the formation of photons.

These structures are generally grown on sapphire substrates or silicon carbide substrates by OMVPE (Metalorganic Vapor Deposition Growth).

Figure 1 shows one example of a standard III-nitride semiconductor LED grown on OMVPE. The semiconductor LED is a sapphire substrate (101), originally doped gallium nitride (GaN) buffer layer (102) with a thickness of 2 μm, silicon-doped 2 μm n-type GaN layer (103), single quantum well or multiple quantum. It consists of an indium gallium nitride active region (104) composed of wells, a current blocking layer (105) made of magnesium-doped p-type AlGaN, and a magnesium-doped p-type GaN layer (106).

This LED structure grows epitaxially on the substrate (in this case, the substrate is sapphire) so that multiple LEDs are formed on the substrate surface and the electrical terminals (207, 208) are single as shown in FIG. It will be arranged on each of the n-type GaN layer (203) and the p-type GaN layer (206) of the LED.

Group III nitride LEDs require a GaN buffer layer (102) with a thickness of about 2 μm when grown on a non-conductive sapphire substrate (Patent Documents 1 and 2). This is to obtain quality material for the device before the n-type layer (103), active region (104), and p-type layer (105, 106) of the device grow. Other methods exist, but generally this extended 2 μm thickness requires that the GaN buffer layer (102) coalesce during growth resulting in device quality material.

Standard group III nitride semiconductor LEDs are semiconductor (N)_GaN= 2.4) and air (N)_airSince the refractive index between = 1) is different, light extraction is usually small. Most of the light emitted inside the LED does not leak through the Snell's window to reach the external medium (air), so the extraction efficiency from the LED extraction surface is approximately 6%. is there.

One method of improving light extraction comprises the step of shaping the light emitting surface of the surface of the device in order to reduce the amount of light generated, which generated light is by total internal reflection as described in Patent Document 3. Lost. A molding technique that improves light extraction is to achieve light scattering by optionally textured the surface of the device.

Another method for improving light extraction is to form a layer having a photocrystal structure described in Patent Document 4. Designed according to the above, the photocrystal suppresses the waveguide mode so that more light is extracted from the device by diffraction via vertical or direct mode. Surface texture and photocrystal structures have additional complexity issues due to extra technical and processing steps, which may include additional layer formation or etching steps.

As shown in FIG. 3, some group III nitride LEDs utilize a metal mirror contact portion (308) on the p-type GaN layer (306) side of the device described in Patent Document 5. The metal mirror joint is vapor-deposited after the epitaxial process. In this embodiment, the metal mirror contact portion (308) covers the entire p-GaN layer (306). Adjusting the thickness of the P-GaN layer results in the mirror placement allowing the device to take advantage of the optical cavity (309) effect, as shown in FIGS. 3 and 4. Light emitted from the active region (304) self-interferes due to reflection from a nearby metal mirror (308). The optical cavity effect reduces the total number of horizontal light modes while increasing the emission of light into vertical modes. In this example, the vertical mode is Snell's It is easily extracted through a transparent substrate through a window). As shown in FIG. 4, arranging the center of the active region (304) of the LED at the maximum value of the photoelectric field distribution (401) or in the vicinity of the maximum value is useful for light extraction. The maximum part (402) of the optoelectric field distribution (401) is called the wave antinode. This is because the maximum part is the wave front of the stationary light wave. In general, placing the center of the active region (304) on or near the wave-belt (400) closest to the metal contact (308) will result in more light being snelled. Desirable to allow passage through windows. As shown in FIG. 4, the wave front (402) of the continuous light waves (401) is periodically arranged away from the metal contact portion (308).

The above optical extraction is more easily applied to the p-type GaN layer side of the device. The p-type GaN layer side of this device is readily available for further processing after completion of epitaxial crystal growth. The sapphire substrate is non-conductive, and it is preferable to grow the n-type GaN layer side first. The n-type GaN layer side will be buried, but it is difficult to access the n-type GaN layer side from the side surface of the substrate in a further process because the sapphire is strong and strong.

Resonant cavity light emitting diodes (RCLEDs) or microcavity light emitting diodes (MCLEDs) in two mirrors are a further way to increase the extraction of light from semiconductor light emitting devices. The active region is arranged inside the LED in such a way as to create an optical cavity between two properly arranged mirrors. The two properly arranged mirrors direct the emission of light into vertical or single mode by reducing the total number of optical modes inside the LED.

Combining a high-reflector with a partial-reflector to create a cavity is expected to increase the light emission efficiency in the range of 30% to 50% of a standard LED, as described in Patent Document 6. ing.

The key to the proper functioning of the cavity LED is the placement of the mirror with respect to the active region to obtain resonant or constructive interference.

Combining a metal mirror on the surface of an LED's outer p-type III nitride surface with an active region located on or in the vicinity of a continuous light wave is a standard vapor deposition described in Patent Document 5. It is relatively easy to implement using technology.

One of the techniques for coupling a mirror inside the n-type III nitride region of a continuous light wave antinode or in the vicinity of the wave antinode involves epitaxial growth of a dispersed Bragg reflector (DBR). This dispersed Bragg reflector consists of an alternative layer of semiconductor material, each material having a variety of refractive indexes and a quarter wavelength thickness. Many of these layers need to have sufficient reflectivity in the optical cavity.

While these DBRs grow epitaxially, there are many unique disadvantages to DBRs. The step of changing the layer of material raises the problem of lattice mismatch, which can lead to increased cracks in the wafer, reduced crystallinity, reduced yield, reduced uniformity, and increased manufacturing costs. In addition, DBRs have higher electrical resistance compared to metals and other semiconductor materials, resulting in less current injection into the device.

Patent Document 6 discloses a flip-chip light emitting diode having a resonant optical microcavity. This light emitting diode uses a DBR of continuous light wave antinode or near wave antinode. Device-specific DBRs use materials that are more compatible with the grid and have less need to change layers compared to previous DBR structures. Nevertheless, while the device may be improved over previous DBRs, it does not adequately eliminate the manufacturing complexity and conductivity drawbacks inherent in DBR material composition.

Another method for arranging the mirror in the n-type III nitride region consists of removing any buffer layer and base substrate. This step is followed by a thinning and polishing of the n-type III nitride layer in such a way as to create an interfacial mirror optimally placed in the microcavity.

Patent Document 7 discloses MCLED. The MCLED has an interfacial mirror on the n-type side of the Group III nitride device, which couples with a metal mirror deposited on the p-type III nitride side of the device. The MCLED further has an enclosed active region, which is located on or near the flank of a continuous light wave between the two reflecting surfaces.

The manufacture of this MCLED requires a laser lift-off to remove the substrate, as described in Patent Document 8. In addition, the n-type III nitride layer is precise to create a highly reflective metal mirror deposited on the p-type III nitride surface of the device, as well as to create an interfacial mirror optimally arranged for the active region. Must be etched to the correct thickness.

Although the method has been shown to be functional, the laser lift-off and subsequent etching steps are difficult to commercialize and obtain high yields.

What is desired is a microcavity LED structure that does not require cumbersome material removal or complex stratification. Further, as described above, it is desirable to combine various light extraction structures while enabling high current injection.

