A GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure and its fabrication method

Abstract

This invention relates to a GaAs-based high-power laser epitaxial wafer with an extremely asymmetric three-dimensional structure and its fabrication method. From bottom to top, it comprises: a substrate, a buffer layer, an N-confinement layer, and an Al layer. x2 Ga 1‑ x2 As graded waveguide layer, Al x3 Ga 1‑x3 As N transition layer, In y1 Ga 1‑y1 As quantum well layer, Al y2 Ga 1‑y2 As P transition layer, Al y3 Ga 1‑y3 This invention employs an asymmetric composition gradient waveguide layer, a P-confinement layer, and an ohmic contact layer. The asymmetric composition gradient waveguide structure reduces the interface voltage, avoiding voltage loss and preventing the Al component in the waveguide layer from diffusing into the quantum well. This also reduces series resistance, shifting the optical field towards the N-side, reducing light absorption, and increasing output power. Simultaneously, the N-transition and P-transition layers on both sides of the quantum well serve as a third set of asymmetric structures. While retaining the advantages of extreme double asymmetry structures, this design reduces the threshold current, improves temperature characteristics, and increases conversion efficiency, perfectly addressing the disadvantages of extreme double asymmetry.

Description

Technical Field

[0001] This invention relates to a GaAs-based high-power laser epitaxial wafer with an extreme three-asymmetric structure and its fabrication method, belonging to the field of optoelectronic technology. Background Technology

[0002] Semiconductor lasers have developed rapidly in recent years, gradually replacing traditional solid-state lasers and gas lasers in an increasing number of application fields. Among them, GaAs-based high-power lasers stand out from other semiconductor lasers due to their advantages such as simple fabrication process, small size, high power density, and high electrical conversion efficiency, and are used in many industrial fields. In the industrial field, in order to achieve higher output power to meet the needs of economic and social progress, GaAs-based high-power lasers adopt traditional large-cavity epitaxial structures. However, as the requirements for power, beam quality, and conversion efficiency in industry become increasingly stringent, GaAs-based high-power laser epitaxial structures are beginning to shift towards extreme double-asymmetric structures with advantages such as low series resistance, low loss, and low carrier leakage.

[0003] The extreme double-asymmetric structure is an epitaxial structure characterized by asymmetric composition and thickness of the N-confinement and P-confinement layers, asymmetric thickness of the N-type and P-type waveguide layers, and an extremely thin P-waveguide layer. This structure addresses the problem of traditional large-cavity structures easily introducing higher-order mode lasing, leading to COD and affecting reliability. However, while the ultra-thin P-waveguide layer reduces series resistance, the significant optical field shift towards the N-side results in a lower quantum well confinement factor and gain, leading to an increased threshold current and limiting peak power. Further improvements to the epitaxial structure are still needed.

[0004] Chinese patent document CN111817137A discloses a confined enhancement GaN-based deep ultraviolet laser, comprising, from bottom to top, an N-type electrode, a substrate, an N-type lower confining layer, and an N-type Al. x Ga 1-x N-type lower waveguide layer, active region, P-type Al x Ga 1-x The structure comprises an N-type waveguide layer, a P-type electron blocking layer, a P-type upper confinement layer, a P-type GaN ohmic contact layer, and a P-type electrode; the N-type Al x Ga 1-x N-type lower waveguide layer and P-type Al x Ga 1-x The waveguide layers on N are all of graded Al composition, utilizing N-type Al x Ga 1-x N-type lower waveguide layer and P-type Al x Ga 1-xThe graded Al composition design in the N-type waveguide layer guides the optical field closer to the active region, reducing optical loss, enhancing the quantum well's confinement of charge carriers, suppressing electron leakage, and improving the threshold and output power. The N-type Al in the epitaxial structure disclosed in this patent... x Ga 1-x In the N-type lower waveguide layer, X changes from 0.6 to 0.5, and the P-type Al x Ga 1-x The waveguide layer X on N changes from 0.5 to 0.6, with a thickness of 120 nm for both. While this structure employs a gradient, the thickness and composition remain symmetrical, resulting in a symmetrical optical field distribution. This distribution is more concentrated in the P-type region, leading to greater optical loss and lower output power. Furthermore, the P-type Al... x Ga 1-x The N-waveguide layer has a low doping concentration, resulting in a large series resistance. The thicker the layer, the worse it is for lifespan and thermal stability.

