A low-power AlGaInP red semiconductor laser with an optimized electron blocking layer and its manufacturing method

Abstract

The present invention relates to a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer and a preparation method thereof. The red semiconductor 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 x6 Ga 1‑x6 ) y4 In 1‑y4 P graded electron blocking layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, a bandgap transition layer, and a GaAs cap layer. By optimizing the structure and thickness design of the electron blocking layer, a compositionally graded (Al 1‑x Ga x ) y In 1‑y P structure is inserted into the low-Al composition AlGaInP waveguide layer and the AlInP confinement layer, and the thickness and doping design of this layer are optimized to achieve the purpose of suppressing electron overflow. At the same time, the hole energy is effectively increased, the hole injection efficiency is improved, so that the low-power AlGaInP red laser has a smaller operating current and a higher photoelectric conversion efficiency.

Description

Technical Field

[0001] The present invention relates to a low-power AlGaInP red semiconductor laser with an optimized electron blocking 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 the output power of low-power lasers is relatively small (generally less than 100 mW), the lasers are required to have a lower threshold current, a higher photoelectric conversion efficiency, reduce heat generation, avoid damage to the material performance caused by waste heat, resulting in the decline of the laser performance and affecting the working life of the laser.

[0003] To reduce the threshold current during the operation of the laser, it is necessary to increase the optical confinement factor. The literature 2013 SPIE, 86400E1-7 points out that AlInP as a confinement layer has a higher optical confinement factor, which helps to achieve a low threshold current; the literature IEEE Journal of Quantum Electronics, 27(6), 1991, 1476-1482 points out that when AlInP is used as a confinement layer, the conduction band gap difference between AlInP and the GaInP quantum well is only 190 meV, and the electron confinement ability is poor. The electrons spill out from the active region to the P-type confinement layer more seriously, resulting in an increase in the threshold current, a decrease in the slope efficiency, and the generation of more waste heat. While (Al70Ga30)50In50P and GaInP have the largest conduction band gap difference (270 meV), which can reduce the electron spillage phenomenon to a certain extent and improve the working stability of the laser; the literature IEEE Journal of Quantum Electronics, 31(12), 1995, 2159-2164 points out that using AlGaInP with a low Al composition for the waveguide layer and the barrier layer helps to increase the optical gain, increase the slope efficiency, and improve the photoelectric conversion efficiency.

[0004] Using a low-Al composition AlGaInP as the waveguide layer can achieve greater optical gain. Using (Al70Ga30)50In50P as the electron blocking layer reduces electron overflow. At the same time, using AlInP as the confinement layer helps to achieve high gain and low electron overflow under a high confinement factor, thus realizing better optoelectronic performance. However, the literature Phys. Status Solidi. - A Appl. Mater. Sci., 213(1), 2016, 210–214 points out that inserting a P layer into a high-bandgap electron blocking layer will generate polarization negative charges at the interface, thereby forming hole accumulation at the interface, affecting hole injection, and resulting in a decrease in the recombination efficiency and the optoelectronic conversion efficiency. The literature Photonics Res., 7(4), 2019, B1-B6 points out that the gradually changing Al composition has the effect of polarization self-screening, which can effectively increase the hole energy, thereby increasing the hole drift velocity and further improving the hole injection efficiency. However, the literature focuses on the optimization of the AlN electron blocking layer of GaN-based lasers, which is quite different from the AlGaInP laser on a GaAs substrate. The optimization of the electron blocking layer is not applicable and does not involve the optimization of the electron blocking layer thickness. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer and a preparation method thereof. By optimizing the electron blocking layer structure and thickness design, a structure of gradually changing composition (Al1-xGax)yIn1-yP is inserted into the low-Al composition AlGaInP waveguide layer and the AlInP confinement layer, and the thickness design of this layer is optimized to achieve the purpose of suppressing electron overflow. At the same time, the hole energy is effectively increased, the hole injection efficiency is improved, so that the low-power AlGaInP red laser has a smaller operating current and a higher optoelectronic conversion efficiency.

[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 an optimized electron blocking 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 x6 Ga 1-x6 ) y4 In 1-y4 P gradually changing electron blocking layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, a bandgap transition layer, and a GaAs cap layer, which are arranged in sequence from bottom to top;

[0008] Among them, 0.25 ≤ x6 ≤ 0.75, 0.4 ≤ y4 ≤ 0.6;

[0009] Among them, (Al x6 Ga1-x6 ) y4 In 1-y4 The P component changes gradually, x6 changes gradually from 0.25 to 0.75, the Al component increases linearly, the Ga component decreases linearly, the conduction band gap is increased, the electron overflow is blocked, the energy barrier is reduced, and at the same time, the graded structure effectively increases the hole energy, increases the hole drift velocity, thereby improving the hole injection efficiency and the photoelectric conversion efficiency. The growth thickness is 1 - 20 nm.

