A highly uniform long-wavelength GaAs-based high-power laser epitaxial wafer and its fabrication method

Abstract

This invention relates to a highly uniform, long-wavelength GaAs-based high-power laser epitaxial wafer and its fabrication method, belonging to the field of optoelectronic technology. The method includes using MOCVD technology to sequentially grow a GaAs buffer layer and an Al layer on a GaAs substrate from bottom to top. x1 Ga 1‑x1 As N-confined layer, Al x2 Ga 1‑x2 As the lower waveguide layer, Al x3 In y1 Ga 1‑x3‑y1 As quantum well layer, Al x4 Ga 1‑x4 As upper waveguide layer, Al x5 Ga 1‑x5 An AlGaInAs quantum well with an As P confinement layer and a GaAs ohmic contact layer is grown using an atomic distribution method. The group III sources (TMAl, TMGa, TMIn) and group V sources (AsH3) are separated. Growth is stopped before quantum well growth, and the atomic distribution method is combined with low-pressure growth. During growth, AsH3 is stopped, and TMIn is introduced first. At high temperature, TMIn undergoes cleavage, and In atoms are uniformly adsorbed on the epitaxial layer surface. Then, TMAl and TMGa are introduced simultaneously, and the cleaved Al and Ga atoms are distributed on the surface of the In atoms. Finally, AsH3 is introduced to complete the growth of the AlGaInAs quantum well, achieving high-quality, uniform wavelength growth of a high-In-content quantum well.

Description

Technical Field

[0001] This invention relates to a highly uniform long-wavelength GaAs-based high-power laser epitaxial wafer and its fabrication method, belonging to the field of optoelectronic technology. Background Technology

[0002] High-power semiconductor lasers have been increasingly widely used in industrial production, laser communication, laser sensing, medical aesthetics, and military fields in recent years. With extensive research in the field of lasers, the wavelengths of semiconductor lasers have gradually expanded from visible light to invisible light, and the output power has increased from tens of milliwatts to kilowatts. Among them, the demand for long-wavelength high-power lasers has been soaring.

[0003] Advances in long-wavelength lasers have driven the development of AlGaInAs material systems, especially for lasers with wavelengths above 900 nm. As wavelength requirements increase, the In content in the quantum well has also risen accordingly. High-In quantum wells, due to the much slower diffusion rate of In compared to other group III sources like Al and Ga, result in increased surface roughness, a higher number of defects, significantly deteriorating growth quality, and uneven wavelength distribution in the epitaxial wafer. This phenomenon is particularly severe when the wavelength exceeds 1000 nm. The quantum well is crucial for the lasing process of a laser; its growth directly limits the laser's output power and conversion efficiency, and can even affect its lifespan. Therefore, finding a highly uniform long-wavelength epitaxial wafer growth method is essential. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a highly uniform, long-wavelength GaAs-based high-power laser epitaxial wafer and its fabrication method. This invention utilizes MOCVD technology to grow AlGaAs material on a GaAs substrate, with a GaAs buffer layer and an AlGaAs layer sequentially arranged from bottom to top on the GaAs substrate. x1 Ga 1-x1 As N-confined layer, Al x2 Ga 1-x2 As the lower waveguide layer, Al x3 In y1 Ga 1-x3-y1 As quantum well layer, Al x4 Ga 1-x4 As upper waveguide layer, Al x5 Ga 1-x5The invention employs an As P confinement layer and a GaAs ohmic contact layer to grow long-wavelength epitaxial AlGaInAs quantum wells using an atomic distribution method. This involves separating the group III sources (TMAl, TMGa, TMIn) and the group V source (AsH3). Growth is halted before quantum well growth, and the atomic distribution method is combined with low-pressure growth. During growth, AsH3 is stopped, and TMIn is introduced first. At high temperature, TMIn undergoes pyrolysis, causing In atoms to be uniformly adsorbed on the epitaxial layer surface. Then, TMAl and TMGa are simultaneously introduced. Because Al and Ga atoms diffuse at essentially the same rate and have smaller atomic radii than In atoms, the pyrolyzed Al and Ga atoms are distributed on the In atom surface. Finally, AsH3 is introduced to complete the growth of the AlGaInAs quantum well, achieving high-quality, uniform wavelength growth of a high-In-content quantum well.