<patcit num="1"><text>U.S. Pat. No. 4,855,249 (Isamu Akasaki et al., Filing date: August 8, 1989)</text></patcit><patcit num="2"><text>U.S. Pat. No. 5,686,738 (Theodore D. Moustakas, filing date: November 11, 1997)</text></patcit><patcit num="3"><text>U.S. Pat. No. 5,779,924 (Michael R. Krames et al, Jul 14, 1998)</text></patcit><patcit num="4"><text>U.S. Pat. No. 6,831,302 (Alexei A. Erchak et al, Dec 14, 2004)</text></patcit><patcit num="5"><text>U.S. Pat. No. 6,573,537 (Daniel A. Steigerwald et al, Jun 3, 2003)</text></patcit><patcit num="6"><text>U.S. Pat. No. 6,969,874 (Gee et al., November 29, 2005)</text></patcit><patcit num="7"><text>U.S. Patent Application No. 2007/0096127 (P. Morgan Pattison, May 3, 2007)</text></patcit><patcit num="8"><text>U.S. Pat. No. 6,071,795 (Nathan W. Cheung et al, Jun 6, 2000)</text></patcit>

<p> Device structures that take advantage of the improved optical cavity effect of light extraction are described. This device structure consists of an optimally thick and optimally arranged active region in relation to the light extraction properties as well as the various structures of the epitaxially grown metal mirror. For the purposes of this disclosure, the embedded mirror (or mirror structure) is defined as an epitaxially grown metal mirror (GEMM) or GEMM layer.</p>

<p> In some embodiments, the device structure may include an optical cavity with a GEMM and a second mirror. The second mirror can be a dispersion Bragg reflector (DBR), a non-epitaxially grown metal mirror, an interfacial mirror, a GEMM, or any other mirror structure. In other embodiments, the second mirror may be replaced with a rough surface, a photocrystal, or another light extraction structure. Any combination of light extraction structures may be combined with GEMM. Many embodiments are used, including the step of combining multiple light extraction structures on one side or both sides.</p><p> Depending on the structure, the light may travel away from the sides of the substrate and through the top of the device. In other structures, light may propagate through a transparent substrate at the bottom of the device in the form of a "flip chip" MCLED or RCLED. In other structures, light is emitted from one or more directions.</p><p> By arranging the GEMM at or near the continuous light wave nodes to create a resonant cavity device, constructive interference between the light generated in the active region and the light reflected from the GEMM. Sometimes I make it. This allows the light to be directed to a mode (or single mode), increasing the amount of light propagating from the LED. The light produced by the optical cavity device has more directionality and its spectrum is pure compared to standard LEDs.</p><p> By simply adjusting the growth time of the GEMM and even its thickness during epitaxy, the GEMM grows to be non-permeable and highly reflective according to the properties of the bulk material, or by growing semi-transparent. Meet the requirements of different device structures. The materials used in GEMM closely match the lattice constants of the Group III nitride layer and increase device quality.</p><p> A properly used GEMM layer has many advantages over the components of today's well-used device structures such as distributed Bragg reflectors (DBRs) or non-epitaxial mirrors.</p><p> For example, the GEMM layer does not need to layer a myriad of alternative semiconductor materials that create flaws and cracks like DBRs.</p><p> Embedding the planar reflective GEMM layer inside the light emitting device structure to form the optical cavity structure does not involve material removal such as laser lift-off or material etching. The steps to make these alternative structures with GEMM are easy to commercialize because there are fewer intensive steps compared to the other structures described above.</p><p> In addition, the GEMM layer is used as a conductive layer to increase current injection and current distribution. Also, good current shunting improves the certainty of electrostatic discharge.</p>

<figref num="1">An exemplary stack of standard III-nitride LEDs is illustrated.</figref><figref num="2">Illustrate a standard III-nitride LED after the process.</figref><figref num="3">Illustrates a standard III-nitride LED with a non-epitaxial metal mirror contact (308) for improved light extraction.</figref><figref num="4">Illustrations of the conduction band and valence band of a standard Group III nitride LED are illustrated. This group III nitride LED has a non-epitaxial metal mirror contact for improved light extraction and the optoelectric field is approximate.</figref><figref num="5">The deposition of group III nitride LEDs with GEMMs is illustrated according to the first, second, third and fourth embodiments of the present invention.</figref><figref num="6">According to the first embodiment of the present invention, a group III nitride cavity LED (known as a microcavity LED) having a GEMM and a non-epitaxial metal mirror for improved light extraction is illustrated.</figref><figref num="7">The figure of the conduction band and the valence band of the LED of FIG. 6 is illustrated, and the optical electric field is an approximate value.</figref><figref num="8">According to a second embodiment of the present invention, a group III cavity type LED having a GEMM and a non-epitaxial and light transmitting conductor for improved light extraction is illustrated.</figref><figref num="9">The figure of the conduction band and the valence band of the LED in FIG. 8 is illustrated, and the optical electric field is an approximate value.</figref><figref num="10">According to the third embodiment of the present invention, a cavity LED using a resonator whose surface is roughened with a group III nitride surface will be illustrated. This LED has a GEMM that couples with a roughened p-GaN layer and a non-epitaxial, light transmissive conductor for improved light extraction.</figref><figref num="11">The figure of the conduction band and the valence band of the LED of FIG. 10 is illustrated, and the optical electric field is an approximate value.</figref><figref num="12">According to the fourth embodiment of the present invention, a cavity LED utilizing a photocrystal resonator of a group III nitride will be illustrated. This LED has a GEMM that couples with a p-GaN layer of photocrystalline structure and a non-epitaxial, light-transmitting conductor for improved light extraction.</figref><figref num="13a">According to the fourth embodiment of the present invention, the conduction band and valence band diagrams of the LED in FIG. 12 are illustrated, and the optical electric field is an approximate value.</figref><figref num="13b">The photocrystal structure used to extract the waveguide mode is illustrated according to a fourth embodiment of the present invention.</figref><figref num="14">The flow chart of the LED of FIG. 6 is illustrated.</figref><figref num="15">The flow chart of the LED of FIG. 8 is illustrated.</figref><figref num="16">The flow chart of the LED of FIG. 10 is illustrated.</figref><figref num="17">The flow chart of the LED of FIG. 12 is illustrated.</figref>

In the description of the following embodiments, citations are made to the accompanying figures. The attached drawings form part of the reference, and the attached figures show characteristic embodiments in which the present invention is carried out as an example. In the figure, the thickness of the layers and regions is exaggerated for clarity. These embodiments are provided so that this disclosure is thorough and complete and the teachings are conveyed to those skilled in the art. It should be understood that while other embodiments are used, structural changes are made to the extent that they do not deviate from the gist of the present invention.

Semiconductor light emitting structures and devices are described when the light emitting structure grows on the GEMM, in which case the GEMM grows epitaxially on multiple layers or layers of the previously grown Group III nitride. This makes it possible to place the GEMM very precisely and accurately inside the epitaxial structure in order to create an optical cavity effect that extracts a lot of light. In addition, as the mirror grows epitaxially, the thickness of the mirror is controlled to form either a semi-reflector or a non-transparent reflector. Various structures of RCLEDs or MCLEDs with a single mirror or two mirrors are grown and processed by using one or more GEMM layers like any other structure.

By arranging the GEMM relative to the active region, the light emitted from the active region and the light reflected from the GEMM interfere constructively to create an optical cavity effect. The optical cavity effect enhances the efficiency of the device and adjusts the spectral purity and spectral directivity of different and other applications such as lighting, fiber optic communication, biological factor detection, flat panel displays.

By having the GEMM and active region in the optimally bound structure, the second mirror, photocrystal, or rough surface can be additionally bound to improve or adjust the luminescence properties.

The thickness of the GEMM is configured during the growth process to fine-tune the light reflection or transmission characteristics of the mirror (from partial transmission to full transmission). Such controls during epitaxial growth provide the flexibility to take full advantage of the optical cavity effect of many semiconductor light emitting devices.

Device quality GEMMs are further listed below. This device-quality GEMM is located inside the inaccessible group III nitride layer near the active region of the epitaxial stack of conventional group III nitride semiconductor devices. It is well known to those skilled in the art that in standard III-nitride LEDs, the n-type layer usually grows ahead of the p-type layer during the epitaxial growth process. In general, by providing a mirror embedded inside the epitaxial deposit, the optical cavity effect in which the doped layer nevertheless grows first or the optical cavity effect in which the GEMM layer grows inside its epitaxial stack. Bring. The GEMM layer also functions as a highly conductive carrier transport layer embedded throughout the device, improving current injection into either the n-type layer or the p-type layer. In addition, GEMM reduces the damage of problematic electrostatic discharges.