[0010] According to the preferred embodiment of the present invention, the low-power AlGaInP red semiconductor laser with an optimized electron blocking layer includes one or more of the following conditions:

[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 0.5 In 0.5 P lower transition layer;

[0014] IV. The lower confinement layer is an Al 0.52 In 0.48 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; 0.25 ≤ x1 ≤ 0.5, 0.4 ≤ y1 ≤ 0.6;

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

[0017] VII. The barrier layer is an (Al x3 Ga 1-x3 ) y2 In 1-y2 P barrier layer; 0.25 ≤ x3 ≤ 0.55, 0.4 ≤ y2 ≤ 0.6;

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

[0019] IX. The upper waveguide layer is an (Al x5 Ga 1-x5 ) y3 In 1-y3 P upper waveguide layer; 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6;

[0020] X. The first upper confinement layer is Al 0.52 In 0.48 P first upper confinement layer;

[0021] XI. The etch stop layer is Ga x7 In 1-x7 P etch stop layer; 0.5 ≤ x7 ≤ 0.7;

[0022] XII. The second upper confinement layer is Al 0.52 In 0.48 P second upper confinement layer;

[0023] XIII. The bandgap transition layer is Ga 0.5 In 0.5 P bandgap 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 an optimized electron blocking layer, (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer has a doping concentration of 4E17 - 1E18 atoms / cm 3 , x6 varies from 0.4 to 0.7, y4 = 0.5, the thickness is 5 nm, and the doping concentration varies from 4E17 atoms / cm 3 to 7E17 atoms / cm 3 .

[0026] Preferably according to the present invention, the low-power AlGaInP red semiconductor laser with an optimized electron blocking layer 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 0.5 In 0.5 P lower transition layer, and the doping concentration of the Ga 0.5 In 0.5 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 Al 0.52 In 0.48 P lower confinement layer, n-type Al 0.52 In0.48 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 P lower waveguide layer has a thickness of 0.05 - 0.15 nm, is unintentionally doped, 0.25 ≤ x1 ≤ 0.5, 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 P first quantum well has a thickness of 4 - 7 nm, is 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 P barrier layer has a thickness of 5 - 15 nm, is unintentionally doped, 0.25 ≤ x3 ≤ 0.55, 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 P second quantum well has a thickness of 4 - 7 nm, is 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 P upper waveguide layer has a thickness of 0.05 - 0.15 μm, and the doping concentration at 1 / 2 of the thickness away from the quantum well is 4E17 - 1E18 atoms / cm 3 , 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6;

[0035] ⑨. The first upper confinement layer is P-type Al 0.52 In 0.48 P first upper confinement layer, P-type Al 0.52 In 0.48 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 - 30 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x7 ≤ 0.6;

[0037] The second upper confinement layer is P-type Al 0.52 In 0.48 P second upper confinement layer, P-type Al 0.52 In 0.48 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 ;

[0038] The bandgap transition layer is Ga 0.5 In 0.5 P bandgap transition layer, Ga 0.5 In 0.5 The thickness of the P bandgap 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 an optimized electron blocking layer 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 Ga 0.5 In 0.5 P lower transition layer, Ga0.5 In 0.5 The doping concentration of the 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 0.52 In 0.48 P lower confinement layer. 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. The thickness of the (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer is 0.05 nm, unintentionally doped, x1 = 0.4, y2 = 0.5;

[0045] ⑤. The first quantum well is a Ga 1-x2 In x2 P first quantum well. 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. The thickness of the (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer is 7 nm, unintentionally doped, x3 = 0.5, y2 = 0.42;

[0047] ⑦. The second quantum well is a Ga 1-x4 In x4 P second quantum well. 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 an (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer. The thickness of the (Al 1-x5 Ga x5 ) y3In 1-y3 The thickness of the upper waveguide layer is 0.05 μm, and the doping concentration at 1 / 2 thickness away from the quantum well is 4E17 atoms / cm 3 , x5 = 0.4, y3 = 0.5;

[0049] ⑨. The first upper confinement layer is P-type Al 0.52 In 0.48 P first upper confinement layer, P-type Al 0.52 In 0.48 The thickness of the P first upper confinement layer is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 ;

[0050] 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 nm, and the doping concentration is 1E18 atoms / cm 3 , x7 = 0.6;

[0051] The second upper confinement layer is P-type Al 0.52 In 0.48 P second upper confinement layer, P-type Al 0.52 In 0.48 The thickness of the P second upper confinement layer is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 ;

[0052] The bandgap transition layer is Ga 0.5 In 0.5 P bandgap transition layer, Ga 0.5 In 0.5 The thickness of the P bandgap transition layer is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 ;

[0053] The cap layer is a GaAs cap layer, the thickness of the GaAs cap layer is 0.2 μm, and the doping concentration is 7E19 atoms / cm 3 .

[0054] The second aspect of the present invention provides a method for manufacturing a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer, and the method includes the following steps:

[0055] A preparation method of a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer, including performing surface heat treatment on a substrate in an 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, an (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, a bandgap transition layer, and a GaAs cap layer from bottom to top;

[0056] Among them, the conditions for growing the Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer are: the growth temperature is 690 - 710 °C, TMIn, TMAl, TMGa, and PH3 are introduced, and the gas flow ratio of TMAl and TMGa is adjusted to gradually change x6 from a low value to a high value.

