Semiconductor light emitting device

The present invention relates to a semiconductor light emitting device, and relates to a semiconductor light emitting device capable of high current operation and high luminous efficiency by changing the arrangement structure of electrodes.

A semiconductor light emitting device is an element in which a substance contained in the device emits light. For example, an energy generated by recombination of electrons / holes is converted into light in the form of bonding semiconductors using a diode like an LED. It is an element that converts and emits. Such semiconductor light emitting devices are now widely used as lighting, display devices and light sources, and their development tends to be accelerated.

The structure of such a semiconductor-junction light emitting device is generally a junction structure of a p-type semiconductor and an n-type semiconductor. In the semiconductor junction structure, light emission due to electron / hole recombination is possible in the junction region of both semiconductors, but an active layer may be provided between the two semiconductors in order to further activate the light emission. Such a semiconductor-junction light emitting device has a vertical structure and a horizontal structure depending on the position of the electrode for the semiconductor layer, and the horizontal structure includes a growth type (epi-up) and a flip-chip type (flip-chip). is there.

FIG. 1 is a cross-sectional view of a conventional horizontal semiconductor light emitting device, and FIG. 2 is a cross-sectional view of a conventional vertical semiconductor light emitting device. Hereinafter, for convenience of explanation, it is assumed that the semiconductor layer in contact with the substrate is the n-type semiconductor layer and the semiconductor layer provided on the active layer is the p-type semiconductor layer in FIGS. 1 and 2.

First, a horizontal semiconductor light emitting device will be described with reference to FIG. The semiconductor light emitting device 1, which is a horizontal semiconductor light emitting device, includes a non-conductive substrate 13, an n-type semiconductor layer 12, an active layer 11, and a p-type semiconductor layer 10. The n-type semiconductor layer 12 is provided with an n-type electrode 15 and the p-type semiconductor layer 10 is provided with a p-type electrode 14 and is electrically connected to an external power source (not shown) for applying a voltage or the like. Has been done.

When a voltage is applied to the semiconductor light emitting device 1 via the electrodes 14 and 15, electrons move from the n-type semiconductor layer 12 and holes move from the p-type semiconductor layer 10, and the electrons and holes move. The recombination causes light emission. The semiconductor light emitting device 1 includes an active layer 11, and light emission is generated in the active layer 11. In the active layer 11, the light emission of the semiconductor light emitting device 1 is activated and emits light. For electrical connection, the n-type electrode is located on the n-type semiconductor layer 12 and the p-type electrode is located on the p-type semiconductor layer 10 with the minimum contact resistance value.

The position of the electrodes may change depending on the type of substrate. For example, in the case of a sapphire substrate in which the non-conductive substrate 13 is a non-conductive substrate as shown in the figure, the electrodes of the n-type semiconductor layer 12 are non-conductive substrates. It is provided on the 13 and must be provided on the n-type semiconductor layer 12.

<p> Therefore, when the n-type electrode 15 is provided on the n-type semiconductor layer 12, it can be seen that the upper p-type semiconductor layer 10 and the active layer 11 are consumed due to the formation of the ohmic contact portion. By forming such an electrode, the light emitting area of the semiconductor light emitting device 1 is reduced, and thereby the light emitting efficiency is also reduced.</p><p> In order to overcome some other problems including such a problem, a semiconductor light emitting device using a conductive substrate instead of a non-conductive substrate has been shown.</p><p> The light emitting element 2 shown in FIG. 2 is a vertical semiconductor light emitting element, and an n-type electrode 25 can be provided on the substrate by using the conductive substrate 23. Alternatively, in FIG. 2, the n-type electrode is provided on the conductive substrate 23, but after the semiconductor layer is grown using the non-conductive substrate, the substrate is removed and the n-type electrode is directly placed on the n-type semiconductor layer. Can be provided to manufacture a vertical light emitting element.</p><p> When the conductive substrate 23 is used, a voltage can be applied to the n-type semiconductor layer 22 via the conductive substrate 23, so that an electrode can be provided on the substrate itself.</p><p> Therefore, as shown in FIG. 2, the n-type electrode 25 is provided on the conductive substrate 23, the p-type electrode 24 is provided on the p-type semiconductor layer 20, and a vertical structure type semiconductor light emitting device is manufactured.</p><p> However, in this case, especially when manufacturing a large-area light emitting device for high output, it is required that the ratio of the area of the electrode to the substrate is high for current dispersion. This has the disadvantages of limiting light extraction and reducing light loss and luminous efficiency due to light absorption.</p><p> The horizontal semiconductor light emitting device and the vertical semiconductor light emitting device described with reference to FIGS. 1 and 2 each have a problem that the light emitting area of the semiconductor light emitting element is reduced, and thereby the luminous efficiency is also reduced. In addition, there is a problem that the light extraction is limited and the light loss and the luminous efficiency are reduced due to the light absorption.</p><p> Therefore, there is an urgent need to develop a semiconductor light emitting device having a new structure that solves the problems of the conventional semiconductor light emitting device as described above.</p><p> Therefore, an object of the present invention is to provide a semiconductor light emitting device having a new structure. Another object of the present invention is to provide a semiconductor light emitting device having high luminous efficiency. Still another object of the present invention is to provide a high current semiconductor light emitting device.</p>