[0005] Chinese patent document CN112636164A discloses an ultrathin insulating layer semiconductor laser and its fabrication method. The semiconductor laser includes a first electrode, a second electrode, a substrate disposed between the first and second electrodes and arranged sequentially from the first electrode toward the second electrode, a first metallization layer, a first confinement layer, a first waveguide layer, a first transition layer, an active layer, a second transition layer, a second waveguide layer, a second confinement layer, and a second metallization layer. At least two trenches are formed on the upper surface of the second metallization layer, and carrier-confining insulating protrusions are provided between adjacent trenches. An antireflection film and a silver reflective etching film are deposited on the front and rear cavity surfaces, respectively. The transition layers used on both sides of the active region in this patent only serve to prevent excess elements from entering the quantum well and have no effect on the optical field, threshold, or power. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a GaAs-based high-power laser epitaxial wafer with an extreme three-asymmetric structure and its fabrication method.

[0007] The technical solution of the present invention is as follows:

[0008] An epitaxial wafer for a high-power GaAs-based laser with an extremely asymmetric structure comprises, from bottom to top: a substrate, a buffer layer, an N-confinement layer, and an Al layer. x2 Ga 1-x2 As graded waveguide layer, Al x3 Ga 1-x3 As N transition layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As P transition layer, Al y3 Ga 1-y3As is a graded waveguide layer, a P-confined layer, and an ohmic contact layer.

[0009] According to a preferred embodiment of the present invention, the substrate is a GaAs substrate.

[0010] According to a preferred embodiment of the present invention, the buffer layer is a GaAs material doped with silicon atoms, with a thickness of 100-300 nm and a silicon atom doping concentration of 2 × 10⁻⁶. 18 -5×10 18 atoms / cm 3 Preferably, the thickness of the buffer layer is 300 nm; the silicon atom doping concentration is 3 × 10⁻⁶. 18 atoms / cm 3 .

[0011] According to a preferred embodiment of the present invention, the N-confining layer is an Al layer doped with silicon atoms. x1 Ga 1-x 1As material, 0.3≤x1≤0.6, thickness 2-3μm, silicon atom doping concentration 5×10⁻⁶. 17 -2×10 18 atoms / cm 3 Preferably, the thickness of the N-confinement layer is 2.5 μm, x1 = 0.4, and the silicon atom doping concentration is 1 × 10⁻⁴. 18 atoms / cm 3 .

[0012] According to a preferred embodiment of the present invention, the Al x2 Ga 1-x2 The thickness of the As-graded waveguide layer is 0.8-1.5 μm, x2 gradually increases from 0.3 to 0.4, and the silicon atom doping concentration is 5 × 10⁻⁶. 17 -2×10 18 atoms / cm 3 Preferably, the Al x2 Ga 1-x2 The thickness of the As-based graded waveguide layer is 1 μm, x2 gradually increases from 0.3 to 0.37, and the silicon doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 .

[0013] According to a preferred embodiment of the present invention, the Al x3 Ga 1-x3 The thickness of the As-N transition layer is 10-30 nm, and x3 gradually changes from 0.4 to 0.1; preferably, the Al x3 Ga 1-x3 The thickness of the As-N transition layer is 20 nm, and x3 gradually changes from 0.37 to 0.1.

[0014] According to a preferred embodiment of the present invention, the In y1 Ga1-y1 The thickness of the As quantum well layer is 5-10 nm, and 0.1 ≤ y1 ≤ 0.2; preferably, the In... y1 Ga 1-y1 The thickness of the As quantum well layer is 7 nm, and y1 = 0.15.

