Method for manufacturing red light semiconductor laser with non-absorption window

Abstract

The present invention discloses a method for manufacturing a red semiconductor laser with a non-absorption window, comprising: defining a non-absorption region at the cavity surfaces at both ends of a red semiconductor laser chip, removing the ohmic contact layer of the non-absorption region; growing a ZnO film and a SiO2 mask in the non-absorption region; placing a sample wafer of a red semiconductor laser chip in a vacuum and high temperature environment to diffuse and form a non-absorption window; and removing the SiO2 mask and the ZnO film on the surface of the sample wafer of the red semiconductor laser chip. The present invention provides a non-absorption window process for a red semiconductor laser of an AlGaInP material system, thereby expanding the band gap width of the light-emitting region, realizing a blue shift of the PL spectrum, reducing the energy absorption of the light-emitting cavity surface, reducing the cavity surface temperature, reducing the probability of cavity surface burnout, and improving the maximum output power, reliability, and service life of the red semiconductor laser.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor lasers, and in particular relates to a method for manufacturing a red light semiconductor laser with a non-absorption window. Background Art

[0002] Semiconductor laser is a coherent radiation light source, which has been widely used in the fields of optical fiber communication, optical disk, laser printer, laser scanner, laser pointer (laser pen), etc., and is the laser with the largest production volume. In terms of materials used, semiconductor lasers have a variety of materials such as gallium (Ga), arsenic (As), indium (I n), phosphorus (P), etc. The red light semiconductor laser chip uses the AlGaInP material system. Due to the short wavelength of red light and the large energy of a single photon, it is easy to cause cavity surface catastrophic damage (COD) on the light output surface, which is one of the main reasons affecting its reliability and high power output. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for manufacturing a red light semiconductor laser with a non-absorption window.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A method for manufacturing a red light semiconductor laser with a non-absorption window comprises the following steps:

[0006] S100, growing a SiO2 mask on a red light semiconductor laser chip sample wafer of an AlGaInP material system, defining non-absorption regions at the cavity surfaces at both ends of the red light semiconductor laser chip, and removing the SiO2 mask in the non-absorption region by photolithography and etching;

[0007] S200, removing the ohmic contact layer located in the non-absorption region on the red light semiconductor laser chip sample wafer;

[0008] S300, growing a ZnO film in the non-absorption region, and growing a SiO2 mask again on the surface of the red light semiconductor laser chip sample wafer;

[0009] S400, placing a red light semiconductor laser chip sample wafer in a vacuum and high temperature environment to diffuse and form a non-absorption window;

[0010] S500, removing the SiO2 mask and the ZnO film on the surface of the red light semiconductor laser chip sample wafer;

[0011] S600, completing the subsequent preparation process of the red light semiconductor laser.

[0012] Furthermore, the red light semiconductor laser chip includes a GaAs substrate layer, a buffer layer, an n-type intermediate layer, an n-type cladding layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer, a p-type cladding layer, an etching resistance layer, a p-type intermediate layer and an ohmic contact layer, which are arranged in sequence from bottom to top.

[0013] Furthermore, the quantum well active layer includes a plurality of quantum well layers and a plurality of quantum barrier layers, and the quantum well layers and quantum barrier layers are arranged at intervals.

[0014] Furthermore, the material of the quantum well layer is GaInP, and the material of the quantum barrier layer is AlGaInP.

[0015] Furthermore, the non-absorption window diffuses to the n-type cladding layer.

[0016] Furthermore, the width of the non-absorption region is 10 μm to 200 μm.

[0017] Furthermore, the width of the non-absorption region is 30 μm to 60 μm.

[0018] Furthermore, the thickness of the ZnO thin film layer is 10nm to 50nm.

[0019] Furthermore, the step S400 includes the following sub-steps:

[0020] Place the red light semiconductor laser chip sample wafer into a quartz tube and evacuate it to 1Pa to 10Pa;

[0021] The quartz tube is placed in a furnace tube at 500°C to 650°C for high temperature diffusion for 3h to 4h, thereby forming a non-absorption window in the non-absorption area;

[0022] The red semiconductor laser chip sample wafer is allowed to cool naturally.

[0023] Furthermore, in the step S600, the subsequent preparation process of the red light semiconductor laser includes ridge waveguide etching, window opening, electrode preparation, alloying, thinning, scribing and coating.