[0057] Specifically, a preparation method of a low-power AlGaInP red semiconductor laser with an optimized graded electron blocking layer, the method includes the following steps:

[0058] S1, Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it up to 720 ± 10 °C in an H2 environment for baking, and introduce AsH3 to perform surface heat treatment on the GaAs substrate;

[0059] S2, Slowly reduce the temperature to 660 ± 10 °C, and the cooling rate is not less than 30 °C / min. Continue to introduce TMGa and AsH3 to grow a GaAs buffer layer on the GaAs substrate;

[0060] S3, Keep the temperature at 660 ± 10 °C, continue to introduce TMIn, TMGa, and PH3, and grow Ga 0.5 In 0.5 P lower transition layer on the GaAs buffer layer;

[0061] S4, Gradually change the temperature to 700 ± 10 °C, and the heating rate is not more than 60 °C / min. Introduce TMAl, TMIn, and PH3 to grow an n-type Al 0.52 In 0.48 P lower confinement layer on the lower transition layer;

[0062] S5, Gradually change the temperature to 650 ± 10 °C, and the cooling rate is 20 - 60 °C / min. Introduce TMAl, TMIn, TMGa, and PH3 to grow an (Al 1-x1 Ga x1 ) y1 In1-y1 Lower waveguide layer;

[0063] 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;

[0064] 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;

[0065] 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;

[0066] S9. Gradually change the temperature to 700 ± 10 °C at a heating rate of 20 - 60 °C / min, and continue to introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer;

[0067] S10. Keep the temperature at 700 ± 10 °C, and continue to introduce TMIn, TMAl, TMGa, and PH3 to grow (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer; Adjust the gas flow ratio of TMIn, TMAl, and TMGal so that x6 gradually changes from a low value to a high value;

[0068] S11. Keep the temperature at 700 ± 10 °C, and continue to introduce TMIn, TMAl, and PH3 to grow P-type Al 0.52 In 0.48 P first upper confinement layer;

[0069] 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;

[0070] S13. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow P-type Al 0.52 In 0.48 P second upper confinement layer;

[0071] S14. Keep the temperature at 700 ± 10 °C, introduce TMIn, TMAl, TMGa and PH3, and grow Ga 0.5 In 0.5 P bandgap transition layer;

[0072] S15. Reduce the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the bandgap transition layer.

[0073] 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 .

[0074] Preferably according to the present invention, in step S3, the doping concentration of the Ga 0.5 In 0.5 P lower transition layer is 1E18 - 3E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; more preferably, the thickness is 0.12 μm and the doping concentration is 2E18 atoms / cm 3 .

[0075] Preferably according to the present invention, in step S4, the thickness of the n-type Al 0.52 In 0.48 P lower confinement layer is 0.5 - 1.5 μm, and the doping concentration is 5E17 - 3E18 atoms / cm 3 ; more preferably, the thickness is 1.05 μm and the doping concentration is 1E18 atoms / cm 3 .

[0076] Preferably according to the present invention, in step S5, the thickness of (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer is 0.05 - 0.15 μm, unintentionally doped, 0.25 ≤ x1 ≤ 0.5, 0.4 ≤ y1 ≤ 0.6; more preferably, x1 = 0.4, y2 = 0.5, and the thickness is 0.05 μm.

[0077] Preferably according to the present invention, in step S6, the Ga1-x2 In x2 The thickness of the first quantum well of P is 4 - 7 nm, unintentionally doped, 0.3 ≤ x2 ≤ 0.7; further preferably, x2 = 0.4 and the thickness is 5 nm.

[0078] Preferably according to the present invention, in step S7, (Al 1-x3 Ga x3 ) y2 In 1-y2 The thickness of the P barrier layer is 5 - 15 nm, unintentionally doped, 0.25 ≤ x3 ≤ 0.55, 0.4 ≤ y2 ≤ 0.6; further preferably, x3 = 0.5, y2 = 0.42 and the thickness is 7 nm.

[0079] Preferably according to the present invention, in step S8, 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; further preferably, x4 = 0.4 and the thickness is 5 nm.

[0080] Preferably according to the present invention, in step S9, the (Al 1-x5 Ga x5 ) y3 In 1-y3 The thickness of the P upper waveguide layer is 0.05 - 0.15 μm, the doping concentration at the 1 / 2 thickness away from the quantum well is 4E17 - 1E18 atoms / cm 3 , 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6; further preferably, x5 = 0.4, y3 = 0.5, the thickness is 0.05 μm, and the doping concentration at the 1 / 2 thickness away from the quantum well is 4E17 atoms / cm 3 .

[0081] Preferably according to the present invention, in step S10, the (Al x6 Ga 1-x6 ) y4 In 1-y4 The thickness of the P graded electron blocking layer is 1 - 20 nm, the doping concentration is 4E17 - 1E18 atoms / cm 3 , 0.25 ≤ x6 ≤ 0.75, 0.4 ≤ y4 ≤ 0.6; further preferably, x6 gradually changes from 0.4 to 0.7, y4 = 0.5, the thickness is 5 nm, and the doping concentration gradually changes from 4E17 atoms / cm 3 to 7E17 atoms / cm 3 .

[0082] Preferably according to the present invention, in step S11, the P-type Al 0.52 In 0.48The thickness of the first P 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 .

[0083] Preferably according to the present invention, in step S12, the P-type Ga 1-x7 In x7 The thickness of the P etch stop layer is 10 - 30 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x7 ≤ 0.6; More preferably, x7 = 0.6, the thickness is 10 nm, and the doping concentration is 1E18 atoms / cm 3 .

