Semiconductor laser diode

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a semiconductor laser diode formed by forming an n-type clad layer, an active layer, and a p-type clad layer on a semiconductor substrate.

【0002】

[Conventional technology]

Laser processing technology is attracting attention in various fields because it can process materials that were previously difficult to process and can process complex and fine shapes. The laser light emitted from the fiber laser apparatus used in the laser processing apparatus is condensed after passing through the transmission system by the optical fiber and irradiated to the object to be processed. Efficient laser machining requires a high-power laser device to excite the fiber laser device. Moreover, miniaturization of the laser processing apparatus itself is also desired, and for that purpose, miniaturization of the laser apparatus for excitation is also required. Under these circumstances, it is desired to put a high-power and long-life semiconductor laser diode (LD) into practical use.

【0003】

Conventional high-power semiconductor laser diodes have been made of GaAs-AlGaAs materials. However, the laser manufactured by this material system has a problem that the characteristics suddenly deteriorate, and the cause is considered to be the Al atom.

【0004】

[Problems to be Solved by the Invention]

To solve such problems, In_1-xGa_xAs_yP_1-yWith (0 x 1, 0 y 1) as the active layer, (Al_xGa_1-x)_0.5In_0.5Development of a semiconductor LD with P (0 x 1) as a clad layer is underway. (Hereinafter, unless the composition ratio is particularly mentioned, they are referred to as InGaAsP and AlGaInP.) In this semiconductor LD, since InGaAsP containing no Al is used as the active layer, there is no risk of sudden deterioration, and the clad layer is high. Since AlGaInP, which is an energy bandgap material, is used, carriers and light can be effectively trapped. Therefore, it is expected that a high-quality and highly reliable high-output semiconductor LD can be obtained.

【0005】

Nevertheless, until now, sufficient studies have not been conducted on structural parameters such as the mixed crystal composition ratio of the clad layer and the optical guide layer including the active layer, the carrier concentration, and the film thickness. In particular, although the carrier concentration of the clad layer has been examined in the InP clad layer of the long wavelength LD for optical communication, it has hardly been examined in the semiconductor LD having AlGaInP as the clad layer.

【0006】

The present invention has been made in view of such circumstances, and an object of the present invention is to increase the output of a semiconductor laser diode.

【0007】

[Means for solving problems]

In the semiconductor laser diode according to the present invention, at least an n-type clad layer to which an n-type impurity atom is added, an active layer, and a p-type clad layer to which a p-type impurity atom is added are formed on a semiconductor substrate. The hole concentration in the p-type clad layer is C (cm).^-3), And the concentration of the p-type impurity atom in the p-type clad layer is D (cm).^-3) 0.75 × D C D ... (1) 1.5 × 10¹⁷cm^-3C 9.5 x 10¹⁷cm^-3 ... (2) It is characterized in that the equations (1) and (2) represented by are satisfied at the same time. In this way, the output of the laser beam can be improved as compared with the conventional case.

【0008】

Also, the hole concentration C is 3.0 × 10¹⁷cm^-3C 9.5 x 10¹⁷cm^-3 ... (3) It is more preferable to further satisfy the equation (3) represented by. As a result, the output of the laser beam can be further improved.

【0009】

Further, in the semiconductor laser diode according to the present invention, the semiconductor substrate is GaAs and the p-type clad layer is (Al)._xGa_1-x)_yIn_1-yIt may be characterized in that P (0 x 1, 0 y 1), and the active layer is In._1-xGa_xAs_yP_1-yIt may be (0 x 1, 0 y 1). With this configuration, the active layer is formed by InGaAsP that does not contain Al, and the clad layer is formed by AlGaInP that has a large energy band gap, so that a semiconductor laser diode having a long life and high output can be realized.

【0010】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the method for manufacturing a semiconductor laser diode (LD) according to the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be used for the same elements, and duplicate description will be omitted. Further, in the drawings, the dimensional ratios, including the ratio of the layer thickness of each epitaxial layer grown on the GaAs substrate, do not always match those described.

【0011】

FIG. 1 is a configuration diagram schematically showing the structure of the semiconductor LD according to the present embodiment. As shown in the figure, the semiconductor LD1 is a Separate Confinement Heterostructure (SCH) type LD, and the n-type clad layer 3, the optical guide layer 4, and the active layer 5 are placed on the n-type GaAs substrate 2. The optical guide layer 6, the p-type clad layer 7, and the contact layer 8 are sequentially formed and configured. Further, a striped electrode 9 is formed on the contact layer 8, and an electrode 10 is formed on the entire back surface of the n-type GaAs substrate 2.

