A GaAs-based high-power laser epitaxial wafer with coupled waveguide structure and its fabrication method

Abstract

This invention provides a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure and its fabrication method. The epitaxial wafer of this invention comprises, from bottom to top: a substrate, a buffer layer, an N-confinement layer, and an Al layer. x2 Ga 1‑x2 As low Al built-in waveguide layer, Al x3 Ga 1‑x3 As high Al built-in waveguide layer, Al x4 Ga 1‑x4 As the first Al component graded waveguide layer, In y1 Ga 1‑y1 As quantum well layer, Al y2 Ga 1‑y2 The laser epitaxial wafer structure and growth method of this invention effectively reduce the voltage at the interface, avoid the voltage loss caused by the abrupt interface in the abrupt waveguide, and further shift the optical field to the N-side, thereby reducing the optical confinement factor and optical absorption, increasing the output power, and reducing the far-field divergence angle. This improves beam quality, avoids lasing of higher-order films, and extends the lifespan of the laser.

Description

Technical Field

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

[0002] Semiconductor lasers offer advantages such as light weight, small size, high reliability, low cost, and long lifespan. In recent years, with continuous increases in output power, semiconductor lasers have gradually replaced traditional solid-state lasers and gas lasers in a growing number of application areas. High-power semiconductor lasers are the pump sources for most high-performance laser systems, boasting high photoelectric conversion efficiency and ease of manufacturing. Industrial and military applications based on high-power semiconductor lasers are rapidly developing globally, encompassing materials processing, communications, medical applications, laser printing, laser displays, automation control, and military defense equipment. Although the output power and beam quality of semiconductor lasers have improved significantly in recent years, further improvements in these aspects are still needed to meet increasing industrial demands.

[0003] One effective way to improve the output power of semiconductor lasers is to optimize the epitaxial structure. Traditional epitaxial structure optimization methods, such as optimizing the thickness and doping gradient of the P-type waveguide layer, can improve the output power, but this method will lead to a larger divergence angle and a decrease in beam quality. Using a narrow waveguide structure can significantly reduce the spot size and improve beam quality, but the output power is relatively low. Using a large optical cavity structure is also the most frequently used optimization method. It reduces the vertical divergence angle of the laser, optimizes the beam quality, and also improves the power, but it is easy to introduce lasing of higher-order modes, resulting in COD and affecting reliability.

[0004] Chinese patent document CN111817137A discloses a confined enhancement GaN-based deep ultraviolet laser, which, from bottom to top, consists of an N-type electrode, a substrate, an N-type lower confinement layer, and an N-type Al layer. 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 gradient Al composition design in the N-type waveguide layer guides the light 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. In this patent, the Al composition of the N-type waveguide layer is gradiented from 0.6 to 0.5, and the Al composition of the P-type waveguide layer is gradiented from 0.5 to 0.6. This overall gradient of the waveguide layer prevents further shifting of the light field towards the N-side, resulting in greater light absorption and lower efficiency. Furthermore, the symmetrical structure of this patent leads to a thicker P-side, increasing series resistance and causing excessive waste heat, resulting in poorer output power, COD stability, and lifespan parameters of the device.

[0005] Chinese patent document CN107732656A discloses an epitaxial structure for a low-threshold, small-divergence-angle semiconductor laser, comprising a substrate (1), a buffer layer (2), an n-type lower confinement layer (3), an n-type lower mode extension layer (4), an n-type lower low-refractive-index layer (5), a graded lower waveguide layer (6), a lower barrier layer (7), an active layer (8), an upper barrier layer (9), a graded upper waveguide layer (10), a p-type upper low-refractive-index layer (11), a p-type upper mode extension layer (12), a p-type upper confinement layer (13), and an ohmic contact layer (14). The low-refractive-index layers (5) and (11), and the mode extension layers (4) and (12) are optimized. Through this design, the present invention presents a novel epitaxial structure that introduces a low-refractive-index layer and a mode extension layer to reduce the vertical divergence angle of the laser, achieving a small divergence angle while maintaining a low threshold current density. This patent employs a symmetrical structure with N-side and P-side. Since the composition and thickness of the P-side are basically the same as those of the N-side, although the light is extended through the waveguide layer, the light field is shifted towards the N-side. This makes it impossible to solve the problem of light absorption by holes on the P-side, resulting in a decrease in efficiency. Furthermore, due to the greater thickness of the P-side, the series resistance is larger, which not only results in a larger voltage but also generates excess waste heat that further reduces the device's output power, COD power, and aging life.