[0084] Preferably according to the present invention, in step S13, the P-type Al 0.52 In 0.48 The thickness of the second P upper confinement layer is 0.5 - 1.2 μm, and the doping concentration is 5E17 - 1.5E18 atoms / cm 3 ; More preferably, the P-type Al 0.5 In 0.5 The thickness of the second P upper confinement layer is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 .

[0085] Preferably according to the present invention, in step S14, the P-type Ga 0.5 In 0.5 The thickness of the P bandgap 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 .

[0086] 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 0.2 μm, and the doping concentration is 7E19 atoms / cm 3 .

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

[0088] By optimizing the structure and thickness design of the electron blocking layer, and inserting a compositionally graded (Al 1-x Ga x ) y In1-y The P structure is adopted, and the thickness and doping design of this layer are optimized to achieve the purpose of suppressing electron overflow. Meanwhile, the hole energy is effectively increased, the hole injection efficiency is improved, so that the low-power AlGaInP red light laser has a smaller working current and a higher photoelectric conversion efficiency. Brief Description of the Drawings

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

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

[0091] Figure 2 It is a schematic diagram of the conduction band of the structure (a) of the laser described in the present invention and the conventional structure (b).

[0092] Figure 3 It is a broken line graph showing the change of the slope efficiency of the laser described in the present invention at different thicknesses of the graded electron blocking layer.

[0093] In the figure: the abscissa is the thickness, unit: nm; the ordinate is the slope efficiency. Detailed implementation manners

[0094] The present invention will be further described below in conjunction with embodiments and the accompanying drawings. However, it is not limited thereto.

[0095] Embodiment 1:

[0096] As Figure 1 shown, a low-power AlGaInP red semiconductor laser with an optimized gradual electron blocking layer, the laser includes a GaAs substrate, a GaAs buffer layer, a Ga 0.5 In 0.5 P lower transition layer, an Al 0.52 In 0.48 P lower confinement layer, an (Al x1 Ga 1-x1 ) y1 In 1-y1 P lower waveguide layer, a Ga x2 In 1-x2 P first quantum well, an (Al x3 Ga 1-x3 ) y2 In 1-y2 P barrier layer, a Ga x4 In 1-x4 P second quantum well, an (Al x5 Ga 1-x5 ) y3 In 1-y3 P upper waveguide layer, an (Al x6 Ga 1-x6 ) y4 In 1-y4 P gradual electron blocking layer, an Al 0.52 In 0.48 P first upper confinement layer, a Ga x7 In 1-x7 P etch stop layer, an Al 0.52 In 0.48 P second upper confinement layer, a Ga 0.5 In 0.5 P bandgap transition layer and a GaAs cap layer.

[0097] Its preparation method includes the following steps:

[0098] 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;

[0099] S2. Slowly reduce the temperature to 660 ± 10 °C at a rate of no 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 doping element is Si;

[0100] S3. Keep the temperature at 660 ± 10 °C, and continue to introduce TMIn, TMGa and PH3 to grow a Ga 0.5 In 0.5 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 doping element is Si;

[0101] S4. Slowly change the temperature to 700 ± 10 °C at a rate of no more than 60 °C / min, and introduce TMAl, TMIn, and PH3 to grow an n-type Al 0.52 In 0.48 P lower confinement layer on the lower transition layer; the growth thickness is 1.05 μm and the doping concentration is 1E18 atoms / cm 3 , and the doping element is Si;

[0102] S5. Slowly change the temperature to 650 ± 10 °C at a rate of 20 - 60 °C / min, and 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 = 0.4, y2 = 0.5, and the growth thickness is 0.05 μm;

[0103] S6. Keep the temperature at 650 ± 10 °C, and continue to introduce TMIn, TMGa and PH3 to grow a Ga 1-x2 In x2 P first quantum well on the lower waveguide layer; the first quantum well is unintentionally doped, x2 = 0.4, and the growth thickness is 5 nm;

[0104] S7. Keep the temperature at 650 ± 10 °C, and introduce TMAl, TMIn, TMGa and PH3 to grow (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer on the first quantum well; the barrier layer is unintentionally doped, x3 = 0.5, y2 = 0.42, and the growth thickness is 7 nm;

[0105] S8. Keep the temperature at 650 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow Ga on the barrier layer 1- x4 In x4 P second quantum well; the second quantum well is unintentionally doped, x4 = 0.4, and the growth thickness is 5 nm;

[0106] S9. Gradually change the temperature to 700 ± 10 °C at a heating rate of 20 - 60 °C / min, continue to introduce TMAl, TMIn, TMGa and PH3, and grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer; the growth thickness is 0.05 μm, x5 = 0.4, y3 = 0.5, and the doping concentration at 1 / 2 thickness away from the quantum well is 4E17 atoms / cm 3 ;

[0107] S10. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer; (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer is unintentionally doped, that is, no doping source is introduced, adjust the gas flow ratio of TMIn, TMAl, TMGal, so that x6 gradually changes from 0.25 to 0.75, y4 = 0.5, the growth thickness is 10 nm, and the doping concentration gradually changes from 4E17 atoms / cm 3 gradually changes to 7E17 atoms / cm 3 ;

[0108] S11. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl and PH3, and grow P-type Al 0.52 In 0.48 P first upper confinement layer; the growth thickness is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 , and the doping element is Mg;

[0109] S12. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow P-type Ga 1-x7 In x7 P etch stop layer; the growth thickness is 10 nm, x7 = 0.6, and the doping concentration is 1E18 atoms / cm 3, the doping element is Mg;

[0110] S13, keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow a P-type Al 0.52 In 0.48 P second upper confinement layer on the corrosion termination layer; the growth thickness is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 , the doping element is Mg;

[0111] S14, keep the temperature at 700 ± 10 °C, introduce TMIn, TMAl, TMGa and PH3, and grow a Ga 0.5 In 0.5 P bandgap transition layer on the second upper confinement layer; the growth thickness is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 , the doping element is Mg;

[0112] S15, lower the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the bandgap transition layer; the growth thickness is 0.2 μm, and the doping concentration is 7E19 atoms / cm 3 , the doping element is C.