[0005] The technical solution of the present invention is as follows:

[0006] A method for fabricating a long-wavelength GaAs-based high-power laser epitaxial wafer with high uniformity includes the following steps:

[0007] (1). Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat the H2 environment to 740-780℃ and bake for 20-40 minutes, then introduce AsH3, and the reaction chamber pressure is 50-70mbar. Perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen on the substrate surface and prepare for step (2).

[0008] According to a preferred embodiment of the present invention, the high-temperature heat treatment temperature in step (1) is 780°C, the baking time is 30 minutes, and the reaction chamber pressure is 60 mbar.

[0009] (2). When the temperature of the reaction chamber drops to 720-750℃, TMGa and AsH3 are introduced to grow a GaAs buffer layer with a thickness of 100-300nm on the GaAs substrate.

[0010] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (2) is 730°C, the growth thickness is 300 nm, and the doping concentration is 2E18-5E18 atoms / cm². 3 The reaction chamber pressure is 50-70 mbar;

[0011] In the particularly preferred step (2), the doping concentration is 3E18 atoms / cm³. 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0012] (3) When the reaction chamber temperature drops to 640-680℃, TMAl, TMGa and AsH3 are introduced to grow Al on the substrate from step (2). x1 Ga 1-x1As N confinement layer, with a thickness of 2-3 μm;

[0013] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (3) is 680°C, the growth thickness is 2.5 μm, 0.3 ≤ x1 ≤ 0.5, and the doping concentration is 5E17-2E18 atoms / cm². 3 The reaction chamber pressure is 50-70 mbar;

[0014] In the particularly preferred step (3), x1 = 0.4, the doping concentration is 1E18 atoms / cm³. 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0015] (4) Maintain the temperature at 640-680℃. After step (3) is completed, introduce TMAl, TMGa and AsH3 to grow Al. x2 Ga 1-x2 The As waveguide layer has a thickness of 500-800 nm.

[0016] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (4) is 680°C, the growth thickness is 700 nm, 0.1 ≤ x2 ≤ 0.3, and the doping concentration is 5E17-2E18 atoms / cm². 3 The reaction chamber pressure is 50-70 mbar;

[0017] In the particularly preferred step (4), x2 = 0.3, and the doping concentration is 7E17 atoms / cm³. 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0018] (5). Keep the temperature at 640-680℃. After step (4) is completed, stop the flow of TMAl, TMGa and AsH3 and stop the growth for 5-15 seconds.

[0019] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (5) is 660°C, the growth stop time is 10s, and the reaction chamber pressure is 30-50mbar.

[0020] In the particularly preferred step (5), the reaction chamber pressure is 40 mbar;

[0021] (6) Maintain the temperature at 640-680℃. After step (5) is completed, first introduce TMIn for 2-5 seconds (T1), then introduce TMGa and TMAl for 15-20 seconds (T2), and TMAl for 1-4 seconds (T3). Introduce TMGa and TMAl simultaneously, and finally introduce AsH3 to grow Al with a thickness of 5-10 nm. x3 In y1 Ga 1-y1-x3 As a quantum well layer;

[0022] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (6) is 660°C, T1 is 3s, T2 is 16s, T3 is 2s, the growth thickness is 7nm, and Al x3 In y1 Ga 1-y1-x3 In the As quantum well, the values ​​of x3 are 0.2-0.5, y1 are 0.1-0.2, and the reaction chamber pressure is 30-50 mbar.