[0024] In the present invention, a non-absorption zone is defined at the laser cavity surface, and doped Zn ions are introduced into the non-absorption zone by growing a ZnO film, and then a method of high-temperature diffusion of a furnace tube is used to realize quantum well intermixing, and a non-absorption window is formed in the non-absorption zone, so that the wavelength blue shift amount of the non-absorption zone can be controlled, the band gap width of the light-emitting region can be expanded, the PL spectrum blue shift can be realized, the energy absorption of the light-emitting cavity surface can be reduced, the cavity surface temperature can be lowered, the cavity surface burning probability can be reduced, the maximum output power of the red light semiconductor laser can be increased, and the reliability and service life of the red light semiconductor laser can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0026] Figure 1 Schematic diagram of the structure of a red light semiconductor laser chip sample.

[0027] Figure 2 The flowchart is a method for manufacturing a red semiconductor laser with a non-absorption window according to an embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the structure after removing the SiO2 mask of the non-absorption area.

[0029] Figure 4 Schematic diagram of the structure after removing the ohmic contact layer of the non-absorption area.

[0030] Figure 5 Schematic diagram of the structure after growing ZnO thin film.

[0031] Figure 6 This is a schematic diagram of the structure after the Si O2 mask is grown again on the surface of the red light semiconductor laser chip sample wafer.

[0032] Figure 7 Schematic diagram of the structure after diffusion forms a non-absorption window.

[0033] Figure 8 Schematic diagram of the structure after removing the SiO2 mask and ZnO film.

[0034] Fig. 9 This is a comparison of the PL spectra of the absorption and non-absorption regions of the red light semiconductor laser sample.

[0035] Fig.10 Zn for red semiconductor laser samples 2+ Performance graph of doping depth.

[0036] Fig.11 This is a comparison chart of the COD thresholds of the red light semiconductor laser sample obtained by the method of this embodiment and the ordinary red light semiconductor laser.

[0037] The accompanying drawings in the specification are numeraled as follows:

[0038] GaAs substrate layer-100; buffer layer 110; n-type intermediate layer-120; n-type cladding layer-130; lower waveguide layer-140; quantum well active layer-150; upper waveguide layer-160; p-type cladding layer-170; resist layer-180; p-type intermediate layer-190; ohmic contact layer-200; SiO2 mask-210; ZnO film-220; non-absorption region-300; non-absorption window-310. DETAILED DESCRIPTION

[0039] The following describes the implementation methods of the present invention through specific examples. The illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention. The following embodiments and features in the embodiments may be combined with each other without conflict.

[0040] The red light semiconductor laser chip is an AlGaInP material system chip, see Figure 1 The red light semiconductor laser chip generally includes a GaAs substrate layer 100, a buffer layer 110, an n-type intermediate layer 120, an n-type cladding layer 130, a lower waveguide layer 140, a quantum well active layer 150, an upper waveguide layer-160, a p-type cladding layer-170, a resist layer-180, a p-type intermediate layer 190 and an ohmic contact layer 200 arranged in sequence from bottom to top. The quantum well active layer 150 includes a plurality of quantum well layers and a plurality of quantum barrier layers, and the quantum well layers and the quantum barrier layers are arranged at intervals. The material of the quantum well layer is GaInP, and the material of the quantum barrier layer is AlGaInP.

[0041] Red light semiconductor lasers use AlGaInP material system. The band gap difference between the active layer quantum well GaInP and the limiting layer AlGaInP material system is small, so the limiting ability of injected carriers is poor, which is easy to generate leakage current. This will not only reduce the internal quantum efficiency of the semiconductor laser and the power conversion efficiency, but also cause the characteristic temperature of the device to become lower and the output power to be more sensitive to temperature. In addition, the red light semiconductor laser has a short wavelength and high photon energy. When working at high power, it requires higher resistance to burnout of the cavity surface. Therefore, to obtain a highly reliable, long-life, and practical red light semiconductor laser, extremely complex window processes and cavity surface coating processes are required to improve the COD level.

[0042] The COD of semiconductor laser production greatly affects its output power and reliability. The heat absorption of the cavity surface can be reduced by reducing the distribution of light and carriers on the cavity surface and reducing the absorption of the near light of the red semiconductor laser attached to the cavity surface. The non-absorption transparent window structure is one of the methods to solve this problem. The quantum well hybrid technology is to introduce point defects inside the epitaxial layer, promote the mutual diffusion of quantum well and quantum barrier components, increase the bandgap width of the quantum well material, and use the quantum well hybrid technology to form a non-absorption window at the cavity surface, so that the band gap width at the cavity surface is larger than the band gap width of the active area, so as to achieve the blue shift of the peak wavelength in the cavity surface area, reduce the light absorption of the cavity surface, and reduce the cavity surface temperature.

