A low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer and its manufacturing method

Abstract

The present invention relates to a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer and a preparation method thereof. The laser includes a substrate, a buffer layer, a lower transition layer, a lower confinement layer, a lower waveguide layer, a first quantum well, a barrier layer, a second quantum well, an upper waveguide layer, an (Al 1‑x6 Ga x6 ) y4 In 1‑y4 P linearly graded confinement layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, an upper transition layer, and a cap layer, which are sequentially arranged from bottom to top. By optimizing the structural design of the graded confinement layer, the laser provided by the present invention uses a low Al component (Al 1‑x6 Ga x6 ) y4 In 1‑y4 P in combination with a relatively high flow rate of 25 cc of initial Mg doping to suppress the doping hysteresis caused by the Mg doping memory effect, achieve a stable Mg doping gradient of 14 cc, eliminate the doping "shoulder collapse" phenomenon, thereby improving the electro-optical conversion efficiency, reducing the threshold current, and achieving high-reliability operation.

Description

Technical Field

[0001] The present invention relates to a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer and a preparation method thereof, belonging to the technical field of semiconductor lasers. Background Art

[0002] AlGaInP red semiconductor lasers have the characteristics of low price and long life, and have broad application prospects in the fields of medical beauty, laser display, industrial measurement, etc. Since low-power lasers have a relatively small output power (generally less than 100 mW), it is required that the lasers have higher photoelectric conversion efficiency and long-term stable working reliability. However, the conduction band offset of the AlGaInP / GaInP heterojunction is small, and electron overflow is likely to occur, which increases the threshold current of the laser and raises the temperature, resulting in a lower characteristic temperature of the AlGaInP laser and a lower electro-optical conversion efficiency during continuous operation.

[0003] The literature Journal of Crystal Growth, 191(3), 1998, 313-318 points out that high doping of the P confinement layer can increase the quasi-Fermi level position of the P-type confinement layer, increase the effective barrier for blocking leakage electrons, and contribute to reducing the threshold current; but the literature Journal of Alloys and Compounds, 742, 2018, 790-796 points out that when the doping concentration of the P confinement layer is relatively high, dopant diffusion will cause roughening of the interface between the confinement layer and the waveguide layer, and at the same time form non-radiative recombination centers in the active region, resulting in reduced reliability. Therefore, at high doping concentrations, avoiding the diffusion of dopants into the active region and forming a steep growth interface helps to reduce the threshold current and improve the working reliability.

[0004] The literature Japanese Journal of Applied Physicals Letters, 33, 1994, 749-753 points out that due to the memory effect, it is difficult for Mg to obtain a steep doping interface, and the doping content changes linearly, while the Zn doping saturation level is low and it is easy to diffuse; the literature Journal of Crystal Growth, 195, 1998, 132-137 points out that Mg has a slow diffusion rate in materials with a low In content, which helps to form a steep interface; Chinese Patent CN108346972A proposes to use low-Al component (Al x Ga 1-x ) y In 1-y P and high-Al component (Al a Ga 1-a ) b In 1-bThe P forms a superlattice confinement layer, resulting in a steep high-concentration Mg doping, reducing the series resistance of the epitaxial layer, decreasing the generation of Joule heat, and improving the photoelectric conversion efficiency. However, the conduction band bandgap discontinuity of the superlattice structures with different compositions easily forms an interfacial bandgap spike, suppressing carrier transport, affecting the recombination efficiency, and leading to a reduction in the photoelectric conversion efficiency. Summary of the Invention

[0005] To solve the above problems, the present invention provides a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer and a preparation method thereof. Through the design of a graded structure of the confinement layer, an (Al 1-x Ga x ) y In 1-y P structure with a linearly graded Al composition is inserted at the interface between the confinement layer and the waveguide layer. By combining with an increase in the initial Mg doping flux, a steep doping interface and a stable doping amount are achieved, thereby improving the electro-optical conversion efficiency, reducing the threshold current, and enhancing the working reliability.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer is provided. The laser includes a substrate, a buffer layer, a lower transition layer, a lower confinement layer, a lower waveguide layer, a first quantum well, a barrier layer, a second quantum well, an upper waveguide layer, an (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, an upper transition layer, and a cap layer, which are sequentially arranged from bottom to top;

[0008] Among them, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65;

[0009] Among them, the Al composition in the (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer is linearly graded and not less than 0.7 (i.e., x6 ≤ 0.3). By combining with an increase in the initial Mg doping flux, the influence of the Mg memory effect is reduced, and a constant Mg doping amount is ensured; the Al composition content in the (Al 1-x6 Ga x6 ) y4 In 1-y4 P is lower than that in Al 0.5 In 0.5With the P and In components being constant (x4 has a fixed value) and not exceeding 0.5, the diffusion distance of the Mg dopant is reduced; by using a linearly graded Al component to ensure constant Mg doping, low In and low Al components to reduce the doping diffusion distance, a steep doping interface and a constant doping amount are achieved, thereby improving the electro-optical conversion efficiency, reducing the threshold current, and achieving high-reliability operation.

[0010] Preferably according to the present invention, in the low-power AlGaInP red semiconductor laser with optimized restricted layer doping, one or more of the following conditions are included:

[0011] I. The substrate is a GaAs substrate;

[0012] II. The buffer layer is a GaAs buffer layer;

[0013] III. The lower transition layer is a Ga 0.52 In 0.48 P lower transition layer;

[0014] IV. The lower confinement layer is an Al 0.5 In 0.5 P lower confinement layer;

[0015] V. The lower waveguide layer is an (Al x1 Ga 1-x1 ) y1 In 1-y1 P lower waveguide layer; 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6;

[0016] VI. The first quantum well is a Ga 1-x2 In x2 P first quantum well; 0.3 ≤ x2 ≤ 0.7;

[0017] VII. The barrier layer is an (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer; 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6;

[0018] VIII. The second quantum well is a Ga 1-x4 In x4 P second quantum well; 0.3 ≤ x4 ≤ 0.7;

[0019] IX. The upper waveguide layer is an (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer; 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6;

[0020] X. The first upper confinement layer is an Al 0.5 In0.5 P first upper confinement layer;

[0021] XI. The etch stop layer is Ga 1-x7 In x7 P etch stop layer; 0.5 ≤ x7 ≤ 0.6;

[0022] XII. The second upper confinement layer is (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer; 0 ≤ x8 ≤ 0.3, 0.4 ≤ y5 ≤ 0.6;

[0023] XIII. The upper transition layer is Ga 0.52 In 0.48 P upper transition layer;

[0024] XIV. The cap layer is a GaAs cap layer.

[0025] Preferably according to the present invention, in the low-power AlGaInP red semiconductor laser with optimized confinement layer doping, (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer has a thickness of 0.01 - 0.05 μm, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65, and a doping concentration of 3E17 - 7E17 atoms / cm 3 ; Further preferably, x6 gradually changes from 0.3 to 0.05, y4 = 0.6, the thickness is 0.02 μm, the Mg doping flow rate gradually changes from 25 cc to 14 cc, and the doping concentration is stabilized at 5E17 atoms / cm 3 .

