Strain-compensated quantum well material for EELs and method of making same

Abstract

The application provides a strain compensation type quantum well material for an EEL (edge emitting laser) and a preparation method thereof, and belongs to the technical field of semiconductor optoelectronic devices. The material comprises a substrate, a lower limiting layer, a lower waveguide layer, a multi-quantum well active region, a strain compensation shell layer, an upper waveguide layer and an upper limiting layer. The multi-quantum well active region is formed by alternately growing InGaAs quantum well layers with compressive strain and AlGaInP barrier layers with tensile strain, so that strain self-compensation is achieved; the strain compensation shell layer adopts an Al component gradient change structure, so that strain accumulation and quantum confinement Stark effect are further inhibited. The preparation method adopts processes such as molecular beam epitaxy, temperature oscillation, dynamic beam current modulation and multi-layer in-situ annealing, so that the material quality and interface flatness are improved. The application effectively improves the temperature stability, output power and service life of the device, and is suitable for optoelectronic devices such as 905 nm band lasers.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device technology, and in particular to a strain-compensated quantum well material for EEL and its preparation method. Background Technology

[0002] Edge-emitting lasers, as an important component of optoelectronic devices, play a crucial role in fields such as lidar, optical communication, and sensing. Among them, 905nm edge-emitting lasers have attracted widespread attention from the industry due to their core position in lidar systems.

[0003] However, the InGaAs / GaAs quantum well structure used in existing technologies faces several pressing technical challenges. Due to the significant lattice mismatch between InGaAs and the GaAs substrate, substantial compressive strain is generated during quantum well growth. As the quantum well cycle number increases, this strain accumulates, and when it exceeds the material's critical thickness, it leads to crystal defects, severely impacting device performance and reliability. Furthermore, traditional structures exhibit significant wavelength drift and efficiency degradation over a wide temperature range, failing to meet the stringent temperature stability requirements of modern applications. In addition, the quantum confinement Stark effect also enhances the built-in electric field, further limiting device performance improvement.

[0004] This application effectively solves the above-mentioned technical problems through innovative strain-compensated quantum well material design and fabrication methods. By introducing a strain compensation mechanism and bandgap engineering technology, the temperature stability and operational reliability of the device are significantly improved while maintaining high luminous efficiency, providing an effective technical solution for enhancing the performance of 905nm edge-emitting lasers. Summary of the Invention

[0005] This invention provides a strain-compensated quantum well material for EEL and its preparation method, in order to solve the technical problems of strain accumulation and poor temperature stability of quantum well materials in the prior art.

[0006] On one hand, the present invention provides a strain-compensated quantum well material for EEL, comprising: Substrate; A lower confinement layer and a lower waveguide layer are disposed on a substrate; The multi-quantum-well active region comprises alternating InGaAs quantum well layers and AlGaInP barrier layers, wherein the quantum well layers have compressive strain and the barrier layers have tensile strain. A strain-compensating shell is disposed on the active region of the multi-quantum-well, the shell comprising a structure with a gradient variation in Al composition; And an upper waveguide layer and an upper confinement layer disposed on the shell.

[0007] According to the present invention, a strain-compensated quantum well material for EEL is provided, wherein the InGaAs quantum well layer has an In composition of 0.10~0.20, a thickness of 5~10 nm, and a compressive strain of +0.7%~+1.2%; and the AlGaInP barrier layer has an Al composition of 0.15~0.25, a thickness of 8~15 nm, and a tensile strain of -0.6%~-1.0%.

[0008] According to the present invention, a strain-compensated quantum well material for EEL is provided, wherein the strain-compensated shell layer comprises an inner shell layer and an outer shell layer, wherein the Al composition of the inner shell layer is linearly varied from 0.22 to 0.12 and the thickness is 15~35nm; and the Al composition of the outer shell layer is linearly varied from 0.16 to 0.06 and the thickness is 10~25nm.

[0009] According to the present invention, a strain-compensated quantum well material for EEL is provided, wherein the AlGaInP barrier layer is a composite structure comprising a GaInP layer, an AlGaInP layer and a GaInP layer grown sequentially, wherein the thickness of the GaInP layer is 1~4 nm and the thickness of the AlGaInP layer is 5~10 nm.

