Gallium-free antimonide semiconductor infrared laser

Abstract

The invention provides a gallium-free antimonide semiconductor infrared laser, and belongs to the technical field of semiconductor lasers. A classical InGa (As) Sb-AlGaAsSb I type strained quantum well comprises three III group elements of In, Ga and Al and two V group elements of As and Sb. The valence band order of the structure is small, and the binding capacity to a hole is not high, so that the gain of the laser and the capacity of expanding to long wavelength are limited; comprising a GaSb substrate, and a lower cladding layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper cladding layer and a protective layer which are sequentially epitaxially grown on the GaSb substrate, the lower cladding layer and the upper cladding layer are made of an AlAsy3Sb1-y3 material, y3 is greater than or equal to 0.02 and less than or equal to 0.22, quantum barriers of the lower waveguide layer, the upper waveguide layer and the active region are made of an Inx2Al1-x2Asy2Sb1-y2 material matched with the GaSb substrate, x2 is greater than or equal to 0.4 and less than or equal to 0.6, and y3 is greater than or equal to 0.02 and less than or equal to 0.22. A quantum well of the active region is made of an InAsy1Sb1-y1 material, wherein y1 is more than or equal to 0.50 and less than or equal to 0.85; the invention is applied to the antimonide semiconductor infrared laser.

Description

Technical Field

[0001] The invention provides a gallium-free antimonide semiconductor infrared laser, belonging to the technical field of antimonide semiconductor lasers. Background Art

[0002] Antimonide semiconductor lasers show great potential for applications in healthcare, satellite remote sensing, lidar, gas detection, free-space communications, and other fields. Their core is antimonide semiconductor materials. These materials, with their suitably large bandgap width and the ability to manipulate the bandgap through clever bandgap engineering, are ideal for achieving mid-infrared coverage. Currently, for the 2–3 μm band, the classic InGa(As)Sb-AlGaAsSb type I strained quantum well exhibits certain advantages. Epitaxially grown on a commercial GaSb substrate, they use InGa(As)Sb as the quantum well, low-Al Al content AlGaAsSb as the quantum barrier and waveguide layer, and high-Al content AlGaAsSb as the confinement layer, achieving dual confinement of light and electricity to ensure high-quality laser emission.

[0003] The classic InGa(As)Sb-AlGaAsSb type I strained quantum well structure contains three Group III elements—In, Ga, and Al—and two Group V elements—As and Sb. This structure has a relatively small valence band step, resulting in weak hole confinement, which limits the laser's gain and its ability to extend to longer wavelengths. Furthermore, the Ga element introduces defects into the material. Furthermore, there is room for improvement in light field confinement. Summary of the Invention

[0004] To address the problems of the prior art, the present invention proposes a gallium-free antimonide semiconductor infrared laser. Its functional layer is gallium-free, and its band gap is larger, resulting in a stronger hole-binding ability, which improves the laser's gain and its ability to extend to longer wavelengths.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a gallium-free antimonide semiconductor infrared laser, comprising a GaSb substrate, and a lower cladding layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper cladding layer and a protective layer epitaxially grown on the GaSb substrate in sequence, wherein the lower cladding layer and the upper cladding layer are made of AlAs y3 Sb 1-y3 material, wherein 0.02≤y3≤0.22, the quantum barriers of the lower waveguide layer, the upper waveguide layer and the active region are made of In matched with the GaSb substrate x2 Al 1- x2 As y2 Sb 1-y2 material, wherein 0.4≤x2≤0.6, the quantum well of the active region is made of InAsy1 Sb 1-y1 Materials, where 0.50≤y1≤0.85.

[0006] A transition layer A is provided between the GaSb substrate and the lower cladding layer, a transition layer B is provided between the lower cladding layer and the lower waveguide layer, a transition layer C is provided between the upper waveguide layer and the upper cladding layer, and a transition layer D is provided between the upper cladding layer and the protective layer.

[0007] A buffer layer is further provided between the GaSb substrate and the transition layer A.

[0008] The conductivity type of the GaSb substrate is N-type, and the carrier concentration is 2E17-2E18cm -3 , thickness is 450-550um.

[0009] The buffer layer is made of GaSb, has an N-type conductivity, and a carrier concentration of 2E17-2E18 cm -3 , thickness is 400-500nm; The material of the protective layer is GaSb, the conductivity type is P-type, and the carrier concentration is 6E18-2E19cm -3 , with a thickness of 100-300nm.

[0010] The transition layer A is used to achieve a gradual transition of composition between the buffer layer and the lower cladding layer. The conductivity type is N-type and the carrier concentration is 4E17-2E18cm -3 , with a thickness of 20-40nm.