[0026] Preferably according to the present invention, the low-power AlGaInP red semiconductor laser with optimized confinement layer doping includes one or more of the following conditions:

[0027] ①. The buffer layer is a GaAs buffer layer, and the doping concentration of the GaAs buffer layer is 2E18 - 5E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm;

[0028] ②. The lower transition layer is a Ga 0.52 In 0.48 P lower transition layer, and the doping concentration of the Ga 0.52 In 0.48 P lower transition layer is 1E18 - 3E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm;

[0029] ③. The lower confinement layer is an n-type Al0.5 In 0.5 P lower confinement layer, n-type Al 0.52 In 0.48 The thickness of the P lower confinement layer is 0.5 - 1.5 μm, and the doping concentration is 5E17 - 3E18 atoms / cm 3 ;

[0030] ④. The lower waveguide layer is (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer, (Al 1-x1 Ga x1 ) y1 In 1-y1 The thickness of the P lower waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6;

[0031] ⑤. The first quantum well is Ga 1-x2 In x2 P first quantum well, Ga 1-x2 In x2 The thickness of the P first quantum well is 4 - 7 nm, unintentionally doped, 0.3 ≤ x2 ≤ 0.7;

[0032] ⑥. The barrier layer is (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer, (Al 1-x3 Ga x3 ) y2 In 1-y2 The thickness of the P barrier layer is 5 - 15 nm, unintentionally doped, 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6;

[0033] ⑦. The second quantum well is Ga 1-x4 In x4 P second quantum well, Ga 1-x4 In x4 The thickness of the P second quantum well is 4 - 7 nm, unintentionally doped, 0.3 ≤ x4 ≤ 0.7;

[0034] ⑧. The upper waveguide layer is (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer, (Al 1-x5 Ga x5 ) y3 In 1-y3 The thickness of the P upper waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6;

[0035] ⑨. The first upper confinement layer is P-type Al 0.5 In 0.5 P first upper confinement layer, P-type Al 0.5 In 0.5 The thickness of the P first upper confinement layer is 0.1 - 0.3 μm, and the doping concentration is 3E17 - 1.5E18 atoms / cm 3 ;

[0036] ⑩. The etch stop layer is P-type Ga 1-x7 In x7 P etch stop layer, P-type Ga 1-x7 In x7 The thickness of the P etch stop layer is 10 - 50 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x6 ≤ 0.6;

[0037] The second upper confinement layer is P-type (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer, P-type (Al 1-x8 Ga x8 ) y5 In 1- y5 The thickness of the P second upper confinement layer is 0.5 - 1.2 μm, and the doping concentration is 5E17 - 1.5E18 atoms / cm 3 ; 0.05 ≤ x7 ≤ 0.3, 0.4 ≤ y4 ≤ 0.6;

[0038] The upper transition layer is P-type Ga 0.52 In 0.48 P upper transition layer, P-type Ga 0.52 In 0.48 The thickness of the P upper transition layer is 0.01 - 0.05 μm, and the doping concentration is 1E18 - 3E18 atoms / cm 3 ;

[0039] The cap layer is a GaAs cap layer, the thickness of the GaAs cap layer is 0.1 - 0.5 μm, and the doping concentration is 4E19 - 1E20 atoms / cm 3 .

[0040] According to the preference of the present invention, the low-power AlGaInP red semiconductor laser with optimized confinement layer doping includes one or more of the following conditions:

[0041] ①. The buffer layer is a GaAs buffer layer, and the doping concentration of the GaAs buffer layer is 4E18 atoms / cm 3 , and the thickness is 0.2 μm;

[0042] ②. The lower transition layer is a Ga 0.52 In 0.48 P lower transition layer, and the doping concentration of the Ga 0.52 In 0.48 P lower transition layer is 2E18 atoms / cm 3 , and the thickness is 0.12 μm;

[0043] ③. The lower confinement layer is an n-type Al 0.5 In 0.5 P lower confinement layer, and the thickness of the n-type Al 0.52 In 0.48 P lower confinement layer is 1.05 μm, and the doping concentration is 1E18 atoms / cm 3 ;

[0044] ④. The lower waveguide layer is an (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer, and the thickness of the (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer is 0.07 μm, unintentionally doped, x1 = 0.5, y2 = 0.5;

[0045] ⑤. The first quantum well is a Ga 1-x2 In x2 P first quantum well, and the thickness of the Ga 1-x2 In x2 P first quantum well is 5 nm, unintentionally doped, x2 = 0.4;

[0046] ⑥. The barrier layer is an (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer, and the thickness of the (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer is 6 nm, unintentionally doped, x3 = 0.65, y2 = 0.5;

[0047] ⑦. The second quantum well is a Ga 1-x4 In x4 P second quantum well, and the thickness of the Ga 1-x4 In x4 P second quantum well is 5 nm, unintentionally doped, x4 = 0.4;

[0048] ⑧. The upper waveguide layer is (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer, (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer has a thickness of 0.07 μm, is unintentionally doped, x5 = 0.5, y3 = 0.5;

[0049] ⑨. The first upper confinement layer is a P-type Al 0.5 In 0.5 P first upper confinement layer, P-type Al 0.5 In 0.5 P first upper confinement layer has a thickness of 0.2 μm and a doping concentration of 7E17 atoms / cm 3 ;

[0050] ⑩. The etch stop layer is a P-type Ga 1-x7 In x7 P etch stop layer, P-type Ga 1-x7 In x7 P etch stop layer has a thickness of 10 nm and a doping concentration of 2E18 atoms / cm 3 , x6 = 0.6;

[0051] The second upper confinement layer is a P-type (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer, P-type (Al 1-x8 Ga x8 ) y5 In 1- y5 P second upper confinement layer has a thickness of 0.8 μm and a doping concentration of 1.2E18 atoms / cm 3 ; x7 = 0.25, y6 = 0.5;

[0052] The upper transition layer is a P-type Ga 0.52 In 0.48 P upper transition layer, P-type Ga 0.52 In 0.48 P upper transition layer has a thickness of 0.02 μm and a doping concentration of 2E18 atoms / cm 3 ;

[0053] The cap layer is a GaAs cap layer, and the GaAs cap layer has a thickness of 0.02 μm and a doping concentration of 7E19 atoms / cm 3 .

[0054] The second aspect of the present invention provides a method for preparing a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer. The method includes the following steps: surface heat treatment of the substrate is carried out in an MOCVD growth chamber, and then a buffer layer, a lower transition layer, a lower confinement layer, a lower waveguide layer, a first quantum well, a barrier layer, a second quantum well, an upper waveguide layer, an (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, an upper transition layer, and a cap layer are epitaxially grown in sequence from bottom to top;

[0055] Among them, the conditions for growing the (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer are: the growth temperature is 690 - 710 °C, TMAl, TMIn, TMGa, and PH3 are introduced, x6 gradually changes from 0.15 to 0.05, and the Mg doping flow rate gradually changes from 25 cc to 14 cc.

