A method for processing the cavity surface of a semiconductor laser and a semiconductor laser

Abstract

The present application discloses a semiconductor laser cavity surface processing method and a semiconductor laser, wherein the method stacks and places laser chips that have been cleaved and pre-processed in the atmosphere into a sample injection cavity for a first heat treatment, then sequentially performs a second heat treatment in a growth cavity, injects a reducing gas shock and performs a third heat treatment, and injects a fluorine-containing ion source gas to perform a surface fluorination treatment on the surface of a GaAs substrate to generate a first thickness of a wide bandgap metal fluoride layer on the surface of the GaAs substrate, and injects a hydrogen-nitrogen ion source gas and evaporates a metal aluminum source to generate a second thickness of a hydrogenated aluminum nitride layer on the metal fluoride layer, and obtains a passivation layer composed of a metal fluoride layer and a hydrogenated aluminum nitride layer. The present application can reduce the surface state density of the cavity surface of a GaAs-based semiconductor laser, enhance the performance of resisting optical catastrophic damage, and thus improve the performance and reliability of the semiconductor laser.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor laser processes, and in particular to a semiconductor laser cavity surface processing method and a semiconductor laser. Background Art

[0002] During the preparation of semiconductor laser chips, it is necessary to cleave along the crystal plane to form two parallel mirrors to form a resonant cavity. This process will inevitably destroy a small amount of chemical bonds and increase the surface state density of the cavity surface. The existence of surface states has a great influence on the physical properties of semiconductor laser chips such as charge transfer and resistivity. When the cleavage surface is exposed to the atmospheric environment, the surface dangling bonds combine with oxygen to generate irregular oxide defects and form non-radiative recombination centers, which greatly increase the possibility of optical catastrophic damage (COD) on the cavity surface. In order to improve the interface state of the cavity surface and facilitate the growth of optical dielectric films on the front and rear cavity surfaces, the prior art usually uses vacuum cleavage to complete the cleavage step in an ultra-high vacuum device, and then directly grows a passivation layer. Although this method ensures good device performance, it is complicated to operate and inefficient, and the manual cleavage process is also prone to damage to the cavity surface. For this reason, the prior art also uses atmospheric cleavage. After the cleavage operation is completed in the atmosphere using a wafer splitting device, a passivation layer is grown on the cavity surface in an ultra-high vacuum device. However, this method sometimes still cannot avoid the increase of surface state density and optical catastrophic damage of the cavity surface, thereby affecting the performance and reliability of the semiconductor laser. Therefore, an improved cavity surface treatment process is urgently needed to solve the above technical problems. Summary of the invention

[0003] In view of this, the present application proposes a semiconductor laser cavity surface processing method and a semiconductor laser, which can reduce the surface state density of the GaAs-based semiconductor laser cavity surface, enhance the resistance to optical catastrophic damage, and thus improve the performance and reliability of the semiconductor laser.

[0004] In a first aspect, an embodiment of the present application provides a method for processing a cavity surface of a semiconductor laser, the method comprising:

[0005] Placing the atmospherically cleaved and pre-treated laser chip stack into the injection chamber, and performing a first heat treatment in a first temperature range under a first vacuum environment;

[0006] The laser chips are stacked and placed in a growth chamber, heated to a second temperature range under a second vacuum environment for a second heat treatment, and a reducing gas is injected to impact the GaAs substrate surface of the cavity surface of the laser chip to remove surface oxides, and then heated to a third temperature range for a third heat treatment;

[0007] The surface of the GaAs substrate is subjected to surface fluorination treatment by injecting fluorine-containing ion source gas to generate a wide bandgap metal fluoride layer of the first thickness on the surface of the GaAs substrate, and then the temperature is lowered to the second temperature range, and a hydrogenated aluminum nitride layer of the second thickness is generated on the metal fluoride layer by injecting hydrogen-nitrogen ion source gas and evaporating a metal aluminum source, thereby obtaining a passivation layer composed of the metal fluoride layer and the hydrogenated aluminum nitride layer.

[0008] In a preferred embodiment, the metal fluoride layer includes gallium fluoride (GaF3), and the ratio between the first thickness and the second thickness satisfies a ratio relationship of 1:2.5 to 1:3.

[0009] In a preferred embodiment, the first thickness is 2-5 nm, and the second thickness is 5-15 nm.

[0010] In a preferred embodiment, the first temperature range includes 80-100°C, the second temperature range includes 300-350°C, and the third temperature range includes 500-550°C.

[0011] In a preferred embodiment, the method further comprises:

[0012] After the growth of the passivation layer is completed, the evaporation is terminated, the heating is maintained at the second temperature range, and the passivation layer is annealed by injecting a hydrogen ion source gas.