【0012】

As the n-type GaAs substrate 2, it is desirable to use a substrate whose surface has a crystal plane orientation inclined in a predetermined direction from the (100) plane. The inclination angle was set to 6 ° in the present embodiment, but it is preferable to appropriately determine the crystallinity of the AlGaInP layer growing on the substrate 2 by conducting a preliminary experiment. In addition, the electron concentration of the n-type GaAs substrate 2 is 5 × 10.¹⁷cm^-3Degree.

【0013】

The n-type clad layer 3 was lattice-matched with the n-type GaAs substrate 2, and silicon (Si) was added as an n-type impurity (Al)._xGa_1-x)_0.5In_0.5Consists of P. Here, by changing the Al composition ratio x, the bandgap energy can be changed from 1.91 eV (InGaP) to 2.4 eV (AlInP) in a state of lattice matching with the n-type GaAs substrate 2. In this embodiment, a preliminary experiment was carried out to determine the composition ratio. The method and result will be briefly described.

【0014】

FIG. 2 is a graph showing how the light output of the semiconductor LD changes depending on the bandgap energy (Eg) of the n-type clad layer. That is, by changing the Al composition ratio x, several types of semiconductor LDs having different Eg of the n-type clad layer made of AlGaInP were produced, and the light output was plotted against the Eg of the clad layer. The semiconductor LD produced in this preliminary experiment has substantially the same configuration as the semiconductor LD1 having the SCH structure shown in FIG. From Fig. 2, it can be seen that the optical output of the semiconductor LD depends on Eg. The inventor speculates that the reason is that the state of light confinement changes as Eg, that is, the composition ratio x changes. From the result of this preliminary experiment, the Al composition ratio x that maximizes the light output is obtained, and the optimum Al composition ratio x is obtained (Al)._xGa_1-x)_0.5In_0.5P was designated as the n-type clad layer 3 of the semiconductor LD1.

【0015】

The electron concentration of the n-type clad layer 3 was also determined by a preliminary experiment. Here, the preliminary experiment will be briefly described.

【0016】

FIG. 3 is a graph showing how the light output of the semiconductor LD changes depending on the supply amount of the n-type impurity raw material supplied at the time of forming the n-type clad layer 3. In the figure, D / III on the horizontal axis is silane (SiH), which is a doping raw material.₄) The ratio of the supply amount of gas and group III raw material is shown. From FIG. 3, it can be seen that the light output of the semiconductor LD changes when the supply amount of the doping raw material is changed relative to the supply amount of the group III raw material. From this result, the optimum condition was the D / III ratio (about 0.14) at which the optical output of the semiconductor LD was the maximum value, and when the semiconductor LD1 was manufactured, the n-type clad layer 3 was formed under this condition. Specifically, under these conditions, the electron concentration of the n-type clad layer 3 is 5 × 10.¹⁷cm^-3Is. The film thickness of the n-type clad layer 3 is preferably about 0.5 to 1.0 μm.

【0017】

The optical guide layer 4 is undoped In_xGa_1-xConsists of P. Here, the In composition ratio x is about 0.5, which gives InGaP lattice-matched to the n-type GaAs substrate 2. The film thickness of the optical guide layer 4 is preferably about 300 to 500 nm. Such an optical guide layer 4 is a high-quality layer in which the density of lattice defects such as misfit dislocations is reduced, whereby light can be effectively confined.

【0018】

The active layer 5 is an undoped In_1-xGa_xAs_yP_1-yConsists of. Here, the Ga composition ratio x is 0.87, and the As composition ratio y is 0.75. This allows In_1-xGa_xAs_yP_1-yIs lattice-matched with GaAs substrate 2. Further, the Eg at this time is 1.55 eV, and the light having a wavelength of about 808 nm obtained by converting this Eg into a wavelength is oscillated and emitted in the semiconductor LD1. The film thickness of the active layer 5 is about 8 to 15 nm.

【0019】

The optical guide layer 6 is undoped In like the optical guide layer 4._xGa_1-xIt is composed of P, and its composition ratio x and film thickness are the same as those of the optical guide layer 4.

【0020】

Zinc (Zn) was added to the p-type clad layer 7 as a p-type impurity (Al)._xGa₁_-x)_0.5In_0.5Consists of P. Here, the Al composition ratio x and the film thickness are the same as those of the n-type clad layer 3. The hole concentration is 1.5 x 10 as described later.¹⁷cm^-3From 9.5 × 10¹⁷cm^-3It was changed in the range up to.