[0043] The patent with authorization announcement number CN112072469A performs N ion implantation on AlGaInP material system lasers, and then performs rapid thermal annealing at 750°C in a nitrogen atmosphere to induce quantum well intermixing in the active area. This method performs quantum well intermixing on the entire active area of ​​the laser, aiming to adjust the peak wavelength of the laser and realize a shorter wavelength light-emitting device, rather than only adjusting the band gap in the non-absorption window area of ​​the cavity surface to prevent COD.

[0044] The patent invention with the above authorization announcement number CN104158087 is mainly aimed at the intermixing of InGaAs / AlGaAs quantum well structures. The method used is not applicable to the quantum well intermixing of AlGaInP material system, and cannot achieve the bandgap blue shift of the non-absorption window of the AlGaInP material system laser. The authorization announcement number CN112072469A performs quantum well intermixing on the entire active area of ​​the AlGaInP material system laser, aiming to adjust the peak wavelength of the laser and realize a shorter wavelength light-emitting device, rather than adjusting the bandgap of the non-absorption window area of ​​the cavity surface to prevent COD.

[0045] See also Figure 2 , Figure 2 The flowchart of an embodiment of the method for manufacturing a red semiconductor laser having a non-absorption window 310 of the present invention. The method for manufacturing a red semiconductor laser having a non-absorption window 310 of the present embodiment comprises the following steps:

[0046] S100, please refer to Figure 3 , a SiO2 mask 210 is grown on a red semiconductor laser chip sample wafer, and a non-absorption region 300 is defined at the cavity surfaces at both ends of the red semiconductor laser chip, and the SiO2 mask 210 of the non-absorption region 300 is removed by photolithography to expose the ohmic contact layer 200. The width of the non-absorption region 300 is generally 10 μm to 200 μm, preferably 30 μm to 60 μm.

[0047] S200, please refer to Figure 4, remove the ohmic contact layer 200 located in the non-absorption region 300 on the red light semiconductor laser chip sample wafer. The ohmic contact layer 200 in the non-absorption region 300 can be removed by using sulfuric acid and hydrogen peroxide etching solution.

[0048] S300, growing a layer of ZnO film 220 in the non-absorption region 300 to provide Zn ions for diffusion; and growing a SiO2 mask 210 again on the surface of the red light semiconductor laser chip sample wafer to limit the diffusion direction of Zn ions and prevent Zn ions from diffusing outward. The ZnO film 220 layer can be grown by reactive magnetron sputtering; the thickness of the ZnO film 220 layer is 10nm to 50nm.

[0049] S400, placing a red light semiconductor laser chip sample wafer in a vacuum and high temperature environment to diffuse and form a non-absorption window 310; specifically, the following steps may be included:

[0050] S410, placing the red semiconductor laser chip sample wafer into a quartz tube, and evacuating the tube to 1Pa-10Pa to provide a vacuum environment for the red semiconductor laser chip sample wafer.

[0051] S420 , placing the quartz tube in a furnace tube at 500° C. to 650° C. for high temperature diffusion for 3 h to 4 h, thereby forming a non-absorbing window 310 in the non-absorbing region 300 that diffuses to the n-type cladding layer 130 .

[0052] S430, allowing the red light semiconductor laser chip sample wafer to cool naturally.

[0053] S500, removing all dielectric films on the surface of the red light semiconductor laser chip sample wafer, namely, the SiO2 mask 210 and the ZnO film 220. At this point, the manufacturing process of the non-absorption window 310 region is completed.

[0054] S600, completing the subsequent preparation process of the red semiconductor laser. After completing the production process of the non-absorption window 310 area, the remaining steps are conventional ridge waveguide etching, window opening, electrode preparation, alloying, thinning, scribing, coating and other conventional steps in the laser, thereby completing the preparation of the red semiconductor laser sample.

[0055] See also Fig. 9 and Fig.10 This embodiment tests the PL spectra of the absorption region and non-absorption region 300 of the red light semiconductor laser obtained by the above process and the Zn 2+ Doping depth, by Fig. 9 It can be seen that the PL spectrum in the non-absorption region 300 is blue-shifted by about 40nm compared to the absorption region. Fig.10 It can be seen that the Zn in the non-absorption region 300 2+The doping depth is greater than 2μm, which effectively realizes the Zn 2+ Doping.