[0056] Specifically, a method for preparing a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer: the method includes the following steps:

[0057] S1. Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it to 720 ± 10 °C in an H2 environment for baking, and introduce AsH3 to perform surface heat treatment on the GaAs substrate;

[0058] S2. Slowly reduce the temperature to 680 ± 10 °C, with a cooling rate of not less than 30 °C / min, and continue to introduce TMGa and AsH3 to grow a GaAs buffer layer on the GaAs substrate;

[0059] S3. Keep the temperature at 680 ± 10 °C, continue to introduce TMIn, TMGa, and PH3, and grow a Ga 0.52 In 0.48 P lower transition layer on the GaAs transition layer;

[0060] S4. Gradually change the temperature to 700 ± 10 °C, with a heating rate of not more than 60 °C / min, introduce TMAl, TMIn, and PH3, and grow an n-type Al 0.5 In 0.5 P lower confinement layer on the lower transition layer;

[0061] S5. Gradually change the temperature to 650 ± 10 °C, introduce TMAl, TMIn, TMGa, and PH3, and grow an (Al 1-x1 Gax1 ) y1 In 1-y1 P lower waveguide layer;

[0062] S6, Keep the temperature at 650 ± 10 °C, and continue to introduce TMIn, TMGa, and PH3 to grow Ga 1-x2 In x2 P first quantum well;

[0063] S7, Keep the temperature at 650 ± 10 °C, introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer;

[0064] S8, Keep the temperature at 650 ± 10 °C, and continue to introduce TMIn, TMGa, and PH3 to grow Ga 1- x4 In x4 P second quantum well;

[0065] S9, Gradually change the temperature to 700 ± 10 °C, and continue to introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer;

[0066] S10, Keep the temperature at 700 ± 10 °C, and continue to introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer;

[0067] S11, Keep the temperature at 700 ± 10 °C, and continue to introduce TMIn, TMAl, and PH3 to grow P-type Al 0.5 In 0.5 P first upper confinement layer;

[0068] S12, Keep the temperature at 700 ± 10 °C, and continue to introduce TMIn, TMGa, and PH3 to grow P-type Ga 1-x7 In x7 P etch stop layer;

[0069] S13. The temperature is maintained at 700 ± 10 °C, and TMIn, TMAl, TMGa and PH3 are continuously introduced to grow a P-type (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer on the corrosion termination layer;

[0070] S14. The temperature is maintained at 700 ± 10 °C, and TMIn, TMGa and PH3 are introduced to grow a Ga 0.52 In 0.48 P upper transition layer on the second upper confinement layer;

[0071] S15. The temperature is reduced to 540 ± 10 °C, and TMGa and AsH3 are continuously introduced to grow a GaAs cap layer on the upper transition layer.

[0072] Preferably according to the present invention, in step S2, the doping concentration of the GaAs buffer layer is 2E18 - 5E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; more preferably, the thickness is 0.2 μm and the doping concentration is 4E18 atoms / cm 3 .

[0073] Preferably according to the present invention, in step S3, the doping concentration of the Ga 0.52 In 0.48 P lower transition layer is 1E18 - 3E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; more preferably, the thickness of the Ga 0.52 In 0.48 P lower transition layer is 0.12 μm and the doping concentration is 2E18 atoms / cm 3 .

[0074] Preferably according to the present invention, in step S4, the thickness of the n-type Al 0.5 In 0.5 P lower confinement layer is 0.5 - 1.5 μm and the doping concentration is 5E17 - 3E18 atoms / cm 3 ; more preferably, the thickness of the n-type Al 0.5 In 0.5 P lower confinement layer is 1.05 μm and the doping concentration is 1E18 atoms / cm 3 .

[0075] Preferably according to the present invention, in step S5, (Al 1-x1 Ga x1 ) y1 In 1-y1The thickness of the lower waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6; further preferably, x1 = 0.5, y2 = 0.5, and the thickness is 0.07 μm.

[0076] According to the preference of the present invention, in step S6, the 1-x2 In x2 The thickness of the first GaInP quantum well is 4 - 7 nm, unintentionally doped, 0.3 ≤ x2 ≤ 0.7; further preferably, x2 = 0.4, and the thickness is 5 nm.

[0077] According to the preference of the present invention, in step S7, (Al 1-x3 Ga x3 ) y2 In 1-y2 The thickness of the InP barrier layer is 5 - 15 nm, unintentionally doped, 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6; further preferably, x3 = 0.65, y2 = 0.5, and the thickness is 6 nm.

[0078] According to the preference of the present invention, in step S8, the 1-x4 In x4 The thickness of the second GaInP quantum well is 4 - 7 nm, unintentionally doped, 0.3 ≤ x4 ≤ 0.7; further preferably, x4 = 0.4, and the thickness is 5 nm.

[0079] According to the preference of the present invention, in step S9, (Al 1-x5 Ga x5 ) y3 In 1-y3 The thickness of the upper waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6; further preferably, x5 = 0.5, y3 = 0.5, and the thickness is 0.07 μm.

[0080] According to the preference of the present invention, in step S10, (Al 1-x6 Ga x6 ) y4 In 1-y4 The thickness of the (AlGa)InP linearly graded confinement layer is 0.01 - 0.05 μm, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65, and the doping concentration is 3E17 - 7E17 atoms / cm 3 ; further preferably, x6 gradually changes from 0.15 to 0.05, y4 = 0.6, the thickness is 0.02 μm, and the Mg doping flow rate gradually changes from 25 cc to 14 cc, achieving a stable doping concentration of 5E17 atoms / cm 3 .

[0081] Preferably according to the present invention, in step S11, the P-type Al 0.5 In 0.5 The thickness of the first P-type upper confinement layer is 0.1 - 0.3 μm, and the doping concentration is 3E17 - 1.5E18 atoms / cm 3 ; More preferably, the thickness is 0.2 μm and the doping concentration is 7E17 atoms / cm 3 .

[0082] Preferably according to the present invention, in step S12, the P-type Ga 1-x6 In x6 The thickness of the P-type etch stop layer is 10 - 50 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x6 ≤ 0.6; More preferably, x6 = 0.6, the thickness is 10 nm, and the doping concentration is 2E18 atoms / cm 3 .

[0083] Preferably according to the present invention, in step S13, the P-type (Al 1-x7 Ga x7 ) y4 In 1-y4 The thickness of the second P-type upper confinement layer is 0.5 - 1.2 μm, and the doping concentration is 5E17 - 1.5E18 atoms / cm 3 , 0.05 ≤ x7 ≤ 0.3, 0.4 ≤ y4 ≤ 0.6; More preferably, x7 = 0.25, y6 = 0.5, the thickness is 0.8 μm, and the doping concentration is 1.2E18 atoms / cm 3 .