[0113] By optimizing the structure and thickness design of the electron blocking layer, a composition-graded (Al 1-x Ga x ) y In 1-y P structure is inserted into the low-Al-component AlGaInP waveguide layer and the AlInP confinement layer, and the thickness and doping design of this layer are optimized to achieve the purpose of suppressing electron overflow. At the same time, the hole energy is effectively increased, the hole injection efficiency is improved, and the low-power AlGaInP red-light laser has a smaller operating current and a higher photoelectric conversion efficiency.

[0114] It can be seen from Figure 2 that the newly added graded electron blocking layer in the present invention has an increased conduction band gap difference with the quantum well, enhanced ability to hinder electron overflow, and at the same time, the graded structure has a weakened hindering effect on hole accumulation, which helps to improve the hole injection efficiency.

[0115] Example 2:

[0116] A preparation method of a low-power AlGaInP red-light semiconductor laser with an optimized graded electron blocking layer 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 660 ± 10 °C at 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; the growth thickness is 0.2 μm, and the doping concentration is 4E18 atoms / cm 3 , and the doping element is Si;

[0119] S3. Keep the temperature at 660 ± 10 °C, and continue to introduce TMIn, TMGa, and PH3 to grow Ga 0.5 In 0.5 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 doping element is Si;

[0120] S4. Slowly change the temperature to 700 ± 10 °C at a heating rate of not greater than 60 °C / min, and introduce TMAl, TMIn, and PH3 to grow an n-type Al 0.52 In 0.48 P lower confinement layer on the lower transition layer; the growth thickness is 1.05 μm, and the doping concentration is 1E18 atoms / cm 3 , and the doping element is Si;

[0121] S5. Slowly change the temperature to 650 ± 10 °C at a cooling rate of 20 - 60 °C / min, and 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 = 0.4, y2 = 0.5, and the growth thickness is 0.05 μm;

[0122] 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 on the lower waveguide layer; the first quantum well is unintentionally doped, x2 = 0.4, and the growth thickness is 5 nm;

[0123] S7. Keep the temperature at 650 ± 10 °C, and introduce TMAl, TMIn, TMGa, and PH3 to grow (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer on the first quantum well; the barrier layer is unintentionally doped, x3 = 0.5, y2 = 0.42, and the growth thickness is 7 nm;

[0124] S8. Keep the temperature at 650 ± 10 °C, continue to introduce TMIn, TMGa, and PH3, and grow Ga on the barrier layer. 1- x4 In x4 P second quantum well; the second quantum well is unintentionally doped, x4 = 0.4, and the growth thickness is 5 nm.

[0125] S9. Slowly change the temperature to 700 ± 10 °C at a heating rate of 20 - 60 °C / min, continue to introduce TMAl, TMIn, TMGa, and PH3, and grow (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer; the growth thickness is 0.05 μm, x5 = 0.4, y3 = 0.5, and the doping concentration at 1 / 2 of the thickness away from the quantum well is 4E17 atoms / cm 3 ;

[0126] S10. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa, and PH3, and grow (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer; (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer is unintentionally doped, that is, no doping source is introduced, adjust the gas flow ratio of TMIn, TMAl, and TMGal, so that x6 gradually changes from 0.4 to 0.7, y4 = 0.5, the growth thickness is 5 nm, and the doping concentration gradually changes from 4E17 atoms / cm 3 to 7E17 atoms / cm 3 ;

[0127] S11. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, and PH3, and grow P-type Al 0.52 In 0.48 P first upper confinement layer; the growth thickness is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 , and the doping element is Mg;

[0128] S12. Keep the temperature at 700 ± 10 °C, continue to introduce TMIn, TMGa, and PH3, and grow P-type Ga 1-x7 In x7 P etch stop layer; the growth thickness is 10 nm, x7 = 0.6, and the doping concentration is 1E18 atoms / cm 3, the doping element is Mg;

[0129] S13, maintain the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow a P-type Al 0.52 In 0.48 P second upper confinement layer on the corrosion termination layer; the growth thickness is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 , the doping element is Mg;

[0130] S14, maintain the temperature at 700 ± 10 °C, introduce TMIn, TMAl, TMGa and PH3, and grow a Ga 0.5 In 0.5 P bandgap transition layer on the second upper confinement layer; the growth thickness is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 , the doping element is Mg;

[0131] S15, reduce the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the bandgap transition layer; the growth thickness is 0.2 μm, and the doping concentration is 7E19 atoms / cm 3 , the doping element is C.