[0013] In a preferred embodiment, the pretreatment includes: placing the laser chip in deionized water for ultrasonic treatment, while introducing an oxidizing gas into the deionized water to form an oxide on the surface of the GaAs substrate of the cavity surface of the laser chip.

[0014] In a preferred embodiment, the method further comprises:

[0015] A diamond-like carbon film of a third thickness, a silicon dioxide film of a fourth thickness, an aluminum oxide film or an aluminum nitride film of a fifth thickness, and a silicon dioxide film of a sixth thickness are sequentially deposited on the passivation layer of the front cavity of the laser chip through a deposition coating process to form a composite antireflection film.

[0016] In a preferred embodiment, the method further comprises:

[0017] A diamond-like film of the seventh thickness and a silicon dioxide film of the eighth thickness are cyclically and alternately deposited on the passivation layer of the back cavity of the laser chip by a deposition coating process, and a diamond-like film of the ninth thickness is deposited on the last silicon dioxide film to form a composite high-reflection film; or a diamond-like film of the seventh thickness is deposited on the passivation layer of the back cavity of the laser chip by a deposition coating process, and a silicon dioxide film of the eighth thickness and a tantalum pentoxide film of the ninth thickness are cyclically and alternately deposited on the diamond-like film, and a tantalum pentoxide film of the tenth thickness is deposited on the last silicon dioxide film of the eighth thickness to form a composite high-reflection film.

[0018] In a second aspect, an embodiment of the present application provides a semiconductor laser, comprising:

[0019] A passivation layer consisting of a metal fluoride layer of a first thickness and a hydrogenated aluminum nitride layer of a second thickness is formed on the surface of the GaAs substrate at the cavity surface.

[0020] In a preferred embodiment, the semiconductor laser further comprises:

[0021] A composite antireflection film formed on the passivation layer of the front cavity and consisting of a diamond-like carbon film of a third thickness, a silicon dioxide film of a fourth thickness, an aluminum oxide film or an aluminum nitride film of a fifth thickness, and a silicon dioxide film of a sixth thickness in sequence;

[0022] A composite high-reflection film formed on the passivation layer of the back cavity is composed of a diamond-like film of the seventh thickness, a silicon dioxide film of the eighth thickness, and a diamond-like film of the ninth thickness on the last silicon dioxide film in a cyclic alternating manner; or a composite high-reflection film is composed of a diamond-like film of the seventh thickness, a silicon dioxide film of the eighth thickness, and a tantalum pentoxide film of the ninth thickness, and a tantalum pentoxide film of the tenth thickness on the last silicon dioxide film of the eighth thickness.

[0023] This application can at least achieve the following beneficial effects:

[0024] In the embodiment of the present application, the surface of the GaAs substrate is subjected to surface fluorination treatment by injecting fluorine-containing ion source gas to generate a wide bandgap metal fluoride layer of a first thickness on the surface of the GaAs substrate, and a hydrogenated aluminum nitride layer of a second thickness is generated on the metal fluoride layer by injecting hydrogen-nitrogen ion source gas and evaporating a metal aluminum source, thereby obtaining a passivation layer composed of the metal fluoride layer and the hydrogenated aluminum nitride layer, which can effectively prevent external injected carriers from entering the active region of the laser, reduce the non-radiative recombination rate of the laser cavity surface, reduce the surface state density of the laser cavity surface, and further enhance the anti-catastrophic optical damage (COD) performance, thereby improving the performance and reliability of the semiconductor laser.

[0025] Furthermore, in the embodiment of the present application, a composite anti-reflection film and a composite high-reflection film formed by stacking two or more thin film materials with different refractive indices are deposited on the passivation layer composed of the metal fluoride layer and the hydrogenated aluminum nitride layer, respectively, and the performance and reliability of the semiconductor laser can be further improved on the basis of meeting the optical performance requirements of the front and rear cavity surfaces of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope of the present application.

[0027] Figure 1 It is a schematic flow chart of a method for processing a cavity surface of a semiconductor laser according to an embodiment of the present application;

[0028] Figure 2 is a structural schematic diagram of a cavity surface processing device according to an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of laser chips stacked in a fixture according to an embodiment of the present application;

[0030] Figure 4 is a schematic diagram of the internal structure of a growth chamber according to an embodiment of the present application;

[0031] Figure 5A is a schematic cross-sectional view of a metal fluoride layer on the substrate surface of a laser chip according to an embodiment of the present application;

[0032] Figure 5B is a schematic cross-sectional view of a passivation layer on the substrate surface of a laser chip according to an embodiment of the present application;

[0033] Figure 6 is a schematic cross-sectional view of a composite antireflection film on the front cavity surface of a laser chip according to the first embodiment of the present application;

[0034] Figure 7 is a cross-sectional schematic diagram of a composite antireflection film on the front cavity surface of a laser chip according to a second embodiment of the present application;