[0084] Preferably according to the present invention, in step S14, the P-type Ga 0.52 In 0.48 The thickness of the P-type upper transition layer is 0.01 - 0.05 μm, and the doping concentration is 1E18 - 3E18 atoms / cm 3 ; More preferably, the thickness is 0.02 μm and the doping concentration is 2E18 atoms / cm 3 .

[0085] Preferably according to the present invention, in step S15, the thickness of the cap layer is 0.1 - 0.5 μm, and the doping concentration is 4E19 - 1E20 atoms / cm 3 ; More preferably, the thickness is 0.02 μm and the doping concentration is 7E19 atoms / cm 3 .

[0086] Preferably according to the present invention, the dopant in steps S2 - S4 is Si or Se, the dopant in steps S10 - S14 is Mg, and the dopant in step S15 is C.

[0087] The beneficial effects of the present invention are as follows:

[0088] By optimizing the design of the graded confinement layer structure, the present invention inserts an (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer and an Al 0.5 In 0.5 P first upper confinement layer, and inserts an (Al 1-x6 Ga x6 ) y4 In 1-y4 P linear graded confinement layer structure. By using a low-Al composition (Al 1-x6 Ga x6 ) y4 In 1-y4 P and combining with a relatively high flow rate of 25 cc of initial Mg doping, it suppresses the doping hysteresis caused by the Mg doping memory effect, realizes the stable Mg doping gradient to 14 cc, and eliminates the doping "shoulder" phenomenon; by using a low-In and low-Al composition (Al 1-x6 Ga x6 ) y4 In 1-y4 P, it reduces the Mg doping diffusion distance, realizes a steep doping interface, thereby improving the electro-optical conversion efficiency, reducing the threshold current, and achieving high-reliability operation. Description of the Drawings

[0089] Figure 1 is a schematic diagram of the structure of a conventional laser (a) and the laser described in Embodiment 1 (b);

[0090] In the figure: 1 is a GaAs substrate, 2 is a GaAs buffer layer, 3 is a Ga 0.52 In 0.48 P lower transition layer, 4 is an Al 0.5 In 0.5 P lower confinement layer, 5 is an (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer, 6 is a Ga 1-x2 In x2 P first quantum well, 7 is an (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer, 8 is a Ga 1-x4 In x4 P second quantum well, 9 is an (Al 1-x5 Ga x5 ) y3 In 1-y3The P upper waveguide layer, 10 is (Al 1-x6 Ga x6 ) y4 In 1- y4 The P linear gradient confinement layer, 11 is Al 0.5 In 0.5 The P first upper confinement layer, 12 is Ga 1-x7 In x7 The P etch stop layer, 13 is (Al 1- x8 Ga x8 ) y5 In 1-y5 The P second upper confinement layer, 14 is Ga 0.52 In 0.48 The P upper transition layer, 15 is a GaAs cap layer.

[0091] Figure 2 It is a comparison diagram of the SIMS test results of the Mg doping (3) of the laser described in Example 1, the conventional laser structure (1), and the conventional laser structure with the same increased initial Mg doping flow rate (2).

[0092] In the figure: 1 is the conventional laser structure (1), 2 is the laser with the increased initial Mg doping flow rate of the conventional structure, and 3 is the laser described in Example 1; the abscissa is the thickness (μm), and the ordinate is the doping concentration.

[0093] Figure 3 It is a PIV test curve graph of the Mg doping (3) of the laser described in Example 1, the conventional laser structure (1), and the conventional laser structure with the same increased initial Mg doping flow rate (2).

[0094] In the figure: 1 is the conventional laser structure (1), 2 is the laser with the increased initial Mg doping flow rate of the conventional structure, and 3 is the laser described in Example 1; the abscissa is the current (mA), and the ordinate is the power (mW). Specific implementation manners

[0095] The present invention will be further described below in conjunction with the embodiments and the drawings. But it is not limited thereto.

[0096] Example 1:

[0097] As Figure 1 (b) shows, an optimized confinement layer doped low-power AlGaInP red semiconductor laser, the laser comprising a GaAs substrate, a GaAs buffer layer, Ga 0.52 In 0.48 P lower transition layer, Al 0.5 In 0.5 P lower confinement layer, (Al x1 Ga1-x1 ) y1 In 1-y1 P lower waveguide layer, Ga 1-x2 In x2 P first quantum well, (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer, Ga 1-x4 In x4 P second quantum well, (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer, (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer, Al 0.5 In 0.5 P first upper confinement layer, Ga 1-x7 In x7 P etch stop layer, (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer, Ga 0.52 In 0.48 P upper transition layer and GaAs cap layer.

[0098] The preparation method includes the following steps:

[0099] S1. Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it in an H2 environment to 720 ± 10 °C for baking, and introduce AsH3 to perform surface heat treatment on the GaAs substrate;

[0100] S2. Slowly reduce the temperature to 680 ± 10 °C at a rate not less than 30 °C / min, and continue to introduce TMGa and AsH3 to grow a GaAs buffer layer on the GaAs substrate; the growth thickness is 0.2 μm, and the doping concentration is 4E18 atoms / cm 3 , and the dopant is Si;

[0101] S3. Keep the temperature at 680 ± 10 °C, and continue to introduce TMIn, TMGa, and PH3 to grow Ga 0.52 In 0.48 P lower transition layer on the GaAs transition layer; the growth thickness is 0.12 μm, and the doping concentration is 2E18 atoms / cm 3 , and the dopant is Si;

[0102] S4. Slowly change the temperature to 700 ± 10 °C at a heating rate not exceeding 60 °C / min. Introduce TMAl, TMIn, and PH3 to grow an n-type Al 0.5 In 0.5 P lower confinement layer; the growth thickness is 1.05 μm and the doping concentration is 1E18 atoms / cm 3 , and the dopant is Si;

[0103] S5. Slowly change the temperature to 650 ± 10 °C. Introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer; the lower waveguide layer is unintentionally doped, x1 = 0.5, y2 = 0.5, and the thickness is 0.07 μm;

[0104] S6. Keep the temperature at 650 ± 10 °C and continue to introduce TMIn, TMGa, and PH3 to grow Ga 1-x2 In x2 P first quantum well; the first quantum well is unintentionally doped, x2 = 0.4, and the thickness is 5 nm;

[0105] S7. Keep the temperature at 650 ± 10 °C. Introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer; (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer is unintentionally doped, x3 = 0.65, y2 = 0.5, and the thickness is 6 nm;

[0106] S8. Keep the temperature at 650 ± 10 °C and continue to introduce TMIn, TMGa, and PH3 to grow Ga 1- x4 In x4 P second quantum well; the second quantum well is unintentionally doped, x4 = 0.4, and the thickness is 5 nm;

[0107] S9. Slowly change the temperature to 700 ± 10 °C and continue to introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer; (Al 1-x5 Ga x5 )y3 In 1-y3 The upper waveguide layer is unintentionally doped, x5 = 0.5, y3 = 0.5, and the thickness is 0.07 μm;