【0021】

The contact layer 8 is made of p-type GaAs, and Zn is added at a high concentration as a p-type impurity. Specifically, the hole concentration of the contact layer 8 is 5 × 10.¹⁹~2×10²⁰cm^-3This allows good ohm-like contact between the electrode 9 formed on the contact layer 8 and the contact layer 8 to be achieved. The electrode 9 is made of gold (Au) and zinc, and the electrode 10 formed on the back surface of the n-type GaAs substrate 2 is made of indium (In).

【0022】

Next, a method for manufacturing the semiconductor LD1 having the above structure will be described. This manufacturing method can be divided into a crystal growth step, an electrode forming step, and a device forming step, and these steps are sequentially carried out.

【0023】

That is, in the crystal growth step, the n-type clad layer 3 (AlGaInP), light, is placed on the n-type GaAs substrate 2 by a normal procedure using an organometallic chemical vapor deposition (MOCVD) apparatus. The guide layer 4 (InGaP), the active layer 5 (InGaAsP), the optical guide layer 6 (InGaP), the p-type clad layer 7 (AlGaInP), and the contact layer 8 (GaAs) are sequentially epitaxially grown. Here, the raw materials used are trimethylgallium (TMGa), triethyl Gallium (TEGa), trimethylaluminum (TMAl), trimethylindium (TMIn), and arsine (AsH).₃), And phosphine (PH)₃) Is preferable. By appropriately adjusting the supply amount of these raw materials for each of the layers 3 to 8, layers 3 to 8 having a predetermined composition ratio as described above are obtained. In addition, when the n-type clad layer 3 grows, the doping raw material SiH₄Is supplied, and dimethylzinc (Dimethyl Zinc: DMZn) or diethylzinc (Diethyl Zinc: DEZn) is supplied during the growth of the p-type clad layer 7. The growth temperature of each layer 3 to 7 may be appropriately set, but in consideration of the crystallinity of the obtained layer, the growth temperature of each layer is preferably about 600 ° C to 750 ° C.

【0024】

Next, in the electrode forming step, the electrode 9 made of AuZn is vapor-deposited on the contact layer 8 by vacuum deposition, and then the In electrode 10 is vapor-deposited on the back surface of the n-type GaAs substrate 2. At the time of vapor deposition of the electrode 9, a mask having a striped electrode shape is placed on the contact layer 8, and Au-Zn is vapor-deposited through the mask to form the striped electrode 9.

【0025】

Then, in the element conversion step, the n-type GaAs substrate 2 is diced to form a chip to obtain the semiconductor LD1. The semiconductor LD1 produced in the present embodiment is not provided with a reflective film on the light emitting surface (end surface, cleavage surface) so that the laser light is emitted from both the light emitting surfaces.

【0026】

Next, the optical output characteristics of the semiconductor LD1 manufactured as described above will be described.

【0027】

FIG. 4 is a graph showing how the light output and the electric-light conversion efficiency of the laser light emitted from the semiconductor LD1 change with respect to the hole concentration of the p-type clad layer 3. That is, a plurality of semiconductor LD1s having different hole concentrations in the p-type clad layer 3 are produced, their optical outputs are measured, the electrical-optical conversion efficiency is calculated, and these measured values and calculated values are used as the hole concentrations. It is plotted against. In the figure, black circles indicate light output, and white squares, that is, η = 2P / IV ...... (4) Is shown. In equation (4), V indicates the voltage (V) applied to the semiconductor LD1, and I indicates the current (A) flowing when the voltage V is applied. Further, P indicates the light output (W) of the laser light emitted from the semiconductor LD1, and is a value measured on one of the light emitting surfaces. In the semiconductor LD1, considering that laser light of the same intensity is emitted from both light emitting surfaces, the value of P is doubled in the equation (4). The experimental results described below are for driving the semiconductor LD1 under the constant current condition of I = 2 (A).

【0028】

As can be seen from FIG. 4, the light output and the electric-light conversion efficiency of the semiconductor LD1 vary greatly depending on the hole concentration of the p-type clad layer 3. However, no clear hole concentration dependence was found in the change. For example, the hole concentration is about 4x10¹⁷cm^-3In the case of, the result is that the optical output is about 1.05 (W) (point P in the figure).₁), On the other hand, the result is about 0.91 (W) (point P in the figure).₂) Is also obtained. In addition, the hole concentration is 9.2 x 10¹⁷~9.5×10¹⁷cm^-3In the case of, the result is that the light output is about 0.95 (W) (point P).₃) And 0.92 (W) (point P)₄) Has been obtained.