[0006] The demand for high-power semiconductor lasers is increasing, with higher requirements for power and beam quality. Therefore, it is crucial to find an epitaxial structure that can balance output power and beam quality. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure and its fabrication method.

[0008] The technical solution of the present invention is as follows:

[0009] A GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure comprises, from bottom to top: a substrate, a buffer layer, an N-confinement layer, and an Al layer. x2 Ga1-x2 As low Al built-in waveguide layer, Al x3 Ga 1-x3 As high Al built-in waveguide layer, Al x4 Ga 1-x4 As the first Al component graded waveguide layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As a second Al component graded waveguide layer, a P confinement layer, and an ohmic contact layer.

[0010] According to a preferred embodiment of the present invention, the substrate is a GaAs substrate.

[0011] 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 .

[0012] 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, 0.2≤x1≤0.4, thickness 1-1.8μm, silicon atom doping concentration 5×10⁻⁶ 17 -2×10 18 atoms / cm 3 Preferably, the thickness of the N-confinement layer is 1.5 μm, x1 = 0.3, and the silicon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 .

[0013] According to a preferred embodiment of the present invention, the Al x2 Ga 1-x2 The thickness of the As-based low-Al embedded waveguide layer is 0.1-0.2 μm, where 0.1 ≤ x² ≤ 0.3, 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 low-Al embedded waveguide layer is 0.1 μm, x2 = 0.2, and the silicon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 .

[0014] According to a preferred embodiment of the present invention, the Alx3 Ga 1-x3 The thickness of the As high-Al built-in waveguide layer is 0.05-0.07 μm, where 0.7 ≤ x3 ≤ 0.9; preferably, the Al... x3 Ga 1-x3 The thickness of the As high-Al built-in waveguide layer is 0.06 μm, and x3 = 0.8.

[0015] According to a preferred embodiment of the present invention, the Al x4 Ga 1-x4 The thickness of the first Al component graded waveguide layer is 0.1-0.2 μm, and x4 gradually changes from 0.7 to 0.1; preferably, the Al... x4 Ga 1-x4 The thickness of the first Al component graded waveguide layer is 0.1 μm, and x4 is graded from 0.6 to 0.2.

[0016] According to a preferred embodiment of the present invention, the In y1 Ga 1-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.

[0017] According to a preferred embodiment of the present invention, the Al y2 Ga 1-y2 The thickness of the second Al-component graded waveguide layer is 0.1-0.2 μm, and y2 gradually changes from 0.1 to 0.8. Preferably, the Al... y2 Ga 1-y2 The thickness of the second Al component graded waveguide layer is 0.1 μm, and y2 gradually changes from 0.2 to 0.8.

[0018] According to a preferred embodiment of the present invention, the P-confining layer is Al doped with carbon atoms. y3 Ga 1-y3 As material, 0.7≤y3≤0.9, thickness 1-3μm, carbon atom doping concentration 1×10⁻⁶ 18 -3×10 18 atoms / cm 3 Preferably, the thickness of the P-confining layer is 1.5 μm, y3 = 0.8, and the carbon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 .

[0019] 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 / cm3 Preferably, the thickness of the ohmic contact layer is 300 nm; the silicon atom doping concentration is 5 × 10⁻⁶. 19 atoms / cm 3 .