[0035] Figure 8 is a cross-sectional schematic diagram of a composite high-reflection film on the back cavity surface of a laser chip according to the first embodiment of the present application;

[0036] Fig. 9 is a cross-sectional schematic diagram of a composite high-reflection film on the back cavity surface of a laser chip according to the second embodiment of the present application;

[0037] Fig. 10Ais a refractive index curve diagram of a passivation layer formed according to an embodiment of the present application;

[0038] Fig. 10B is an absorption coefficient curve diagram of a passivation layer formed according to an embodiment of the present application;

[0039] Fig.11A is a reflectivity curve diagram of the composite antireflection film formed according to the first embodiment of the present application;

[0040] Fig. 11B is a reflectivity curve diagram of a composite antireflection film formed according to the second embodiment of the present application;

[0041] Fig. 12A is a reflectivity curve diagram of a composite high-reflective film formed according to the first embodiment of the present application;

[0042] Fig. 12B It is a reflectivity curve diagram of the composite high-reflective film formed according to the second embodiment of the present application. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. However, it should be understood that the described embodiments are only some exemplary embodiments of the present application, rather than all embodiments, and therefore the following detailed description of the embodiments of the present application is not intended to limit the scope of protection claimed in the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0044] It should be noted that the terms "first", "second", etc. in the specification and claims of this application are only used to distinguish and describe similar objects, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance.

[0045] As mentioned above, the prior art usually uses a vacuum cleavage method to complete the cleavage step in an ultra-high vacuum device, and then directly grows a passivation layer. Although this method ensures good device performance, it is complicated to operate and inefficient, and the manual cleavage process is also prone to damage to the cavity surface. For this reason, the prior art also uses an atmospheric cleavage method, using a wafer splitting device in the atmosphere to complete the cleavage operation, and then growing a passivation layer on the cavity surface in an ultra-high vacuum device. However, this method sometimes still cannot avoid the increase in the surface state density of the cavity surface and the optical catastrophic damage of the cavity surface, thereby affecting the performance and reliability of the semiconductor laser. For this reason, the embodiment of the present application proposes a cavity surface processing method and a semiconductor laser of a semiconductor laser, which can reduce the surface state density of the cavity surface of a GaAs-based semiconductor laser, enhance the performance of anti-optical catastrophic damage, thereby improving the performance and reliability of the semiconductor laser, and meeting the process requirements of the cavity surface of a GaAs-based semiconductor laser.

[0046] Figure 1 FIG. 1 is a flow chart of a method for processing the cavity surface of a semiconductor laser according to an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0047] Step S1, placing the laser chip stack that has been cleaved and pre-treated in the atmosphere into a sample injection chamber, and performing a first heat treatment in a first temperature range under a first vacuum environment;

[0048] Step S2, placing the laser chip stack in a growth chamber under a second vacuum environment and heating it to a second temperature range for a second heat treatment, and injecting reducing gas to impact the GaAs substrate surface of the cavity surface of the laser chip to remove surface oxides, and then heating it to a third temperature range for a third heat treatment;

[0049] Step S3, performing surface fluorination treatment on the surface of the GaAs substrate by injecting fluorine-containing ion source gas to generate a wide bandgap metal fluoride layer of the first thickness on the surface of the GaAs substrate, then cooling to the second temperature range, injecting hydrogen-nitrogen ion source gas and evaporating a metal aluminum source to generate a second thickness of hydrogenated aluminum nitride layer on the metal fluoride layer, and obtaining a passivation layer consisting of the metal fluoride layer and the hydrogenated aluminum nitride layer.

[0050] In this embodiment, for a semiconductor laser based on a GaAs substrate, it is necessary to subject the laser chip that has been cleaved and pre-processed in the atmosphere to a series of process treatments through a cavity surface processing device. The cavity surface includes a front cavity and / or a back cavity. The laser chip may include a laser bar. Figure 2 Schematic diagram of the structure of the cavity surface processing device according to the embodiment of the present application. Figure 2As shown, the cavity surface treatment device includes a sample injection chamber 10, a transition chamber 20 and a growth chamber 30 connected in sequence, and also includes a conveying mechanism 40 for conveying the laser bar from the sample injection chamber 10 to the growth chamber 30. Among them, the sample injection chamber 10 is an interface for interacting with the external environment, and is used for the laser bar after atmospheric cleavage and pretreatment to enter and output the cavity of the cavity surface treatment device, which can maintain a low vacuum environment. The sample injection chamber 10 is equipped with a heating system, which can perform preliminary heat treatment on the laser bar. The transition chamber 20 is a transition chamber between the sample injection chamber 10 and the growth chamber 30, which can maintain a high vacuum environment. Through the conveying mechanism 40, the laser bar can be sent to the growth chamber 30 for cavity surface treatment. The growth chamber 30 is a cavity used for heat treatment, passivation treatment and other processing processes on the laser bar, and can maintain an ultra-high vacuum environment.