GEMM materials include a variety of metals and metal compounds. These metals and intermetallic compounds grow to closely match the underlying Group III nitride structure, avoiding the difficulty of high dislocation densities. In addition, the GEMM material is a heat-expandable material that is lattice-matched to the Group III nitride structure, avoiding the difficulty of cracking and dislocation densities.

The GEMM layer is a compensatory metal and / or a group IVB metal Zr, Hf, (if x is between 0 and 1, or between 0 and 1, Hf._xZr_1-x), And transition metal niborates ZrB2, HfB2, YB2, and (for x + y + z = 1, Hf_xZr_yY_zB₂), Transition metal nitrides ZrN, HfN, TiN, and (x + y + z = 1), Hf_xZr_yY_zConsists of metal compounds such as N).

The bulk conductivity of the GEMM material is about 30 times more conductive than the moderately doped Group III nitride layer currently incorporated into the luminescent structure. The high conduction properties of GEMM create a path for current flow to improve charge carrier transport across the device and mitigate the effects of unwanted electrostatic discharges.

The excellent conductivity of GEMM prioritizes epitaxially growing the highly resistant p-type and n-type materials of group III nitride light-emitting devices prior to the active region. This makes it possible to make more flexibility in designing the surface texture of the upper surface of the n-type epitaxial layer away from the side surface of the substrate.

&lt;Technical considerations using GEMM&gt; The details of the photon emission process in LEDs are usually related to the association of light emission with electromagnetic mode. Without the introduction of cavities, uniform and spontaneous radiators would radiate uniformly inside the bulk material and the radiation would cover the entire 4π solid angle.

In all the light emitted in the bulk material, the normal angle and the critical angle θ_c= sin^-1(N_{out out}/ N_GaN), Only the radioactive material propagating to the interface between the bulk material and the external medium flows out of the bulk material into the external medium regardless of the presence of cavities. This outflow "window" is known as Snell's window.

LED extraction efficiency is critical angle θ compared to the mode in which it occurs_cEqual to the ratio of modes included within the range of.

When the photoelectromagnetic mode is limited to one or more dimensions, what is considered the optical mode density in free space is reorganized. The above-mentioned rearrangement of the optical mode density in free space also changes the radiation path while increasing or decreasing the frequency.

The radiation extracted by the cavity only propagates within the discrete mode and therefore in the direction controlled by the cavity. Each mode equally contains a portion of the total radiated power.

The extraction efficiency of a standard LED or RC LED is equal to the amount of light emitted through the Snell's window compared to the amount of light generated. However, due to the confinement of light, changes in the radiation distribution inside the RC LED cause more light to flow out of the Snell's window than a bulk LED.

RCLEDs have a higher emission output than standard LEDs, but because the active region is located on or near the various cavities of a continuous light wave, most of the RCLED's cavity length can be varied. However, the light emission output does not change. In the area of RCLED, the proportion of modes extracted into the waveguide mode through the Snell's window is always constant as the cavity length decreases. This is because the active region is arranged on or near the various wave cavities of the continuous light wave.

However, the order of the cavity Int (2N)_GaNL_c/ λ) is 2N²_GaNLess than (note that the function Int (X) rounds X to an integer, N_GaNIs the refractive index for GaN, λ is the wavelength of light in vacuum, L_cWhen the cavity length decreases to the point (where is the cavity length), a transition occurs. The number of waveguide modes continues to decrease and the LED extraction efficiency increases, but the number of modes extracted through the Snell's window is constant (eg, 1 mode). This region of cavity length is called the microcavity region, and RC LEDs operating in this region are called MC LEDs.

The nano-optical cavity effect is produced by using the planar reflection GEMM in the vicinity of the active region of the LED. By having a thickness sufficient for the GEMM to reflect, the radiation is oriented away from the GEMM so that it is extracted away from the sides of the substrate and through the top of the device. By being thin enough that the GEMM is semi-reflective, the radiation is directed through the semi-reflector so that it is extracted through the Snell's window. Such GEMMs are very useful in a myriad of LED structures as described herein.

In order to use GEMM as described above, GEMM must have certain properties that allow reliable epitaxial growth and commercialization of MCLEDs, RCLEDs, or designed templates. The GEMM must be compatible with Group III nitride materials in properties such as lattice constant, coefficient of thermal expansion, temperature stability, reflectivity, and electrical properties.

Since the continuous light wave is a cavity illuminant having a periodic function, this cavity illuminant has a cavity of appropriate length and an active region on or near the undulation of the continuous light wave. It's like being placed in. The structure of the cavities described herein follows the relationship that the cavity length LC is equal to d1 + d2, as shown in FIG. At this time, d1 = the distance between the center of the active region and GEMM. d1 = (0.25λ / N) + M (0.5λ / N) -PD1.

d2 = distance between the center of the active region and the second mirror or reflective interface. If the second mirror is metal, d2 = (0.25λ / N) + M (0.5λ / N) -PD2, and if the second mirror is a DBR or roughened surface d2 = (0.75λ / N) + M (0.5λ / N), λ is the wavelength of light generated by the active region in vacuum. N is the refractive index of the group III nitride material. M is an integer multiple starting from 0 for half the wavelength in the group III nitride. PD1 and PD2 are the penetration depths of light into the GEMM and the second mirror (if metal), respectively. Since the thickness of the GEMM layer is modified, the position as a result of PD (penetration depth) needs to be modified. For clarity, the second mirror or extraction interface is located on top of the p-GaN layer (508) away from the substrate (501) in FIG.

The thickness of the radiation region is limited to values less than 0.25λ / N to ensure that the active region is located only on or near the wave flank of a continuous light wave. Efficiency is reduced if the active region is not centered and is arranged to extend outside this width to nodes of the same mode.

The error in the arrangement of the active region depends on the width of the active region. The thicker the active region, the less error there is in optimal performance. W as shown in Figure 5_ARIf is the width of the active region, the error is 0.125 (λ / N) -0.5 (W)_AR). Other light extractions, such as photocrystals or multiple photocrystals, and other devices with roughened surfaces or shapes derived from standard LEDs, even if errors related to the placement of the active region are discarded. If the structure is not available, the device will only function inefficiently.

In addition, the roughened surface or photocrystal may be useful for light extraction in a waveguide mode or multiple waveguide modes. Moreover, by designing the device, the waveguide elements combine with the features of the intentionally roughened or photocrystalline structure to form a "waveguide extraction mode". By optimizing the device structure, the waveguide mode is exclusively extracted through the use of the optical microcavity effect using GEMM. This is done, in particular, through the rearrangement of the optical mode density in free space. The above method is shown in one or more embodiments below.

&lt;First embodiment&gt; The structural diagram and band diagram of the first embodiment are shown in FIGS. 6 and 7, respectively.

GEMM (604) can be used for optical resonator semiconductor light emitting devices of various shapes. In the first embodiment, the GEMM (604) grows thin due to its highly reflective bulk property, so that the GEMM (604) may be partially light-transmitting or partially light-reflecting. To do. The first embodiment utilizes a planar Group III nitride material growth template. This template consists of a device quality sapphire substrate (601), i-GaN buffer layer (602) and n-GaN layer (603). Therefore, the crystal quality of GEMM (604) is planar and specular, and also gives the device quality a planar and specular characteristic. Since the GEMM (604) is lattice-matched to the n-GaN layer (603), the portion having the desired thickness is equal to or less than the critical thickness of epitaxial.