[0010] According to the present invention, a strain-compensated quantum well material for EEL is provided, wherein the multi-quantum well active region further includes a strain transition layer disposed between the quantum well layer and the barrier layer, wherein the strain transition layer is an (AlGaAs / GaAs) superlattice structure with 2 to 6 periods and a total thickness of 10 to 30 nm.

[0011] On the other hand, the present invention provides a method for preparing strain-compensated quantum well materials, comprising the following steps: Provide GaAs substrates; A lower confinement layer and a lower waveguide layer are sequentially grown on the substrate; A multi-quantum-well active region is grown on the lower waveguide layer by alternating InGaAs quantum well layers and AlGaInP barrier layers at a temperature of 500-550℃ using molecular beam epitaxy. A strain-compensated shell is grown on the multi-quantum-well active region, and the linear gradient of the Al composition is achieved by controlling the Al beam. A waveguide layer and an upper confinement layer are sequentially grown on the shell.

[0012] According to a method for preparing strain-compensated quantum well materials provided by the present invention, when growing the active region of the multi-quantum well, a temperature oscillation technique is used, and the growth temperature is periodically varied between 500 and 550°C, with a variation period of 15 to 40 seconds.

[0013] According to a method for preparing strain-compensated quantum well materials provided by the present invention, multi-layer in-situ annealing is performed during the growth process, including: annealing at a temperature of 570-610°C for 15-40 seconds after every 2-3 quantum well cycles.

[0014] According to a method for preparing strain-compensated quantum well materials provided by the present invention, when growing the strain-compensated shell, dynamic beam modulation technology is used, and the Al beam is modulated according to a triangular wave or a sine wave, with a modulation amplitude of ±10% of the nominal value.

[0015] The method for preparing strain-compensated quantum well material according to the present invention further includes a cavity surface treatment step after growth, including: forming a laser cavity surface by cleaving along the (110) crystal plane, sequentially depositing an Al2O3 and HfO2 composite passivation film on the cavity surface, depositing an antireflection film with a reflectivity of 0.3~1.2% on the front cavity surface, and depositing a high reflectivity film with a reflectivity of 94~99% on the rear cavity surface.

[0016] The strain-compensated quantum well material for EEL and its preparation method provided by this invention have the following advantages compared with the prior art: (1) The present invention provides a strain-compensated quantum well material for EEL and its preparation method. By adopting a multi-quantum well structure with alternating growth of InGaAs quantum well layer and AlGaInP barrier layer, and designing a strain-compensated shell with Al composition gradient, the strain accumulation and quantum confinement Stark effect caused by lattice mismatch in the traditional InGaAs / GaAs quantum well structure are solved, and the beneficial effects of effectively suppressing dislocation generation and significantly reducing wavelength temperature drift are achieved.

[0017] (2) The present invention provides a strain-compensated quantum well material for EEL and its preparation method. By adopting a GaInP / AlGaInP / GaInP composite barrier layer structure and setting a (AlGaAs / GaAs) superlattice strain transition layer between the quantum well layer and the barrier layer, the limitations of single barrier layer materials in carrier confinement and strain compensation and the problem of interface stress abrupt change are solved, and the beneficial effects of optimizing band structure, enhancing carrier confinement capability and realizing smooth strain transition are achieved.

[0018] (3) The present invention provides a strain-compensated quantum well material for EEL and its preparation method. By adopting temperature oscillation growth technology and dynamic beam modulation technology and implementing multi-layer in-situ annealing treatment, the problems of interface roughness, composition fluctuation and crystal defects caused by traditional growth methods are solved, and the beneficial effects of improving material uniformity, realizing precise composition gradient control and effectively repairing crystal defects are achieved.

[0019] (4) The present invention provides a strain-compensated quantum well material for EEL and its preparation method. Through the synergistic optimization of the overall technical solution, including the design of the dual gradient shell structure and the optimized cavity surface processing technology, the comprehensive performance bottleneck of traditional 905nm edge-emitting laser in terms of temperature stability, reliability and lifetime is solved, and the beneficial effects of achieving low threshold current, high output power and long working lifetime are achieved at the same time. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the layered structure of the strain-compensated quantum well material provided in Embodiment 1 of the present invention; Figure 2 This is a detailed structural schematic diagram of the multi-quantum-well active region provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the Al composition gradient change of the strain compensation shell provided in Embodiment 1 of the present invention; Figure 4 This is a process flow diagram of the preparation method provided in Embodiment 1 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The following is combined with Figures 1-4 This invention describes a strain-compensated quantum well material for EEL and its preparation method.