[0108] S10, the temperature is maintained at 700 ± 10 °C, and TMAl, TMIn, TMGa, and PH3 are continuously introduced to grow (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer on it; x6 is gradually changed from 0.15 to 0.05, y4 = 0.6, the thickness is 0.02 μm, the dopant is Mg, and the Mg doping flow rate is gradually changed from 25 cc to 14 cc to achieve a stable doping concentration of 5E17 atoms / cm 3 ;

[0109] S11, the temperature is maintained at 700 ± 10 °C, and TMIn, TMAl, and PH3 are continuously introduced to grow a P-type Al 0.5 In 0.5 P first upper confinement layer on the linearly graded confinement layer; the growth thickness is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 , and the dopant is Mg;

[0110] S12, the temperature is maintained at 700 ± 10 °C, and TMIn, TMGa, and PH3 are continuously introduced to grow a P-type Ga 1-x7 In x7 P etch stop layer on the first upper confinement layer; the growth thickness is 10 nm, x6 = 0.6, and the doping concentration is 2E18 atoms / cm 3 , and the dopant is Mg;

[0111] S13, the temperature is maintained at 700 ± 10 °C, and TMIn, TMAl, TMGa, and PH3 are continuously introduced to grow a P-type (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer on the etch stop layer; the growth thickness is 0.8 μm, x7 = 0.25, y6 = 0.5, and the doping concentration is 1.2E18 atoms / cm 3 , and the dopant is Mg;

[0112] S14, the temperature is maintained at 700 ± 10 °C, and TMIn, TMGa, and PH3 are introduced to grow Ga 0.52 In 0.48 P upper transition layer on the second upper confinement layer; the growth thickness is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 , and the dopant is Mg;

[0113] S15. Lower the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the upper transition layer; the growth thickness is 0.02 μm, and the doping concentration is 7E19 atoms / cm 3 , and the dopant is C.

[0114] From Figure 1 (a) and Figure 1 (b) The comparison structure shows that the present invention newly adds an (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer. Using the linear gradient of the Al component to ensure constant Mg doping, low In and low Al components to reduce the doping diffusion distance, realizing a steep doping interface and a constant doping amount, thereby improving the electro-optical conversion efficiency, reducing the threshold current, and achieving high-reliability operation.

[0115] Example 2:

[0116] A preparation method of a low-power AlGaInP red semiconductor laser with optimized confinement layer doping includes the following steps:

[0117] S1. Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it to 720 ± 10 °C in an H2 environment for baking, and introduce AsH3 to perform surface heat treatment on the GaAs substrate;

[0118] S2. Slowly reduce the temperature to 680 ± 10 °C, with a cooling rate of not less than 30 °C / min, continue to introduce TMGa and AsH3, and grow a GaAs buffer layer on the GaAs substrate; the growth thickness is 0.15 μm, and the doping concentration is 3E18 atoms / cm 3 , and the dopant is Si;

[0119] S3. Keep the temperature at 680 ± 10 °C, continue to introduce TMIn, TMGa, and PH3, and grow a Ga 0.52 In 0.48 P lower transition layer on the GaAs transition layer; the growth thickness is 0.2 μm, and the doping concentration is 1.5E18 atoms / cm 3 , and the dopant is Si;

[0120] S4. Slowly change the temperature to 700 ± 10 °C, with a heating rate of not more than 60 °C / min, introduce TMAl, TMIn, and PH3, and grow an n-type Al 0.5 In 0.5 P lower confinement layer on the lower transition layer; the growth thickness is 1.2 μm, and the doping concentration is 1.5E18 atoms / cm 3 , and the dopant is Si;

[0121] S5, Slowly change the temperature to 650 ± 10 °C, introduce TMAl, TMIn, TMGa and PH3, and grow (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer on the lower confinement layer; the lower waveguide layer is unintentionally doped, x1 = 0.6, y2 = 0.4, and the thickness is 0.1 μm;

[0122] S6, Keep the temperature at 650 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow Ga 1-x2 In x2 P first quantum well on the lower waveguide layer; the first quantum well is unintentionally doped, x2 = 0.5, and the thickness is 6 nm;

[0123] S7, Keep the temperature at 650 ± 10 °C, introduce TMAl, TMIn, TMGa and PH3, and grow (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer; (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer is unintentionally doped, x3 = 0.6, y2 = 0.55, and the thickness is 8 nm;

[0124] S8, Keep the temperature at 650 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow Ga 1- x4 In x4 P second quantum well on the barrier layer; the second quantum well is unintentionally doped, x4 = 0.4, and the thickness is 6 nm;

[0125] S9, Slowly change the temperature to 700 ± 10 °C, continue to introduce TMAl, TMIn, TMGa and PH3, and grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer on the second quantum well; (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer is unintentionally doped, x5 = 0.6, y3 = 0.6, and the thickness is 0.1 μm;

[0126] S10, Keep the temperature at 700 ± 10 °C, continue to introduce TMAl, TMIn, TMGa and PH3, and grow (Al 1-x6Ga x6 ) y4 In 1-y4 P linear graded confinement layer; x6 is graded from 0.2 to 0.05, y4 = 0.55, thickness is 0.03 μm, dopant is Mg, Mg doping flow rate is graded from 25 cc to 14 cc, achieving a stable doping concentration of 4E17 atoms / cm 3 ;

[0127] S11, keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl and PH3, and grow a P-type Al 0.5 In 0.5 P first upper confinement layer; the growth thickness is 0.15 μm, the doping concentration is 9E17 atoms / cm 3 , dopant is Mg;

[0128] S12, keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow a P-type Ga 1-x7 In x7 P etch stop layer; the growth thickness is 30 nm, x6 = 0.5, the doping concentration is 1E18 atoms / cm 3 , dopant is Mg;

[0129] S13, keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow a P-type (Al 1-x8 Ga x8 ) y5 In 1-y5 P second upper confinement layer; the growth thickness is 1 μm, x7 = 0.4, y6 = 0.55, the doping concentration is 1E18 atoms / cm 3 , dopant is Mg;

[0130] S14, keep the temperature at 700 ± 10 °C, introduce TMIn, TMGa and PH3, and grow a Ga 0.52 In 0.48 P upper transition layer; the growth thickness is 0.03 μm, the doping concentration is 1E18 atoms / cm 3 , dopant is Mg;

[0131] S15, lower the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the upper transition layer; the growth thickness is 0.03 μm, the doping concentration is 9E19 atoms / cm 3 , dopant is C.

[0132] Example 3:

[0133] A preparation method of a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, the steps of which are as described in Example 2, except that x6 gradually changes from 0.3 to 0.05, y4 = 0.6, and the thickness is 0.03 μm.

[0134] Example 4:

[0135] A preparation method of a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, the steps of which are as described in Example 2, except that x6 gradually changes from 0.25 to 0.05, y4 = 0.6, and the thickness is 0.02 μm.