[0051] In step S1 of this embodiment, Figure 3 As shown, the laser chips that have been cleaved and pre-treated in the atmosphere, such as a group of laser bars 302, are stacked and placed in the injection chamber 10 through the fixture 50, and a first heat treatment is performed in a first temperature range in a first vacuum environment (i.e., a low vacuum environment). In one embodiment, the first temperature range can be a temperature range heated to 80-120°C, and the first heat treatment time can be maintained for 30-60 minutes, in order to remove the residual water vapor on the surface of the GaAs substrate of the laser bar 302 that has been cleaved and pre-treated in the atmosphere.

[0052] In one embodiment, the pretreatment may include: placing the group of laser bars 302 in hot deionized water for ultrasonic treatment, for example, deionized water in a temperature range of 80 to 100° C., and simultaneously introducing an oxygen-containing oxidizing gas into the deionized water to form oxides on the GaAs substrate surfaces of the front and rear cavity surfaces of the group of laser bars 302.

[0053] In a preferred embodiment, the group of laser bars 302 can be placed in hot deionized water for ultrasonic treatment for 10 to 30 minutes, and an oxidizing gas of oxygen (O2) or ozone (O3) is introduced into the deionized water to form a dense oxide layer on the surface of the GaAs substrate of the front and rear cavities. Then, isopropanol can be used to rinse and remove moisture from the surface of the GaAs substrate, and then blown dry with nitrogen. This pretreatment process can remove organic matter, particle contamination and irregular oxide layers on the surface of the GaAs substrate of the laser bar 302, initially obtain a smooth and flat surface, and at the same time, generate a dense oxide layer on the GaAs substrate, avoiding interface differences between different batches of atmospheric cleavage laser bars 302.

[0054] In step S2 of this embodiment, first, after the group of laser bars 302 undergo a first heat treatment in the injection chamber 10, the group of laser bars 302 are stacked and placed in the growth chamber 30 and heated to a second temperature range greater than the first temperature range under a second vacuum environment (i.e., an ultra-high vacuum environment) for a second heat treatment.

[0055] like Figure 4 As shown, the growth chamber 30 may include a heating stage 301, a rotatable sample carrier 303, an electron beam evaporation device 305, a radio frequency ion source 306, and a vacuum maintenance system 307. The heating stage 301 is used to heat the growth chamber 30 to maintain a predetermined temperature range. The rotatable sample carrier 303 is used to carry the group of laser bars 302 to expose the front and rear cavity surfaces to the growth chamber 30 for a series of heat treatment, passivation treatment and other treatment processes. The electron beam evaporation device 305 is used to evaporate the metal source 304 through an electron beam. The radio frequency ion source 306 is used to inject different ion source gases into the growth chamber 30 to achieve different surface treatments on the front and rear cavity surfaces.

[0056] In one embodiment, the temperature in the growth chamber 30 can be heated to a second temperature range of 300-350° C. by a heating stage 301 to perform a second heat treatment on the group of laser bars 302. The second heat treatment can be maintained for 60-120 minutes to further remove water, oxygen and other molecules adsorbed on the surface of the group of laser bars 302 to prevent the surface dangling bonds generated in the subsequent ion source treatment process from being oxidized.

[0057] In step S2 of this embodiment, a reducing gas is then injected through the RF ion source 306 to impact the GaAs substrate surface of the front and rear cavity surfaces of the group of laser bars 302 to remove the surface oxides generated in the pretreatment, and then heated to a third temperature range greater than the second temperature range for a third heat treatment.

[0058] In one embodiment, the reducing gas injected by the RF ion source 306 may include but is not limited to H2, NH3, HF, CH4 and mixed gases thereof. The RF ion source 306 may use a low power of, for example, 100-300W to repeatedly impact the GaAs substrate surface of the front and rear cavities of the group of laser bars 302, thereby removing the surface oxides generated in the pretreatment. Preferably, the reducing gas may be an ion source gas containing a highly reducing element H.

[0059] In one embodiment, the temperature in the growth chamber 30 can then be heated to a third temperature range of 500-550° C. by a heating stage 301 to perform a third heat treatment on the group of laser bars 302. The third heat treatment can be maintained for 30-60 minutes, with the purpose of sublimating As atoms and As oxides on the surface of the GaAs substrate in the front and rear cavities of the group of laser bars 302, exposing more Ga dangling bonds.

[0060] In step S3 of this embodiment, a fluorine-containing ion source gas is injected through the radio frequency ion source 306 to perform a surface fluorination treatment on the surface of the GaAs substrate to generate a wide bandgap metal fluoride layer of a first thickness on the surface of the GaAs substrate.