<p> In order to solve the above problems and achieve the object, the semiconductor light emitting element according to the embodiment of the present invention includes a conductive substrate, a first electrode layer, an insulating layer, a second electrode layer, and a second semiconductor layer. , The active layer and the first semiconductor layer are laminated in this order, and the second electrode layer includes one or more regions where a part of the surface forming an interface with the second semiconductor layer is exposed. The first electrode layer penetrates the second electrode layer, the second semiconductor layer, and the active layer, and penetrates to a certain region of the first semiconductor layer through a plurality of contact holes. It is provided so as to extend to a certain region of the first semiconductor layer and be electrically connected to the first semiconductor layer, and the insulating layer is provided between the first electrode layer and the second electrode layer. And the first electrode layer, the second electrode layer, the second semiconductor layer, and the active layer are provided on the side surface of the contact hole to insulate the first electrode layer and the first electrode layer. It is desirable that the area of contact with the semiconductor layer is 3 to 13% of the area of the semiconductor light emitting element.</p><p> Further, the contact holes can be uniformly arranged. Further, it is desirable that the number of the contact holes is 5 to 50. Further, the area of the semiconductor light emitting device is 1000000 μm.²The area of contact between the first electrode layer and the semiconductor layer is 30,000 μm.²~ 130,000 μm²Is desirable.</p><p> Further, it is desirable that the distance between the center points of the contact holes adjacent to each other in the contact hole is 100 μm to 400 μm.</p><p> An electrode pad portion provided on the exposed region of the second electrode layer can be further included. Further, the exposed region of the second electrode layer can be provided at the corner of the semiconductor light emitting device. In addition, the second electrode layer can reflect the light emitted from the active layer. Further, the second electrode layer can contain any one of Ag, Al and Pt.</p><p> Further, it is desirable that the conductive substrate is a metallic substrate containing any one of Au, Ni, Cu and W. Further, it is desirable that the conductive substrate is a semiconductor substrate containing any one of Si, Ge and GaAs.</p>

<p> Therefore, according to the semiconductor light emitting device of the present invention, the maximum light emitting area can be secured by partially providing the first electrode on the light emitting surface and arranging the remaining part below the active layer. ..</p><p> Further, by uniformly arranging the electrodes arranged on the light emitting surface, the current can be stably dispersed even when a high operating current is applied.</p><p> Further, the current can be uniformly distributed, the current concentration phenomenon can be alleviated by the high current operation, and the reliability can be improved.</p>

<figref num="1">FIG. 1 is a diagram showing a conventional horizontal semiconductor light emitting device.</figref><figref num="2">FIG. 2 is a cross-sectional view of a conventional vertical semiconductor light emitting device.</figref><figref num="3">FIG. 3 is a plan view showing a semiconductor light emitting device according to an embodiment of the present invention.</figref><figref num="4">FIG. 4 is a cross-sectional view showing a semiconductor light emitting device according to an embodiment of the present invention.</figref><figref num="5">Figure 5 shows an area of 1000 x 1000 μm.²It is a graph which shows the n-type ohmic contact resistance and p-type ohmic contact resistance of the semiconductor light emitting device of.</figref><figref num="6">FIG. 6 is a graph showing the total resistance of the first contact resistance and the second contact resistance due to the contact area where the first semiconductor layer and the first electrode layer are in contact with each other.</figref><figref num="7">FIG. 7 is a graph showing the luminous efficiency based on the contact area between the first semiconductor layer and the first electrode layer.</figref>

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings of the semiconductor light emitting device. The embodiments shown herein have been described by way of example so that the ideas of the present invention can be fully communicated to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other embodiments. The size of the device in each drawing may be exaggerated for convenience of drawing. The same reference number throughout the specification indicates the same component.