【0029】

The present inventor has repeatedly considered these results and has come to pay attention to the hole activation rate in the p-type clad layer 3. That is, focusing on the fact that not all the Zn atoms added to the crystals of AlGaInP constituting the p-type clad layer 3 act as acceptors, further research was conducted on the relationship between the activation rate and the light output.

【0030】

The present inventor first investigated the relationship between the hole concentration of AlGaInP and the hole activation rate. FIG. 5 shows how the hole concentration and hole activation rate of AlGaInP constituting the p-type clad layer 3 change with respect to the supply amount of DEZn supplied during the formation of the p-type clad layer 3. Is shown. Here, the activation rate is defined by the ratio C / D of the hole concentration C of AlGaInP to the Zn atom concentration D. The hole concentration C was measured by the CV method, and the Zn atom concentration D was measured by secondary ion mass spectrometry (SIMS). The horizontal axis D / III in the figure shows the supply amount of DEZn standardized by the total supply amount of Group III raw materials. However, in reality, the supply of Group III raw materials was kept constant and the supply of DEZn was changed.

【0031】

As can be seen from FIG. 5, the hole concentration increases as the D / III ratio increases, reaches a maximum value when the D / III ratio is about 0.6, and then decreases. The activation rate is 1 when the D / III ratio is about 0.1 or less, and when the amount of Zn atoms added is small as described above, all the Zn atoms added to AlGaInP are acceptors. You can see that. However, as the D / III ratio is increased to 0.1 or higher, the activation rate decreases. When the D / III ratio at which the hole concentration reaches the maximum value is about 0.6, the activation rate is about 0.5, and when the D / III ratio is increased to about 2.0, the activation rate decreases to about 0.15. Resulting in.

【0032】

The present inventor considers the reason why the activation rate decreases as the D / III ratio increases as follows. That is, when the amount of Zn atoms added to AlGaInP increases, Zn atoms can be incorporated not only into the crystal sites of group III constituent atoms but also into the crystal sites and interstitial positions of group V constituent atoms. Zn atoms taken in other than such predetermined sites not only no longer act as acceptors, but may also form complex defects. Such composite defects tend to form deep levels, which result in trapping holes. Considering this way, the decrease in hole concentration with the increase in D / III ratio can be explained.

【0033】

Further, if the above-mentioned composite defect is formed, this defect can adversely affect not only the hole concentration but also the optical characteristics of AlGaInP. From this, it is considered that the activation rate is an index of the crystallinity of AlGaInP, and the present inventor next considers the relationship between the activation rate and the optical output and the electric-optical conversion efficiency of the semiconductor LD1. It was.

【0034】

FIG. 6 shows how the light output and the electric-light conversion efficiency of the semiconductor LD1 change with respect to the hole activation rate of the p-type clad layer 3. This figure is a plot of the results shown in FIG. 4 against the activation rate, and the point P in FIG.₁, P₂, P₃, ...... and point P in Fig. 6₁₁, P₁₂, P₁₃, ... are the results obtained from the same semiconductor LD1.

【0035】

In FIG. 6, as shown by the reference line (broken line), the light output tends to increase as the activation rate increases, and the activation rate is particularly high in the range of about 0.8 or more. It can be seen that the increase in light output is remarkable with respect to the increase in.

【0036】

However, even though the activation rate is 1, the point P in FIG.₁₁When the light output is about 1.05 (W) as in, point P₁₆And P₁₇In some cases, the light output is about 0.94 (W). After considering these differences, it was found that the cause can be understood from Fig. 4. That is, in FIG. 4, P₁₁, P₁₆, P₁₇Point P corresponding to₁, P₆, P₇Compared with P, which has a large optical output₁Light output is smaller than P₆And P₇It can be seen that the hole concentration is low.

【0037】

On the contrary, in FIG. 4, the point P in which the hole concentrations are substantially the same.₁And P₂The reason why there is a large difference in the optical output from and is understood from Fig. 6. That is, P in FIG.₁₁And P₁₂Compared with P₁₁The activation rate is as high as 1, P₁₂It can be seen that the activation rate is low (0.15). Although the hole concentrations are almost the same, the point P₁And P₂The difference in the activation rate between the two is considered to be due to other factors that worsen the activation rate, such as the formation of complex defects due to excess Zn atoms as described above.