[0023] In the particularly preferred step (6), Al x3 In y1 Ga 1-y1-x3 In the As quantum well layer, x3 takes the value of 0.3, y1 takes the value of 0.15, and the reaction chamber pressure is 40 mbar;

[0024] (7). Maintain the temperature at 640-680℃, in step (6) Al x3 In y1 Ga 1-y1-x3 After the As quantum well layer is grown, TMAl, TMGa, and AsH3 are introduced to continue growing an Al layer with a thickness of 500-800 nm. x4 Ga 1-x4 As upper waveguide layer;

[0025] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (7) is 680°C, the growth thickness is 600 nm, and Al x4 Ga 1-x4 In the As waveguide layer, x4 ranges from 0.1 to 0.3, with a doping concentration of 1E17-5E17 atoms / cm². 3 The doping source is CBr4, and the reaction chamber pressure is 50-70 mbar;

[0026] In the particularly preferred step (7), Al x4 Ga 1-x4 The value of x4 in the As waveguide layer is 0.3, and the doping concentration is 3E17 atoms / cm². 3 The reaction chamber pressure is 60 mbar;

[0027] (8) Maintain the temperature at 640-680℃. After step (7) is completed, introduce TMAl, TMGa and AsH3 to grow Al. x5 Ga 1-x5 The AsP confinement layer has a thickness of 1-3 μm;

[0028] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (8) is 680°C, the growth thickness is 1.5 μm, 0.7 ≤ x5 ≤ 0.9, and the doping concentration is 1E18-3E18 atoms / cm².3 The reaction chamber pressure is 50-70 mbar;

[0029] In the particularly preferred step (8), x5 = 0.8, and the doping concentration is 2E18 atoms / cm³. 3 The doping source was CBr4, and the reaction chamber pressure was 60 mbar.

[0030] (9) When the reaction chamber temperature drops to 540-560℃, TMGa and AsH3 are introduced, and Al... x5 Ga 1-x5 GaAs ohmic contact layers with a thickness of 100-300 nm are grown on the As P confinement layer;

[0031] According to a preferred embodiment of the present invention, the reaction chamber temperature in step (9) is 550°C, the growth thickness is 300 nm, and the doping concentration is 9E18-5E19 atoms / cm². 3 The reaction chamber pressure is 50-70 mbar;

[0032] In the particularly preferred step (9), the doping concentration is 5E19 atoms / cm³. 3 The doping source was CBr4, and the reaction chamber pressure was 60 mbar.

[0033] A highly uniform long-wavelength GaAs-based high-power laser epitaxial wafer prepared using the above-described method comprises, from bottom to top, a GaAs substrate, a GaAs buffer layer, and an Al layer. x1 Ga 1-x1 As N confinement layer, Al x2 Ga 1-x2 As lower waveguide layer, Al x3 In y1 Ga 1-x3-y1 As quantum well layer, Al x4 Ga 1-x4 As upper waveguide layer, Al x5 Ga 1-x5 As P confinement layer, GaAs ohmic contact layer;

[0034] 0.3≤x1≤0.5, 0.1≤x2≤0.3, x3 takes the value of 0.2-0.5, y1 takes the value of 0.1-0.2, x4 takes the value of 0.1-0.3, and 0.7≤x5≤0.9.

[0035] In this invention, Si2H6 is selected for doping on the N side and CBr4 is selected for doping on the P side. The role of doping on the N side is to provide electrons, and the potential difference achieved by the change of the doping gradient is conducive to the migration of electrons into the quantum well. The role of doping on the P side is to provide holes, and the potential difference achieved by the change of the doping gradient is conducive to the migration of holes into the quantum well, ultimately realizing the recombination of holes and electrons in the quantum well.

[0036] The beneficial effects of this invention are as follows:

[0037] This invention employs an atomic distribution method for growing quantum wells of long-wavelength epitaxial wafers. Taking AlGaInAs quantum wells as an example, the growth process involves stopping the flow of AsH3 and first introducing TMI. At high temperature, TMI undergoes pyrolysis, and In atoms are uniformly adsorbed on the surface of the epitaxial layer. Then, TMIAl and TMIGa are introduced simultaneously. Because the diffusion rates of Al and Ga atoms are basically the same and their atomic radii are smaller than those of In atoms, the pyrolyzed Al and Ga atoms are distributed on the surface of the In atoms. Finally, AsH3 is introduced to complete the growth of the AlGaInAs quantum well (the traditional growth method involves first introducing AsH3, and then simultaneously introducing TMIAl, TMIGa, and TMI into the reaction chamber to grow the AlGaInAs quantum well).