[0061] In one embodiment, a fluorine-containing ion source gas of high purity sulfur hexafluoride (SF6) is injected through the radio frequency ion source 306. The radio frequency ion source 306 can use a power of 300-350W to impact the GaAs substrate surface of the front and rear cavities of the group of laser bars 302 for a predetermined time, such as a duration of 5-10 minutes, so that the surface of the GaAs substrate is fluorinated by the fluorine-containing ion source gas of sulfur hexafluoride (SF6). Figure 5A As shown, such a surface fluorination treatment can generate a wide bandgap gallium fluoride (GaF 3 ) metal fluoride layer 401 of a first thickness on the GaAs substrate surface of the front and rear cavities of the laser bar 302 .

[0062] In step S3 of this embodiment, the temperature is then lowered to the second temperature range again, for example, the temperature can be lowered to 350° C. by the heating stage 301, a hydrogen-nitrogen ion source gas is injected through the radio frequency ion source 306, and a metal aluminum source is evaporated through the electron beam evaporation device 305, and a second thickness of hydrogenated aluminum nitride layer (α-AlN:H x ) 402, to obtain the passivation layer 400 composed of the metal fluoride layer 401 and the hydrogenated aluminum nitride layer 402, such as Figure 5B shown.

[0063] Since the bandgap width of gallium fluoride (GaF3) is much larger than that of GaAs, and can reach a bandgap width of 7.6eV, this wide-bandgap metal fluoride layer 401 can effectively prevent external injected carriers from entering the active region of the laser, reduce the non-radiative recombination rate of the laser cavity surface, and reduce the surface state density of the laser cavity surface. At the same time, the wide-bandgap metal fluoride layer 401 has low absorption of light. Further, a hydrogenated aluminum nitride layer 402 is superimposed and grown on the wide-bandgap gallium fluoride (GaF3) metal fluoride layer 401 to form a double-layer composite passivation layer 400. Due to the low absorption and high refractive properties of the hydrogenated aluminum nitride layer 402, the superimposed passivation layer 400 further enhances the anti-optical catastrophic damage (COD) performance on the basis of reducing the surface state density of the GaAs-based semiconductor laser cavity surface, thereby improving the performance and reliability of the semiconductor laser.

[0064] In one embodiment, the hydrogen-nitrogen ion source gas may include ammonia (NH3) or a mixture of nitrogen (N2) and hydrogen (H2) in a ratio of 1:6. Meanwhile, the RF ion source 306 may use a power of 350-400W, and the evaporation speed of the electron beam evaporation device 305 is 0.05-0.1Å / s.

[0065] In one embodiment, the ratio between the first thickness and the second thickness satisfies a ratio of 1:2.5 to 1:3. Preferably, since the metal fluoride layer 401 and the hydrogenated aluminum nitride layer 402 are too thin to effectively protect the cavity surface, and too thick will prolong the process time and waste production capacity. Therefore, preferably, the first thickness can be 2 to 5 nm; the second thickness can be 5 to 15 nm.

[0066] In one embodiment, the method may further include:

[0067] After the growth of the passivation layer 400 is completed, the evaporation is terminated, the heating is maintained at the second temperature range, and a hydrogen-containing ion source gas, such as hydrogen (H2), is injected through the radio frequency ion source 306 to perform annealing on the passivation layer 400. The advantage of this is that highly active atomic H can be used to improve the crystal order of the passivation layer 400, improve the film quality of the passivation layer 400, and release the film stress.

[0068] In one embodiment, after the group of laser bars 302 undergoes the passivation layer growth process in the growth chamber 30, they are taken out from the cavity surface processing equipment through the injection chamber 10, and then a conventional deposition coating process, such as a magnetron sputtering process, can be used to form a composite anti-reflection film 500 and a composite high-reflection film 600 on the passivation layer 400 of the front cavity and the back cavity of the group of laser bars 302, respectively. The composite anti-reflection film 500 and the composite high-reflection film 600 are composed of two or more thin film materials with different refractive indices, and the number of layers is not less than two. By depositing the composite anti-reflection film 500 and the composite high-reflection film 600 on the passivation layer 400 composed of the metal fluoride layer 401 and the hydrogenated aluminum nitride layer 402, the performance and reliability of the semiconductor laser can be further improved on the basis of meeting the optical performance requirements of the front and rear cavity surfaces of the semiconductor laser.

[0069] In one embodiment, the method further comprises:

[0070] A third thickness of diamond-like carbon film, a fourth thickness of silicon dioxide film, a fifth thickness of aluminum oxide film or aluminum nitride film, and a sixth thickness of silicon dioxide film are sequentially deposited on the passivation layer 400 of the front cavity of the group of laser bars 302 by a deposition coating process to form a composite antireflection film 500.