Once the 2 μm i-GaN buffer layer (602) and the 2 μm n-GaN layer (603) have grown on the sapphire substrate (601), the GEMM (604) has a specific thickness of resonant cavity (less than 20 nm). grow up. For this reason, GEMM (604) is partially light-transmitting or partially light-reflecting. Once the GEMM (604) grows on the n-GaN layer (603), the second n-GaN layer (605) reaches a specific thickness (up to 1200 Å), which is the optimum thickness for the resonant cavity (611). grow up. This is because the active region (606) is located at or near the wave belly (702). The wave antinode (702) is at the maximum value of the photoelectric field (701) as shown in FIG. 7, and the width is 0.25λ / N._GaNWithin. (N_GaNIs the refractive index and λ is the emission wavelength in vacuum. )

In a first embodiment, the illustrated RCLED emits light at a wavelength of 500 nm with a cavity length (611) (inside the microcavity region) of about 3000 Å. The light generated in the active region (606) is between the non-epitaxial metal mirror (610) with thickness and high reflectivity and the GEMM (604) with thinness and partial reflectivity and partial transparency. Resonates with. The cavities are arranged with mirrors (604) and (610) at intervals, and the light generated by the active region (606) resonates between the mirrors. Since the mirrors (604) and (610) are spaced apart, the half-wave integer of the light generated by the active region (606) is compatible between the mirrors (604) and (610) in the nitride material. To do. The active region (606) is arranged between the mirrors, and the generated light constructively interferes with the light reflected from both mirrors (604) and (610). Resonant light is emitted from the GEMM (604) side of the device through the sapphire substrate (601) (see FIGS. 6 and 7).

FIG. 7 shows a state in which the center of the active region (606) of the MCLED is positioned at the maximum value position (702) of the optical electric field distribution (701) or near the maximum value position of the optical electric field distribution (701). ing. The maximum part (702) of the photoelectric field distribution (701) is called the wave antinode (702) because it is the wave antinode of the stationary light wave. The reduction in the number of waveguide modes and the increase in light extraction through the Snell's window centered the active region (606) on the contact part of the non-epitaxial metal mirror (610) and the wave front closest to the GEMM (604), or It is necessary to place it near the contact part (610) and GEMM (604) of the non-epitaxial metal mirror closest to the waveguide. As shown in FIG. 7, the wave front (702) of the stationary light wave is arranged at a certain interval from the contact portion of the non-epitaxial metal mirror (610) and the GEMM (604).

The following are factors to consider in this embodiment. a) Device quality and planar n-type GaN layer template (603) b) Thickness, flatness, specular reflectance and permeability of GEMM layer (604) grown on first n-type GaN layer (603) c) Thickness of the second n-type conductive layer (605) grown on GEMM (604) and device quality of the second n-type conductive layer (605). d) Position of active region (606) with respect to surrounding mirrors (604), (610) e) Thickness of p-type conductive layers (607) and (608), and f) Reflective properties of non-epitaxial metal contact (610)

It is interesting to detune the structure of the device in place of obtaining a higher light extraction effect by promoting directional and spectral narrowing. This is done by adjusting the quantum well configuration or quantum well width to increase the wavelength of the device and at the same time keep the parameters constant. As a result, the stationary light wave is sent to an inclined position away from the perpendicular line of the device. This adjustment is made only if the angle is within the range of Snell's window. Otherwise, the light outside the critical angle will be reflected back to the device. The critical angle of Snell's window is sin^-1(N_exit/ N_GaN). N_exitIs the index of refraction of the device and also N_GaNIs the refractive index of gallium nitride.

Laser lift-off is not required to form the MCLED, but removing the sapphire substrate (601) provides advantages for thermal extraction or n-side roughing. In addition, if the substrate is not opaque (eg silicon), the silicon substrate is selectively etched to form the functional device structure shown in FIG. This device structure is formed without a substrate, with or without buffers between GEMMs.

This example is not intended to be limited in that the cavity length, emission wavelength and structural features vary. Therefore, the active region is optimally arranged within the range of the optical electric field of the extraction mode in a constant radiation wavelength and radiation direction.

As an example of the modified form, the use of a thinner non-epitaxial metal mirror (610) can be mentioned. This thickness is about 20 nm, like GEMM (604), and emits light from both sides of the planar device.

As an example of other modifications of the structure shown in FIG. 6, a GEMM layer of 20 μm or less is placed on the p-GaN layer or on the p-GaN layer, and a thick non-epitaxial metal mirror is placed on the transparent metal contact portion. It can be replaced with. This causes light to leak from the top and bottom surfaces of the device.

Another example consists of photocrystals embedded within the structure of FIG. 6 which interferes with the extraction of waveguide modes or the formation of waveguide modes. This will be further described in the fourth embodiment.

&lt;Second embodiment&gt; The structural diagram and band diagram of the second embodiment are shown in FIGS. 8 and 9, respectively.

GEMM (804) can be used for optical resonator semiconductor light emitting devices of various shapes. In the second embodiment, GEMM (804) exhibits bulk reflective properties because it grows thicker due to its highly reflective bulk properties. The second embodiment utilizes a planar Group III nitride material growth template. This template consists of a device quality sapphire substrate (801), i-GaN buffer layer (802) and n-GaN layer (803). As such, the crystal quality of GEMM (804) is planar and specular, and gives device quality a planar and specular characteristic. Since the GEMM (804) is lattice-matched to the n-GaN layer (803), the portion having the desired thickness is equal to or less than the critical thickness of epitaxial.

Once the 2 μm i-GaN buffer layer (802) and the 2 μm n-GaN layer (803) grow on the sapphire substrate (801), the GEMM (804) grows to the thickness of the resonant cavity (150 nm or less). To do. Once the GEMM (804) grows, the second n-GaN layer (805) grows to a specific thickness (up to 1260 Å) optimal for the resonant cavity (812). This is because, as shown in FIG. 9, the active region (806) is located at the maximum (902) of the optoelectric field (901) within the range of 0.25λn-GaN in width. (N_GaNIs the refractive index and λ is the emission wavelength in vacuum. )

In a second embodiment, the illustrated MCLED emits light at a wavelength of 500 nm with a cavity length (812) (within the microcavity region) of approximately 2600 Å. The light generated in the active region (806) resonates between the thick GEMM (804) and the p-GaN layer (808) and the interface of the transmissive contact (810). The cavities are arranged with mirrors (804) and (813) spaced apart, and the light generated by the active region (806) resonates between the mirrors. Since the mirrors (804) and (813) are spaced apart, the half-wave integer of the light generated by the active region (606) plus a quarter of the wavelength is in the nitride material. Fits between mirrors (804) and (813). The active region (806) is arranged between the mirrors, and the generated light constructively interferes with the light reflected from both mirrors (804) and (810). The resonant light is emitted from the transparent contact portion (810) side of the device.

FIG. 9 shows a state in which the center of the active region (806) of the LED is positioned at the maximum value position (902) of the optical electric field distribution (901) or near the maximum value position of the optical electric field distribution (901). ing. The maximum (902) of the optical electric field distribution (901) is called the wave antinode (902) because it is the wave antinode of the stationary light wave. Placing the center of the active region (806) closer to the wave antinode closest to the mirror, or near the wave antinode closest to the mirror, reduces the number of waveguide modes and increases light extraction through the Snell's window. I need. It is most preferable to arrange the mirrors so that the cavity length is small. As shown in FIG. 9, the wave fronts (902) of the stationary light wave are arranged at regular intervals from the p-GaN / transmissive conductive interface (813) and GEMM (804).

The following are factors to consider in this embodiment. a) Device quality and planar n-type GaN layer template (803) or i-GaN buffer layer (802) template b) Thickness, flatness and specular reflectance of the GEMM layer (804) grown on the first n-type GaN layer (803) c) Thickness of the second n-type conductive layer (805) grown on GEMM (804) and device quality of the second n-type conductive layer (805). d) Position of active region (806) relative to surrounding mirrors (804), (810) e) Thickness of p-type conductive layers (807) and (808), and f) Reflective properties of p-GaN / transparent conductive interface (813) and thickness of GEMM (804) and transparent conductor (810)

Device efficiency is better than that of standard LEDs, but it is interesting to have the device change the wavelength of light within its structure. Thereby, the enhancement of directional and spectral narrowing is replaced by higher light extraction efficiency. This is done by adjusting the quantum well configuration or quantum well width to increase the wavelength of the device and at the same time keep the parameters constant. It sends a stationary light wave to an inclined position away from the perpendicular of the device. This adjustment is made only if the angle is within the range of Snell's window. Otherwise, the light outside the critical angle will be reflected back to the device. The critical angle of Snell's window is sin^-1(N_exit/ N_GaN). N_exitIs the index of refraction outside the device, and N_GaNIs the refractive index of gallium nitride.