[0011] The transition layer B is used to achieve a gradual transition of composition between the lower cladding layer and the lower waveguide layer, and has a thickness of 40-60 nm.

[0012] The transition layer C is used to achieve a gradual transition of composition between the upper cladding layer and the upper waveguide layer, and has a thickness of 40-60 nm.

[0013] The transition layer D is used to achieve a gradual transition of composition between the upper cladding layer and the protective layer. The conductivity type is P-type and the carrier concentration is 6E18-2E19cm -3 , with a thickness of 40-60nm.

[0014] The active region is composed of strained InAs y1 Sb 1-y1 and In lattice-matched to the substrate x2 Al 1-x2 As y2 Sb 1-y2 Each quantum well is sandwiched by two quantum barriers, the thickness of the quantum well is 6-15nm, the number is 1-5, and the thickness of the quantum barrier is 15-40nm.

[0015] The advantages of this invention over existing technologies include: compared with classic structures, the new laser has a larger band gap, stronger carrier confinement, and is conducive to increased gain. Furthermore, the cladding (i.e., confinement layer) has a lower refractive index, which enhances the optical field confinement. Furthermore, the improved thermal conductivity facilitates the development of high-power lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings: Figure 1 Schematic diagram of the structure of the laser of the present invention; Figure 2 Schematic diagram of parameters of the laser of the present invention, wherein (a) is a schematic diagram of the flat band energy band of the laser, (b) is a schematic diagram of the refractive index of the laser, and (c) is a schematic diagram of the thermal conductivity of the laser. DETAILED DESCRIPTION

[0017] like Figure 1 and 2 As shown, the present invention provides a gallium-free antimonide semiconductor infrared laser using compressively stressed InAs y1 Sb 1-y1 As the quantum well of the active region, where 0.50≤y1≤0.85, to produce different degrees of compressive stress; with In matching the substrate x2 Al 1-x2 As y2 Sb 1-y2 As a quantum barrier and waveguide layer, where 0.4≤x2≤0.6, y2 changes with the change of x2 to ensure In x2 Al 1-x2 As y2 Sb 1-y2 There is no lattice mismatch or micro-mismatch with GaSb, where the lattice matching condition is: y2=(0.344*x2+0.040) / (0.473-0.052*x2); with AlAs under weak tension y3 Sb 1-y3 As a cladding, wherein 0.02≤y3≤0.22.

[0018] The laser of the present invention is described in detail below based on specific embodiments.

[0019] Example 1 The specific structure is as follows: It includes the substrate, lower cladding layer, lower waveguide layer, active area, upper waveguide layer, upper cladding layer and protective layer from bottom to top. It uses GaSb substrate with N-type conductivity. The lower cladding material is InAs. 0.2 Sb 0.8 , the conductive type is N type; the lower waveguide layer material is In 0.5Al 0.5 As 0.474 Sb 0.526 ; The active region is composed of strained InAs 0.75 Sb 0.25 (quantum well) and In lattice-matched to the substrate 0.5 Al 0.5 As 0.474 Sb 0.526 (quantum barrier) composition; the upper waveguide layer material is In 0.5 Al 0.5 As 0.474 Sb 0.526 , maintaining lattice matching with the substrate; the upper cladding material is AlAs 0.2 Sb 0.8 , the conductivity type is P type; the protective layer is made of GaSb material, and the conductivity type is P type.

[0020] Example 2 On the basis of Example 1, a component or doping gradient layer is added between each functional layer, and its specific structure is as follows: (1) GaSb is used as substrate, the conductivity type is N-type, and the carrier concentration is 2E17-2E18cm -3 ; (2) Buffer layer: material is GaSb, conductivity type is N-type, carrier concentration is 2E17-2E18cm -3 , thickness is 450-550um; (3) Lower cladding: material is AlAs 0.2 Sb 0.8 , the conductivity type is N-type, and the carrier concentration is 5E17-2E18cm -3 , thickness is 1500-3000nm; (4) Transition layer A: realizes the compositional transition between the buffer layer and the lower cladding layer, with an N-type conductivity and a carrier concentration of 4E17-2E18cm -3 , thickness is 20-40nm; (5) Lower waveguide layer: material is In 0.5 Al 0.5 As 0.474 Sb 0.526 , maintaining lattice matching with the substrate, with a thickness of 200-400nm; (6) Transition layer B: realizes the composition gradient transition between the lower cladding layer and the lower waveguide layer, with a thickness of 40-60nm; (7) Active region: strained InAs 0.75 Sb 0.25 (quantum well) and In lattice-matched to the substrate 0.5 Al 0.5 As0.474 Sb 0.526 Each quantum well is sandwiched between two quantum barriers. The thickness of the quantum wells is 6-15nm, and the number of quantum wells is 1-5. The thickness of the quantum barriers is 15-40nm.