[0136] Test Example

[0137] The conventional laser structure with a Mg doping flow rate of 14 cc, the laser structure with an increased initial Mg doping flow rate of 25 cc, and the laser structure prepared in Example 1 of the present invention were respectively subjected to SIMS testing and PIV testing.

[0138] The SIMS testing method is as follows: After bombarding the sample with a high-energy ion beam (primary ion), the ions sputtered are analyzed using a mass spectrometer, and the sample is etched layer by layer to obtain the elemental concentration information in the sample.

[0139] The PIV testing method is as follows: The grown epitaxial wafer undergoes processes such as photolithography, dissociation, coating, and packaging. The current is increased from 0 mA to 40 mA, and the generated optical power is measured using an optical integrating sphere, and the PIV curve is output according to the photoelectric conversion.

[0140] Table 1 PIV test results

[0141]

[0142] The SIMS test results are as Figure 2 shown. From the comparison results, it can be seen that when the Mg doping flow rate of the conventional laser structure is constant, the Mg doping lags behind, and the "shoulder collapse" phenomenon is obvious (the Mg doping amount decreases linearly); when the initial Mg doping flow rate is increased to 25 cc, the "shoulder collapse" phenomenon is improved to a certain extent, and there is still a slight doping lag phenomenon; the laser structure of the present invention has a basically horizontal Mg doping, no obvious "shoulder collapse" phenomenon, and the doping lag phenomenon is significantly improved compared with the conventional structure.

[0143] The PIV test results are as Figure 3As shown in Table 1, from the comparison results, it can be seen that the laser structure of the present invention suppresses the doping hysteresis caused by the Mg doping memory effect, realizes stable Mg doping, the threshold current is reduced from 12.4 to 11 mA (a decrease of 11%), and at the same time the slope efficiency is increased from 0.71 to 0.81 W / A (an increase of 14%). This shows that the doping hysteresis effect is alleviated and the photoelectric conversion efficiency is improved. It helps to obtain higher photoelectric conversion efficiency and working reliability.

Claims

1. A low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer. The laser includes a substrate, a buffer layer, a lower transition layer, a lower confinement layer, a lower waveguide layer, a first quantum well, a barrier layer, a second quantum well, an upper waveguide layer, (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, an upper transition layer, and a cap layer, which are arranged in sequence from bottom to top; Among them, The upper waveguide layer is (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6; The first upper limiting layer is Al 0.5 In 0.5 P the first upper limiting layer; (Al 1-x6 Ga x6 ) y4 In 1-y4 In the Al component in the P linear gradient confinement layer has a linear gradient, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65, the thickness is 0.01 - 0.05 μm, the dopant is Mg, the Mg doping flow rate gradually changes from 25 cc to 14 cc, and the doping concentration is stable at 5E17 atoms / cm 3 。 2. The low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer according to claim 1, wherein In the low-power AlGaInP red semiconductor laser with optimized confinement layer doping, it includes one or more of the following conditions: I. The substrate is a GaAs substrate; II. The buffer layer is a GaAs buffer layer; III. The lower transition layer is Ga 0.52 In 0.48 P lower transition layer; IV. The lower confinement layer is Al 0.5 In 0.5 P lower confinement layer; V. The lower waveguide layer is (Al x1 Ga 1-x1 ) y1 In 1-y1 P lower waveguide layer; 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6; VI. The first quantum well is Ga 1-x2 In x2 P first quantum well; 0.3 ≤ x2 ≤ 0.7; VII. The stack layer is (Al 1-x3 Ga x3 ) y2 In 1-y2 P stack layer; 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6; VIII. The second quantum well is Ga 1-x4 In x4 P second quantum well; 0.3≤x4≤0.7； IX. The corrosion termination layer is Ga 1-x7 In x7 P corrosion termination layer; 0.5 ≤ x7 ≤ 0.6; X. The second upper confinement layer is (Al 1-x8 Ga x8 ). y5 In 1-y5 P second upper confinement layer; 0 ≤ x8 ≤ 0.3, 0.4 ≤ y5 ≤ 0.6; XI. The upper transition layer is Ga 0.52 In 0.48 P upper transition layer; XII. The cap layer is a GaAs cap layer.

3. The low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that, The said (Al 1-x6 Ga x6 ) y4 In 1-y4 In the P linear gradient confinement layer, x6 gradually changes from 0.3 to 0.05, y4 = 0.6, and the thickness is 0.02 μm.

4. The low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that The low-power AlGaInP red semiconductor laser with optimized confinement layer doping includes one or more of the following conditions: ①. The buffer layer is a GaAs buffer layer, and the doping concentration of the GaAs buffer layer is 2E18 - 5E18 atoms / cm 3 , the thickness is 0.1 - 0.3 μm, and the dopant is Si; ②. The lower transition layer is Ga 0.52 In 0.48 P lower transition layer, Ga 0.52 In 0.48 The doping concentration of the P lower transition layer is 1E18 - 3E18 atoms / cm 3 , the thickness is 0.1 - 0.3 μm, and the dopant is Si; ③. The lower confinement layer is an n-type Al 0.5 In 0.5 P lower confinement layer, n-type Al 0.52 In 0.48 The thickness of the P lower confinement layer is 0.5 - 1.5 μm, and the doping concentration is 5E17 - 3E18 atoms / cm 3 , and the dopant is Si; ④. The lower waveguide layer is (Al 1-x1 Ga x1 ). y1 In 1-y1 P lower waveguide layer, (Al 1-x1 Ga x1 ). y1 In 1-y1 The thickness of the InP lower waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6; ⑤. The first quantum well is a Ga 1-x2 In x2 P first quantum well, and the Ga 1-x2 In x2 P first quantum well has a thickness of 4 - 7 nm, is unintentionally doped, and 0.3 ≤ x2 ≤ 0.7; ⑥. The stack layer is (Al 1-x3 Ga x3 ), y2 In 1-y2 P stack layer, (Al 1-x3 Ga x3 ), y2 In 1-y2 The thickness of the P stack layer is 5 - 15 nm, unintentionally doped, 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6; ⑦. The second quantum well is Ga 1-x4 In x4 P second quantum well, Ga 1-x4 In x4 P second quantum well has a thickness of 4 - 7 nm, is unintentionally doped, and 0.3 ≤ x4 ≤ 0.7; ⑧. The upper waveguide layer is (Al 1-x5 Ga x5 ). y3 In 1-y3 P upper waveguide layer, (Al 1-x5 Ga x5 ). y3 In 1-y3 The thickness of the InP upper waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6; ⑨. The first upper confinement layer is P-type Al 0.5 In 0.5 P first upper confinement layer, P-type Al 0.5 In 0.5 The thickness of the P first upper confinement layer is 0.1 - 0.3 μm, and the doping concentration is 3E17 - 1.5E18 atoms / cm 3 , and the dopant is Mg; ⑩. The corrosion termination layer is a P-type Ga 1-x7 In x7 P corrosion termination layer, and the P-type Ga 1-x7 In x7 The thickness of the P corrosion termination layer is 10 - 50 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x7 ≤ 0.6, and the dopant is Mg; ⑪. The second upper confinement layer is of P-type (Al 1-x8 Ga x8 ). y5 In 1-y5 P second upper confinement layer, of P-type (Al 1-x8 Ga x8 ). y5 In 1-y5 The thickness of the P second upper confinement layer is 0.5 - 1.2 μm, and the doping concentration is 5E17 - 1.5E18 atoms / cm 3 ; 0.05 ≤ x8 ≤ 0.3, 0.4 ≤ y5 ≤ 0.6, and the dopant is Mg; ⑫. The upper transition layer is P-type Ga 0.52 In 0.48 P upper transition layer, P-type Ga 0.52 In 0.48 The thickness of the P upper transition layer is 0.01 - 0.05 μm, and the doping concentration is 1E18 - 3E18 atoms / cm 3 , and the dopant is Mg; ⑬. The cap layer is a GaAs cap layer, the thickness of the GaAs cap layer is 0.1 - 0.5 μm, and the doping concentration is 4E19 - 1E20 atoms / cm 3 , and the dopant is C.