Laser lift-off is not required to form the MCLED, but removing the sapphire substrate (801) provides benefits for thermal extraction and current injection from the removed substrate side of the device.

This example is not intended to be limited in that the cavity length, emission wavelength and structural features vary. Therefore, the active region is optimally arranged within the range of the optical electric field of the extraction mode in a constant radiation wavelength and radiation direction.

As an example of the modified form of the structure shown in FIG. 8, GEMM of 20 nm or less is arranged in the p-GaN layer (808) or on the p-GaN layer (808). As a result, the layer of GEMM is arranged at or near the node in addition to the GEMM layer (804) having a thickness already existing. Synchrotron radiation is emitted from the p-GaN layer (808) side of the device. Further using this method, MCLEDs with a one-cavity order are achieved with light extraction efficiencies up to 90% possible. In this case, the mirror surrounds the wave of 1.

&lt;Third embodiment&gt; Structural diagrams and band diagrams of the third embodiment are shown in FIGS. 10 and 11, respectively.

GEMM (1004) can be used for optical resonator semiconductor light emitting devices of various shapes. In a third embodiment, GEMM (1004) exhibits bulk reflective properties because it grows thicker due to its highly reflective bulk properties. The third embodiment utilizes a planar Group III nitride material growth template. This template consists of a device quality sapphire substrate (1001), i-GaN buffer layer (1002) and n-GaN layer (1003). As such, the crystal quality of GEMM (1004) is planar and specular, and gives device quality a planar and specular characteristic. Since GEMM (1004) is lattice-matched to the Group III nitride n-GaN layer (1003), the portion having the desired thickness is less than or equal to the critical thickness of epitaxial.

Once the 2 μm i-GaN buffer layer (1002) and the 2 μm n-GaN layer (1003) have grown on the sapphire substrate (1001), the GEMM (1004) is a resonant cavity that utilizes the roughened surface. It grows to a thickness (150 nm or more). Once the GEMM (1004) grows on the template, the second n-GaN layer (1005) grows to a specific thickness (up to 1260 Å) optimal for the optical cavity (1012) effect. In this case, as shown in FIG. 11, the center of the active region (1006) has a width of 0.25λ / N._GaNIt is arranged at the maximum (1102) of the optical electric field (1101) within the range of. (N_GaNIs the refractive index and λ is the emission wavelength in vacuum. )

The third embodiment of the roughened p-GaN layer (1008) is characterized in that the roughened surface is close to the wavelength of the synchrotron radiation in the semiconductor or larger than the wavelength of the synchrotron radiation in the semiconductor. It has various variations such as having. The features are irregular or regular.

The roughened surfaces of FIGS. 10 and 11 are not shown to scale. The feature means that it is only used in terms of expression.

If the features are irregular, the device works in a way that gives the photons numerous opportunities to find the escape cone. If the light does not pass through the Snell's window first, the irregular reflecting surface of the roughened interface will change the direction of the radiation at various angles. This redirected radiation is directed towards the GEMM and reflected elsewhere along the roughened joint. This process continues until the light is absorbed or the light leaks from the light emitting element.

If the properties are regular, the device still operates in such a way that the photon reflects and gives the photon numerous opportunities to find the escape cone. However, most of the light emitted from the active region to the roughened p-type GaN layer surface is scattered, diffracted and extracted.

The surface is roughened, but Snell's law further applies: That is, it must be taken into account that most impact emissions will leak when determining surface properties. When light propagating perpendicular to the device leaks from the device, the localization of surface properties and the angle between the localizations of the device are critical angles θ._c= sin^-1(N_{out out}/ N_GaN) It becomes the following.

The illustrated optical cavity LED emits 500 nm light (within the range of the microcavity) with an efficient cavity length of approximately 2600 Å. The light generated within the active region (1006) constructively self-interferes with the light reflected from the thick GEMM (1044). Normally, the roughened surface is arranged away from the active region, so that the semiconductor interface (1013) is arranged on or near the wave antinode. Constructive interference light is emitted from the transparent contact portion (1010) side of the device.

FIG. 11 shows a state in which the center of the active region (1006) of the LED is arranged at the maximum value position of the photoelectric field distribution (1101) or near the maximum value position (1102). The maximum (1102) of the optical electric field distribution (1101) is called the wave antinode (1102) because it is the wave antinode of continuous light waves. Placing the center of the active region (1006) near the wave front closest to GEMM (1004) or near the wave front closest to GEMM (1004) requires a reduction in the number of waveguide modes and also Snell's window. Increased light extraction through the waveguide is required. As shown in FIG. 11, the wave fronts (1102) of continuous light waves are arranged at regular intervals from the GEMM (1004).

The following are factors to consider in this embodiment. a) Device quality and planar n-type GaN layer template (1003) or i-GaN buffer layer (1002) template b) Thickness, flatness and specular reflectance of the GEMM layer (1004) grown on the first n-type GaN layer (1003) c) Thickness of the second n-type conductive layer (1005) grown on GEMM (1004) and device quality of the second n-type conductive layer (1005) d) Position of active region (1006) relative to surrounding mirror (1004) and roughened surface e) Thickness of p-type layers (1007), (1008), and f) Thickness of transparent conductor (1010)

Laser lift-off is not required to form an optical cavity LED that utilizes a roughened surface, but removing the sapphire substrate benefits heat extraction and current injection from the removed substrate side of the device. ..

This example is not intended to be limited in that constructive interference lengths, emission wavelengths and structural features vary. Therefore, the active region is optimally arranged within the range of the optical electric field having a constant radiation wavelength and a constructive interference length in the radiation direction.

Another example is optimized by the collision of emissions on a roughened surface and invasion of surface properties. Therefore, light is reflected from surface to surface within the property. This continues until the light leaks through the Snell's window.

Another example is optimized by exclusively extracting the waveguide mode using the optical microcavity effect, especially by rearranging the free space of the optical mode concentration to extract the waveguide mode. Therefore, the extraction mode is oriented perpendicular to the extraction surface. The extraction surface is off the axis of the perpendicular of the flat substrate and the perpendicular of the layer following it. In this arrangement, no vertical extraction mode is required and only waveguide mode or single waveguide mode is considered optimal for this device.

&lt;Fourth embodiment&gt; Structural diagrams and band diagrams of the fourth embodiment are shown in FIGS. 12 and 13, respectively.

GEMM (1204) can be used for optical resonator semiconductor light emitting devices of various shapes. In a fourth embodiment, GEMM (1204) exhibits bulk reflective properties because it grows thicker due to its highly reflective bulk properties. The fourth embodiment utilizes a planar Group III nitride material growth template. This template consists of a device quality sapphire substrate (1201), i-GaN buffer layer (1202) and n-GaN layer (1203). As such, the crystal quality of GEMM (1204) is planar and specular, and gives device quality a planar and specular characteristic. Since GEMM (1204) is lattice-matched to the n-GaN layer (1203), the portion with the desired thickness is less than or equal to the epitaxial critical thickness.

Once the 2 μm i-GaN buffer layer (1202) and the 2 μm n-GaN layer (1203) grow on the sapphire substrate (1201), the GEMM (1204) grows to a thickness (150 nm or more). .. This thickness is the optimum thickness for a resonance cavity that utilizes photons. This layer is preferably kept below the critical thickness. Once the GEMM (1204) grows on the template, the second n-GaN layer (1205) grows to a specific thickness (up to 1260 Å) optimal for the effect of the optical cavity (1012). In this case, as shown in FIG. 13, the center of the active region (1206) has a width of 0.25λ / N._GaNIt is arranged inside the maximum (1302) of the optical electric field (1301) within the range of. (N_GaNIs the refractive index and λ is the emission wavelength in vacuum. )

Resonant cavity LEDs using photonic crystals have a wavelength-scale two-dimensional periodic structure (1213). This LED enhances the performance of the device by adjusting various factors such as: The elements are, that is, the position of GEMM (1204), the grating depth, the grating spacing, the width of the grating hole, the grating curve factor, and the like. These elements are configured to operate the waveguide mode (1303) by: That is, it is derived by suppressing the formation of modes, extracting the waveguide mode via diffraction, or concentrating the waveguide mode through reflection to increase photorecycling, or by various combinations of these three structures. It is configured to operate the waveguide.