[0038] In addition, a low-pressure growth method is adopted during the growth process to form a higher quality quantum well and avoid the aggregation of In atoms. During the epitaxial growth of this invention, the growth pressure of the other structural layers is 60 mbar, and the AlGaInAs quantum well is 40 mbar. In the traditional growth method, the growth pressure of the reaction chamber is constant at 60 mbar.

[0039] This invention employs an atomic distribution method, separating Group III and Group V sources by prematurely stopping growth. By adjusting the growth pressure in the reaction chamber, it helps In atoms distribute better, improving both the wavelength uniformity of the epitaxial wafer and the repeatability of growth. Furthermore, this application effectively distinguishes In atoms from Ga and Al atoms, better avoiding the impact of differences in diffusion rates between In, Ga, and Al atoms. The growth method proposed in this invention, through atomic distribution combined with growth-stopping and low-pressure protection, fundamentally solves the uniformity problem caused by different In atom diffusion rates, and is applicable to single-quantum-well and multi-quantum-well products. Attached Figure Description

[0040] Figure 1 This is a diagram of the epitaxial wafer structure for a long-wavelength GaAs-based high-power laser.

[0041] Figure 2 This is a schematic diagram of atomic distribution growth. Detailed Implementation

[0042] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0043] Example 1:

[0044] A method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer, such as... Figure 1 As shown, it includes the following steps:

[0045] (1). Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat the H2 environment to 780℃ for 30 minutes, then introduce AsH3, and the reaction chamber pressure is 60mbar. Perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen on the substrate surface and prepare for step (2).

[0046] (2) When the reaction chamber temperature drops to 730℃, TMGa and AsH3 are introduced to grow a GaAs buffer layer with a thickness of 300nm on the GaAs substrate; the doping concentration is 3E18 atoms / cm. 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0047] (3) When the reaction chamber temperature drops to 680℃, TMAl, TMGa and AsH3 are introduced to grow Al on the substrate from step (2). x1 Ga 1-x1 An As N confinement layer with a thickness of 2.5 μm; x1 = 0.4, doping concentration of 1E18 atoms / cm². 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0048] (4) After maintaining the temperature at 680℃ and completing step (3), introduce TMAl, TMGa and AsH3 to grow Al. x2 Ga 1-x2 The underlying waveguide layer is made of As with a thickness of 700 nm; x² = 0.3, and the doping concentration is 7E¹⁷ atoms / cm². 3 The doping source is Si2H6, and the reaction chamber pressure is 60 mbar.

[0049] (5) Keep the temperature at 660℃. After step (4) is completed, stop the flow of TMAl, TMGa and AsH3 and stop the growth for 10s; the pressure in the reaction chamber is 40mbar.

[0050] (6) Maintain the temperature at 660℃. After step (5) is completed, first introduce TMIn for 3s (T1), then introduce TMGa and TMAl for 16s (T2), and TMAl for 2s (T3). Introduce TMGa and TMAl simultaneously, and finally introduce AsH3 to grow an Al layer with a thickness of 7nm. x3 Iny1 Ga 1-y1-x3 As a quantum well layer; such as Figure 2 As shown;

[0051] Al x3 In y1 Ga 1-y1-x3 In the As quantum well, x3 is 0.3, y1 is 0.15, and the reaction chamber pressure is 40 mbar.

[0052] (7). Maintain the temperature at 680℃, in step (6) Al x3 In y1 Ga 1-y1-x3 After the As quantum well layer was grown, TMAl, TMGa, and AsH3 were introduced to continue growing an Al layer with a thickness of 600 nm. x4 Ga 1-x4 As upper waveguide layer;

[0053] Al x4 Ga 1-x4 In the As waveguide layer, x4 is 0.3, and the doping concentration is 3E17 atoms / cm². 3 The doping source was CBr4, and the reaction chamber pressure was 60 mbar.