3 and 4 are a plan view and a cross-sectional view showing a semiconductor light emitting device according to an embodiment of the present invention. Here, FIG. 4 shows a cross-sectional view taken along the line I-I'of FIG.

Explaining with reference to FIGS. 3 and 4, the semiconductor light emitting device 100 according to the embodiment of the present invention includes a conductive substrate 110, a first electrode layer 120, an insulating layer 130, and a second electrode. A layer 140, a second semiconductor layer 150, an active layer 160, and a first semiconductor layer 170 are provided, and each of these layers is laminated in order.

The conductive substrate 110 is composed of a substance through which electricity can flow. For example, the conductive substrate 110 may be a metallic substrate containing any one of Au, Ni, Cu and W, or a semiconductor substrate containing any one of Si, Ge and GaAs. desirable.

A first electrode layer 120 is laminated on the conductive substrate 110, and the first electrode layer 120 is electrically connected to the conductive substrate 110 and the active layer 160. It is desirable that the material is composed of a material that minimizes the contact resistance between the conductive substrate 110 and the active layer 160.

The first electrode layer 120 is not only provided by being laminated on the conductive substrate 110, but as shown in FIG. 4, a part of the region thereof is the insulating layer 130 and the second electrode layer 140. , Penetrating the second semiconductor layer 150 and the active layer 160, extending through the contact hole 180 penetrating to a certain region of the first semiconductor layer 170, and contacting the first semiconductor layer 170 with the conductive substrate 110. It is provided so as to be electrically connected to the first semiconductor layer 170.

That is, the first electrode layer 120 electrically connects the conductive substrate 110 and the first semiconductor layer 170. Specifically, by electrically connecting via the contact hole 180, the size of the contact hole 180, more specifically, the first electrode layer 120 and the first semiconductor layer 170 are connected via the contact hole 180. It is electrically connected via a contact area 190, which is a contact area.

On the other hand, on the first electrode layer 120, an insulating layer 130 for electrically insulating the first electrode layer 120 and other layers other than the conductive substrate 110 and the first semiconductor layer 170 is provided. Be done. That is, the insulating layer 130 is not only between the second electrode layer 140 but also between the second electrode layer 140 exposed by the contact hole 180, the second semiconductor layer 150, and the side surface of the active layer 160. Is also provided. Further, it is desirable to provide an insulating layer 130 on the side surface of a certain region of the first semiconductor layer 170 through which the contact hole 180 penetrates to insulate.

The second electrode layer 140 is provided on the insulating layer 130. Of course, as described above, the second electrode layer 140 does not exist in a certain region through which the contact hole 180 penetrates.

At this time, as shown, the second electrode layer 140 includes at least one region in which a part of the interface in contact with the second semiconductor layer 150 is exposed, that is, an exposed region 145. An electrode pad portion 147 for connecting an external power source to the second electrode layer 140 can be provided on the exposed region 145. On the other hand, the second semiconductor layer 150, the active layer 160, and the first semiconductor layer 170, which will be described later, are not provided on the exposed region 145. Further, as shown in FIG. 3, it is desirable that the exposed region 145 is provided at the corner of the semiconductor light emitting element 100, in order to maximize the light emitting area of the semiconductor light emitting element 100.

On the other hand, it is desirable that the second electrode layer 140 is composed of any one of Ag, Al and Pt. This is because the second electrode layer 140 is in electrical contact with the second semiconductor layer 150, so that it has the property of minimizing the contact resistance with the second semiconductor layer 150, and is emitted by the active layer 160. This is because it is desirable that the layer is provided as a layer having a function of reflecting the generated light and directing it to the outside to increase the luminous efficiency.

The second semiconductor layer 150 is provided on the second electrode layer 140, the active layer 160 is provided on the second semiconductor layer 150, and the first semiconductor layer 170 is provided on the active layer 160. Here, it is desirable that the first semiconductor layer 170 is an n-type nitride semiconductor and the second semiconductor layer 150 is a p-type nitride semiconductor.