[0015] According to a preferred embodiment of the present invention, the Al y2 Ga 1-y2 The thickness of the As-P transition layer is 3-8 nm, and y2 gradually changes from 0.1 to 0.4. Preferably, the Al... y2 Ga 1-y2 The thickness of the As-P transition layer is 5 nm, and y2 gradually changes from 0.1 to 0.37.

[0016] According to a preferred embodiment of the present invention, the Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 5-15 nm, y3 is graded from 0.3 to 0.9, and the doping concentration of silicon atoms is 5 × 10⁻⁶. 17 -1×10 18 atoms / cm 3 Preferably, the Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 10 nm, y3 is graded from 0.37 to 0.8, and the silicon atom doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 .

[0017] According to a preferred embodiment of the present invention, the P-confining layer is Al doped with carbon atoms. y4 Ga 1-y4 As material, 0.5≤y4≤0.9, thickness 0.5-1μm, carbon atom doping concentration 1×10⁻⁶ 17 -5×10 18 atoms / cm 3 Preferably, the thickness of the P-confining layer is 0.8 μm, y4 = 0.8, and the carbon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 .

[0018] According to a preferred embodiment of the present invention, the ohmic contact layer is a carbon-doped GaAs material with a thickness of 100-300 nm and a carbon atom doping concentration of 9 × 10⁻⁶. 18 -5×10 19 atoms / cm 3 Preferably, the thickness of the ohmic contact layer is 300 nm; the silicon atom doping concentration is 5 × 10⁻⁶. 19 atoms / cm 3 .

[0019] The above-mentioned GaAs-based high-power laser epitaxial wafer with an extremely three-asymmetric structure includes the following steps:

[0020] The substrate underwent surface heat treatment in the MOCVD growth chamber, followed by epitaxial growth of a buffer layer, a buffer layer, an N-confinement layer, and an Al layer sequentially from bottom to top. x2 Ga 1-x2 As graded waveguide layer, Al x3 Ga 1-x3 As N transition layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As P transition layer, Al y3 Ga 1-y3 As consists of a graded waveguide layer, a confinement layer, and an ohmic contact layer.

[0021] According to a preferred embodiment of the present invention, the GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure includes the following steps:

[0022] (1) Place the GaAs substrate in the growth chamber of the MOCVD equipment and bake it at 740-780℃ for 20-40 minutes in H2 environment. Then, introduce AsH3 and bake for 20-40 minutes to obtain the heat-treated GaAs substrate. Perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen on the substrate surface and prepare for step (2).

[0023] (2) Lower the temperature to 720-750℃, introduce TMGa and AsH3, and grow a GaAs buffer layer on the GaAs substrate.

[0024] (3) Lower the temperature to 640-680℃, introduce TMAl, TMGa and AsH3, and grow Al on the GaAs buffer layer. x1 Ga 1- x1 As N confinement layer;

[0025] (4) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al x1 Ga 1-x1 Al grown on N-confinement layer x2 Ga 1-x2 As under graded waveguide layer;

[0026] (5) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al x2 Ga 1-x2 Al grown on the lower graded waveguide layer x3 Ga 1-x3 As N transition layer;

[0027] (6) Maintain the temperature at 640-680℃, and introduce TMGa, TMIn, and AsH3 into Al. x3 Ga 1-x3 In grown on the N transition layer y1 Ga 1-y1 As a quantum well layer;

[0028] (7) Maintain the temperature at 640-680℃, introduce TMAl, TMGa and AsH3, and in In y1 Ga 1-y1 Al grown on As quantum well layer y2 Ga 1-y2 As P transition layer;

[0029] (8) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al y2 Ga 1-y2 Al grows on the As P transition layer y3 Ga 1-y3 As with a graded waveguide layer;

[0030] (9) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al y3 Ga 1-y3 Al grown on a graded waveguide layer of As y4 Ga 1-y4 As P confinement layer;

[0031] (10) Lower the temperature to 540-560℃, introduce TMGa and AsH3, and in Al y4 Ga 1-y4 GaAs ohmic contact layers are grown on As P confinement layers.