[0054] (8) Maintain the temperature at 680℃. After step (7) is completed, introduce TMAl, TMGa and AsH3 to grow Al. x5 Ga 1-x5 The AsP confinement layer has a thickness of 1.5 μm; x5 = 0.8, and the doping concentration is 2E18 atoms / cm². 3 The doping source was CBr4, and the reaction chamber pressure was 60 mbar.

[0055] (9) When the reaction chamber temperature drops to 550℃, TMGa and AsH3 are introduced, and Al... x5 Ga 1-x5 A GaAs ohmic contact layer with a thickness of 300 nm is grown on an As P confinement layer; the doping concentration is 5E19 atoms / cm². 3 The doping source was CBr4, and the reaction chamber pressure was 60 mbar.

[0056] Example 2:

[0057] A method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer is described in Example 1, except that in step (1), the GaAs substrate is placed in the growth chamber of an MOCVD equipment, heated to 740°C in an H2 environment for 40 minutes, and then AsH3 is introduced. The reaction chamber pressure is 50 mbar to perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen from the substrate surface and prepare for step (2). In step (2), the reaction chamber temperature is 720°C, the growth thickness is 100 nm, and the doping concentration is 2E18 atoms / cm². 3 The reaction chamber pressure was 50 mbar; the reaction chamber temperature in step (3) was 640℃, the growth thickness was 2 μm, x1 = 0.3, and the doping concentration was 5E17 atoms / cm. 3 The reaction chamber pressure is 50 mbar; the reaction chamber temperature in step (4) is 640℃, the growth thickness is 500 nm, x2 = 0.1, and the doping concentration is 5E17 atoms / cm. 3 The reaction chamber pressure is 50 mbar; the reaction chamber temperature in step (5) is 640℃, the growth stop time is 10 s, and the reaction chamber pressure is 30 mbar; the reaction chamber temperature in step (6) is 640℃, T1 is 2 s, T2 is 15 s, T3 is 1 s, and the growth thickness is 5 nm. x3 In y1 Ga 1-y1-x3 In the As quantum well, x3 is 0.2, y1 is 0.1, and the reaction chamber pressure is 30 mbar; the reaction chamber temperature in step (7) is 640℃, and the growth thickness is 500 nm. x4 Ga 1-x4 In the As waveguide layer, x4 is 0.1, and the doping concentration is 1E17 atoms / cm². 3 The doping source was CBr4, and the reaction chamber pressure was 50 mbar; the reaction chamber temperature in step (8) was 640℃, the growth thickness was 1 μm, x5 = 0.7, and the doping concentration was 1E18 atoms / cm. 3 The reaction chamber pressure was 50 mbar; the reaction chamber temperature in step (9) was 540 °C, the growth thickness was 100 nm, and the doping concentration was 9E18 atoms / cm². 3 The reaction chamber pressure is 50 mbar.

[0058] Example 3:

[0059] A method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer is described in Example 1, except that in step (1), the GaAs substrate is placed in the growth chamber of an MOCVD equipment, heated to 760°C in an H2 environment for 20 minutes, and then AsH3 is introduced. The reaction chamber pressure is 70 mbar to perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen from the substrate surface and prepare for step (2). In step (2), the reaction chamber temperature is 750°C, the growth thickness is 200 nm, and the doping concentration is 5E18 atoms / cm. 3 The reaction chamber pressure was 70 mbar; the reaction chamber temperature in step (3) was 680℃, the growth thickness was 3 μm, x1 = 0.5, and the doping concentration was 2E18 atoms / cm. 3 The reaction chamber pressure is 70 mbar; the reaction chamber temperature in step (4) is 680℃, the growth thickness is 800 nm, x2 = 0.3, and the doping concentration is 2E18 atoms / cm. 3 The reaction chamber pressure is 70 mbar; the reaction chamber temperature in step (5) is 680℃, the growth stop time is 10 s, and the reaction chamber pressure is 50 mbar; the reaction chamber temperature in step (6) is 680℃, T1 is 5 s, T2 is 20 s, T3 is 4 s, and the growth thickness is 10 nm. x3 In y1 Ga 1-y1-x3 In the As quantum well, x3 is 0.5, y1 is 0.2, and the reaction chamber pressure is 50 mbar; the reaction chamber temperature in step (7) is 680℃, and the growth thickness is 800 nm. x4 Ga 1-x4 In the As waveguide layer, x4 is 0.3, and the doping concentration is 5E17 atoms / cm². 3 The doping source was CBr4, and the reaction chamber pressure was 70 mbar; the reaction chamber temperature in step (8) was 680℃, the growth thickness was 3 μm, x5 = 0.9, and the doping concentration was 3E18 atoms / cm. 3 The reaction chamber pressure was 70 mbar; the reaction chamber temperature in step (9) was 560 °C, the growth thickness was 300 nm, and the doping concentration was 5E19 atoms / cm². 3 The reaction chamber pressure is 70 mbar.

[0060] Example 4:

[0061] A method for fabricating a high-power GaAs-based epitaxial wafer with high uniformity and long wavelength is provided, the steps of which are as described in Example 1, except that the growth stop time in step (5) is 5s.

[0062] Example 5:

[0063] A method for fabricating a long-wavelength GaAs-based high-power laser epitaxial wafer with high uniformity, the steps are as described in Example 1, except that the growth stop time in step (5) is 15s.

[0064] Example 6:

[0065] A highly uniform long-wavelength GaAs-based high-power laser epitaxial wafer prepared using the method described in Example 1 comprises, from bottom to top, a GaAs substrate, a GaAs buffer layer, and an Al layer. x1 Ga 1-x1 As N confinement layer, Al x2 Ga 1-x2 As lower waveguide layer, Al x3 In y1 Ga 1-x3-y1 As quantum well layer, Al x4 Ga 1-x4 As upper waveguide layer, Al x5 Ga 1-x5 As P confinement layer, GaAs ohmic contact layer;

[0066] x1 = 0.4, x2 = 0.3, x3 = 0.3, y1 = 0.15, x4 = 0.3, x5 = 0.8.

[0067] Comparative Example 1:

[0068] The quantum well layer was grown by first introducing AsH3 and then simultaneously introducing TMGa, TMAl and TMIn to form an Alx3Iny1Ga1-y1-x3As quantum well layer. The remaining growth conditions were the same as in Example 1 (the purpose of which is to compare the atomic distribution growth method used in this application with conventional growth).

[0069] Comparative Example 2:

[0070] In step 6, the value of y1 is increased from 0.15 in Example 1 to 0.3, while the rest of the conditions are the same as in Example 1 (because the more In content, the larger y1 is, the longer the wavelength. This comparative example is to verify the effect of the atomic distribution growth method at a longer wavelength).

[0071] Comparative Example 3:

[0072] In step 6, the value of y1 is increased from 0.15 in Example 1 to 0.3. The quantum well layer is grown by first introducing AsH3 and then simultaneously introducing TMGa, TMAl, and TMIn. x3 In y1 Ga 1-y1-x3As the quantum well layer, the rest of the conditions are the same as in Example 1 (because the higher the In content, the larger the y1, the longer the wavelength. This comparative example is to compare the difference between the atomic distribution growth method and the traditional growth method at a longer wavelength).