In this fourth embodiment, an example (see FIG. 13b) of extracting a waveguide mode (1303) using a photocrystal (1214) is provided.

The photocrystal structure is not shown to scale in FIGS. 12, 13a and 13b. The feature means that it is only expressive.

In a fourth embodiment, the RCLED utilizing a photocrystal (1214) emits 500 nm light with a cavity length (1213) of about 2600 Å (within the microcavity region). The light generated in the active region (1206) resonates between the thick GEMM (1204) and the junction of the p-GaN layer and the transparent contact interface (1215). Since the cavities are spaced by mirrors (1204) and (1215), the light generated by the active region (1206) resonates between the mirrors. Since the mirrors (1204) and (1215) are spaced apart, the half-wave integer plus a quarter of the wavelength of light generated by the active region (1206) is in the nitride material. Fits between mirrors (1204) and (1215). Since the active region (1206) is located between the mirrors, the generated light constructively interferes with the reflected light. The resonant light is emitted from the transparent contact portion (1210) side of the device.

As shown in FIG. 13b, the waveguide mode tends to be diffracted vertically from the radiation plane.

The following are factors to consider in this embodiment. a) Device quality and planar first n-type GaN layer template (1203) or i-GaN buffer layer (1202) template b) Thickness, flatness and specular reflectance of the GEMM layer (1204) grown on the first n-type GaN layer (1203) c) Thickness of the second n-type conductive layer (1205) grown on the device quality GEMM (1204) d) Position of the active region (1206) with respect to the surrounding mirror (1204), semiconductor junction surface (1215) and photocrystal (1214) e) Thickness of p-type conductive layers (1207) and (1208), and f) Depth and structure of holes (1212) in photocrystals (1214)

Laser lift-off is not required to form the MCLED, but removing the sapphire substrate provides benefits for thermal extraction and current injection from the removed substrate side of the device.

This example does not limit the cavity length, photocrystal lattice and emission wavelength, which may be of various structures. The active region is therefore located at or near the center of the wave belly within the cavity extraction mode and the set of photocrystal extraction modes.

An example of a modified form of the structure shown in FIG. 12 comprises a transparent contact portion (1210). This contact (1210) is replaced with a reflective metal mirror with a thickness (150 nm or more) as the GEMM layer (1204) decreases to a thickness of about 20 nm. Furthermore, if the cavity thickness (1213) is adjusted so that both metal mirrors are placed near the nodal points, the active region remains on or near the wave front. Further, the photocrystal is designed so that the generated waveguide light is diffracted in the vertical mode or the waveguide mode is suppressed. This structure allows the MCLED to have photocrystals on the device side of the thick reflective metal mirror.

The holes in the p-GaN layer that make up the photocrystal are not evenly distributed in the layer shown, but this does not mean that the photocrystal structure cannot be made more uniform. As shown, there are various photocrystal structures.

&lt;Fifth, sixth, seventh and eighth embodiments&gt; The fifth, sixth, seventh and eighth embodiments are similar to the first, second, third and fourth embodiments, respectively. The fifth, sixth, seventh and eighth embodiments are in a different order from the above-described embodiments in the epitaxial structure. In general, the n-type layer grows before the p-type layer as described in the above-described embodiment. The doped epitaxial layers and active regions of the fifth, sixth, seventh and eighth embodiments grow in reverse order and are summarized in Table 1 below. The general epitaxial order of the fifth, sixth, seventh and eighth embodiments is clarified as follows. That is, the order is sapphire / i-GaN / GEMM / p-GaN / p-AlGaN / active region / n-GaN. Examples of epitaxial structures are summarized in Table 1.

<img file="JP2010500751A_D0001.tif" />

In a fifth embodiment, the treatment operation is the same as in the first embodiment, but reflective ohm contacts are deposited on the n-GaN layer.

In the sixth, seventh and eighth embodiments, the processing operations (FIGS. 15 to 17) are the same as in the second, third and fourth embodiments, with the n-terminal and p-terminal being other. Will be replaced instead.

The important point of arranging the center of the active region on or near the wave front of a light mode designed to emit a certain amount of radiation is, as described in the above embodiments, these summarized embodiments. Applies to.

&lt;Epitaxy and processing&gt; &lt;General epitaxy growth and first, second, third and fourth embodiments&gt; As an example, FIG. 5 shows an array of epitaxial layers contained within a general base epitaxial structure for the first, second, third and fourth embodiments. The material layer grows using metalorganic vapor phase epitaxy (OMVPE), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), physical vapor deposition (PVD), and the like. These may be a single means, or combination, and / or variants thereof. The growth conditions that produce these layers are influenced by the tools used. In some embodiments, the epitaxial structure includes:

(1) Growth of epitaxial material on sapphire substrate (501) The quality of the continuous epitaxial layers (502, 503, 504, 505, 506, 507, 508) formed on the substrate (501) depends on the orientation, surface roughness and / or surface treatment of the substrate (501). It is a thing.

(2) Originally doped GaN buffer layer (502) This layer is originally a doped GaN buffer layer and has a thickness of about 2 μm. The quality of the successive epitaxial layers (503, 504, 505, 506, 507, 508) formed on the layer (502) depends on the initial growth conditions when formed on this substrate (501).

(3) Dope n-type GaN layer (503) The layer is 2 μm Si-doped GaN and functions as an n-type layer that conducts electricity to the GEMM layer (504) in the treated luminescent material. The density of the electrified carrier is about 5 times 10 ^ 18 per cubic centimeter. Doping of this layer near above the GEMM (504) interface may be increased or decreased to optimize ohm contact. The quality of the continuous epitaxial layer formed on top of this layer depends on the thickness of this layer.

(4) GEMM layer (504) The crystal quality of this layer depends on the growth conditions and crystal quality of the previous layers (502), (503) and substrate (501). The GEMM layer (504) is composed of a refractory metal and / or a metal compound. The metal compound is, for example, a group IVB metal (Zr, Hf, etc. (Hf)._xZr_1-x)), Zirconium dibolation transition metals (ZrB2, HfB2, YB2, etc. (Hf)_xZr_yY_zB₂, At this time x + y + z = 1)) and transition metal nitrides (ZrN, HfN, TiN, etc. (Hf)_xZr_yY_zN, at this time x + y + z = 1))) etc. As a further example, the thin GEMMs (504), (604) used in the first and fifth embodiments have a thickness of about 20 nm, are partially transparent and reflective, and have weak absorbency. .. GEMMs (504), (804), (1004), (1204) with the thicknesses used in the second, third, fourth and sixth, seventh, and eighth embodiments have thicknesses greater than about 150 nm. And exhibits bulk reflection characteristics. The thickness of GEMM grows epitaxially below the critical thickness of crystal relaxation. In the second (see FIGS. 8 and 9) and sixth, third (see 10 and 11) and seventh, and fourth (see 12 and 13) and eighth embodiments, the device is generated. It is designed away from the sapphire substrate so that the emitted light propagates through the device. That is, the thickness of GEMM (504), (804), (1004), (1204) is sufficient to not reflect any light passing through GEMM (504), (804), (1004), (1204). The thickness. The structure of GEMM (504) is that this layer (504) is lattice-aligned in layers at the top and bottom. GEMM (504) can be below the critical thickness. Here, the critical thickness is a thickness at which assembly distortion due to lattice mismatch, configuration, and thickness is alleviated by forming anomalies in the material.

(5) Dope thin n-type layer (505) Si-doped GaN functions as an n-type layer in the luminescent material. Also, the doped thin n-type layer (505) is one side of the optical cavity and comprises a single mirror or two mirrors. The layer thickness is the thickness at which the active region (506) is arranged on or near the wave front of a continuous light wave (maximum point of the optical electric field). The density of the electrified carrier is about 5 times 10 ^ 18 per cubic centimeter. This layer, near the interface of the lower layer, is increased or decreased in doping thickness to optimize ohm contact.