[0032] According to a preferred embodiment of the present invention, in step (1), the temperature is raised to 780°C in an H2 environment and baked for 30 minutes, and then AsH3 is introduced and baked for another 30 minutes.

[0033] According to a preferred embodiment of the present invention, in step (2), the reaction temperature is 730°C; and the doping source is Si2H6.

[0034] According to a preferred embodiment of the present invention, in step (3), the reaction temperature is 680°C; and the doping source is Si2H6.

[0035] According to a preferred embodiment of the present invention, in step (4), the reaction temperature is 680°C; and the doping source is Si2H6.

[0036] According to a preferred embodiment of the present invention, in step (5), the reaction temperature is 680°C.

[0037] According to a preferred embodiment of the present invention, in step (6), the reaction temperature is 680°C.

[0038] According to a preferred embodiment of the present invention, in step (7), the reaction temperature is 660°C.

[0039] According to a preferred embodiment of the present invention, in step (8), the reaction temperature is 680°C.

[0040] According to a preferred embodiment of the present invention, in step (9), the reaction temperature is 680°C; and the doping source is CBr4.

[0041] According to a preferred embodiment of the present invention, in step (10), the reaction temperature is 550°C; and the doping source is CBr4.

[0042] Beneficial effects:

[0043] 1. This invention reduces the interface voltage using an asymmetric compositionally graded waveguide structure, avoiding the voltage loss caused by abrupt interface band steps in the waveguide. It also prevents the Al component in the waveguide layer from diffusing into the quantum well, reduces series resistance to shift the optical field towards the N-side, reduces absorption loss on the P-side, lowers the quantum well confinement factor, and increases power. Furthermore, Al... y3 Ga 1-y3 The gradient waveguide layer on As employs an extremely thin structural design, reducing the series resistance of the overall epitaxial structure. This not only further increases power but also reduces waste heat generation, improving reliability. Simultaneously, N-transition layers and P-transition layers of different thicknesses are introduced on both sides of the quantum well as a third set of asymmetric structures. This retains the advantages of extreme double asymmetry while reducing the threshold current, improving temperature characteristics, and increasing conversion efficiency, perfectly addressing the drawbacks of extreme double asymmetry.

[0044] 2. 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 N-side doping is to provide electrons, and the potential difference created by the change in doping gradient is conducive to the migration of electrons into the quantum well. The role of P-side doping is to provide holes, and the potential difference created by the change in doping gradient is conducive to the migration of holes into the quantum well. Ultimately, holes and electrons recombine in the quantum well, thereby enhancing the luminous efficiency of the laser. Attached Figure Description

[0045] Figure 1 This is a diagram of the epitaxial structure of GaAs based on an extreme three-asymmetric structure. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0047] Unless otherwise specified, all raw materials used in the embodiments are conventional raw materials and are commercially available; all methods used are existing methods unless otherwise specified.

[0048] Example 1

[0049] A method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure, comprising the following steps:

[0050] (1) Place the GaAs substrate in the growth chamber of the MOCVD equipment, heat it to 780°C in H2 environment for 30 minutes, then introduce AsH3 and bake for 30 minutes to obtain the heat-treated GaAs substrate; perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen on the substrate surface and prepare for step (2).