[0020] The above-mentioned method for fabricating GaAs-based high-power laser epitaxial wafers with coupled waveguide structures includes the following steps:

[0021] 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 low Al built-in waveguide layer, Al x3 Ga 1-x3 As high Al built-in waveguide layer, Al x4 Ga 1-x4 As the first Al component graded waveguide layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As a second Al component graded waveguide layer, a P confinement layer, and an ohmic contact layer.

[0022] According to a preferred embodiment of the present invention, the method for fabricating the GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure includes the following steps:

[0023] (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).

[0024] (2) Lower the temperature to 720-750℃, introduce TMGa and AsH3, and grow a GaAs buffer layer on the heat-treated GaAs substrate.

[0025] (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;

[0026] (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 low-Al built-in waveguide layer;

[0027] (5) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al x2 Ga 1-x2 Al grown on low-Al built-in waveguide layer x3 Ga 1-x3 As high Al built-in waveguide layer;

[0028] (6) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al x3 Ga 1-x3 Al grown on high Al built-in waveguide layer x4 Ga 1-x4 As the first Al component graded waveguide layer;

[0029] (7) Maintain the temperature at 640-680℃, introduce TMGa, TMIn and AsH3, and in Al x4 Ga 1-x4 In grown on the first Al component graded waveguide layer y1 Ga 1-y1 As a quantum well layer;

[0030] (8) Maintain the temperature at 640-680℃, introduce TMAl, TMGa and AsH3, and in IIn y1 Ga 1-y1 Al grown on As quantum well layer y2 Ga 1-y2 As the second Al component graded waveguide layer;

[0031] (9) Maintain the temperature at 640-680℃, and introduce TMAl, TMGa and AsH3, in Al y2 Ga 1-y2 Al is grown on the second Al component graded waveguide layer. y3 Ga 1-y3 As P confinement layer;

[0032] (10) Lower the temperature to 540-560℃, introduce TMGa and AsH3, and in Al y3 Ga 1-y3 GaAs ohmic contact layers are grown on As P confinement layers.

[0033] 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.

[0034] According to a preferred embodiment of the present invention, in step (2), the reaction temperature is 730°C; and the doping source is Si2H6.

[0035] According to a preferred embodiment of the present invention, in step (3), the reaction temperature is 680°C; and the doping source is Si2H6.

[0036] According to a preferred embodiment of the present invention, in step (4), the reaction temperature is 680°C; and the doping source is Si2H6.

[0037] According to a preferred embodiment of the present invention, in step (5), the reaction temperature is 680°C.

[0038] According to a preferred embodiment of the present invention, in step (6), the reaction temperature is 680°C.

[0039] According to a preferred embodiment of the present invention, in step (7), the reaction temperature is 660°C.

[0040] According to a preferred embodiment of the present invention, in step (8), the reaction temperature is 680°C.

[0041] According to a preferred embodiment of the present invention, in step (9), the reaction temperature is 680°C; and the doping source is CBr4.

[0042] According to a preferred embodiment of the present invention, in step (10), the reaction temperature is 550°C; and the doping source is CBr4.

[0043] Technical features of the present invention:

[0044] This invention meticulously decomposes the waveguide layer, dividing the N-waveguide layer into three parts: the first part is a doped low-Al embedded waveguide layer with a thickness of 0.1-0.2 μm; the second part is a doped high-Al embedded waveguide layer with a thickness of 0.05-0.07 μm; and the third part is an undoped Al-component graded waveguide layer with a thickness of 0.1-0.2 μm, where the Al composition gradually changes from 0.7 to 0.1. The P-side waveguide layer also employs an undoped Al-component graded waveguide layer with a thickness of 0.1-0.2 μm, where the Al composition gradually changes from 0.1 to 0.8. This is achieved through a coupling waveguide on the N-side. The greater refractive index difference between low-Al and high-Al waveguides is more conducive to the expansion of the light field on the N-side. The asymmetric structure further shifts the light field to the N-side without increasing the thickness of the N-side, reducing the optical confinement factor and increasing output power. It also reduces the far-field divergence angle, improves beam quality, avoids lasing of higher-order films, and increases the lifespan of the laser. Furthermore, the composition-gradient waveguide layer reduces the interface voltage, avoiding the voltage loss caused by abrupt interfaces in abrupt waveguides, and also prevents the Al composition in the waveguide layer from diffusing into the quantum well. The thin P-type waveguide layer design reduces series resistance, further shifting the light field to the N-side while reducing waste heat generation and improving product stability.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. This invention selects Al with gradually changing components. x Ga 1-x As material, in In y1 Ga 1-y1 As quantum well layers are respectively set with Al x4 Ga 1-x4 As the first Al component graded waveguide layer and Al y2 Ga 1-y2 As the second Al-component graded waveguide layer, it effectively reduces the voltage at the interface, avoids the voltage loss caused by the abrupt interface in the abrupt waveguide, and also prevents the Al component in the first Al-component graded waveguide layer and the second Al-component graded waveguide layer from diffusing into the quantum well.

[0047] 2. In this invention, Al is disposed on the N-confining layer. x2 Ga 1-x2 As low Al built-in waveguide layer and Al x3 Ga 1-x3 As a high-Al built-in waveguide layer, the light field is shifted to the N-side without increasing the thickness of the N-side. Furthermore, the thin second Al composition gradient waveguide layer design reduces the series resistance and further shifts the light field to the N-side. This reduces the optical confinement factor and light absorption, increases the output power, and decreases the far-field divergence angle. This not only improves the beam quality and avoids lasing of higher-order films, but also extends the lifespan of the laser. Attached Figure Description

[0048] Figure 1 The diagram shows the epitaxial wafer structure of the GaAs-based high-power laser with a coupled waveguide structure prepared in Example 1. Detailed Implementation

[0049] The present invention will be further described below with reference to embodiments and accompanying drawings.

[0050] 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.

[0051] Example 1

[0052] A method for fabricating a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure, comprising the following steps:

[0053] (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).

[0054] (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 ;

[0055] (3) The temperature was lowered to 680℃, and TMAl, TMGa and AsH3 were introduced to grow an Al layer with a thickness of 1.5 μm on the GaAs buffer layer. x1 Ga 1-x1 As an N-confinement layer, x1 = 0.3, the doping source is Si2H6, and the silicon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 ;

[0056] (4) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al x1 Ga 1-x1 Al with a thickness of 0.1 μm is grown on an As N confinement layer. x2 Ga 1-x2 The As low-Al built-in waveguide layer uses Si2H6 as the doping source, and the silicon atom doping concentration is 1×10⁻⁶. 18 atoms / cm 3 x2 = 0.2;

[0057] (5) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al x2 Ga 1-x2 Al with a thickness of 0.06 μm is grown on an As low-Al built-in waveguide layer. x3 Ga 1-x3 As high Al built-in waveguide layer, x3=0.8;

[0058] (6) Maintain the temperature at 680℃, and introduce TMAl, TMGa, and AsH3 into Al. x3 Ga 1-x3 Al with a thickness of 0.1 μm is grown on an As high-Al built-in waveguide layer. x4 Ga 1-x4 As the first Al component graded waveguide layer, x4 is graded from 0.6 to 0.2;

[0059] (7) Maintain the temperature at 660℃, introduce TMGa, TMIn and AsH3, and in Al x4 Ga 1-x4 An In layer with a thickness of 7 nm is grown on the first Al component graded waveguide layer. y1 Ga 1-y1 As a quantum well layer, y1 = 0.15;

[0060] (8) Maintain the temperature at 680℃, introduce TMAl, TMGa and AsH3, and in In y1 Ga 1-y1 Al with a thickness of 0.1 μm is grown on the As quantum well layer. y2 Ga 1-y2 As is the second Al-component graded waveguide layer, where y2 is graded from 0.2 to 0.8;

[0061] (9) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al y2 Ga 1-y2 An Al layer with a thickness of 1.5 μm is grown on the second Al composition graded waveguide layer. y3 Ga 1-y3 The As P confinement layer uses CBr4 as the doping source, with a carbon atom doping concentration of 2 × 10⁻⁶. 18 atoms / cm 3 y3 = 0.8;

[0062] (10) Lower the temperature to 550℃, introduce TMGa and AsH3, and in Al y3 Ga 1-y3 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 .

