Low-temperature in-situ oxidation preparation method of AlGaAs system semiconductor laser cavity mask

Abstract

The invention provides a low-temperature in-situ oxidation preparation method of an AlGaAs system semiconductor laser cavity surface film, and relates to the technical field of semiconductor lasers. According to the method, atomic-scale bonded Al-O covalent bonds (binding energy gt, 5eV) are generated on the cavity surface of the AlGaAs system laser through a low-temperature in-situ oxygen ion oxidation process, interface self-purification is achieved through Ga / As volatility, and a gradient oxidation passivation layer of non-stoichiometric AlOx is formed. As the generated oxidation passivation layer 13 is atomic-scale bonding, high interface bonding energy of the generated oxidation passivation layer can be ensured, thermal stress under high power can be borne, and the bearable power limit can be improved. And the AlGaAs epitaxial layer is oxidized at normal temperature, so that the damage of high-energy ions to the quantum well structure and the lattice integrity is avoided due to the low-temperature characteristic, and the yield of the high-power semiconductor laser is improved. Due to the low-temperature characteristic and the atomic-scale bonding capacity, the problem of interface defects of traditional deposition is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically to a low-temperature in-situ oxidation preparation method for the cavity film of an AlGaAs semiconductor laser. Background Technology

[0002] Catastrophic optical mirror damage (COMD) has long been a critical bottleneck in the field of high-power semiconductor lasers. When the local photon density at the front cavity surface (emitting surface) of the laser exceeds 10... 6 At W / cm², a series of chain reactions are triggered: high-energy photons are absorbed by the interband gap of the semiconductor material, generating electron-hole pairs. These carriers recombine nonradiatively at cavity surface defects, releasing heat and causing a sudden increase in local temperature. This temperature rise causes the material's band gap to shrink, leading to an exponential increase in the absorption coefficient, ultimately resulting in an uncontrollable thermal runaway cycle, manifested as cavity surface melting, cracks, or ablation pits. This process not only directly causes instantaneous device failure but also severely restricts the output power and long-term reliability of lasers, becoming a core obstacle to the development of kilowatt-level industrial lasers and high-density optical communication systems.

[0003] To suppress COMD, the industry commonly uses physical vapor deposition (PVD) technology to grow passivation films (such as AlN, Al2O3, SiN) on the cavity surface. x (etc.), among which ion beam deposition (IBD) and electron beam deposition (EBD) are the mainstream processes. However, these two technologies have fundamental drawbacks: First, ion beam deposition relies on high-energy argon ions (>50 eV) sputtering the target to form a film layer on the cavity surface primarily based on physical adsorption. Firstly, this method does not alter the chemical structure of the cavity surface film; instead, it achieves physical adsorption between the film layer (e.g., SiO2, Al2O3) and the AlGaAs surface through intermolecular forces (van der Waals forces), resulting in a low binding energy of only 0.1-0.5 eV. This weak interfacial bonding cannot withstand the thermal stress under high power and is easily stripped during thermal cycling, hitting a physical limit for power enhancement. Secondly, the extremely high energy of the sputtered ions bombards the cavity surface lattice, disrupting the quantum well structure and lattice integrity, inducing dislocation density, and creating carrier recombination centers, leading to low yields in high-power semiconductor lasers. Finally, the high porosity of the film layer severely hinders heat transfer to the heat sink.

[0004] Second, electron beam deposition faces even more severe thermal management challenges. The film formed by electron beam deposition has a columnar structure, and some Ga and As atoms on the AlGaAs surface have dangling bonds (unsaturated bonds), which can form weak chemical bonds with O and N atoms in the film. The high interfacial state density makes it a hotbed for nonradiative recombination and a preferred trigger point for COMD. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a low-temperature in-situ oxidation preparation method for the cavity film of AlGaAs semiconductor lasers, which has the advantages of low-temperature processing and atomic-level bonding, effectively overcoming the constraints of COMD on laser power and reliability.

[0006] The technical solution adopted by this invention to solve its technical problem is: A low-temperature in-situ oxidation preparation method for the cavity film of an AlGaAs semiconductor laser includes the following steps: S1, the AlGaAs semiconductor laser wafer is cleaved into strips; S2, place the bar strip into the coating chamber and make the light-emitting surface of the bar strip face downwards; S3, Evacuate the vacuum chamber to bring the air pressure inside the coating chamber to the first preset value; S4, turn on the microwave source and adjust the microwave power to the first preset value, then introduce Ar; S5, adjust the microwave power to the second preset value, and evacuate the vacuum chamber to make the air pressure in the coating chamber reach the second preset value. Then, introduce O2 to generate an oxide passivation layer on the light-emitting surface of the bar. S6. Adjust the position of the bar strip so that the high side of the bar strip faces downward, and then repeat the operation of steps S3-S5 to form an oxide passivation layer on the high side of the bar strip. S7 deposits an antireflection film on the light-emitting side and a high-reflection film on the high-reflection side.

[0007] Furthermore, in step S2, the coating chamber is cleaned before the bar is placed into the coating chamber.