[0051] (2) The temperature was lowered to 730℃, and TMGa and AsH3 were introduced to grow a GaAs buffer layer with a thickness of 300nm on the heat-treated GaAs substrate; the doping source was Si2H6, and the silicon atom doping concentration was 2×10⁻⁶. 18 atoms / cm 3 ;

[0052] (3) The temperature was lowered to 680℃, and TMAl, TMGa and AsH3 were introduced to grow Al with a thickness of 2.5 μm on the GaAs buffer layer. x1 Ga 1-x1 As an N-confinement layer, x1 = 0.4, the doping source is Si2H6, and the silicon atom doping concentration is 1 × 10⁻⁴. 18 atoms / cm 3 ;

[0053] (4) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al x1 Ga 1-x1 Al with a thickness of 1 μm is grown on the As N-confinement layer. x2 Ga 1-x2 A graded waveguide layer is formed on top of As, with x2 gradually decreasing from 0.3 to 0.4. The doping source is Si2H6, and the silicon atom doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 ;

[0054] (5) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al x2 Ga 1-x2 A 20nm thick Al layer is grown on an As-graded waveguide layer. x3 Ga 1-x3 As an N transition layer, x3 gradually changes from 0.37 to 0.1;

[0055] (6) Maintain the temperature at 680℃, introduce TMGa, TMIn and AsH3, and in Al x3 Ga 1-x3 In with a thickness of 7 nm is grown on the As-N transition layer. y1 Ga 1-y1 As a quantum well layer, y1 = 0.15;

[0056] (7) Maintain the temperature at 660℃, introduce TMAl, TMGa and AsH3, and in In y1 Ga 1-y1 Al with a thickness of 5 nm is grown on the As quantum well layer. y2 Ga 1-y2 As a transition layer, y2 gradually changes from 0.1 to 0.37;

[0057] (8) Maintain the temperature at 680℃, and introduce TMAl, TMGa, and AsH3 into Al. y2 Ga 1-y2 Al with a thickness of 10 nm is grown on the As-P transition layer. y3 Ga 1-y3 A graded waveguide layer is formed on As, with y3 gradually decreasing from 0.37 to 0.8, and the silicon atom doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 ;

[0058] (9) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al y3 Ga 1-y3 An Al layer with a thickness of 0.8 μm is grown on an As graded waveguide layer. y4 Ga 1-y4 As a P-confined layer, y4 = 0.8, the doping source is CBr4, and the carbon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 ;

[0059] (10) Lower the temperature to 550℃, introduce TMGa and AsH3, and in Al y4 Ga 1-y4 A 300 nm thick GaAs ohmic contact layer is grown on an As P confinement layer, with CBr4 as the doping source and a carbon atom doping concentration of 5 × 10⁻⁶. 19 atoms / cm 3 .

[0060] Example 2

[0061] A method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely asymmetric structure, as described in Example 1, except that:

[0062] Step (2): The thickness of the GaAs buffer layer is 100 nm; the doping concentration of silicon atoms is 3 × 10⁻⁶. 18 atoms / cm 3 .

[0063] Step (3): Al x1 Ga 1-x The thickness of the 1As N confinement layer is 2 μm, and the silicon atom doping concentration is 8 × 10⁻⁶. 17 atoms / cm 3

[0064] Step (4): Al x2 Ga 1-x2 The thickness of the As-based graded waveguide layer is 0.8 μm, and the silicon atom doping concentration is 8 × 10⁻⁶. 17 atoms / cm 3 .

[0065] Step (5): Al x3 Ga 1-x3 The thickness of the As-N transition layer is 10 nm, and x3 gradually changes from 0.4 to 0.1.

[0066] Step (6): In y1 Ga 1-y1 The thickness of the As quantum well layer is 5 nm, and y1 = 0.1.

[0067] Step (7): Al y2 Ga 1-y2 The thickness of the As-P transition layer is 3 nm, and y2 gradually changes from 0.1 to 0.4.

[0068] Step (8): Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 5 nm, y3 is graded from 0.3 to 0.9, and the silicon atom doping concentration is 5 × 10⁻⁶. 17 atoms / cm 3 .

[0069] Step (9): Al y4 Ga 1-y4 The thickness of the As-P confinement layer is 0.5 μm, y4 = 0.5, and the carbon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 .