5. The low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that, The low-power AlGaInP red semiconductor laser with optimized confinement layer doping includes one or more of the following conditions: ①. The buffer layer is a GaAs buffer layer, the doping concentration of the GaAs buffer layer is 4E18 atoms / cm 3 , the thickness is 0.2 μm, and the dopant is Si; ②. The lower transition layer is Ga 0.52 In 0.48 P lower transition layer, Ga 0.52 In 0.48 The doping concentration of the P lower transition layer is 2E18 atoms / cm 3 , the thickness is 0.12 μm, and the dopant is Si; ③. The lower confinement layer is n-type Al 0.5 In 0.5 P lower confinement layer, n-type Al 0.52 In 0.48 The thickness of the P lower confinement layer is 1.05 μm, and the doping concentration is 1E18 atoms / cm 3 , and the dopant is Si; ④. The lower waveguide layer is (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer, (Al 1-x1 Ga x1 ) y1 In 1-y1 The thickness of the P lower waveguide layer is 0.07 μm, unintentionally doped, x1 = 0.5, y1 = 0.5; ⑤. The first quantum well is Ga 1-x2 In x2 P first quantum well, Ga 1-x2 In x2 The thickness of the first quantum well is 5 nm, unintentionally doped, x2 = 0.4; ⑥. The stack layer is (Al 1-x3 Ga x3 ). y2 In 1-y2 P stack layer, (Al 1-x3 Ga x3 ). y2 In 1-y2 The thickness of the P stack layer is 6 nm, unintentionally doped, x3 = 0.65, y2 = 0.5; ⑦. The second quantum well is Ga 1-x4 In x4 P second quantum well, Ga 1-x4 In x4 P second quantum well has a thickness of 5 nm, is unintentionally doped, and x4 = 0.4; ⑧. The upper waveguide layer is (Al 1-x5 Ga x5 ). y3 In 1-y3 P upper waveguide layer, (Al 1-x5 Ga x5 ). y3 In 1-y3 The thickness of the P upper waveguide layer is 0.07 μm, unintentionally doped, x5 = 0.5, y3 = 0.5; ⑨. The first upper confinement layer is P-type Al 0.5 In 0.5 P first upper confinement layer, P-type Al 0.5 In 0.5 The thickness of the P first upper confinement layer is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 , and the dopant is Mg; ⑩. The corrosion termination layer is P-type Ga 1-x7 In x7 P corrosion termination layer, P-type Ga 1-x7 In x7 The thickness of the P corrosion termination layer is 10 nm, and the doping concentration is 2E18 atoms / cm 3 , x7 = 0.6, and the dopant is Mg; ⑪. The second upper confinement layer is of P-type (Al 1-x8 Ga x8 ). y5 In 1-y5 P second upper confinement layer, of P-type (Al 1-x8 Ga x8 ). y5 In 1-y5 The thickness of the P second upper confinement layer is 0.8 μm, and the doping concentration is 1.2E18 atoms / cm 3 ; x8 = 0.25, y5 = 0.5, and the dopant is Mg; ⑫. The upper transition layer is P-type Ga 0.52 In 0.48 P upper transition layer, P-type Ga 0.52 In 0.48 The thickness of the P upper transition layer is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 , and the dopant is Mg; ⑬. The cap layer is a GaAs cap layer with a thickness of 0.02 μm and a doping concentration of 7E19 atoms / cm 3 , and the dopant is C.

6. A preparation method of a low-power AlGaInP red semiconductor laser with optimized doping of a confinement layer, characterized in that, Including performing surface heat treatment on a substrate in a MOCVD growth chamber, and then epitaxially growing a buffer layer, a lower transition layer, a lower confinement layer, a lower waveguide layer, a first quantum well, a barrier layer, a second quantum well, an upper waveguide layer, (Al 1-x6 Ga x6 ), y4 In 1-y4 P linearly graded confinement layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, an upper transition layer, and a cap layer from bottom to top; Among them, the upper waveguide layer is (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6; The first upper confinement layer is Al 0.5 In 0.5 P first upper confinement layer; (Al 1-x6 Ga x6 ) y4 In 1-y4 In the linearly graded confinement layer of P, the Al composition is linearly graded, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65, the thickness is 0.01 - 0.05 μm, the dopant is Mg, the Mg doping flow rate is gradually changed from 25 cc to 14 cc, and the doping concentration is stabilized at 5E17 atoms / cm 3 ; The growth conditions are: the growth temperature is 690 - 710 °C, and TMAl, TMIn, TMGa and PH3 are introduced.