[0024] Figure 1 This is a schematic diagram of the layered structure of the strain-compensated quantum well material provided in Embodiment 1 of the present invention.

[0025] like Figure 1As shown in Embodiment 1 of the present invention, a strain-compensated quantum well material for EELs comprises the following core structure from bottom to top: substrate, lower confinement layer, lower waveguide layer, multi-quantum-well active region, strain-compensated shell, upper waveguide layer, and upper confinement layer. This layered structure constitutes a complete optical and electrical confinement system, providing an optimized carrier recombination and photon emission environment for edge-emitting lasers.

[0026] Figure 2 This is a detailed structural schematic diagram of the multi-quantum well active region provided in Embodiment 1 of the present invention.

[0027] like Figure 2 As shown in Embodiment 1 of the present invention, a strain-compensated quantum well material for EEL is provided. The specific structure of its multi-quantum-well active region includes: a strain transition layer, an InGaAs quantum well layer, an AlGaInP barrier layer, and a composite barrier layer structure. The composite barrier layer structure employs a GaInP / AlGaInP / GaInP sandwich design. This innovative structure not only provides effective carrier confinement but also achieves precise strain compensation through the lattice constant differences of the different materials.

[0028] Figure 3 This is a schematic diagram of the Al composition gradient change of the strain compensation shell provided in Embodiment 1 of the present invention.

[0029] like Figure 3 As shown in Embodiment 1 of the present invention, a strain-compensated quantum well material for EEL is provided, wherein the Al composition of the inner shell of the strain-compensating shell gradually changes from 0.25 to 0.15, and the Al composition of the outer shell further gradually changes from 0.15 to 0.08. This dual-gradient design generates a corresponding charge distribution through polarization effect, effectively shielding the built-in electric field in the quantum well.

[0030] Figure 4 This is a process flow diagram of the preparation method provided in Embodiment 1 of the present invention.

[0031] like Figure 4 As shown in Embodiment 1 of the present invention, a method for fabricating strain-compensated quantum well materials for EELs is provided. The main process flow includes: substrate pretreatment, molecular beam epitaxy, temperature oscillation control, dynamic beam modulation, multilayer in-situ annealing, and cavity surface treatment. The synergistic optimization of these process steps ensures high material quality and excellent device performance.

[0032] In this invention, the strain compensation mechanism achieves the design of a multi-quantum-well active region structure by precisely controlling the strain relationship between the InGaAs quantum well layer and the AlGaInP barrier layer. The compressive strain of the quantum well layer and the tensile strain of the barrier layer are balanced, effectively suppressing the generation of defects caused by lattice mismatch.

[0033] In this invention, the polarization field compensation mechanism achieves a dual-gradient shell structure by designing a strain compensation shell with a gradient change in Al composition. The linear gradient of Al composition generates a specific polarization charge distribution, which effectively shields the built-in electric field in the quantum well.

[0034] In this invention, band engineering optimization is achieved by using a GaInP / AlGaInP / GaInP composite barrier structure, which optimizes carrier confinement. The band shift of different materials forms a stepped barrier, which enhances the confinement and injection efficiency of carriers.

[0035] In this invention, interface quality control is achieved by setting a (AlGaAs / GaAs) superlattice strain transition layer, which enables a smooth strain transition. The superlattice structure effectively mitigates stress abrupt changes at the interface between materials with different lattice constants. In this invention, molecular beam epitaxy (MBE) achieves precise fabrication of multi-quantum well active regions by controlling the growth temperature within the range of 500-550°C. The optimized temperature range provides the necessary conditions for the growth of high-quality materials.

[0036] In this invention, the temperature oscillation growth technique improves interface quality by periodically changing the growth temperature within a specific range. The temperature fluctuation promotes the surface migration of atoms, resulting in an atomically smooth interface.

[0037] In this invention, the multi-layer in-situ annealing process achieves crystal defect repair by inserting multiple annealing steps during the growth process. The periodic heat treatment effectively eliminates point defects and stress concentrations generated during the growth process.

[0038] In this invention, dynamic beam modulation technology achieves precise control of Al components by modulating the Al beam according to a specific waveform, wherein the real-time adjustment of the beam ensures the accurate realization of gradient changes.