[0070] Step (10): The GaAs thickness is 100 nm, and the carbon atom doping concentration is 1 × 10⁻⁶. 19 atoms / cm 3 .

[0071] The other steps and conditions are the same as in Example 1.

[0072] Example 3

[0073] A method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely asymmetric structure, as described in Example 1, except that:

[0074] Step (2): The thickness of the GaAs buffer layer is 200 nm; the doping concentration of silicon atoms is 5 × 10⁻⁶. 18 atoms / cm 3 .

[0075] Step (3): Al x1 Ga 1-x The thickness of the 1As N confinement layer is 3 μm, and the silicon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3

[0076] Step (4): Al x2 Ga 1-x2 The thickness of the As-based graded waveguide layer is 1.5 μm, and the silicon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 .

[0077] Step (5): Al x3 Ga 1-x3 The thickness of the As-N transition layer is 30 nm, and x3 gradually changes from 0.4 to 0.1.

[0078] Step (6): In y1 Ga 1-y1 The thickness of the As quantum well layer is 10 nm, and y1 = 0.2.

[0079] Step (7): Al y2 Ga 1-y2 The thickness of the As-P transition layer is 8 nm, and y2 gradually changes from 0.1 to 0.4.

[0080] Step (8): Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 15 nm, y3 is graded from 0.3 to 0.9, and the doping concentration of silicon atoms is 1 × 10⁻⁶. 18 atoms / cm 3 .

[0081] Step (9): Al y4 Ga 1-y4 The thickness of the As-P confinement layer is 1 μm, y4 = 0.9, and the carbon atom doping concentration is 5 × 10⁻⁶. 18 atoms / cm 3 .

[0082] Step (10): The GaAs thickness is 100 nm, and the carbon atom doping concentration is 1 × 10⁻⁶. 19 atoms / cm 3 .

[0083] The other steps and conditions are the same as in Example 1.

[0084] Example 4

[0085] A method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely asymmetric structure, as described in Example 1, except that:

[0086] In step (5), the reaction temperature is 670℃.

[0087] In step (6), the reaction temperature is 670℃.

[0088] In step (7), the reaction temperature is 650℃.

[0089] In step (8), the reaction temperature is 670℃.

[0090] In step (9), the reaction temperature is 670℃.

[0091] In step (10), the reaction temperature is 555℃.

[0092] The other steps and conditions are the same as in Example 1.

[0093] Comparative Example 1

[0094] A method for fabricating a laser epitaxial wafer includes the following steps:

[0095] AlGaAs material was grown on a GaAs substrate using MOCVD technology. The GaAs substrate, from bottom to top, consisted of a GaAs buffer layer, an Alx1Ga1-x1As N-confinement layer, an Alx2Ga1-x2As lower graded waveguide layer, an Iny1Ga1-y1As quantum well layer, an Aly2Ga1-y2As upper graded waveguide layer, an Aly3Ga1-y3As P-confinement layer, and a GaAs ohmic contact layer. The composition and growth conditions of this comparative example were consistent with those of Example 1, except that the N-transition layers before and after the quantum well were removed.

[0096] Test case

[0097] Laser testing was performed on the laser epitaxial wafers prepared in Example 1 and Comparative Example 1.

[0098] The specific method is as follows: A laser epitaxial wafer is used to fabricate a laser chip. The laser consists of a laser chip, In solder, a Cu heat sink, and a ceramic heat sink. The laser chip is soldered onto the Cu heat sink and ceramic heat sink using In solder. A pulse tester was used at room temperature and a test current of 20A. The test data are shown in Table 1 below.