[0071] Figure 6 FIG. 5 is a schematic cross-sectional view of a composite antireflection film 500 on the front cavity surface of a laser chip according to the first embodiment of the present application. Figure 6 As shown, in the first embodiment, the composite antireflection film 500 on the front cavity surface of the laser bar 302 sequentially includes a diamond-like carbon film (DLC) 501 of the third thickness, a silicon dioxide film (SiO2) 502 of the fourth thickness, an aluminum oxide film (AL2O3) 503a of the fifth thickness, and a silicon dioxide film (SiO2) 504 of the sixth thickness. As an example, the third thickness can be 103nm, the fourth thickness is 170nm, the fifth thickness is 81nm, and the sixth thickness is 170nm.

[0072] Figure 7 FIG. 5 is a cross-sectional schematic diagram of a composite antireflection film 500 on the front cavity surface of a laser chip according to the second embodiment of the present application. Figure 7 As shown, in the second embodiment, the composite antireflection film 500 on the front cavity surface of the laser bar 302 sequentially includes a diamond-like carbon film (DLC) 501 of the third thickness, a silicon dioxide film (SiO2) 502 of the fourth thickness, an aluminum nitride film (ALN) 503b of the fifth thickness, and a silicon dioxide film (SiO2) 504 of the sixth thickness. As an example, the third thickness may be 51 nm, the fourth thickness may be 170 nm, the fifth thickness may be 198 nm, and the sixth thickness may be 61 nm.

[0073] In one embodiment, the method further comprises:

[0074] A diamond-like film of the seventh thickness and a silicon dioxide film of the eighth thickness are cyclically and alternately deposited on the passivation layer 400 of the back cavity of the group of laser bars 302 by a deposition coating process, and a diamond-like film of the ninth thickness is deposited on the last silicon dioxide film to form a composite high-reflection film 600; or, a diamond-like film of the seventh thickness is deposited on the passivation layer 400 of the back cavity of the group of laser bars 302 by a deposition coating process, and a silicon dioxide film of the eighth thickness and a tantalum pentoxide film of the ninth thickness are cyclically and alternately deposited on the diamond-like film to form a composite high-reflection film 600.

[0075] Figure 8 FIG. 6 is a cross-sectional schematic diagram of a composite high-reflection film 600 on the back cavity surface of a laser chip according to the first embodiment of the present application. Figure 8 As shown, in the first embodiment, the composite high-reflection film 600 on the rear cavity surface of the laser bar 302 includes a diamond-like carbon film (DLC) 601 with a seventh thickness and a silicon dioxide film (SiO2) 602 with an eighth thickness that are cyclically and alternately deposited, and a diamond-like carbon film (DLC) 603a with a ninth thickness is deposited on the last silicon dioxide film (SiO2) 602. As an example, the seventh thickness may be 103 nm, the eighth thickness may be 170 nm, and the ninth thickness may be 74 nm.

[0076] Fig. 9 FIG. 6 is a cross-sectional schematic diagram of a composite high-reflection film 600 on the back cavity surface of a laser chip according to the second embodiment of the present application. Fig. 9 As shown, in the second embodiment, the composite high-reflection film 600 on the back cavity surface of the laser bar 302 includes a diamond-like carbon film (DLC) 601 of the seventh thickness, and a silicon dioxide film (SiO2) 602 of the eighth thickness and a tantalum pentoxide film (TA2O5) 603b of the ninth thickness that are cyclically and alternately deposited, and a tantalum pentoxide film (TA2O5) 603c of the tenth thickness is deposited on the last silicon dioxide film (SiO2) 602 of the eighth thickness. As an example, the seventh thickness can be 205nm, the eighth thickness is 170nm, the ninth thickness is 116nm, and the tenth thickness is 186nm.

[0077] The present application also proposes a semiconductor laser, which is suitable for being generated by the cavity surface processing method of any of the above embodiments, and the semiconductor laser comprises:

[0078] A passivation layer 400 is formed on the surface of the GaAs substrate at the cavity surface and is composed of a metal fluoride layer 401 with a first thickness and a hydrogenated aluminum nitride layer 402 with a second thickness.

[0079] In one embodiment, the semiconductor laser further comprises:

[0080] A composite antireflection film 500 formed on the passivation layer 400 of the front cavity and composed of a diamond-like carbon film (DLC) 501 with a third thickness, a silicon dioxide film (SiO2) 502 with a fourth thickness, an aluminum oxide film (AL2O3) 503a with a fifth thickness, and a silicon dioxide film (SiO2) 504 with a sixth thickness in sequence; or a composite antireflection film 500 composed of a diamond-like carbon film (DLC) 501 with a third thickness, a silicon dioxide film (SiO2) 502 with a fourth thickness, an aluminum nitride film (ALN) 503b with a fifth thickness, and a silicon dioxide film (SiO2) 504 with a sixth thickness in sequence;