[0039] In this invention, the cavity surface processing technology achieves improved laser resonator quality through synergistic optimization of cleavage, passivation, and coating. The composite passivation film and the precisely controlled reflective film system together ensure the long-term stability of the cavity surface.

[0040] In a preferred embodiment of the present invention, the In composition of the InGaAs quantum well layer is 0.11~0.19, more preferably 0.12~0.18; the thickness is 6~9 nm, more preferably 7~8 nm; and the compressive strain is +0.8%~+1.1%, more preferably +0.9%~+1.0%.

[0041] In a preferred embodiment of the present invention, the Al composition of the AlGaInP barrier layer is 0.16~0.23, more preferably 0.18~0.22; the thickness is 9~13nm, more preferably 10~12nm; and the tensile strain is -0.6%~-0.9%, more preferably -0.7%~-0.8%.

[0042] In a preferred embodiment of the present invention, in the strain compensation shell, the Al composition of the inner shell varies from 0.23 to 0.13, more preferably from 0.25 to 0.15; the thickness is 20 to 30 nm, more preferably from 25 to 30 nm; the Al composition of the outer shell varies from 0.14 to 0.08, more preferably from 0.15 to 0.08; the thickness is 15 to 22 nm, more preferably from 18 to 20 nm.

[0043] In a preferred embodiment of the present invention, the thickness of the GaInP layer in the AlGaInP barrier layer is 1.5~3.5nm, more preferably 2~3nm; the thickness of the AlGaInP layer is 6~9nm, more preferably 7~8nm.

[0044] In a preferred embodiment of the present invention, the number of superlattice periods in the strain transition layer is 3 to 5, more preferably 4 to 5; the total thickness is 15 to 25 nm, more preferably 18 to 22 nm.

[0045] In a preferred embodiment of the present invention, the growth temperature of the multi-quantum well active region is 510~540℃, and more preferably 515~530℃.

[0046] In a preferred embodiment of the present invention, the temperature oscillation technology has a temperature change range of 505~545℃, more preferably 510~530℃; and a change period of 20~35 seconds, more preferably 25~30 seconds.

[0047] In a preferred embodiment of the present invention, the annealing temperature in the multilayer in-situ annealing process is 575~605℃, more preferably 580~600℃; the annealing time is 20~35 seconds, more preferably 25~30 seconds.

[0048] In a preferred embodiment of the present invention, the reflectivity of the front cavity surface is 0.4-1.0%, more preferably 0.5-0.8%, and the reflectivity of the rear cavity surface is 95-98%, more preferably 96-97.5%.

[0049] Example 1 Provide a GaAs substrate ((100) crystal orientation, off-angle <0.1°) and perform pretreatment, including ultrasonic cleaning in acetone and isopropanol for 5 minutes each, then acid etching with H2SO4:H2O2:H2O=3:1:1 solution for 30 seconds, rinse with deionized water and blow dry with N2; Molecular beam epitaxy (VG V80H system, background vacuum <2×10⁻⁶) was employed. -10 Torr) epitaxial structure growth: First, a 100 nm thick GaAs buffer layer (Si doped 5 × 10⁻⁶) is grown at 580 °C. 18 cm -3 (V / III ratio 20:1, growth rate 0.8 μm / h), then a 1000 nm thick Al layer was grown. 0.50 Ga 0.50 As lower confinement layer (Si doped 1×10⁻⁶) 18 cm -3 ) and 150nm thick Al 0.15 Ga 0.85 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a temperature oscillation technique (temperature variation range ±10℃, period 30 seconds). First, a 20nm thick layer of (Al) was grown. 0.20 Ga 0.80 As / GaAs)×5 superlattice strained transition layer, followed by alternating growth of 8-period In 0.13 Ga 0.87 As quantum well layer (7 nm thick, compressive strain +0.9%) and Al 0.20 Ga 0.68 In 0.12 A P-barrier layer (12 nm thick, tensile strain -0.7%), wherein the barrier layer adopts a composite structure, namely a 2 nm Ga... 0.51 In 0.49 P / 8nm Al 0.25 Ga 0.63 In 0.12 P / 2nmGa 0.51 In 0.49 P; In the active region, a strain-compensated shell is grown, comprising an inner shell (Al composition linearly graded from 0.25 to 0.15, thickness 30 nm) and an outer shell (Al composition linearly graded from 0.15 to 0.08, thickness 20 nm), with a 5 nm thick Ga core inserted in between. 0.51 In 0.49 P-spacer layer. The shell was grown at 580℃ using dynamic beam modulation technology (Al beam modulated by a triangular wave with a modulation amplitude of ±10%). Subsequently, a 120nm thick Al layer was grown. 0.20 Ga 0.80 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 800nm ​​thick Al 0.50 Ga 0.50 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×10 19 cm -3 ); During the growth process, after every two quantum well cycles, in-situ annealing is performed at 580℃ for 30 seconds; after the growth is completed, overall annealing is performed at 600℃ for 120 seconds. Device fabrication includes: photolithography defining a 3μm stripe width, ICP dry etching (Cl2 / Ar gas, pressure 5mTorr, ICP power 800W) to form a mesa structure, cleaving along the (110) crystal plane to form a 1mm long cavity surface, depositing a 10nm Al2O3 and 5nm HfO2 composite passivation film on the cavity surface (ALD technology, temperature 200℃), depositing an antireflection film with a reflectivity of 0.5% (SiO2 / TiO2 5 pairs) on the front cavity surface, depositing a high reflectivity film with a reflectivity of 95% (SiO2 / TiO2 7 pairs) on the back cavity surface, and finally fabricating p-side electrodes (Ti / Pt / Au, 50 / 50 / 100nm) and n-side electrodes (AuGe / Ni / Au, 100 / 20 / 100nm), and alloying at 400℃ for 30 seconds.