[0008] Furthermore, in step S3, the first preset value of the air pressure in the coating chamber is 1×10⁻ 5 Pa.

[0009] Furthermore, in step S4, the first preset value of microwave power is 150W, the flow rate when Ar is introduced is 20sccm, and the processing time is 20min.

[0010] Furthermore, in step S4, the air pressure inside the coating chamber is 0.15 Pa.

[0011] Furthermore, in step S5, the second preset value of the microwave power ranges from 100 to 500W.

[0012] Furthermore, in step S5, the flow rate of O2 is 10-20 sccm, and the O2 introduction time is 10-60 min.

[0013] Furthermore, in step S5, the thickness of the oxide passivation layer is 8-15 nm.

[0014] Furthermore, the antireflective film is composed of an Al2O3 layer and a SiO2 layer, and the high reflective film is composed of an SiO2 layer and a TiO2 layer.

[0015] Furthermore, the reflectivity of the antireflective film is <5%, and the reflectivity of the high-reflectivity film is >99%.

[0016] The beneficial effects of this invention are: This application provides a low-temperature in-situ oxidation preparation method for the cavity surface film of an AlGaAs semiconductor laser. Through a low-temperature in-situ oxygen ion oxidation process, atomically bonded Al-O covalent bonds (binding energy > 5 eV) are generated on the cavity surface of the AlGaAs laser. The volatility of Ga / As is utilized to achieve interface self-purification, forming a non-stoichiometric AlO₂. x The gradient oxidation passivation layer. Compared with traditional IBD and EBD technologies, this method achieves high interfacial binding energy (Al-O covalent bond binding energy >5eV, compared to 0.1–0.5eV for physical adsorption in IBD), and the process temperature is ≤100℃, effectively breaking through the constraints of COMD on laser power and reliability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a bar prepared by a low-temperature in-situ oxidation method for preparing an AlGaAs system semiconductor laser cavity film according to an embodiment of this application.

[0018] In the diagram: 11. Light-emitting surface; 12. High-reflectivity surface; 13. Oxidation passivation layer; 14. Anti-reflection coating; 15. High-reflectivity coating. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings. The described embodiments are merely a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the protection scope of this application.

[0020] A low-temperature in-situ oxidation preparation method for the cavity film of an AlGaAs semiconductor laser includes the following steps: S1, using a fully automatic dicing machine to cleave AlGaAs semiconductor laser wafers into strips, and then placing the cleaved strips into strip clamps.

[0021] The bar bar clamp described is existing technology, and its specific structure will not be described in detail here.

[0022] S2. Clean the coating chamber of the electron cyclotron resonance coating equipment (ECR) to ensure the chamber is clean. Then, place the bar holder with the bar installed into the coating chamber of the ECR, with the light-emitting surface 11 of the bar facing downwards.

[0023] S3, evacuate the vacuum chamber to bring the air pressure inside the coating chamber to the first preset value.

[0024] As one specific implementation, the first preset value of the air pressure in the coating chamber in this embodiment is 1×10⁻ 5 Pa.

[0025] S4, turn on the microwave source and adjust the microwave power to the first preset value, then introduce Ar.

[0026] Ar is introduced and ionizes into Ar by colliding with electrons in the magnetic field that resonate in a cyclotron. + and e - Ar + With an energy of <10eV, Ar ions bombard the cavity surface under the drive of the substrate potential difference, achieving atomic-level surface cleaning to remove impurities and contaminants such as water vapor from the polished surface 11.

[0027] In one specific implementation, the first preset value of microwave power in this embodiment is 150W, the flow rate when Ar is introduced is 20sccm, and the processing time is 20min.

[0028] Furthermore, in step S4, after Ar is introduced, the air pressure in the coating chamber is maintained at 0.15 Pa.

[0029] S5, adjust the microwave power to the second preset value, and evacuate the vacuum chamber to make the air pressure in the coating chamber reach the second preset value. Then, introduce O2 to generate an oxide passivation layer 13 on the light-emitting surface 11 of the bar.

[0030] The second preset value of microwave power is in the range of 100-500W, the flow rate of O2 is 10-20sccm, the O2 introduction time is 10-60min, and the thickness of the oxide passivation layer 13 is 8-15nm.

[0031] In one embodiment, the second preset value of microwave power is 200W, the second preset value of gas pressure in the coating chamber is 0.01Pa, the flow rate of O2 is 15sccm, the O2 introduction time is 40min, and the thickness of the oxide passivation layer 13 is 10nm.

[0032] Similarly, the introduced O2 will collide with the cyclotron resonating electrons in the magnetic field and ionize into O2. + and e - O +Driven by a potential difference, it undergoes an oxidation reaction with AlGaAs. In this reaction, Al atoms in AlGaAs preferentially react with oxygen ions to form non-stoichiometric AlO. x This refers to the oxide passivation layer 13. Ga atoms react with oxygen ions to form Ga2O3, but because the oxidation of Ga requires higher energy, the formed Ga2O3 is unstable, and some Ga2O3 decomposes during the formation of Ga2O3. As atoms react with oxygen ions to form As2O3, which rapidly sublimates. Since the formed As2O3 is highly toxic, a vacuum system needs to be activated for collection by a vacuum adsorption system.