[0099] Table 1

[0100] Threshold current (A) Power (W) Conversion efficiency (%) Example 1 1.02 24 60％ Comparative Example 1 1.84 18 45％

[0101] As shown in Table 1, the epitaxial wafer of the laser in this invention enables the laser to have a lower threshold current, higher output power and conversion efficiency. This further proves that by introducing N-transition layers and P-transition layers of different thicknesses with varying compositions on both sides of the quantum well as a third set of asymmetric structures, the threshold current is reduced, the temperature characteristics are improved and the conversion efficiency is increased while retaining the advantages of the extreme double asymmetric structure, thus perfectly solving the disadvantages of the extreme double asymmetry.

Claims

1. A GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure, characterized in that, From bottom to top, it includes: substrate, buffer layer, N-confinement layer, Al x2 Ga 1-x2 As graded waveguide layer, Al x3 Ga 1-x3 As N transition layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As P transition layer, Al y3 Ga 1-y3 As graded waveguide layer, P confinement layer and ohmic contact layer; Wherein, the Al x2 Ga 1-x2 The thickness of the As-graded waveguide layer is 0.8-1.5 μm, x2 gradually increases from 0.3 to 0.4, and the silicon atom doping concentration is 5 × 10⁻⁶. 17 -2×10 18 atoms / cm 3 The Al x3 Ga 1-x3 The thickness of the As-N transition layer is 10-30 nm, and x3 gradually changes from 0.4 to 0.1; the In y1 Ga 1-y1 The thickness of the As quantum well layer is 5-10 nm, and 0.1 ≤ y1 ≤ 0.2; the Al y2 Ga 1- y2 The thickness of the As-P transition layer is 3-8 nm, and y2 gradually changes from 0.1 to 0.4; the Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 5-15 nm, y3 is graded from 0.3 to 0.9, and the doping concentration of silicon atoms is 5 × 10⁻⁶. 17 -1×10 18 atoms / cm 3 .

2. The GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 1, characterized in that, Includes one or more of the following conditions: i. The substrate is a GaAs substrate; ii. The buffer layer is a GaAs material doped with silicon atoms, with a thickness of 100-300 nm and a silicon atom doping concentration of 2 × 10⁻⁶. 18 -5×10 18 atoms / cm 3 ; iii. The N-confining layer is Al doped with silicon atoms. x1 Ga 1-x 1As material, 0.3≤x1≤0.6, thickness 2-3μm, silicon atom doping concentration 5×10⁻⁶. 17 -2×10 18 atoms / cm 3 .

3. The GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 2, characterized in that, Includes one or more of the following conditions: i. The thickness of the buffer layer is 300 nm; the silicon atom doping concentration is 3 × 10⁻⁶. 18 atoms / cm 3 ; ii. The thickness of the N-confinement layer is 2.5 μm, x1 = 0.4, and the silicon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 .

4. The GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 1, characterized in that, Includes one or more of the following conditions: i. The Al x2 Ga 1-x2 The thickness of the As-based graded waveguide layer is 1 μm, x2 gradually increases from 0.3 to 0.37, and the silicon doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 ; ii. The Al x3 Ga 1-x3 The thickness of the As-N transition layer is 20 nm, and x3 gradually changes from 0.37 to 0.

1. iii. The In mentioned y1 Ga 1-y1 The thickness of the As quantum well layer is 7 nm, and y1 = 0.15; iv. The Al y2 Ga 1-y2 The thickness of the As-P transition layer is 5 nm, and y2 gradually changes from 0.1 to 0.

37.

5. The GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 1, characterized in that, Includes one or more of the following conditions: i. The Al y3 Ga 1-y3 The thickness of the graded waveguide layer on As is 10 nm, y3 is graded from 0.37 to 0.8, and the silicon atom doping concentration is 7 × 10⁻⁶. 17 atoms / cm 3 ii. The P-confining layer is Al doped with carbon atoms. y4 Ga 1-y4 As material, 0.5≤y4≤0.9, thickness 0.5-1μm, carbon atom doping concentration 1×10⁻⁶ 17 -5×10 18 atoms / cm 3 ; iii. The ohmic contact layer is made of carbon-doped GaAs material with a thickness of 100-300 nm and a carbon atom doping concentration of 9 × 10⁻⁶. 18 -5×10 19 atoms / cm 3 .