[0073] The epitaxial wafers grown in Examples 1, 4, and 5, as well as the three comparative examples, were subjected to whole-wafer photoluminescence (PL) mapping tests:

[0074] Table 1 Comparison of Test Results

[0075] Epitaxial wafer size Longest wavelength (nm) Shortest wavelength (nm) Wavelength difference (nm) Example 1 4 inches 899 896 3 Comparative Example 1 4 inches 904 892 12 Example 4 4 inches 900 894 6 Example 5 4 inches 905 896 9 Comparative Example 2 4 inches 948 951 3 Comparative Example 3 4 inches 946 960 14

[0076] Based on the above data, the quantum well growth method using the atomic distribution of Example 1 significantly improves the wavelength uniformity of the epitaxial wafer compared to the traditional growth method. Too short a growth stop time before quantum well growth (Example 4) leads to incomplete removal of the epitaxial wafer environment, leaving residues that affect the growth effect; too long a time (Example 5) leads to Al… x2 Ga 1-x2 The decomposition of the waveguide layer under As forms dislocations that affect the atomic distribution, resulting in unevenness. However, this is still better than the traditional method (Comparative Example 1). Comparative Examples 2 and 3 show that the atomic distribution at longer wavelengths is also better than the wavelength uniformity of the traditional growth method.

Claims

1. A method for preparing a high-uniformity long-wavelength GaAs-based high-power laser epitaxial wafer, characterized in that, The method comprises the following steps: (1). Put GaAs substrate in the growth chamber of MOCVD equipment, heat to 740-780℃ in H2 environment, bake for 20-40 minutes, then introduce AsH3, the pressure in the reaction chamber is 50-70 mbar, high temperature heat treatment is conducted on GaAs substrate to remove water and oxygen on the surface of the substrate, and preparation for step (2) is made; (2). When the temperature in the reaction chamber drops to 720-750℃, TMGa and AsH3 are introduced to grow GaAs buffer layer with a thickness of 100-300 nm on the GaAs substrate; (3). When the temperature of the reaction chamber is lowered to 640-680°C, TMAl, TMGa and AsH3 are introduced, and Al x1 Ga 1-x1 As N confinement layer, thickness 2-3um; (4). Keep the temperature at 640-680°C, after step (3) is completed, TMAl, TMGa and AsH3 are introduced, and Al x2 Ga 1-x2 As lower waveguide layer, thickness is 500-800nm; (5). After step (4) is completed, the temperature is kept at 640-680℃, the introduction of TMAl, TMGa and AsH3 is stopped, and the growth is stopped for 5-15 s; (6). Keep the temperature at 640-680℃, after step (5) is completed, first introduce TMIn, the introduction time T1 is 2-5s, then introduce TMGa, TMAl, the introduction time T2=15-20s, the introduction time T3 of TMAl is 1-4s, TMGa and TMAl are introduced at the same time, finally introduce AsH3, grow Al x3 In y1 Ga 1-y1-x3 As quantum well layer; (7). Keep the temperature at 640-680°C, and Al x3 In y1 Ga 1-y1-x3 After the growth of the Al x4 Ga 1-x4 As quantum well layer is completed, TMAl, TMGa and AsH3 are introduced, and the growth of the upper waveguide layer with a thickness of 500-800 nm is continued. (8). After step (7) is completed, TMAl, TMGa and AsH3 are introduced to grow Al x5 Ga 1-x5 As P confinement layer, thickness 1-3um; (9). When the temperature of the reaction chamber is lowered to 540-560°C, TMGa and AsH3 are introduced, and Al x5 Ga 1-x5 An ohmic contact layer of GaAs with a thickness of 100-300 nm is grown on the GaP confinement layer.