[0050] Example 2 Provide a GaAs substrate and perform pretreatment (same as in Example 1); Epitaxial structures were grown using molecular beam epitaxy: a 100 nm GaAs buffer layer (Si doped 5 × 10⁻⁶) was grown at 580 °C. 18 cm -3 Then, a 600nm thick Al layer was grown. 0.50 Ga 0.50 As lower confinement layer (Si doped 1×10⁻⁶) 18 cm -3 ) and 150nm thick Al 0.15 Ga 0.85 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a constant temperature growth method (without temperature oscillation). First, a 15 nm thick (AlGaAs / GaAs)×3 superlattice strained transition layer was grown, followed by alternating growth of 6 periods of In. 0.13 Ga 0.87 As quantum well layer (7 nm thick, compressive strain +0.9%) and Al 0.18 Ga 0.82 As barrier layer (thickness 12nm, tensile strain -0.7%), composite barrier layer structure omitted; In the active region, a single-gradient strain-compensated shell (Al composition linearly varied from 0.20 to 0.10, thickness 25 nm) was grown at 580 °C using a fixed beam current (without dynamic modulation). Subsequently, a 150nm thick Al layer was grown. 0.15 Ga 0.85 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 600nm thick Al 0.50 Ga 0.50 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×10 19 cm -3 ); During the growth process, in-situ annealing (600℃, 120 seconds) is performed only once after the entire structure has grown. Device fabrication includes: photolithography to define a 3μm stripe width, ICP dry etching to form a mesa structure, cavity surface cleaving followed by deposition of a 10nm Al2O3 passivation film, deposition of an antireflection film with 1% reflectivity on the front cavity surface, deposition of a high reflectivity film with 95% reflectivity on the rear cavity surface, and electrode fabrication and alloying as in Example 1.