[0132] It can be seen from Figure 3 that the thickness of the graded electron blocking layer gradually increases, the slope efficiency first decreases and then increases, showing an n-type change curve. Therefore, the thickness of the graded electron blocking layer should be between 5 - 10 nm, and the best effect of the present invention is 5 nm.

[0133] Example 3:

[0134] A method for preparing a low-power AlGaInP red semiconductor laser with an optimized graded electron blocking layer, the steps of which are as described in Example 2, the difference is that in S10, grow (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer, where x6 gradually changes from 0.3 to 0.7.

[0135] Example 4:

[0136] A method for preparing a low-power AlGaInP red semiconductor laser with an optimized graded electron blocking layer, the steps of which are as described in Example 2, the difference is that in S10, grow (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer, where x6 gradually changes from 0.4 to 0.7, y4 = 0.5, and the growth thickness is 10 nm.

Claims

1. A low-power AlGaInP red semiconductor laser with an optimized electron blocking 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, an (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, a bandgap transition layer, and a GaAs cap layer, which are arranged in sequence from bottom to top; Among them, The upper waveguide layer is (Al x5 Ga 1-x5 ) y3 In 1-y3 P upper waveguide layer; 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6; The said (Al x6 Ga 1-x6 ) y4 In 1-y4 The P component changes gradually, 0.25 ≤ x6 ≤ 0.75, 0.4 ≤ y4 ≤ 0.6, x6 changes gradually from 0.25 to 0.75, the Al component increases linearly and the Ga component decreases linearly, and the growth thickness is 1 - 20 nm; The first upper confinement layer is Al 0.52 In 0.48 The first upper confinement layer of P.

2. The low-power AlGaInP red semiconductor laser with an optimized electron blocking layer according to claim 1, wherein In the low-power AlGaInP red semiconductor laser with an optimized electron blocking layer, one or more of the following conditions are included: I. The substrate is a GaAs substrate; II. The buffer layer is a GaAs buffer layer; III. The lower transition layer is Ga 0.5 In 0.5 P lower transition layer; IV. The lower confinement layer is Al 0.52 In 0.48 P lower confinement layer; V. The lower waveguide layer is (Al x1 Ga 1-x1 ) y1 In 1-y1 P lower waveguide layer; 0.25 ≤ x1 ≤ 0.5, 0.4 ≤ y1 ≤ 0.6; VI. The first quantum well is Ga x2 In 1-x2 P first quantum well; 0.3 ≤ x2 ≤ 0.7; VII. The stack layer is (Al x3 Ga 1-x3 ) y2 In 1-y2 P stack layer; 0.25 ≤ x3 ≤ 0.55, 0.4 ≤ y2 ≤ 0.6; VIII. The second quantum well is Ga x4 In 1-x4 P second quantum well; 0.3≤x4≤0.7； IX. The etch stop layer is a Ga x7 In 1-x7 P etch stop layer; 0.5 ≤ x7 ≤ 0.7; X. The second upper confinement layer is Al 0.52 In 0.48 P second upper confinement layer; XI. The bandgap transition layer is a Ga 0.5 In 0.5 P bandgap transition layer; XII. The cap layer is a GaAs cap layer.

3. The low-power AlGaInP red semiconductor laser with an optimized gradual electron blocking layer according to claim 1, characterized in that In the low-power AlGaInP red semiconductor laser with an optimized gradual electron blocking layer, (Al x6 Ga 1-x6 ) y4 In 1- y4 The thickness of the P gradual electron blocking layer is 5 nm, x6 gradually changes from 0.4 to 0.7, y4 = 0.5, the thickness is 5 nm, and the doping concentration gradually changes from 4E17 atoms / cm 3 to 7E17 atoms / cm 3 .

4. The low-power AlGaInP red semiconductor laser with an optimized electron blocking layer according to claim 1, wherein One or more of the following conditions are included: ①. The buffer layer is a GaAs buffer layer, the doping concentration of the GaAs buffer layer is 2E18 - 5E18 atoms / cm 3 , the thickness is 0.1 - 0.3 μm, and the doping element is Si; ②. The lower transition layer is Ga 0.5 In 0.5 P lower transition layer, Ga 0.5 In 0.5 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 doping element is Si; ③. The lower confinement layer is n-type Al 0.52 In 0.48 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 doping element 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 0.05 - 0.15 μm, unintentionally doped, 0.25 ≤ x1 ≤ 0.5, 0.4 ≤ y1 ≤ 0.6; ⑤. The first quantum well is a Ga 1-x2 In x2 P first quantum well. The thickness of the Ga 1-x2 In x2 P first quantum well is 4 - 7 nm, 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, 0.25 ≤ x3 ≤ 0.55, 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 P upper waveguide layer is 0.05 - 0.15 μm, and the doping concentration at 1 / 2 of the thickness far from the quantum well is 4E17 - 1E18 atoms / cm 3 , 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6; ⑨. The first upper confinement layer is P-type Al 0.52 In 0.48 P first upper confinement layer, P-type Al 0.52 In 0.48 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 doping element 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 - 30 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x7 ≤ 0.6, and the doping element is Mg; ⑪. The second upper confinement layer is P-type Al 0.52 In 0.48 P second upper confinement layer, P-type Al 0.52 In 0.48 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 , and the doping element is Mg; ⑫. The bandgap transition layer is a Ga 0.5 In 0.5 P bandgap transition layer, and the Ga 0.5 In 0.5 P bandgap transition layer has a thickness of 0.01 - 0.05 μm and a doping concentration of 1E18 - 3E18 atoms / cm 3 , and the doping element is Mg; ⑬. The capping layer is a GaAs capping layer with a thickness of 0.1 - 0.5 μm and a doping concentration of 4E19 - 1E20 atoms / cm 3 , and the doping element is C.