【0038】

From the above, it can be concluded that the light output of the semiconductor LD1 depends on both the hole concentration and the hole activation rate in the p-type clad layer 3 (AlGaInP). Then, in order to obtain the semiconductor LD1 having a sufficiently high light output for practical use, the hole concentration is 1.5 × 10.¹⁷cm^-3Above 9.5 × 10¹⁷cm^-3Below, it was concluded that the activation rate is 0.75 or more and 1.0 or less (that is, 0.75 × D C D with respect to the hole concentration C and the activation rate D). As can be seen by comparing FIGS. 4 and 6, even if the hole concentration is in the above range, a high light output cannot be obtained when the activation rate is less than 0.75.

【0039】

In addition, the activation rate is 0.75 or more and 1.0 or less, and the hole concentration is 3.0 × 10.¹⁷cm^-3Above 9.5 × 10¹⁷cm^-3The following is more preferable. This is because the light output can be further improved.

【0040】

In addition, the hole concentration is 4.0 x 10¹⁷cm^-3More than 6.5 × 10¹⁷cm^-3The activation rate may be 0.8 or more and 1.0 or less (0.8 × D C D). Within such a range, the electric-light conversion efficiency can be improved to 46% or more.

【0041】

Subsequently, the semiconductor LD20, which is configured by using the above-mentioned semiconductor LD1 and is suitable for use in an actual LD array, will be described. The semiconductor LD20 has two end faces perpendicular to the direction in which the electrode 9 extends to the semiconductor LD1 manufactured so that the hole concentration and the hole activation rate of the p-type clad layer 3 are within the above-mentioned suitable ranges. It is obtained by forming a predetermined reflective film on the (cleavage surface). The light generated in the active layer 5 is more effectively confined in the active layer by this reflective film, and as a result, laser oscillation can be effectively performed. A reflective film having a low reflectance is formed on one of the two end faces, and the laser light is emitted through the reflective film having a low reflectance. The resonator length of the semiconductor LD20 is 1000 μm.

【0042】

FIG. 7 is a graph showing the output characteristics of the semiconductor LD20, which is the result of operating the semiconductor LD20 in the continuous wave (CW) mode at a measurement temperature of 25 ° C and measuring its optical output. In the figure, the horizontal axis shows the current flowing through the semiconductor LD20, and the vertical axis shows the light output of the laser beam emitted from the semiconductor LD20 and the electric-light conversion efficiency η. In the semiconductor LD20, since the laser beam is emitted from one surface by the reflective film provided on the end surface, it is not necessary to double the light output P measured only on one surface, and the electric-optical conversion efficiency η is as follows. Given by the formula of.

【0043】

η = P / IV ...... (5) From FIG. 7, it can be seen that the semiconductor LD20 has excellent characteristics of an optical output of 3 W or more and an electric-optical conversion efficiency of 48% (at an optical output of 3 W).

【0044】

As described above, the semiconductor LD20 has a high light output as compared with the semiconductor LD1 manufactured so that the hole concentration and the hole activation rate of the p-type clad layer 3 are both in a suitable range. It is understood that if the hole concentration and the hole activation rate of the p-type clad layer 3 are within a suitable range, good characteristics with high light output can be obtained. ..

【0045】

The life of the semiconductor LD20 was also evaluated. FIG. 8 is a graph showing the time course of the optical output of the semiconductor LD20. That is, when three semiconductor LD20s are manufactured, these are kept at 25 ° C, a current is passed so that the optical output becomes 1 W at the start of the test, and then the semiconductor LD20 is operated at a constant current at that current value. I investigated how the light output changes. As can be seen from FIG. 8, all of the semiconductor LD20s showed a stable optical output until about 3400 hours after that, although the optical output decreased by about 5% within about 200 hours after the start of the test. .. Since the semiconductor LD20 does not contain Al in the active layer 5, defects such as dark lines rarely occur in the active layer 5, and sudden deterioration and the like are unlikely to occur. From the results shown in FIG. 8, it was found that a semiconductor laser having a long life and high reliability can be obtained.

【0046】

Next, an LD array configured by using the above-mentioned semiconductor LD20 will be described. This LD array has a stripe width of 100 μm and a fill factor of 0.2. Figure 9 shows the optical output-current characteristics of the LD array. The driving conditions were CW mode as in the semiconductor LD20, and the measurement temperature was set to 20 ° C.