[0051] Example 3 Provide a GaAs substrate and perform pretreatment (same as in Example 1); Epitaxial structures were grown using molecular beam epitaxy: a 100 nm GaAs buffer layer (Si doped 5 × 10⁻⁶) was grown at 580 °C. 18 cm -3 Then, a 1000nm thick Al layer was grown. 0.50 Ga 0.50 As lower confinement layer (Si doped 1×10⁻⁶) 18 cm -3 ) and 150nm thick Al0.15 Ga 0.85 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a temperature oscillation technique (temperature variation range ±10℃, period 30 seconds). First, a 20nm thick (AlGaAs / GaAs)×5 superlattice strain transition layer was grown. Then, alternating growth of 10-cycle gradient In composition quantum well layers (thickness increased from 6nm to 7nm, In composition from 0.12% to 0.14%, compressive strain from +0.8% to +1.0%) and Al... 0.28 Ga 0.60 In 0.12 P-barrier layer (15nm thick, tensile strain -0.8%), the barrier layer adopts a composite structure; In the active region, a triple-gradient strain-compensated shell was grown, comprising an inner layer (Al composition graded from 0.30 to 0.20, thickness 20 nm), a middle layer (Al composition graded from 0.20 to 0.10, thickness 20 nm), and an outer layer (Al composition graded from 0.10 to 0.05, thickness 15 nm). Shell growth was performed at 580 °C using dynamic beam modulation and pulsed Si doping (peak concentration 1 × 10⁻⁶). 18 cm -3 ); Subsequently, a 120nm thick Al layer was grown. 0.20 Ga 0.80 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 800nm ​​thick Al 0.50 Ga 0.50 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×10 19 cm -3 ); During the growth process, after every two quantum well cycles, the cells are annealed at 580°C for 30 seconds; after the growth is complete, the cells are annealed at 600°C for 120 seconds. The device is fabricated in the same way as in Example 1, but the heat sink is made of nanodiamond composite material (thermal conductivity >1200W / mK), and the bonding is done with AuSnIn composite solder (thermal resistance <8K / W).

[0052] Example 4 Provide a GaAs substrate and perform pretreatment (same as in Example 1); Epitaxial structures were grown using molecular beam epitaxy: a 100 nm GaAs buffer layer (Si doped 5 × 10⁻⁶) was grown at 580 °C. 18 cm -3 Then, a 1500nm thick Al layer was grown. 0.45 Ga 0.55 As lower confinement layer (Si doped 1×10⁻⁶) 18 cm -3 ) and 300nm thick Al 0.08 Ga 0.92 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a temperature oscillation technique (temperature variation range ±10℃, period 30 seconds). First, a 20nm thick (AlGaAs / GaAs)×5 superlattice strained transition layer was grown, followed by 12 alternating periods of In. 0.13 Ga 0.87 As quantum well layer (8 nm thick, compressive strain +0.9%) and Al 0.18 Ga 0.70 In 0.12 P-barrier layer (10nm thick, tensile strain -0.7%), the barrier layer adopts a composite structure; The active region employs an asymmetric strain compensation design, with a compressive strain gradient of +0.7% to +1.1% and then to +0.9%, and a tensile strain gradient of -0.5% to -0.9% and then to -0.7%. In the active region, a strain compensation shell is grown (same as in Example 1). Subsequently, a 250nm thick Al layer was grown. 0.12 Ga 0.88 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 1500nm thick Al 0.45 Ga 0.55 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×10 19 cm -3 ); During the growth process, after every two quantum well cycles, the cells are annealed at 580°C for 30 seconds. Device fabrication includes: photolithography to define a 100μm stripe width, ICP dry etching to form a 2mm long cavity surface, cavity surface treatment is the same as in Example 1, but the electrodes adopt a grid design to reduce series resistance, and a bulk diamond (500μm thick) is used as the heat sink.

[0053] Example 5 Provide a GaAs substrate and perform pretreatment (same as in Example 1); Epitaxial structures were grown using molecular beam epitaxy: a 100 nm GaAs buffer layer (Si doped 5 × 10⁻⁶) was grown at 580 °C. 18 cm -3 Then, a 1000nm thick Al layer was grown. 0.50 Ga 0.50 As lower confinement layer (with gradient doping: 5×10 near the active region) 16 cm -3 , with a source region of 2×10 18 cm -3 ) and 150nm thick Al 0.15 Ga 0.85 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a temperature oscillation technique (temperature variation range ±10℃, period 30 seconds). First, a 20nm thick (AlGaAs / GaAs)×5 superlattice strained transition layer was grown, followed by 4 alternating periods of In. 0.14 Ga 0.86 As quantum well layer (6 nm thick, compressive strain +1.0%) and Al 0.25 Ga 0.63 In 0.12 P-barrier layer (8nm thick, tensile strain -0.8%), the barrier layer adopts a composite structure; In the active region, a strain compensation shell is grown (same as in Example 1). Subsequently, a 120nm thick Al layer was grown. 0.20 Ga 0.80 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 800nm ​​thick Al 0.50 Ga 0.50 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×1019 cm -3 ); During the growth process, after every two quantum well cycles, the cells are annealed at 580°C for 30 seconds. Device fabrication includes: photolithography defining a 1.5μm stripe width, ICP dry etching to form a 3μm deep mesa structure, cavity surface treatment as in Example 1, electrodes using a coplanar waveguide design (characteristic impedance 50Ω), bonding using gold strips (inductance <0.5nH), and packaging as a ceramic microwave package.