[0081] A composite high-reflective film 600 formed on the passivation layer 400 of the back cavity is formed by a diamond-like carbon film (DLC) 601 with a seventh thickness, a silicon dioxide film (SiO2) 602 with an eighth thickness, and a diamond-like carbon film (DLC) 603a with a ninth thickness on the last silicon dioxide film (SiO2) 602 in sequence; or a composite high-reflective film 600 is formed by a diamond-like carbon film (DLC) 601 with a seventh thickness, a silicon dioxide film (SiO2) 602 with an eighth thickness, and a tantalum pentoxide film (TA2O5) 603b with a ninth thickness, and a tantalum pentoxide film (TA2O5) 603c with a tenth thickness on the last silicon dioxide film (SiO2) 602 with an eighth thickness.

[0082] Fig. 10A is a refractive index curve diagram of the passivation layer 400 formed according to an embodiment of the present application, Fig. 10B is a graph of the absorption coefficient of the passivation layer 400 formed according to an embodiment of the present application. Fig. 10A and 10B As shown, taking a 976nm GaAs-based semiconductor laser as an example, the refractive index of the passivation layer 400 grown by the cavity surface processing method of the present application at 976nm is about 2.03, and the absorption coefficient is about 0, indicating that the passivation layer 400 composed of the metal fluoride layer 401 and the hydrogenated aluminum nitride layer 402 in the embodiment of the present application exhibits good low light absorption characteristics and high refractive characteristics, thereby significantly enhancing the anti-optical catastrophic damage (COD) performance of the front and rear cavity surfaces of the semiconductor laser, thereby improving the performance and reliability of the semiconductor laser.

[0083] Fig.11A is a reflectivity curve diagram of the composite antireflection film 500 formed according to the first embodiment of the present application. Fig. 11B is a reflectivity curve diagram of the composite antireflection film 500 formed according to the second embodiment of the present application. Fig.11A and11B As shown, taking a 976nm GaAs-based semiconductor laser as an example, the composite antireflection film 500 grown by the cavity surface processing method of the present application has a high reflectivity at 976nm (such as Fig.11A and 11B The reflectivity of the composite anti-reflection film 500 (as shown by the vertical dotted line in the figure) is about 3%, indicating that the composite anti-reflection film 500 in any embodiment of the present application exhibits good low-reflection characteristics, thereby meeting the optical performance requirements of the front-cavity anti-reflection film and improving the performance and reliability of the semiconductor laser.

[0084] Fig. 12A 4 is a reflectivity curve diagram of the composite high-reflective film 600 formed according to the first embodiment of the present application. Fig. 12B is a reflectivity curve diagram of the composite high-reflection film 600 formed according to the second embodiment of the present application. Fig. 12A and 12B As shown, taking a 976nm GaAs-based semiconductor laser as an example, the composite high-reflection film 600 grown by the cavity surface treatment method of the present application has a high reflectivity at 976nm (such as Fig. 12A and 12B The reflectivity of the composite high-reflection film 600 (as shown by the vertical dotted line in the figure) is about 95%, indicating that the composite high-reflection film 600 in any embodiment of the present application exhibits good high-reflection characteristics, thereby meeting the optical performance requirements of the back-cavity high-reflection film and improving the performance and reliability of the semiconductor laser.

[0085] In the embodiment of the present application, the surface of the GaAs substrate is subjected to surface fluorination treatment by injecting fluorine-containing ion source gas to generate a wide bandgap metal fluoride layer of a first thickness on the surface of the GaAs substrate, and a hydrogenated aluminum nitride layer of a second thickness is generated on the metal fluoride layer by injecting hydrogen-nitrogen ion source gas and evaporating a metal aluminum source, thereby obtaining a passivation layer composed of the metal fluoride layer and the hydrogenated aluminum nitride layer, which can effectively prevent external injected carriers from entering the active region of the laser, reduce the non-radiative recombination rate of the laser cavity surface, reduce the surface state density of the laser cavity surface, and further enhance the anti-catastrophic optical damage (COD) performance, thereby improving the performance and reliability of the semiconductor laser.

[0086] Furthermore, in the embodiment of the present application, a composite anti-reflection film and a composite high-reflection film formed by stacking two or more thin film materials with different refractive indices are deposited on the passivation layer composed of the metal fluoride layer and the hydrogenated aluminum nitride layer, respectively, and the performance and reliability of the semiconductor laser can be further improved on the basis of meeting the optical performance requirements of the front and rear cavity surfaces of the semiconductor laser.

[0087] It should be noted that those skilled in the art can understand that the different implementation methods described in the method embodiments of the present application and their explanations and technical effects achieved are also applicable to the device embodiments of the present application and will not be repeated here.