(6) Active region of illuminant (506) The active region consists of four InGaN quantum wells (thickness 3 nm), separated by a non-doped GaN barrier layer (thickness 6 nm). A quantum well indium composition may be selected to radiate light at any wavelength within the nitride wavelength band. Various thicknesses and compositions of quantum wells, and barrier thicknesses grow. This continues as long as the active region is localized on or near the wave flank of a continuous light wave. The thickness of the active region (506) is less than λ / (4N) when the active region (506) is arranged on or near the wave antinode of the cavity. At this time, λ is the wavelength of light in vacuum produced in the active region, and N is the refractive index of the group III nitride material.

(7) Dope p-type AlGaN layer (507) The magnesium-doped AlGaN layer (507) has a thickness of about 19 nm and may be an electron blocking layer. This layer may be thicker, thinner, or excluded.

(8) Dope p-type GaN layer (508) The magnesium-doped GaN layer (508) functions as a p-type layer of the electrical contacts (610), (810), (1010), and (1210) of the light emitter. In the third embodiment (see FIGS. 10 and 11), the layers (508) and (1008) grow under such growth conditions, so that the surface roughness is intentionally enhanced.

&lt;General epitaxy growth of the fifth, sixth, seventh and eighth embodiments&gt; The epitaxial treatment of the fifth, sixth, seventh and eighth embodiments is the same as that of the above-described embodiment. This structure is shown in Table 1. In these embodiments, it is desired to reduce the possibility of Mg contamination in the active region. This can be reduced by growing the p-GaN layer and the p-AlGaN layer in a chamber separate from the rest of the semiconductor growth.

&lt;Processing step of the first embodiment&gt; FIG. 14 is a flowchart showing an exemplary processing process for processing MCLED or RCLED. The MCLED or RCLED results from the epitaxial structure of FIG. The device operates so that light is emitted from transparent substrates (501), (601). The flowchart begins with the epitaxial structure of FIG. 5 as the base structure.

Block (1401) shows the steps of activation of the p-GaN layers (508), (608) and / or the p-AlGaN layers (507), (607). This step involves activation of the Mg-doped layer. This activation thermally reduces the resistance of the p-GaN layers (508), (608) and / or the p-AlGaN layers (507), (607). Sample is O₂And N₂It is heated to 710 degrees for 10 minutes in the atmosphere of.

Block (1402) shows the process of mesa formation and contact etching of n-GaN layers (503), (603) / thin GEMM (504), (604). The mesas are patterned by photolithography and etched by reactive ion etching to separate the individual devices. The contacts are photolithographically patterned on the mesa and etched by reactive ion etching to expose the n-GaN layers (503), (603) or epitaxial metals (504), (604). As a result, the electrical terminal (609) is later vapor-deposited. The sample is etched in a chlorine atmosphere. Other etching techniques may be used.

Block (1403) shows the step of p-contact end deposition on the upper surface of the mesa. The silver mirror (610) is vapor-deposited by electron beam deposition and functions as an electrical contact part to the p-type GaN layers (508) and (608). Any material that adheres well to the p-doped GaN layer and functions as a highly reflective metal mirror may be used. Other metal deposition techniques may be used.

Block (1404) shows the process of n-contact end deposition on the n-GaN layer and / or the thin top surface of the GEMM. Electrical contacts of n-doped GaN layers (503), (603) and / or thin GEMMs (504), (604) are revealed by photolithography, and by electron beam deposition, n-GaN layers (503), (603). ) And / or deposited on thin GEMMs (504), (604). The contact part usually consists of Ti / Al / Ni / Au (609). Ring-shaped contacts may be used to maximize electrical injection into the device. Other metals and metal deposition techniques may be used.

Block (1405) represents a chemical mechanical polishing process. The backsides of the transparent substrates (501) and (601) are thinned at this point. This is to obtain better thermal extraction and ease of die splitting.

Block (1406) shows the process of die splitting. Die splitting is performed by a scribe &amp; break step, a laser separation or cutting step.

&lt;Processing step of the second embodiment&gt; FIG. 15 is a flowchart showing an exemplary processing process for processing MCLED or RCLED. The MCLED or RCLED results from the epitaxial structure of FIG. The device operates so that light exits through a transparent contact (810). The flowchart begins with the epitaxial structure of FIG. 5 as the base structure.

Block (1501) shows the steps of activation of the p-GaN layers (508), (808) and / or the p-AlGaN layers (507), (807). This step involves activation of the Mg-doped layer. This activation thermally reduces the resistance of the p-GaN layers (508), (808) and the p-type AlGaN layers (507), (807). The sample is O₂And N₂It is heated to 710 degrees for 10 minutes in the atmosphere of.

Block (1502) shows the process of mesa formation and etching of n-GaN layers (503), (803) / GEMM contacts (504), (804). The mesas are patterned by photolithography and etched by reactive ion etching to separate the individual devices. The contacts are photolithographically patterned on the mesa and etched by reactive ion etching to expose the n-GaN layers (503), (803) or GEMM layers (504), (804). As a result, the electrical terminals are later vapor-deposited. The sample may be etched in a chlorine atmosphere. Other etching techniques may be used.

Block (1503) shows the step of p-contact deposition on the upper surface of the mesa. Ni / Au, ITO or any other transparent ohm contacts are deposited by electron beam deposition and serve as electrical contacts to the p-type GaN layers (508), (808). The upper interface of the p-GaN layers (508), (808) functions as one side of the cavity. Other metals and metal deposition techniques may be used.

Block (1504) shows the process of p-contact end deposition on the top surface of a transparent p-type ohm contact (810). The p-type electrode (811) is formed on one side of the conductive layer (810) having transparency. The p-type electrode (811) may be made of, for example, materials such as Ni / Au, Pd / Au, Pd / Ni and Pt.

Block (1505) shows the process of n-contact end deposition on the upper surface of the n-GaN layer (503), (803) or (505), (805) and / or GEMM (504), (804). The electrical contacts are revealed by photolithography and deposited by electron beam deposition. The contacts usually consist of Ti / Al / Ni / Au (609). Ring-shaped contacts may be used to maximize electrical injection into the device. Other metals and metal deposition techniques may be used.

Block (1506) represents a chemical mechanical polishing process. The back side of the transparent substrate is thinned at this point. This is to obtain better thermal extraction and ease of die splitting.

Block (1507) shows the process of die splitting. Die splitting is performed by a scribe &amp; break step, a laser separation or cutting step.

&lt;Processing step of the third embodiment&gt; FIG. 16 is a flowchart showing an exemplary processing process for processing an MCLED or RCLED using a rough surface. The MCLED or RCLED results from the epitaxial structure of FIG. The device operates so that light is emitted from a transparent contact (1010). The flowchart begins with the epitaxial structure of FIG. 5 as the base structure.

The block (1601) shows the rough surface treatment of the p-GaN layers (508) and (1008). The rough surface treatment of the p-GaN layers (508) and (1008) is performed using various techniques shown below. a) Keep the temperature of the growth window lower while the p-GaN layers (508) and (1008) grow. b) Electrochemical etching with or without photolithography c) Chemical etching with or without photolithography d) Ion etching with or without photolithography

Block (1602) shows the steps of activation of the p-GaN layers (508), (1008) and / or the p-AlGaN layers (507), (1007). This step involves activation of the Mg-doped layer. This activation thermally reduces the resistance of the p-GaN layers (508), (1008) and the p-type AlGaN layers (507), (1007). The sample is O₂And N₂It is heated to 710 degrees for 10 minutes in the atmosphere of.

Block (1603) shows the process of mesa formation and etching of n-GaN layers (503), GEMM contacts (504), (1004) with (1003) / thickness. The mesas are patterned by photolithography and etched by reactive ion etching to separate the individual devices. The contacts are photolithographically patterned on the mesa and etched by reactive ion etching to expose the n-GaN layers (503), (1003) and / or GEMM (504), (1004). As a result, the electrical terminals are later vapor-deposited. The sample may be etched in a chlorine atmosphere. Other etching techniques may be used.