[0021] (8) Upper waveguide layer: Material: In 0.5 Al 0.5 As 0.474 Sb 0.526 , maintaining lattice matching with the substrate, with a thickness of 200-400nm; (9) Upper cladding: material is AlAs 0.2 Sb 0.8 , the conductivity type is P-type, and the carrier concentration is 8E17-1E19cm -3 , thickness is 1500-3000nm; (10) Transition layer C: realizes the composition gradient transition between the upper cladding layer and the upper waveguide layer, with a thickness of 40-60 nm; (11) Protective layer: Material is GaSb, conductivity type is P-type, carrier concentration is 6E18-2E19cm -3 , thickness is 100-300nm; (12) Transition layer D: realizes the composition transition between the upper cladding layer and the protective layer, the conductivity type is P-type, and the carrier concentration is 6E18-2E19cm -3 , with a thickness of 40-60nm.

[0022] The present invention can effectively solve the problems of defects caused by Ga element in the material and small valence band order of the material, thereby improving the performance of the laser.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gallium-free antimonide semiconductor infrared laser, comprising a GaSb substrate, and a lower cladding layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper cladding layer and a protective layer epitaxially grown in sequence on the GaSb substrate, characterized in that: The lower cladding layer and the upper cladding layer are made of AlAs y3 Sb 1-y3 material, wherein 0.02≤y3≤0.22, the quantum barriers of the lower waveguide layer, the upper waveguide layer and the active region are made of In matched with the GaSb substrate x2 Al 1-x2 As y2 Sb 1-y2 material, wherein 0.4≤x2≤0.6, the quantum well of the active region is made of InAs y1 Sb 1-y1 Material, where 0.50≤y1≤0.

85.

2. The gallium-free antimonide semiconductor infrared laser according to claim 1, characterized in that: A transition layer A is provided between the GaSb substrate and the lower cladding layer, a transition layer B is provided between the lower cladding layer and the lower waveguide layer, a transition layer C is provided between the upper waveguide layer and the upper cladding layer, and a transition layer D is provided between the upper cladding layer and the protective layer.

3. The gallium-free antimonide semiconductor infrared laser according to claim 2, characterized in that: A buffer layer is also arranged between the GaSb substrate and the transition layer A.

4. A gallium-free antimonide semiconductor infrared laser according to any one of claims 1 to 3, characterized in that: The conductivity type of the GaSb substrate is N-type, and the carrier concentration is 2E17-2E18cm -3 , thickness is 450-550um.

5. The gallium-free antimonide semiconductor infrared laser according to claim 3, characterized in that: The material of the buffer layer is GaSb, the conductivity type is N-type, and the carrier concentration is 2E17-2E18cm -3 , thickness is 400-500nm; The material of the protective layer is GaSb, the conductivity type is P type, and the carrier concentration is 6E18-2E19cm -3 , thickness is 100-300nm.

6. The gallium-free antimonide semiconductor infrared laser according to claim 2, characterized in that: The transition layer A is used to realize the gradual transition of the composition between the buffer layer and the lower cladding layer. The conductivity type is N-type and the carrier concentration is 4E17-2E18cm -3 , thickness is 20-40nm.

7. The gallium-free antimonide semiconductor infrared laser according to claim 2, characterized in that: The transition layer B is used to achieve a gradual transition of the composition between the lower cladding layer and the lower waveguide layer, and has a thickness of 40-60 nm.

8. The gallium-free antimonide semiconductor infrared laser according to claim 2, characterized in that: The transition layer C is used to achieve a gradual transition of the composition between the upper cladding layer and the upper waveguide layer, and has a thickness of 40-60 nm.

9. The gallium-free antimonide semiconductor infrared laser according to claim 2, characterized in that: The transition layer D is used to achieve a gradual transition of the composition between the upper cladding layer and the protective layer. The conductivity type is P type and the carrier concentration is 6E18-2E19cm -3 , thickness is 40-60nm.

10. The gallium-free antimonide semiconductor infrared laser according to any one of claims 5 to 6, characterized in that: The active region is composed of strained InAs y1 Sb 1-y1 and In that is lattice-matched to the substrate x2 Al 1-x2 As y2 Sb 1-y2 Each quantum well is sandwiched by two quantum potential barriers. The thickness of the quantum well is 6-15nm, the number is 1-5, and the thickness of the quantum barrier is 15-40nm.

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