On the other hand, the active layer 160 can be provided by selecting a different substance depending on the substances constituting the first semiconductor layer 170 and the second semiconductor layer 150. That is, since the active layer 160 is a layer that converts energy due to electron / hole recombination into light and emits it, an energy band smaller than the energy band gap of the first semiconductor layer 170 and the second semiconductor layer 150 It is desirable to provide with a substance having a gap.

Figure 5 shows an area of 1000 x 1000 μm.²It is a graph which shows the n-type ohmic contact resistance and p-type ohmic contact resistance of the semiconductor light emitting device of. Explaining with reference to FIG. 5, the semiconductor light emitting device 100 according to the embodiment of the present invention is 1000000 μm.²The resistance of the semiconductor light emitting device 100 is the first electrode layer 120, the second electrode layer 140, and the first semiconductor layer 170, assuming a rectangular chip having a size of 1000 μm in width and 1000 μm in length. , The contact resistance between the second semiconductor layer 150, the second semiconductor layer 150 and the second electrode layer 140 (hereinafter referred to as "first contact resistance"), and the first semiconductor layer 170 and the first electrode. There may be contact resistance with the layer 120 (hereinafter referred to as "second contact resistance"), but the first contact resistance 210 and the second contact resistance 220 are the resistances that show the largest change depending on the contact area.

In particular, as shown in FIG. 5, the second contact resistance 220 shows the largest change as the contact area increases more than the first contact resistance 210. Here, the X-axis in FIG. 5 means the size of the contact area where the first semiconductor layer 170 and the first electrode layer 120 come into contact with each other, and the Y-axis means the size of the contact resistance. The X-axis number is the contact area where the first semiconductor layer 170 and the first electrode layer 120 are in contact, and the contact area where the second semiconductor layer 150 and the second electrode layer 140 are in contact is the semiconductor light emission. Total area of element 100 1000000 μm²The value obtained by subtracting the value of the X-axis from the value is the contact area between the second semiconductor layer 150 and the second electrode layer 140 corresponding to the first contact resistance 210.

Here, the contact area where the first semiconductor layer 170 and the first electrode layer 120 come into contact with each other is the contact area of the first electrode layer 120 via the contact hole 180, as described with reference to FIGS. 3 and 4. It means the total area of the contact areas 190, which is the area in contact with the first semiconductor layer 170, that is, the sum of the areas of each contact area 190 because there are a plurality of contact holes 180.

FIG. 6 is a graph showing the total resistance of the first contact resistance and the second contact resistance due to the contact area where the first semiconductor layer and the first electrode layer are in contact with each other. Explaining with reference to FIG. 6, since the first contact resistor 210 and the second contact resistor 220 of the semiconductor light emitting device 100 according to the embodiment of the present invention are connected in series, the first contact resistor 210 The total resistance 230, which is the sum of the second contact resistance 220 and the second contact resistance 220, is the resistance having the greatest influence according to the contact area among the resistances of the semiconductor light emitting element 100.

Here, as shown in FIG. 6, the value of the total resistance 230 (Y-axis) increases as the contact area between the first semiconductor layer 170 and the first electrode layer 120 (see the value on the X-axis) increases. (See the value of) shows a rapid decrease at the beginning, and the total resistance 230 tends to increase as the contact area between the first semiconductor layer 170 and the first electrode layer 120 increases. I understand that.

On the other hand, the resistance of the semiconductor light emitting device 100 is 1000000 μm in size of the semiconductor light emitting device 100.²In this case, it is desirable that the contact area is 1.6 ohms or less, so that the contact area between the first semiconductor layer 170 and the first electrode layer 120 is 30,000 to 250,000 μm.²Is desirable.

That is, the semiconductor light emitting device 100 of the present invention described with reference to FIGS. 3 and 4 is a contact region which is a region where the first electrode layer 120 and the first semiconductor layer 170 come into contact with each other through the contact hole 180. The total contact area of 190 is 30,000 to 250,000 μm²Is most desirable in terms of contact resistance.

FIG. 7 is a graph showing the luminous efficiency based on the contact area between the first semiconductor layer and the first electrode layer. As described with reference to FIG. 6, the contact area between the first semiconductor layer 170 and the first electrode layer 120 is 30,000 to 250,000 μm.²This seems to increase the luminous efficiency of the semiconductor light emitting device 100 by suppressing the total resistance low, but this increases the contact area between the first semiconductor layer 170 and the first electrode layer 120. Therefore, it is not taken into consideration that the actual light emitting area of the semiconductor light emitting element 100 decreases.