Block (1604) shows the step of p-contact end deposition on the upper surface of the mesa. Ni / Au, ITO or any other transparent ohm contacts are deposited by electron beam deposition and serve as electrical contacts to the p-type GaN layers (508), (1008). The lower interface of the p-GaN layers (508), (1008) functions as one side of the cavity. Other metals and metal deposition techniques may be used.

Block (1605) shows the process of p-contact end deposition on the top surface of a transparent p-type ohm contact (1010). Then, the p-type electrode (1011) is formed on one side of the conductive layer (1010) having transparency. The p-type electrode (1011) may be made of, for example, materials such as Ni / Au, Pd / Au, Pd / Ni and Pt.

The block (1606) is located on the upper surface of the lower n-GaN layer (503), (1003) and / or the GEMM (504), (1004) and / or the upper n-GaN layer (505), (1005) having a thickness. n The process of contact end deposition is shown. The electrical contacts (1009) are revealed by photolithography and deposited by electron beam deposition. The contact part usually consists of Ti / Al / Ni / Au (609). Ring-shaped contacts may be used to maximize electrical injection into the device. Other metals and metal deposition techniques may be used.

Block (1607) shows a chemical mechanical polishing process. The back side of the transparent substrate is thinned at this point. This is to obtain better thermal extraction and ease of die splitting.

Block (1608) shows the process of die splitting. Die splitting is performed by a scribe &amp; break step, a laser separation or cutting step.

&lt;Processing step of the fourth embodiment&gt; FIG. 17 is a flowchart showing an exemplary processing process for processing an MCLED or RCLED using a photocrystal (1214). The MCLED or RCLED results from the epitaxial structure of FIG. As shown in FIG. 12, the device operates so that light is emitted from a transparent contact (1210) / photocrystal (1214). The flowchart begins with the epitaxial structure of FIG. 5 as the base structure.

Block (1701) shows the steps of activation of the p-GaN layers (508), (1208) and / or the p-AlGaN layers (507), (1207). This step involves activation of the Mg-doped layer. This activation thermally reduces the resistance of the p-GaN layers (508), (1208) and the p-type AlGaN layers (507), (1207). The sample is O₂And N₂It is heated to 710 degrees for 10 minutes in the atmosphere of.

Block (1702) shows the step of p-contact end deposition on the upper surface of the mesa. Ni / Au, ITO or any other transparent ohm contacts are deposited by electron beam deposition and serve as electrical contacts to the p-type GaN layer. Other metals and metal deposition techniques may be used.

Block (1703) shows the process of mesa formation and etching of n-GaN layers (503), (1203) / GEMM contacts (504), (1204). The mesas are patterned by photolithography and etched by reactive ion etching to separate the individual devices. The contacts are photolithographically patterned on the mesa and etched by reactive ion etching to expose the n-GaN layers (503), (1203) or GEMM (504), (1204) with thickness. As a result, the electrical terminals are later vapor-deposited. The sample may be etched in a chlorine atmosphere. Other etching techniques may be used.

Block (1704) shows the etching of holes (1212) in the p-GaN layer (1208). Etching of the p-type layers (1207) and (1208) is performed using various techniques shown below. a) Electrochemical etching using photolithography b) Chemical etching using photolithography c) Ion etching using photolithography d) Focused ion beam

Block (1705) shows the process of p-contact end deposition on the top surface of a transparent p-type ohm contact (1210). Then, the p-type electrode (1211) is formed on one side of the conductive layer (1210) having transparency. The p-type electrode (1211) may be made of, for example, materials such as Ni / Au, Pd / Au, Pd / Ni and Pt.

The block (1706) is an n-GaN layer (503), (1203) or (505), (1205) and / or a thickened GEMM (504), (1204) n-contact end deposition step on the top surface. Shown. The electrical contacts are revealed by photolithography and deposited by electron beam deposition. The contact part usually consists of Ti / Al / Ni / Au. Ring-shaped contacts may be used to maximize electrical injection into the device. Other metals and metal deposition techniques may be used.

Block (1707) represents a chemical mechanical polishing process. The back side of the transparent substrate is thinned at this point. This is to obtain better thermal extraction and ease of die splitting.

Block (1708) shows the process of die splitting. Die splitting is performed by a scribe &amp; break step, a laser separation or cutting step.

The thick GEMMs (504) and (1204) in this embodiment have a thickness greater than about 150 nm and exhibit bulk reflection properties. The thickness of GEMM grows epitaxially below the crystal relaxation critical thickness.

&lt;Processing steps of the fifth, sixth, seventh and eighth embodiments&gt; The exemplary processing steps in the fifth, sixth, seventh and eighth embodiments are the same as in the first, second, third and fourth embodiments described above, respectively. The epitaxial structure is shown in Table 1.

For clarity, in a fifth embodiment, the new n-GaN layer contacts are made from a highly reflective metallic material, providing the required ohm manipulation.

In the sixth, seventh and eighth embodiments, a transparent contact portion is not required. Because the n-GaN layer itself has sufficient conductivity, no current-diffusing layer is required. In this further conductive n-GaN layer, the light emitting layer can be easily deformed by etching and photolithography techniques. Therefore, the properties are formed for better light extraction.

Equal traders understand that there are various treatment options that can change. An important point in the process is to advance the process so that the growth structure and optical cavity manipulation are feasible.

&lt;Possible deformations and variations&gt; A) In an alternative embodiment, the epitaxial crystal grows on other substrates (501) and (601), (501) and (801), (501) and (1001), (501) and (1201). .. The substrate is, for example, SiC, GaN, ZnO, MgO, glass, Si, GaAs, AlN, LiGaO.₂, LiAlO₂, NdGaO₃, ScAlMgO₄, Ca₈La₂(PO₄)₆O₂Is. If the substrate is opaque, it is removed to emit light during device operation. B) In alternative embodiments, the type III nitrogen buffer layers (502) and (602), (502) and (802), (502) and (1002), (502) and (1202) are thicker than 2 μm or It may be thin or doped to form electron carriers. C) In an alternative embodiment, the first vapor deposition dope layers (503) and (603), (503) and (803), (503) and (1003), (503) and (1203) are GEMM ( 504) and (604), (504) and (804), (504) and (1004), (504) and (1204) continue to carry current to the device, and the electrical terminals are GEMM (504) and (604), If connected to (504) and (804), (504) and (1004), (504) and (1204), it may be omitted (ie, bulk HfN is gently doped bulk n- Has up to 30 times higher conductivity than GaN). It is desirable to retain this first doped layer during the etching steps (1402), (1502), (1603), (1703) in order to maintain production yield. D) In the first, second, third and fourth embodiments, the p-GaN layer may include tunnel junctions and an additional n-GaN layer, and the new n-GaN layer may provide conductivity and current over the entire LED. Arranged to increase the spread of. E) An important device epitaxial structure (partially permeable and partially reflective GEMM layer) by removing the substrate (opaque or transparent) in the first or fifth embodiment / Accessing GaN / active regions / GaN / (non-epitaxial metal mirrors) may be another option in manufacturing or device performance. F) The GEMM layer is supported by using an epitaxial DBR or a non-epitaxial DBR having a phase matching layer arranged between the GEMM layer and the DBR. G) The thickness of the GEMM layer may be thicker or thinner in the embodiments described. It is also possible to change these thicknesses to obtain results similar to the embodiments. The "window" that changes the thickness may be large in various situations and should not be considered a major change. Important for these embodiments is to manipulate and adjust the effects of the cavities described herein. H) GEMM may be used to promote stimulated emission and photorecycling in the device. Therefore, this increases the quantum efficiency of the device.

&lt;Conclusion&gt; Those skilled in the art understand that other changes will be made without departing from the spirit of the innovative concepts set forth herein. It is not intended that the scope of the invention be limited to the particular embodiments illustrated and described in the embodiments.