[0056] See also Fig.11 In this embodiment, the COD thresholds of the red light semiconductor laser with the non-absorption window 310 obtained by the above process and the ordinary red light semiconductor laser are tested. Fig.11 It can be clearly seen that the COD threshold of the red light semiconductor laser with the non-absorption window 310 is significantly greater than that of the ordinary red light semiconductor laser, which indicates that the process of this embodiment can effectively improve the reliability of the laser chip.

[0057] In this embodiment, a non-absorption region 300 is defined at the laser cavity surface, and Zn ions are introduced into the non-absorption region 300 by growing a ZnO film 220, and then quantum well intermixing is achieved by a furnace tube high temperature diffusion method, and a non-absorption window 310 is formed in the non-absorption region 300, thereby providing a non-absorption window process for a red light semiconductor laser of an AlGaInP material system. By preparing the non-absorption window 310, the wavelength blue shift of the non-absorption region can be controlled, the band gap width of the light-emitting region can be expanded at the cavity surface, the PL spectrum blue shift can be achieved, the energy absorption of the light-emitting cavity surface can be reduced, the cavity surface temperature can be reduced, the cavity surface anti-COMD level can be improved, and the maximum output power of the red light semiconductor laser can be improved. At the same time, when the red light semiconductor laser works for a long time, the cavity surface is not easily damaged, thereby greatly improving the reliability and life of the red light semiconductor laser.

[0058] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for manufacturing a red light semiconductor laser having a non-absorption window, characterized in that: The following steps are involved: S100, growing a SiO2 mask on a red light semiconductor laser chip sample wafer of an AlGaInP material system, defining non-absorption regions at the cavity surfaces at both ends of the red light semiconductor laser chip, and removing the SiO2 mask in the non-absorption region by photolithography and etching; S200, removing the ohmic contact layer located in the non-absorption region on the red light semiconductor laser chip sample wafer; S300, first grow a ZnO film on the surface of the wafer, and then grow a SiO2 mask; S400, placing a red light semiconductor laser chip sample wafer in a vacuum and high temperature environment to diffuse and form a non-absorption window; S500, removing the SiO2 mask and the ZnO film on the surface of the red light semiconductor laser chip sample wafer; S600, completing the subsequent preparation process of the red light semiconductor laser.

2. The method for manufacturing a red semiconductor laser having a non-absorption window according to claim 1, characterized in that: The red light semiconductor laser chip comprises a GaAs substrate layer, a buffer layer, an n-type intermediate layer, an n-type cladding layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer, a p-type cladding layer, an etching resistance layer, a p-type intermediate layer and an ohmic contact layer arranged in sequence from bottom to top.

3. The method for manufacturing a red semiconductor laser having a non-absorption window as claimed in claim 2, characterized in that: The quantum well active layer includes a plurality of quantum well layers and a plurality of quantum barrier layers, and the quantum well layers and the quantum barrier layers are arranged at intervals.

4. The method for manufacturing a red semiconductor laser having a non-absorption window as claimed in claim 3, characterized in that: The material of the quantum well layer is GaInP, and the material of the quantum barrier layer is AlGaInP.

5. The method for manufacturing a red semiconductor laser having a non-absorption window as claimed in claim 2, characterized in that: The non-absorbing window diffuses into the n-type cladding.

6. The method for manufacturing a red semiconductor laser having a non-absorption window according to any one of claims 1 to 5, characterized in that: The width of the non-absorption region is 10 μm to 200 μm.

7. The method for manufacturing a red semiconductor laser with a non-absorption window as claimed in claim 6, characterized in that: The width of the non-absorption region is 30 μm to 60 μm.

8. The method for manufacturing a red semiconductor laser having a non-absorption window according to any one of claims 1 to 5, characterized in that: The thickness of the ZnO thin film layer is 10nm-50nm.

9. The method for manufacturing a red semiconductor laser with a non-absorption window according to any one of claims 1 to 5, characterized in that: The step S400 includes the following sub-steps: Place the red light semiconductor laser chip sample wafer into a quartz tube and evacuate it to 1Pa to 10Pa; The quartz tube is placed in a furnace tube at 500°C to 650°C for high temperature diffusion for 3h to 4h, thereby forming a non-absorption window in the non-absorption area; The red semiconductor laser chip sample wafer is allowed to cool naturally.

10. The method for manufacturing a red semiconductor laser with a non-absorption window according to any one of claims 1 to 5, characterized in that: In the step S600, the subsequent preparation process of the red light semiconductor laser includes ridge waveguide etching, window opening, electrode preparation, alloying, thinning, scribing and coating.

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