That is, as shown in FIG. 7, the luminous efficiency of the semiconductor light emitting device 100 is such that the contact area between the first semiconductor layer 170 and the first electrode layer 120 is 70,000 μm.²Until, the luminous efficiency is increased by lowering the total resistance, but the contact area between the first semiconductor layer 170 and the first electrode layer 120 is 70,000 μm.²If it continues to increase above, the luminous efficiency will decrease. This means that an increase in the contact area between the first semiconductor layer 170 and the first electrode layer 120 means a decrease in the contact area between the second semiconductor layer 150 and the second electrode layer 140, and the semiconductor. This is intended to reduce the amount of light emitted from the light emitting element 100.

Therefore, it is desirable that the contact area between the first semiconductor layer 170 and the first electrode layer 120 is appropriately determined, and more preferably, as shown in FIG. 7, the first semiconductor layer 170 and the first electrode layer 120. The contact area with the electrode layer 120 is 130,000 μm with a luminous efficiency of 90% or more.²It is desirable to be as follows.

In conclusion, in the semiconductor light emitting device 100 according to the embodiment of the present invention, the contact area between the first semiconductor layer 170 and the first electrode layer 120 is 30,000 to 130,000 μm through the contact hole 180.²Is most desirable. This is because the chip size of the semiconductor light emitting device 100 is 1000000 μm.²Therefore, it is shown that the most appropriate contact area is when the contact area between the first electrode layer 170 and the semiconductor layer 120 is 3 to 13% of the area of the semiconductor light emitting device 100.

On the other hand, when the number of contact holes 180 is very small, the first semiconductor layer 170 and the first electrode layer 120 per one contact region 190 between the first semiconductor layer 170 and the first electrode layer 120. The contact area increases, which in turn increases the area of the first semiconductor layer 170 that must be supplied with current, and increases the amount of current that must be supplied in the contact area 190. Therefore, there arises a problem that the current is concentrated in the contact region 190 between the first semiconductor layer 170 and the first electrode layer 120.

Further, when the number of contact holes 180 is very large, the contact holes 180 itself becomes very small, which causes a problem that the contact holes 180 themselves become very dense and difficult in the manufacturing process.

Therefore, it is desirable that the number of contact holes 180 is appropriately selected according to the size of the semiconductor light emitting device 100, that is, the size of the chip. The size of the semiconductor light emitting device 100 is 1000000 μm²In the case of, it is desirable that the number of contact holes 180 is 5 to 50.

On the other hand, although a plurality of contact holes 180 of the semiconductor light emitting element 100 are provided, it is desirable that the contact holes 180 are uniformly arranged. This is because the first semiconductor layer 170 and the first electrode layer 120 come into contact with each other through the contact hole 180, so that the contact hole 180 is uniformly arranged, that is, the first one, in order to uniformly disperse the current. It is desirable that the contact region 190 between the semiconductor layer 170 and the first electrode layer 120 is uniformly arranged.

Here, the size of the semiconductor light emitting device 100 is 1000000 μm.²In the case of, when the number of contact holes 180 is 5 to 50, in order for the semiconductor light emitting elements 100 to be uniformly arranged, the separation distance between the adjacent contact holes among the plurality of contact holes is 100 μm to 400 μm. Can be. Here, the separation distance is a value measured by connecting the center points of adjacent contact holes.

On the other hand, the semiconductor light emitting device 100 can uniformly disperse the current by uniformly arranging a plurality of contact holes 180 as described above, and has a size of 1000000 μm.²In the case of the semiconductor light emitting device of the above, conventionally, it operated at about 350 mA, but in the case of the semiconductor light emitting device 100 according to the embodiment of the present invention, it operates very stably even when a high current of about 2 A is applied. It is possible to provide a semiconductor light emitting device having improved reliability by alleviating the current crowding phenomenon.

It should be considered that the embodiments disclosed this time are merely examples and are not restrictive. The scope of the present invention is shown by the scope of claims, not the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

110 Conductive substrate 120 First electrode layer 130 insulation layer 140 Second electrode layer 150 Second semiconductor layer 160 active layer 170 1st semiconductor layer 180 contact holes 190 Contact area