5. The low-power AlGaInP red semiconductor laser with an optimized electron blocking layer according to claim 1, wherein One or more of the following conditions are included: 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 doping element is Si; ②. The lower transition layer is Ga 0.5 In 0.5 P lower transition layer, Ga 0.5 In 0.5 The doping concentration of the P lower transition layer is 2E18 atoms / cm 3 , the thickness is 0.12 μm, and the doping element is Si; ③. The lower confinement layer is n-type Al 0.52 In 0.48 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 doping element 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 0.05 μm, unintentionally doped, x1 = 0.4, y1 = 0.5; ⑤. The first quantum well is Ga 1-x2 In x2 P first quantum well, Ga 1-x2 In x2 P first quantum well has a thickness of 5 nm, is unintentionally doped, and 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 7 nm, unintentionally doped, x3 = 0.5, y2 = 0.42; 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 0.05 μm, and the doping concentration at 1 / 2 of the thickness away from the quantum well is 4E17 atoms / cm 3 , x5 = 0.4, y3 = 0.5; ⑨. The first upper confinement layer is P-type Al 0.52 In 0.48 P first upper confinement layer, P-type Al 0.52 In 0.48 The thickness of the P first upper confinement layer is 0.2 μm, and the doping concentration is 7E17 atoms / cm 3 , and the doping element 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 1E18 atoms / cm 3 , x7 = 0.6, and the doping element is Mg; ⑪. The second upper limiting layer is P-type Al 0.52 In 0.48 P second upper limiting layer, P-type Al 0.52 In 0.48 The thickness of the P second upper limiting layer is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 , and the doping element is Mg; ⑫. The bandgap transition layer is a Ga 0.5 In 0.5 P bandgap transition layer, Ga 0.5 In 0.5 The thickness of the P bandgap transition layer is 0.02 μm, and the doping concentration is 2E18 atoms / cm 3 , and the doping element is Mg; ⑬. The cap layer is a GaAs cap layer with a thickness of 0.2 μm and a doping concentration of 7E19 atoms / cm 3 , and the doping element is C.

6. A method for preparing a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer, characterized in that It includes performing surface heat treatment on a substrate in an 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 x6 Ga 1-x6 ), y4 In 1-y4 P graded electron blocking layer, a first upper confinement layer, an etch stop layer, a second upper confinement layer, a bandgap transition layer, and a GaAs cap layer in sequence from bottom to top; Among them, the upper waveguide layer is (Al x5 Ga 1-x5 ), y3 In 1-y3 P upper waveguide layer; 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6; The (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer, where 0.25 ≤ x6 ≤ 0.75 and 0.4 ≤ y4 ≤ 0.6; (Al x6 Ga 1-x6 ) y4 In 1-y4 P composition is graded, x6 is graded from 0.25 to 0.75, the Al composition increases linearly and the Ga composition decreases linearly, and the growth thickness is 1 - 20 nm; The (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer is grown under the following conditions: the growth temperature is 690 - 710 °C, TMIn, TMAl, TMGa and PH3 are introduced, and the gas flow rate ratio of TMAl and TMGa is adjusted to make x6 graded from 0.25 to 0.75; The first upper confinement layer is Al 0.52 In 0.48 P first upper confinement layer.

7. A method for fabricating a low-power AlGaInP red semiconductor laser with an optimized electron blocking layer, the method comprising the following steps: 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; S2. Slowly reduce the temperature to 660 ± 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; S3, maintain the temperature at 660±10°C, continue to introduce TMIn, TMGa and PH3, and grow a Ga 0.5 In 0.5 P underlying layer on the GaAs buffer layer; 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 0.52 In 0.48 P lower confinement layer; S5, slowly change the temperature to 650 ± 10 °C, with a cooling rate of 20 - 60 °C / min. Introduce TMAl, TMIn, TMGa, and PH3 to grow an (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer on the said lower confinement layer; S6, maintain the temperature at 650 ± 10 °C, continue to introduce TMIn, TMGa and PH3, and grow Ga 1- x2 In x2 P first quantum well; S7, the temperature is maintained at 650 ± 10 °C, and TMAl, TMIn, TMGa and PH3 are introduced to grow an (Al 1-x3 Ga x3 ) y2 In 1-y2 P barrier layer on the first quantum well; 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; S9, slowly change the temperature to 700 ± 10 °C at a heating rate of 20 - 60 °C / min, 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 described (Al 1-x5 Ga x5 ) y3 In 1-y3 The thickness of the upper waveguide layer of P is 0.05 - 0.15 μm, and the doping concentration at 1 / 2 thickness away from the quantum well is 4E17 - 1E18 atoms / cm 3 , 0.25 ≤ x5 ≤ 0.5, 0.4 ≤ y3 ≤ 0.6; S10, maintain the temperature at 700±10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow an (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer on the upper waveguide layer; Among them, in the (Al x6 Ga 1-x6 ), y4 In 1-y4 P graded electron blocking layer, 0.25 ≤ x6 ≤ 0.75, 0.4 ≤ y4 ≤ 0.6; (Al x6 Ga 1-x6 ), y4 In 1-y4 P composition is graded, x6 is graded from 0.25 to 0.75, Al composition increases linearly and Ga composition decreases linearly, and the growth thickness is 1 - 20 nm; the (Al x6 Ga 1-x6 ), y4 In 1-y4 P graded electron blocking layer is grown under the conditions: growth temperature 690 - 710 °C, adjusting the gas flow ratio of TMAl and TMGa to make x6 graded from 0.25 to 0.75; S11, maintain the temperature at 700±10 °C, continue to introduce TMIn, TMAl and PH3, and grow a P-type Al 0.52 In 0.48 P first upper confinement layer; Among them, the P-type Al 0.52 In 0.48 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; S13, maintain the temperature at 700 ± 10 °C, continue to introduce TMIn, TMAl, TMGa and PH3, and grow a P-type Al 0.52 In 0.48 P second upper confinement layer; S14, maintain the temperature at 700 ± 10 °C, introduce TMIn, TMAl, TMGa and PH3, and grow a Ga 0.5 In 0.5 P bandgap transition layer on the second upper confinement layer; S15. Reduce the temperature to 540 ± 10 °C, continue to introduce TMGa and AsH3, and grow a GaAs cap layer on the bandgap transition layer.