2. The method of claim 1, wherein the method further comprises the steps of: The high temperature thermal treatment of step (1) has a temperature of 780°C, a baking time of 30 minutes, and a reaction chamber pressure of 60 mbar; the reaction chamber temperature of step (2) is 730°C, the growth thickness is 300 nm, and the doping concentration is 2E18-5E18 atoms / cm 3 ; the reaction chamber pressure is 50-70 mbar; the reaction chamber temperature of step (3) is 680°C, the growth thickness is 2.5 um, 0.3≤x1≤0.5, and the doping concentration is 5E17-2E18 atoms / cm 3 ; the reaction chamber pressure is 50-70 mbar; the reaction chamber temperature of step (4) is 680°C, the growth thickness is 700 nm, 0.1≤x2≤0.3, and the doping concentration is 5E17-2E18 atoms / cm 3 ; and the reaction chamber pressure is 50-70 mbar. ​ 3. The method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer according to claim 2, characterized in that, The doping concentration in step (2) is 3E18 atoms / cm 3 The doping source is Si2H6 and the reaction chamber pressure is 60 mbar. In step (3), x1=0.4 and the doping concentration is 1E18 atoms / cm 3 The doping source is Si2H6 and the reaction chamber pressure is 60 mbar. In step (4), x2=0.3 and the doping concentration is 7E17 atoms / cm 3 The doping source is Si2H6 and the reaction chamber pressure is 60 mbar.

4. The method of claim 1, wherein the method further comprises: The temperature in the reaction chamber in step (5) is 660℃, the growth is stopped for 10 s, and the pressure in the reaction chamber is 30-50 mbar.

5. The method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer according to claim 4, characterized in that, In step (5), the pressure in the reaction chamber is 40 mbar.

6. The method of claim 1, wherein the method further comprises: The reaction chamber temperature of the step (6) is 660°C, T1 is 3s, T2 is 16s, T3 is 2s, the growth thickness is 7nm, Al x3 In y1 Ga 1-y1-x3 The value of x3 in the GaAs quantum well is 0.2-0.5, the value of y1 is 0.1-0.2, and the reaction chamber pressure is 30-50mbar.

7. The method for fabricating a high-uniformity, long-wavelength GaAs-based high-power laser epitaxial wafer according to claim 6, characterized in that, Al in step (6) x3 In y1 Ga 1-y1-x3 x3 in the As quantum well layer is 0.3, y1 is 0.15, and the reaction chamber pressure is 40 mbar.

8. The method of claim 1, wherein the method further comprises: The reaction chamber temperature of the step (7) is 680℃, the growth thickness is 600nm, Al x4 Ga 1-x4 The value of x4 in the upper waveguide layer is 0.1-0.3, and the doping concentration is 1E17-5E17 atoms / cm 3 , the doping source is CBr4, and the reaction chamber pressure is 50-70mbar; the reaction chamber temperature of the step (8) is 680℃, the growth thickness is 1.5um, 0.7≤x5≤0.9, and the doping concentration is 1E18-3E18 atoms / cm 3 , the reaction chamber pressure is 50-70mbar; the reaction chamber temperature of the step (9) is 550℃, the growth thickness is 300nm, and the doping concentration is 9E18-5E19 atoms / cm 3 , and the reaction chamber pressure is 50-70mbar.

9. The method of claim 8, wherein the method further comprises the steps of: Al in step (7) x4 Ga 1-x4 As upper waveguide layer x4 = 0.3, doping concentration = 3E17 atoms / cm 3 , reaction chamber pressure = 60 mbar; in step (8) x5 = 0.8, doping concentration = 2E18 atoms / cm 3 , doping source = CBr4, reaction chamber pressure = 60 mbar; in step (9) doping concentration = 5E19 atoms / cm 3 , doping source = CBr4, reaction chamber pressure = 60 mbar. ​ 10. A high-uniformity long-wavelength GaAs-based high-power laser epitaxial wafer prepared by the method of any one of claims 1-9, comprising, from bottom to top, a GaAs substrate, a GaAs buffer layer, an Al Ga As N confining layer, an Al Ga As lower waveguide layer, an Al In Ga As quantum well layer, an Al Ga As upper waveguide layer, an Al Ga As P confining layer, and a GaAs ohmic contact layer. x1 Ga 1-x1 As N x2 Ga 1-x2 As x3 In y1 Ga 1-x3-y1 As x4 Ga 1-x4 As x5 Ga 1-x5 As P 0.3≤x1≤0.5, 0.1≤x2≤0.3, x3 is 0.2-0.5, y1 is 0.1-0.2, x4 is 0.1-0.3, and 0.7≤x5≤0.9.

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