[0088] The above describes the exemplary embodiments of the present application. It should be understood that the above exemplary embodiments are not restrictive but illustrative, and the protection scope of the present application is not limited thereto. It should be understood that those skilled in the art can modify and vary the embodiments of the present application without departing from the spirit and scope of the present application, and these modifications and variations should be within the protection scope of the present application.

Claims

1. A method for processing the cavity surface of a semiconductor laser, characterized in that: The method comprises: Placing the atmospherically cleaved and pre-treated laser chip stack into the injection chamber, and performing a first heat treatment in a first temperature range under a first vacuum environment; The laser chips are stacked and placed in a growth chamber, heated to a second temperature range under a second vacuum environment for a second heat treatment, and then a reducing gas is injected to impact the GaAs substrate surface of the cavity surface of the laser chip to remove surface oxides, and then heated to a third temperature range for a third heat treatment; Subsequently, the surface of the GaAs substrate is subjected to surface fluorination treatment by injecting fluorine-containing ion source gas to generate a wide-bandgap metal fluoride layer of the first thickness on the surface of the GaAs substrate, and then the temperature is lowered to the second temperature range, and a second thickness of a hydrogenated aluminum nitride layer is generated on the metal fluoride layer by injecting hydrogen-nitrogen ion source gas and evaporating a metal aluminum source, so as to obtain a passivation layer consisting of the metal fluoride layer and the hydrogenated aluminum nitride layer; wherein the first temperature range is 80-100°C, the second temperature range is 300-350°C, and the third temperature range is 500-550°C, the metal fluoride layer includes gallium fluoride (GaF3), and the ratio between the first thickness and the second thickness satisfies a ratio relationship of 1:2.5-1:

3.

2. The method for processing the cavity surface of a semiconductor laser according to claim 1, characterized in that: The first thickness is 2-5 nm, and the second thickness is 5-15 nm.

3. The method for processing the cavity surface of a semiconductor laser according to claim 1, characterized in that: The method further comprises: After the growth of the passivation layer is completed, the evaporation is terminated, the heating is maintained at the second temperature range, and the passivation layer is annealed by injecting a hydrogen ion source gas.

4. The method for processing the cavity surface of a semiconductor laser according to claim 1, characterized in that: The pretreatment comprises: placing the laser chip in deionized water for ultrasonic treatment, and simultaneously introducing an oxidizing gas into the deionized water to form oxide on the surface of the GaAs substrate of the cavity surface of the laser chip.

5. The method for processing the cavity surface of a semiconductor laser according to claim 1, characterized in that: The method also includes: depositing a third thickness of diamond-like carbon film, a fourth thickness of silicon dioxide film, a fifth thickness of aluminum oxide film or aluminum nitride film, and a sixth thickness of silicon dioxide film on the passivation layer of the front cavity of the laser chip in sequence through a deposition coating process to form a composite antireflection film.

6. The method for processing the cavity surface of a semiconductor laser according to claim 1 or 5, characterized in that: The method further comprises: A diamond-like film of the seventh thickness and a silicon dioxide film of the eighth thickness are cyclically and alternately deposited on the passivation layer of the back cavity of the laser chip by a deposition coating process, and a diamond-like film of the ninth thickness is deposited on the last silicon dioxide film to form a composite high-reflection film; or a diamond-like film of the seventh thickness is deposited on the passivation layer of the back cavity of the laser chip by a deposition coating process, and a silicon dioxide film of the eighth thickness and a tantalum pentoxide film of the ninth thickness are cyclically and alternately deposited on the diamond-like film, and a tantalum pentoxide film of the tenth thickness is deposited on the last silicon dioxide film of the eighth thickness to form a composite high-reflection film.

7. A semiconductor laser, characterized in that: Applicable to being generated by the cavity surface processing method according to any one of claims 1 to 6, comprising: A passivation layer consisting of a metal fluoride layer of a first thickness and a hydrogenated aluminum nitride layer of a second thickness is formed on the surface of the GaAs substrate at the cavity surface.

8. The semiconductor laser according to claim 7, characterized in that The semiconductor laser further comprises: A composite antireflection film formed on the passivation layer of the front cavity and consisting of a diamond-like carbon film of a third thickness, a silicon dioxide film of a fourth thickness, an aluminum oxide film or an aluminum nitride film of a fifth thickness, and a silicon dioxide film of a sixth thickness in sequence; A composite high-reflection film formed on the passivation layer of the back cavity is composed of a diamond-like film of the seventh thickness, a silicon dioxide film of the eighth thickness, and a diamond-like film of the ninth thickness on the last silicon dioxide film in a cyclic alternating manner; or a composite high-reflection film is composed of a diamond-like film of the seventh thickness, a silicon dioxide film of the eighth thickness, and a tantalum pentoxide film of the ninth thickness, and a tantalum pentoxide film of the tenth thickness on the last silicon dioxide film of the eighth thickness.

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