[0063] Example 2

[0064] A method for fabricating a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure, as described in Example 1, except that:

[0065] 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 .

[0066] Step (3): Al x1 Ga 1-x The thickness of the 1As N confinement layer is 1.2 μm, and the silicon atom doping concentration is 8 × 10⁻⁶. 17 atoms / cm 3

[0067] Step (4): Al x2 Ga 1-x2 The thickness of the As low-Al embedded waveguide layer is 0.15 μm, and the silicon atom doping concentration is 8 × 10⁻⁶. 17 atoms / cm 3 .

[0068] Step (5): Al x3 Ga 1-x3 The thickness of the As high-Al built-in waveguide layer is 0.05 μm.

[0069] Step (6): The Al x4 Ga 1-x4 The thickness of the first Al component graded waveguide layer is 0.15 μm.

[0070] Step (7): In y1 Ga 1-y1 The thickness of the As quantum well layer is 8 nm.

[0071] Step (8): Al y2 Ga 1-y2 The thickness of the second Al component graded waveguide layer is 0.15 μm.

[0072] Step (9): Al y3 Ga 1-y3 The thickness of the As-P confinement layer is 2 μm, and the carbon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 .

[0073] Step (10): The GaAs thickness is 100 nm, and the carbon atom doping concentration is 1 × 10⁻⁶. 19 atoms / cm 3 .

[0074] The other steps and conditions are the same as in Example 1.

[0075] Example 3

[0076] A method for fabricating a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure, as described in Example 1, except that:

[0077] Step (2): The thickness of the GaAs buffer layer is 200 nm; the doping concentration of silicon atoms is 3 × 10⁻⁶. 18 atoms / cm 3 .

[0078] Step (3): Al x1 Ga 1-x The thickness of the 1As N confinement layer is 1.3 μm, and the silicon atom doping concentration is 9 × 10⁻⁶. 17 atoms / cm 3

[0079] Step (4): Al x2 Ga 1-x2 The thickness of the As low-Al embedded waveguide layer is 0.17 μm, and the silicon atom doping concentration is 9 × 10⁻⁶.17 atoms / cm 3 .

[0080] Step (5): Al x3 Ga 1-x3 The thickness of the As high-Al built-in waveguide layer is 0.055 μm.

[0081] Step (6): The Al x4 Ga 1-x4 The thickness of the first Al component graded waveguide layer is 0.13 μm.

[0082] Step (7): In y1 Ga 1-y1 The thickness of the As quantum well layer is 7 nm.

[0083] Step (8): Al y2 Ga 1-y2 The thickness of the second Al-component graded waveguide layer is 0.16 μm.

[0084] Step (9): Al y3 Ga 1-y3 The thickness of the As-P confinement layer is 2 μm, and the carbon atom doping concentration is 2 × 10⁻⁶. 18 atoms / cm 3 .

[0085] Step (10): The GaAs thickness is 100 nm, and the carbon atom doping concentration is 2 × 10⁻⁶. 19 atoms / cm 3 .

[0086] The other steps and conditions are the same as in Example 1.

[0087] Example 4

[0088] A method for fabricating a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure, as described in Example 1, except that:

[0089] In step (5), the reaction temperature is 670℃.

[0090] In step (6), the reaction temperature is 670℃.

[0091] In step (7), the reaction temperature is 650℃.

[0092] In step (8), the reaction temperature is 670℃.

[0093] In step (9), the reaction temperature is 670℃.