[0054] Example 6 Provide a GaAs substrate and perform pretreatment (same as in Example 1); Epitaxial structures were grown using molecular beam epitaxy: a 100 nm GaAs buffer layer (Si doped 5 × 10⁻⁶) was grown at 580 °C. 18 cm -3 Then, a 1000nm thick Al layer was grown. 0.50 Ga 0.50 As lower confinement layer (Si doped 1×10⁻⁶) 18 cm -3 ) and 150nm thick Al 0.15 Ga 0.85 As under-waveguide layer (Si doped 5×10) 17 cm -3 ); The active region was grown at 520℃ using a temperature oscillation technique (temperature variation range ±10℃, period 30 seconds). First, a 20nm thick strained superlattice buffer layer ((InGaAs / GaAs)×20 periods) was grown, followed by alternating growth of 8 periods of In. 0.18 Ga 0.82 As quantum well layer (8 nm thick, compressive strain +1.4%) and Al 0.15 Ga 0.73 In 0.12 P-barrier layer (15nm thick, tensile strain -0.8%), the barrier layer adopts a composite structure; In the active region, a graded bandgap shell (AlGaAsSb, with a bandgap that gradually changes from 1.6 eV to 1.4 eV) is grown. Subsequently, a 120nm thick Al layer was grown. 0.20 Ga 0.80 As upper waveguide layer (Be doped 5×10) 17 cm -3 ), 30nm thick Al 0.35 Ga 0.65 As electron blocking layer (Be-doped 1×10⁻⁶) 18 cm -3 ), 800nm ​​thick Al 0.50 Ga0.50 As confinement layer (Be doped 5×10) 17 cm -3 ) and a 200nm thick GaAs contact layer (Be-doped 1×10 19 cm -3 ); During the growth process, after every two quantum well cycles, the cells are annealed at 580℃ for 30 seconds; the wavelength is controlled during growth by real-time infrared temperature measurement (accuracy ±0.5℃) and in-situ calibration. The device fabrication process is the same as in Example 1.

[0055] The strain-compensated quantum well materials for EEL prepared in Examples 1-6 were subjected to performance tests. The performance test results are shown in Table 1 below (test conditions: 25℃, unless otherwise stated).

[0056] Table 1. Summary of Performance Test Results

[0057] As demonstrated by Examples 1, 3, and 5, this invention achieves excellent temperature stability. The temperature coefficients of Examples 1, 3, and 5 reach 0.18 nm / ℃, 0.12 nm / ℃, and 0.19 nm / ℃, respectively, which are significantly better than the typical 0.3~0.4 nm / ℃ level in the prior art. In particular, Example 3, through a three-gradient shell and enhanced strain compensation design, further reduces the temperature coefficient to 0.12 nm / ℃, fully meeting the stringent requirements of automotive lidar for wide-temperature operating stability.

[0058] As demonstrated by Examples 1, 4, and 5, this invention achieves diverse application requirements while maintaining high performance. Example 1, as a baseline solution, achieves the best balance in terms of threshold current (22mA), output power (250mW), and lifetime (15,000 hours). Example 4, through a large optical cavity design and a 12-cycle quantum well structure, achieves an ultra-high output power of 850mW. Example 5, through a thin-well design and a low-capacitance structure, obtains a high-speed modulation bandwidth of 12GHz, fully demonstrating the scalability and application flexibility of this technical solution.

[0059] As demonstrated by Examples 1-6, this invention significantly improves device reliability through an innovative strain compensation mechanism. The characteristic temperature T0 of each example reaches above 180K, with Example 3 reaching 280K, indicating a substantial reduction in the device's sensitivity to temperature changes. Furthermore, the expected lifetime of all examples at 50°C exceeds 8000 hours, with Examples 1 and 3 reaching 15000 hours, proving the outstanding long-term reliability advantage of this invention.

[0060] As demonstrated by Examples 1-6, the present invention exhibits excellent precision and scalability in wavelength control. The center wavelength control in Examples 1-5 remains within an extremely narrow range of 905.0-905.5 nm, reflecting a high degree of process consistency. Example 6 successfully extends the wavelength to 935 nm, showcasing the potential of this technical solution in wavelength tuning and providing more options for different application scenarios.