[0033] ECR oxygen ion oxidation preferentially generates atomically bonded Al-O bonds through an energy-selective reaction. Simultaneously, the volatility of Ga and As enables interfacial self-purification, thereby forming AlO in non-stoichiometric proportions. x The oxide passivation layer 13 is mainly composed of atoms. Because the generated oxide passivation layer 13 is atomically bonded, it ensures that the generated oxide passivation layer 13 (i.e., non-stoichiometric AlO₂) is maintained. x The high interfacial bonding energy of AlGaAs allows it to withstand thermal stress under high power, thus increasing the power limit it can withstand. Furthermore, the low-temperature characteristics of oxidizing the AlGaAs epitaxial layer at room temperature prevent high-energy ions from damaging the quantum well structure and lattice integrity, improving the yield of high-power semiconductor lasers. Therefore, the low-temperature in-situ oxidation method for preparing the cavity film of AlGaAs semiconductor lasers provided in this application fundamentally solves the interfacial defect problem of traditional deposition methods due to its low-temperature characteristics and atomic-level bonding capability.

[0034] S6. Adjust the position of the bar strip so that the high negative side 12 of the bar strip faces downward, and then repeat the operation of steps S3-S5 to form an oxide passivation layer 13 on the high negative side 12 of the bar strip.

[0035] S7, an antireflection film 14 is deposited on the light-emitting surface 11, and a high-reflection film 15 is deposited on the high-reflection surface 12, resulting in the following: Figure 1 The bar shown.

[0036] In one specific embodiment, the antireflective coating 14 in this example is composed of overlapping Al2O3 and SiO2 layers with an overlap period of 1, and the reflectivity of the antireflective coating 14 is <5%. The high reflectivity coating 15 is composed of overlapping SiO2 and TiO2 layers with an overlap period of 6, and the reflectivity of the high reflectivity coating 15 is >99%.

[0037] The antireflective coating 14 and the high reflective coating 15 can be prepared by electron beam evaporation, sputtering, or ion plating.

[0038] As a specific implementation, the antireflection film 14 and the high reflectivity film 15 described in this embodiment are prepared by electron beam evaporation process.

[0039] Other embodiments obtained by those skilled in the art based on the embodiments provided in this application by combining, splitting, or reorganizing the embodiments of this application do not exceed the protection scope of this application.

[0040] The above detailed embodiments have provided a detailed explanation of the purpose, technical solutions, and beneficial effects of the embodiments of this application. The above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. That is, any modifications, equivalent substitutions, improvements, etc., made on the basis of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A method for low-temperature in-situ oxidation preparation of cavity films in AlGaAs semiconductor lasers, characterized in that: Includes the following steps, S1, the AlGaAs semiconductor laser wafer is cleaved into strips; S2, place the bar strip into the coating chamber and make the light-emitting surface (11) of the bar strip face downward; S3, Evacuate the vacuum chamber to bring the air pressure inside the coating chamber to the first preset value; S4, turn on the microwave source and adjust the microwave power to the first preset value, then introduce Ar; S5, adjust the microwave power to the second preset value, and evacuate the vacuum chamber to make the air pressure in the coating chamber reach the second preset value, and then introduce O2 to generate an oxide passivation layer (13) on the light-emitting surface (11) of the bar. S6, adjust the position of the bar strip so that the high side (12) of the bar strip faces downward, and then repeat the operation of steps S3-S5 to form an oxide passivation layer (13) on the high side (12) of the bar strip. S7, deposit an antireflection film (14) on the light-emitting surface (11) and a high-reflection film (15) on the high-reflection surface (12).

2. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S2, the coating chamber is cleaned before the bar strip is placed into the coating chamber.

3. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S3, the first preset value of the air pressure in the coating chamber is 1×10⁻ 5 Pa.

4. The method for low-temperature in-situ oxidation preparation of the cavity film of an AlGaAs semiconductor laser according to claim 1, characterized in that: In step S4, the first preset value of microwave power is 150W, the flow rate of Ar when it is introduced is 20sccm, and the processing time is 20min.

5. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S4, the air pressure inside the coating chamber is 0.15 Pa.

6. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S5, the second preset value of microwave power ranges from 100 to 500W.

7. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S5, the flow rate of O2 is 10-20 sccm, and the O2 introduction time is 10-60 min.

8. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: In step S5, the thickness of the oxide passivation layer (13) is 8-15 nm.

9. The method for low-temperature in-situ oxidation preparation of cavity films for AlGaAs semiconductor lasers according to claim 1, characterized in that: The antireflective film (14) is formed by overlapping Al2O3 and SiO2 layers, and the high reflective film (15) is formed by overlapping SiO2 and TiO2 layers.

10. The method for low-temperature in-situ oxidation preparation of the cavity film of an AlGaAs semiconductor laser according to claim 9, characterized in that: The reflectivity of the antireflective coating (14) is <5%, and the reflectivity of the high reflectivity coating (15) is >99%.

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