7. A preparation method of a low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that, The method includes the following steps: S1. Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it in an H2 environment to 720 ± 10 °C for baking, and introduce AsH3 to perform surface heat treatment on the GaAs substrate; S2. Slowly reduce the temperature to 680 ± 10 °C, with a cooling rate not less than 30 °C / min, and continue to introduce TMGa and AsH3 to grow a GaAs buffer layer on the GaAs substrate; Among them, the doping concentration of the GaAs buffer layer is 2E18 - 5E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; S3, maintain the temperature at 680 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow a Ga 0.52 In 0.48 P underlying layer on the GaAs transition layer; Among them, the Ga 0.52 In 0.48 The doping concentration of the P lower transition layer is 1E18 - 3E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; S4, Slowly change the temperature to 700 ± 10 °C at a heating rate not exceeding 60 °C / min, introduce TMAl, TMIn, and PH3, and grow an n-type Al 0.5 In 0.5 P lower confinement layer; Among them, the thickness of the n-type Al 0.5 In 0.5 P lower confinement layer is 0.5 - 1.5 μm, and the doping concentration is 5E17 - 3E18 atoms / cm 3 ; S5, Slowly change the temperature to 650 ± 10 °C, introduce TMAl, TMIn, TMGa, and PH3, and grow an (Al 1- x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer on the said lower confinement layer; Among them, the (Al 1-x1 Ga x1 ) y1 In 1-y1 The thickness of the lower waveguide layer of P is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x1 ≤ 0.7, 0.4 ≤ y1 ≤ 0.6 S6. The temperature is maintained at 650 ± 10 °C, and TMIn, TMGa and PH3 are continuously introduced to grow Ga 1- x2 In x2 P first quantum well; Among them, the Ga 1-x2 In x2 The thickness of the first quantum well of P is 4 - 7 nm, unintentionally doped, and 0.3 ≤ x2 ≤ 0.7; S7, Keep the temperature at 650 ± 10 °C, introduce TMAl, TMIn, TMGa and PH3, and grow an (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer on the first quantum well; Among them, the (Al 1-x3 Ga x3 ). y2 In 1-y2 P barrier layer has a thickness of 5 - 15 nm, is unintentionally doped, 0.3 ≤ x3 ≤ 0.7, 0.4 ≤ y2 ≤ 0.6; At S8, the temperature is maintained at 650 ± 10 °C, and TMIn, TMGa, and PH3 are continuously introduced to grow Ga 1-x4 In x4 P second quantum well; Among them, the Ga 1-x4 In x4 The thickness of the second quantum well of P is 4 - 7 nm, unintentionally doped, 0.3 ≤ x4 ≤ 0.7; S9, Slowly change the temperature to 700 ± 10 °C, continue to introduce TMAl, TMIn, TMGa and PH3, and grow an (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer on the second quantum well; Among them, the (Al 1-x5 Ga x5 ). y3 In 1-y3 The thickness of the upper waveguide layer of P is 0.05 - 0.15 μm, unintentionally doped, 0.3 ≤ x5 ≤ 0.7, 0.4 ≤ y3 ≤ 0.6; S10, maintain the temperature at 700 ± 10 °C, continue to introduce TMAl, TMIn, TMGa and PH3, and grow an (Al 1-x6 Ga x6 ) y4 In 1-y4 P linearly graded confinement layer on the upper waveguide layer; where (Al 1-x6 Ga x6 ) y4 In 1-y4 The Al component in the P linear gradient confinement layer has a linear gradient, 0.05 ≤ x6 ≤ 0.3, 0.55 ≤ y4 ≤ 0.65, and the thickness is 0.01 - 0.05 μm; the growth conditions are: the growth temperature is 690 - 710 °C, TMAl, TMIn, TMGa and PH3 are introduced, the dopant is Mg, the Mg doping flow rate is gradually changed from 25 cc to 14 cc, and the doping concentration is stable at 5E17 atoms / cm 3 ; S11, maintain the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl and PH3, and grow a P-type Al 0.5 In 0.5 P first upper confinement layer; Among them, the P-type Al 0.5 In 0.5 The thickness of the first upper limiting layer of P is 0.1 - 0.3 μm, and the doping concentration is 3E17 - 1.5E18 atoms / cm 3 ; S12, maintain the temperature at 700 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow a P-type Ga 1-x7 In x7 P etch stop layer; Among them, the P-type Ga 1-x7 In x7 The thickness of the P corrosion termination layer is 10 - 50 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.5 ≤ x7 ≤ 0.6; S13, Maintain the temperature at 700 ± 10 °C, and continue to introduce TMIn, TMAl, TMGa, and PH3 to grow a P-type (Al 1-x8 Ga x8 )) y5 In 1-y5 P second upper confinement layer on the corrosion termination layer; Among them, the P-type (Al 1-x8 Ga x8 )) y5 In 1-y5 P second upper confinement layer has a thickness of 0.5 - 1.2 μm and a doping concentration of 5E17 - 1.5E18 atoms / cm 3 , 0 ≤ x8 ≤ 0.3, 0.4 ≤ y5 ≤ 0.6; S14, maintain the temperature at 700 ± 10 °C, introduce TMIn, TMGa and PH3, and grow a Ga 0.52 In 0.48 P upper transition layer on the second upper confinement layer; Among them, the P-type Ga 0.52 In 0.48 The thickness of the transition layer on P is 0.01 - 0.05 μm, and the doping concentration is 1E18 - 3E18 atoms / cm 3 ; S15. Reduce the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the upper transition layer; Among them, the thickness of the capping layer is 0.1 - 0.5 μm, and the doping concentration is 4E19 - 1E20 atoms / cm 3 .

8. The preparation method of the low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that, In step S2, the thickness of the GaAs buffer layer is 0.2 μm and the doping concentration is 4E18 atoms / cm 3 ; In step S3, the Ga 0.52 In 0.48 The thickness of the P lower transition layer is 0.12 μm, and the doping concentration is 2E18 atoms / cm 3 ; In step S4, the thickness of the n-type Al 0.5 In 0.5 P lower confinement layer is 1.05 μm, and the doping concentration is 1E18 atoms / cm 3 ; In steps S2 - S4, the dopant is Si.

9. The preparation method of the low-power AlGaInP red semiconductor laser with optimized doping of the confinement layer, characterized in that, In step S5, the thickness of the (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer is 0.07 μm, x1 = 0.5, y1 = 0.5; In step S6, the Ga 1-x2 In x2 P first quantum well has a thickness of 5 nm and x2 = 0.4; In step S7, the thickness of the (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer is 6 nm, x3 = 0.65, and y2 = 0.5; In step S8, the Ga 1-x4 In x4 The thickness of the second InP quantum well is 5 nm, and x4 = 0.4; In step S9, the thickness of the (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer is 0.07 μm, x5 = 0.5, y3 = 0.

5.

10. The preparation method of the low-power AlGaInP red-light semiconductor laser with optimized doping of the confinement layer, characterized in that, In step S10, the thickness of the (Al 1-x6 Ga x6 )) y4 In 1-y4 P linearly graded confinement layer is 0.02 μm, x6 is graded from 0.3 to 0.05, and y4 = 0.6; In step S11, the P-type Al 0.5 In 0.5 The thickness of the P first upper limiting layer is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 ; In step S12, the P-type Ga 1-x7 In x7 The thickness of the P etch stop layer is 10 nm, x7 = 0.6, and the doping concentration is 2E18 atoms / cm 3 ; In step S13, the thickness of the P-type (Al 1-x8 Ga x8 )) y5 In 1-y5 P second upper confinement layer is 0.8 μm, x8 = 0.25, y5 = 0.5, and the doping concentration is 1.2E18 atoms / cm 3 ; In step S14, the P-type Ga 0.52 In 0.48 The thickness of the InP upper transition layer is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 ; In step S15, the thickness of the capping layer is 0.02 μm and the doping concentration is 7E19 atoms / cm 3 ; In steps S10 - S14, the dopant is Mg, and in step S15, the dopant is C.

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