【0047】

As can be seen from FIG. 9, this LD array showed a high optical output of 43 (W) and an excellent result of an electric-optical conversion efficiency of 50% or more (at an optical output of 40 (W)). From this, it is understood that the hole concentration and the hole activation rate of the p-type clad layer 3 of the semiconductor LD1, 20 according to the present embodiment are in the above-mentioned range.

【0048】

The present invention is not limited to the above embodiment, and various modifications are possible. For example, In of active layer 5_1-xGa_xAs_yP_1-yAlthough it was determined that the composition ratios x and y of the above were lattice-matched with the GaAs substrate 2, the active layer 5 may be elastically distorted by intentionally shifting from the lattice matching conditions. Thereby, further high light output can be realized.

【0049】

In addition, the Eg is 1.55 eV after lattice matching with the GaAs substrate 2._1-xGa_xAs_yP_1-yHowever, the active layer 5 is not limited to this, and InGaP having a composition ratio y of zero and lattice-matched to the GaAs substrate 2 may be used. In this way, a semiconductor LD having a shorter oscillation wavelength of 653 to 680 nm can be obtained.

【0050】

In addition, as active layer 5 (Al_xGa_1-x)_0.5In_0.5P may be used. Then, if the composition ratio x is appropriately determined, a semiconductor LD having a shorter oscillation wavelength can be obtained. In this case, it goes without saying that the Eg of the clad layers 3 and 7 must be sufficiently larger than the Eg of the active layer 5.

【0051】

Furthermore, in the above embodiment, the hole concentration of the p-type clad layer 7 is measured by the CV method, but the present invention is not limited to this, and a measurement method utilizing the Hall effect or an etching profiler device is used. You may measure. Further, in the preliminary experiment, not only the above-mentioned suitable hole concentration conditions were obtained, but also the actually manufactured semiconductor LD was subjected to reverse engineering, that is, the electrode 9 and the contact layer 8 were formed. The hole concentration of the p-type clad layer 7 may be measured after removing the above.

【0052】

Furthermore, although only the MOCVD method has been shown in the crystal growth step of the embodiment, the scope of application of the present invention is not limited to this, and VPE (vapor phase growth method), MBE (molecular beam epitaxy), etc. It can be carried out using any semiconductor crystal growth method such as MOMBE (organic metal molecular beam epitaxy), CBE (chemical beam deposition method), and LPE (liquid phase growth method).

【0053】

[Effect of the invention]

As described above, the semiconductor laser diode according to the present invention has 0.75 × D C D and 1.5 × 10 with respect to the hole concentration C and the hole activation rate D of the p-type clad layer.¹⁷cm^-3C 9.5 x 10¹⁷cm^-3Since the above relationships are satisfied at the same time, the output of the semiconductor laser diode can be increased.

[Simple explanation of drawings]

[Figure 1]

FIG. 1 is a configuration diagram schematically showing the structure of the semiconductor laser diode according to the present embodiment.

[Figure 2]

FIG. 2 is a graph showing how the light output of the semiconductor LD changes depending on the bandgap energy (Eg) of the n-type clad layer.

[Fig. 3]

FIG. 3 is a graph showing how the light output of the semiconductor LD changes depending on the supply amount of the n-type impurity raw material supplied at the time of forming the n-type clad layer.

[Fig. 4]

FIG. 4 is a graph showing how the light output and the electric-light conversion efficiency of the laser light emitted from the semiconductor LD change with respect to the hole concentration of the p-type clad layer.

[Fig. 5]

FIG. 5 shows how the hole concentration and hole activation rate of AlGaInP constituting the p-type clad layer change with respect to the amount of DEZn supplied during the formation of the p-type clad layer. It is a graph.

[Fig. 6]

FIG. 6 is a graph showing how the light output and the electric-light conversion efficiency of the semiconductor LD change with respect to the hole activation rate of the p-type clad layer.

[Fig. 7]

FIG. 7 is a graph showing the output characteristics of the semiconductor LD.

[Fig. 8]

FIG. 8 is a graph showing the time course of the optical output of the semiconductor LD.

[Fig. 9]

FIG. 9 is a graph showing the optical output-current characteristics of the LD array.

[Explanation of symbols]

1 ... semiconductor LD, 2 ... substrate, 3 ... n-type clad layer, 4 ... optical guide layer, 5 ... active layer, 6 ... optical guide layer, 7 ... p Molded clad layer, 8 ... contact layer, 9 ... electrode, 10 ... electrode.