6. The GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 5, characterized in that, Includes one or more of the following conditions: i. The thickness of the P-confined layer is 0.8 μm, y4 = 0.8, and the carbon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 ; ii. The thickness of the ohmic contact layer is 300 nm; the silicon atom doping concentration is 5 × 10⁻⁶. 19 atoms / cm 3 .

7. A method for fabricating a GaAs-based high-power laser epitaxial wafer with an extreme tri-asymmetric structure as described in any one of claims 1-6, comprising the steps of: The substrate underwent surface heat treatment in the MOCVD growth chamber, followed by epitaxial growth of a buffer layer, a buffer layer, an N-confinement layer, and an Al layer sequentially from bottom to top. x2 Ga 1-x2 As graded waveguide layer, Al x3 Ga 1-x3 As N transition layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As P transition layer, Al y3 Ga 1-y3 As consists of a graded waveguide layer, a confinement layer, and an ohmic contact layer.

8. The method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 7, characterized in that, Including the following steps: (1) Place the GaAs substrate in the growth chamber of the MOCVD equipment and bake it at 740-780℃ for 20-40 minutes in H2 environment. Then introduce AsH3 and bake for 20-40 minutes to obtain the heat-treated GaAs substrate. Perform high-temperature heat treatment on the GaAs substrate to remove water and oxygen on the substrate surface and prepare for step (2). (2) Reduce the temperature to 720-750℃, introduce TMGa and AsH3, and grow a GaAs buffer layer on the GaAs substrate; (3) Reduce the temperature to 640-680℃, introduce TMAl, TMGa and AsH3, and grow Al on the GaAs buffer layer. x1 Ga 1-x1 As N confinement layer; (4) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3 into Al x1 Ga 1-x1 Al grown on N-confinement layer x2 Ga 1-x2 As under graded waveguide layer; (5) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3 into Al x2 Ga 1-x2 Al grown on the lower graded waveguide layer x3 Ga 1-x3 As N transition layer; (6) Maintain the temperature at 640-680℃, introduce TMGa, TMIn and AsH3, and in Al x3 Ga 1-x3 In grown on the N transition layer y1 Ga 1-y1 As a quantum well layer; (7) Maintain the temperature at 640-680℃, introduce TMAl, TMGa and AsH3, and in In y1 Ga 1-y1 Al grown on As quantum well layer y2 Ga 1-y2 As P transition layer; (8) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3 into Al y2 Ga 1-y2 Al grows on the As P transition layer y3 Ga 1-y3 As with a graded waveguide layer; (9) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3 into Al y3 Ga 1-y3 Al grown on a graded waveguide layer of As y4 Ga 1-y4 As P confinement layer; (10) Lower the temperature to 540-560℃, introduce TMGa and AsH3, and in Al y4 Ga 1-y4 GaAs ohmic contact layers are grown on As P confinement layers.

9. The method for fabricating a GaAs-based high-power laser epitaxial wafer with an extremely tri-asymmetric structure as described in claim 8, characterized in that, Includes one or more of the following conditions: i. In step (1), the temperature is raised to 780°C in H2 environment and baked for 30 minutes, then AsH3 is introduced and baked for another 30 minutes; ii. In step (2), the reaction temperature is 730℃; the doping source is Si2H6; iii. In step (3), the reaction temperature is 680℃; the doping source is Si2H6; iv. In step (4), the reaction temperature is 680℃; the doping source is Si2H6; v. In step (5), the reaction temperature is 680℃; vi. In step (6), the reaction temperature is 680℃; vii. In step (7), the reaction temperature is 660℃; viii. In step (8), the reaction temperature is 680℃; ix. In step (9), the reaction temperature is 680℃; the doping source is CBr4; x. In step (10), the reaction temperature is 550℃; the doping source is CBr4.

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