[0094] In step (10), the reaction temperature is 555℃.

[0095] The other steps and conditions are the same as in Example 1.

[0096] Comparative Example 1

[0097] A method for fabricating a laser epitaxial wafer includes the following steps:

[0098] (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).

[0099] (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 ;

[0100] (3) The temperature was lowered to 680℃, and TMAl, TMGa and AsH3 were introduced to grow an Al layer with a thickness of 1.5 μm on the GaAs buffer layer. x1 Ga 1-x1 As an N-confinement layer, x1 = 0.3, the doping source is Si2H6, and the silicon atom doping concentration is 1 × 10⁻⁶. 18 atoms / cm 3 ;

[0101] (4) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al x1 Ga 1-x1 Al with a thickness of 0.26 μm is grown on an As N confinement layer. x2 Ga 1-x2 As is the first Al component graded waveguide layer, x2 is graded from 0.3 to 0.2;

[0102] (5) Maintain the temperature at 660℃, introduce TMGa, TMIn and AsH3, and in Al x2 Ga 1-x2 In with a thickness of 7 nm is grown on an As composition graded waveguide layer. y1 Ga 1-y1 As a quantum well layer, y1 = 0.15;

[0103] (6) Maintain the temperature at 680℃, introduce TMAl, TMGa and AsH3, and in In y1 Ga 1-y1 Al with a thickness of 0.1 μm is grown on the As quantum well layer. y2 Ga 1-y2As is the second Al component graded waveguide layer, y2 is graded from 0.2 to 0.8;

[0104] (7) Maintain the temperature at 680℃, and introduce TMAl, TMGa and AsH3, in Al y2 Ga 1-y2 An Al layer with a thickness of 1.5 μm is grown on the second Al composition graded waveguide layer. y3 Ga 1-y3 The As P confinement layer uses CBr4 as the doping source, with a carbon atom doping concentration of 2 × 10⁻⁶. 18 atoms / cm 3 y3 = 0.8;

[0105] (8) Lower the temperature to 550℃, introduce TMGa and AsH3, and in Al y3 Ga 1-y3 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 .

[0106] Test case

[0107] Laser testing was performed on the laser epitaxial wafers prepared in Example 1 and Comparative Example 1.

[0108] Laser epitaxial wafers were used to fabricate laser chips. The laser consisted of a laser chip, In solder, a Cu heat sink, and a ceramic heat sink. The laser chip was soldered onto the Cu heat sink and ceramic heat sink using In solder. Pulse testing was performed at room temperature and a test current of 10A using a bar-based comprehensive performance tester.

[0109] The test data is shown in Table 1 below:

[0110]

[0111] As shown in Table 1, the epitaxial wafer of the laser in this invention enables the laser to have higher output power and conversion efficiency, smaller horizontal and vertical divergence angles, and lower threshold current, which not only improves beam quality and avoids lasing of higher-order films, but also extends the lifespan of the laser.

Claims

1. A GaAs-based high power laser epitaxial wafer with a coupled waveguide structure, comprising, in order from bottom to top: substrate, buffer layer, N confinement layer, Al x2 Ga 1-x2 As low Al built-in waveguide layer, Al x3 Ga 1-x3 As high Al built-in waveguide layer, Al x4 Ga 1-x4 As first Al composition graded waveguide layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As second Al composition graded waveguide layer, P confinement layer and ohmic contact layer; Wherein, the Al x2 Ga 1-x2 As low Al built-in waveguide layer is 0.1-0.2 μm, 0.1≤x2≤0.3, the doping concentration of silicon atoms is 5×10 17 -2×10 18 atoms / cm 3 ; The Al x3 Ga 1-x3 As high Al built-in waveguide layer thickness of 0.05-0.07 μm, 0.7≤x3≤0.9; The Al x4 Ga 1-x4 As the thickness of the first Al component graded waveguide layer is 0.1-0.2 μm, x4 is graded from 0.7 to 0.1; The Al y2 Ga 1-y2 As the thickness of the second Al component graded waveguide layer is 0.1-0.2 μm, y2 is graded from 0.1 to 0.