[0061] As demonstrated in Example 2, this invention achieves a reasonable balance of performance through structural optimization. Example 2 simplifies the structure and reduces costs while maintaining acceptable performance levels (threshold current 28mA, temperature coefficient 0.25nm / ℃, lifetime 10,000 hours), proving the feasibility of this technical solution in cost-sensitive applications and providing strong support for the industrialization of this technology.

[0062] In summary, this invention, through its innovative strain-compensated quantum well structure and optimized fabrication process, has achieved significant improvements in key performance indicators such as temperature stability, output power, modulation speed, and device lifetime, providing an effective technical solution for performance breakthroughs in 905nm and extended wavelength side-emitting lasers.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A strain-compensated quantum well material for EEL, characterized in that, include: Substrate; A lower confinement layer and a lower waveguide layer are disposed on a substrate; The multi-quantum-well active region comprises alternating InGaAs quantum well layers and AlGaInP barrier layers, wherein the quantum well layers have compressive strain and the barrier layers have tensile strain. A strain-compensating shell is disposed on the active region of the multi-quantum-well, the shell comprising a structure with a gradient variation in Al composition; And an upper waveguide layer and an upper confinement layer disposed on the shell.

2. The strain-compensated quantum well material according to claim 1, characterized in that, The InGaAs quantum well layer has an In composition of 0.10~0.20, a thickness of 5~10 nm, and a compressive strain of +0.7%~+1.2%; the AlGaInP barrier layer has an Al composition of 0.15~0.25, a thickness of 8~15 nm, and a tensile strain of -0.6%~-1.0%.

3. The strain-compensated quantum well material according to claim 1, characterized in that, The strain compensation shell includes an inner shell and an outer shell. The Al composition of the inner shell is linearly varied from 0.22 to 0.12, and the thickness is 15~35nm. The Al composition of the outer shell is linearly varied from 0.16 to 0.06, and the thickness is 10~25nm.

4. The strain-compensated quantum well material according to claim 1, characterized in that, The AlGaInP barrier layer is a composite structure, comprising GaInP layer, AlGaInP layer and GaInP layer grown sequentially, wherein the thickness of GaInP layer is 1~4nm and the thickness of AlGaInP layer is 5~10nm.

5. The strain-compensated quantum well material according to claim 1, characterized in that, The multi-quantum-well active region also includes a strain transition layer disposed between the quantum well layer and the barrier layer. The strain transition layer is an (AlGaAs / GaAs) superlattice structure with 2 to 6 periods and a total thickness of 10 to 30 nm.

6. A method for preparing the strain-compensated quantum well material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Provide GaAs substrates; A lower confinement layer and a lower waveguide layer are sequentially grown on the substrate; A multi-quantum-well active region is grown on the lower waveguide layer by alternating InGaAs quantum well layers and AlGaInP barrier layers at a temperature of 500-550℃ using molecular beam epitaxy. A strain-compensated shell is grown on the multi-quantum-well active region, and the linear gradient of the Al composition is achieved by controlling the Al beam. A waveguide layer and an upper confinement layer are sequentially grown on the shell.

7. The method according to claim 6, characterized in that, When growing the multi-quantum well active region, a temperature oscillation technique is used, and the growth temperature is periodically varied between 500 and 550°C, with a variation period of 15 to 40 seconds.

8. The method according to claim 6, characterized in that, The growth process involves multi-layer in-situ annealing, including annealing at 570-610℃ for 15-40 seconds after every 2-3 quantum well cycles.

9. The method according to claim 6, characterized in that, When growing the strain-compensated shell, dynamic beam modulation technology is used, and the Al beam is modulated according to a triangular wave or sine wave, with a modulation amplitude of ±10% of the nominal value.

10. The method according to claim 6, characterized in that, It also includes a cavity surface treatment step after growth, including: forming a laser cavity surface by cleaving along the (110) crystal plane, depositing Al2O3 and HfO2 composite passivation films sequentially on the cavity surface, depositing an antireflection film with a reflectivity of 0.3~1.2% on the front cavity surface, and depositing a high reflectivity film with a reflectivity of 94~99% on the rear cavity surface.

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