8. The preparation method of the low-power AlGaInP red semiconductor laser with an optimized electron blocking layer according to claim 7, characterized in that, 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; In step S3, the Ga 0.5 In 0.5 doping concentration of the P lower transition layer is 1E18 - 3E18 atoms / cm 3 , and the thickness is 0.1 - 0.3 μm; In step S4, the thickness of the n-type Al 0.52 In 0.48 P lower confinement layer is 0.5 - 1.5 μm, and the doping concentration is 5E17 - 3E18 atoms / cm 3 ; In step S5, (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, 0.25 ≤ x1 ≤ 0.5, 0.4 ≤ y1 ≤ 0.6; In step S6, the Ga 1-x2 In x2 The thickness of the first InP quantum well is 4 - 7 nm, unintentionally doped, 0.3 ≤ x2 ≤ 0.7; In step S7, (Al 1-x3 Ga x3 ) y2 In 1-y2 The thickness of the P layer is 5 - 15 nm, unintentionally doped, 0.25 ≤ x3 ≤ 0.55, 0.4 ≤ y2 ≤ 0.6; In step S8, the Ga 1-x4 In x4 The thickness of the P second quantum well is 4-7 nm, unintentionally doped, 0.3 ≤ x4 ≤ 0.7; In step S9, the thickness of the (Al 1-x5 Ga x5 ) y3 In 1-y3 P upper waveguide layer is 0.05 μm, x5 = 0.4, y3 = 0.5, and the doping concentration at 1 / 2 of the thickness away from the quantum well is 4E17 atoms / cm 3 ; In step S10, the thickness of the (Al x6 Ga 1-x6 ) y4 In 1-y4 P graded electron blocking layer is 5 nm, x6 is graded from 0.4 to 0.7, y4 = 0.5, and the doping concentration is graded from 4E17 atoms / cm 3 to 7E17 atoms / cm 3 ; In step S11, the P-type Al 0.52 In 0.48 The thickness of the first upper limiting layer of P 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 - 30 nm, and the doping concentration is 5E17 - 2E18 atoms / cm 3 , 0.4 ≤ x7 ≤ 0.6; In step S13, the P-type Al 0.52 In 0.48 The thickness of the second upper limiting layer of P is 0.5 - 1.2 μm, and the doping concentration is 5E17 - 1.5E18 atoms / cm 3 ; In step S14, the P-type Ga 0.5 In 0.5 The thickness of the P-bandgap transition layer is 0.01 - 0.05 μm, and the doping concentration is 1E18 - 3E18 atoms / cm 3 ; In step S15, the thickness of the capping layer is 0.1 - 0.5 μm, and the doping concentration is 4E19 - 1E20 atoms / cm 3 .

9. The preparation method of the low-power AlGaInP red semiconductor laser with an optimized electron blocking layer according to claim 8, 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 0.5 In 0.5 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 0.52 In 0.48 P lower confinement layer is 1.05 μm, and the doping concentration is 1E18 atoms / cm 3 ; In step S5, the (Al 1-x1 Ga x1 ) y1 In 1-y1 P lower waveguide layer has a thickness of 0.05 μm, x1 = 0.4, y1 = 0.5; In step S6, the Ga 1-x2 In x2 first quantum well of P 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 7 nm, x3 = 0.5, y2 = 0.42; In step S8, the Ga 1-x4 In x4 P second quantum well has a thickness of 5 nm and x4 = 0.4; 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 1E18 atoms / cm 3 ; In step S13, the P-type Al 0.52 In 0.48 The thickness of the second upper limiting layer of P is 0.8 μm, and the doping concentration is 1E18 atoms / cm 3 ; In step S14, the P-type Ga 0.5 In 0.5 The thickness of the P-bandgap 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 0.2 μm and the doping concentration is 7E19 atoms / cm 3 .

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