8.

2. A GaAs-based high power laser epitaxial wafer with a coupled waveguide structure as claimed in claim 1, characterized in that, comprise 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 doping concentration of silicon atoms of 2 x 1018-5 x 1019atoms / cm3. 18 -5 x 1019atoms / cm3. 18 -5 x 1019atoms / cm3. 3 ​ iii. The N-limiting layer is Al doped with silicon atoms x1 Ga 1-x 1As material, 0.2≤x1≤0.4, thickness 1-1.8 μm, doping concentration of silicon atoms 5x1019atoms / cm3 17 -2x1019atoms / cm3 18 -2x1019atoms / cm3 3 .

3. A GaAs-based high power laser epitaxial wafer with a coupled waveguide structure as set forth in claim 2, wherein, comprise one or more of the following conditions: i. the thickness of the buffer layer is 300 nm; the doping concentration of silicon atoms is 3 x 1018atoms / cm2 18 ; and 3 ; ii. The N limiting layer has a thickness of 1.5 μm, x1=0.3, and a doping concentration of 1 x 1018 atoms / cm3 18 3 .​ 4. The GaAs-based high power laser epitaxial wafer with coupled waveguide structure of claim 1, wherein, comprise one or more of the following conditions: i, the In y1 Ga 1-y1 The thickness of the As quantum well layer is 5-10 nm, and 0.1≤y1≤0.

2. ii. The P-limiting layer is Al doped with carbon atoms y3 Ga 1-y3 As material, 0.7≤y3≤0.9, with a thickness of 1-3 μm and a doping concentration of carbon atoms of 1 x 10 18 -3 x 10 18 atoms / cm 3 ; iii. The ohmic contact layer is a carbon atom doped GaAs material with a thickness of 100-300 nm and a carbon atom doping concentration of 9 x 1019atoms / cm3. 18 -5 x 1018atoms / cm3 19 -5 x 1018atoms / cm3 3 .

5. A GaAs-based high power laser epitaxial wafer with a coupled waveguide structure as set forth in claim 4, wherein, comprise one or more of the following conditions: i, the In y1 Ga 1-y1 The thickness of the As quantum well layer is 7 nm, and y1=0.

15. ii. The thickness of the P-limiting layer is 1.5 μm, y3=0.8, and the doping concentration of carbon atoms is 2 x 10 18 atoms / cm 3 ; iii. The thickness of the ohmic contact layer is 300 nm; the doping concentration of silicon atoms is 5 x 1019 atoms / cm 19 3 .​ 6. The GaAs-based high power laser epitaxial wafer with coupled waveguide structure of claim 1, wherein, The Al x2 Ga 1-x2 As low Al built-in waveguide layer is 0.1 μm, x2=0.2, the doping concentration of silicon atoms is 1 x 10 18 atoms / cm 3 .

7. The GaAs-based high power laser epitaxial wafer with coupled waveguide structure of claim 1, wherein, The Al x3 Ga 1-x3 As high Al built-in waveguide layer is 0.06 μm, x3=0.

8.

8. The GaAs-based high power laser epitaxial wafer with coupled waveguide structure of claim 1, wherein, The Al x4 Ga 1-x4 As the thickness of the first Al composition-graded waveguide layer is 0.1 μm, x4 is graded from 0.6 to 0.

2.

9. The GaAs-based high power laser epitaxial wafer with coupled waveguide structure of claim 1, wherein, The Al y2 Ga 1-y2 As the thickness of the second Al composition graded waveguide layer is 0.1 μm, y2 is graded from 0.2 to 0.

8.

10. The method for preparing a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure according to any one of claims 1-9, comprising the steps of: The substrate is subjected to surface thermal treatment in a MOCVD growth chamber, and then buffer layer, buffer layer, N confinement layer, Al x2 Ga 1-x2 As low Al built-in waveguide layer, Al x3 Ga 1-x3 As high Al built-in waveguide layer, Al x4 Ga 1-x4 As first Al composition gradient waveguide layer, In y1 Ga 1-y1 As quantum well layer, Al y2 Ga 1-y2 As second Al composition gradient waveguide layer, P confinement layer and ohmic contact layer; wherein, The Al x2 Ga 1-x2 As low Al built-in waveguide layer has a thickness of 0.1-0.2 μm, 0.1≤x2≤0.3, and a doping concentration of silicon atoms of 5x1018atoms / cm 17 -2x1019atoms / cm 18 3 ;​ The Al x3 Ga 1-x3 As high Al built-in waveguide layer thickness of 0.05-0.07 μm, 0.7≤x3≤0.9; The Al x4 Ga 1-x4 As the thickness of the first Al component graded waveguide layer is 0.1-0.2 μm, x4 is graded from 0.7 to 0.1; The Al y2 Ga 1-y2 As the thickness of the second Al component graded waveguide layer is 0.1-0.2 μm, y2 is graded from 0.1 to 0.

8.

11. The method for preparing a GaAs-based high-power laser epitaxial wafer with a coupled waveguide structure according to claim 10, comprising the steps of: (1) placing a GaAs substrate in a growth chamber of a MOCVD device, baking at 740-780℃ for 20-40 minutes under H2 environment, then baking for 20-40 minutes under AsH3, to obtain a heat-treated GaAs substrate; high-temperature heat treatment is performed on the GaAs substrate to remove water and oxygen on the surface of the substrate, and to prepare for step (2); (2) reducing the temperature to 720-750℃, and introducing TMGa and AsH3 to grow a GaAs buffer layer on the heat-treated GaAs substrate; (3) The temperature is lowered to 640-680°C, TMAl, TMGa and AsH3 are introduced, and Al x1 Ga 1-x1 As N confinement layer (4) The temperature is maintained at 640-680°C, TMAl, TMGa and AsH3 are introduced, and Al x1 Ga 1-x1 As N restriction layer is grown on the Al x2 Ga 1-x2 As low Al built-in waveguide layer; (5) Maintaining the temperature at 640-680°C, TMAl, TMGa and AsH3 are introduced to grow Al x2 Ga 1-x2 As low Al built-in waveguide layer on the Al x3 Ga 1-x3 Ga high Al built-in waveguide layer; (6) keeping the temperature at 640-680 °C, introducing TMAl, TMGa and AsH3, and growing an Al x3 Ga 1-x3 As first Al composition graded waveguide layer on the Al x4 Ga 1-x4 As high Al built-in waveguide layer; (7) Maintaining the temperature at 640-680°C, TMGa, TMIn and AsH3 are introduced, and Al x4 Ga 1-x4 As first Al component graded waveguide layer y1 Ga 1-y1 As quantum well layer (8) The temperature is maintained at 640-680 °C, TMAl, TMGa and AsH3 are introduced, and Al y1 Ga 1-y1 As quantum well layers are grown on In y2 Ga 1-y2 As second Al composition graded waveguide layer; (9) Maintaining the temperature at 640-680°C, TMAl, TMGa and AsH3 are introduced, and Al y2 Ga 1-y2 As the second Al component graded waveguide layer is grown on the Al y3 Ga 1-y3 As P confinement layer; (10) The temperature is lowered to 540-560°C, TMGa and AsH3 are introduced, and a GaAs ohmic contact layer is grown on the AlGaAs P-limiting layer. y3 Ga 1-y3 As P-limiting layer.

12. The method of claim 11, wherein the GaAs-based high power laser epitaxial wafer with a coupled waveguide structure is prepared by the steps of: comprise one or more of the following conditions: ​ i. in step (1), baking at 780℃ for 30 minutes under H2 environment, then baking for 30 minutes under AsH3; 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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