A gallium-free antimonide semiconductor infrared laser

Abstract

The invention provides a gallium-free antimonide semiconductor infrared laser, belonging to the technical field of semiconductor lasers; the classic InGa(As)Sb‑AlGaAsSb I-type strained quantum well contains three III-group elements, In, Ga and Al, and two V-group elements, As and Sb. The valence band order of this structure is relatively small, and the ability to bind holes is not strong, which limits the gain of the laser and the ability to expand to long wavelengths; it includes 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, 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 InAs y1 Sb 1‑y1 Material, wherein 0.50≤y1≤0.85; the present invention is applied to antimonide semiconductor infrared lasers.

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 have shown great application potential in the fields of medical treatment, satellite remote sensing, lidar, gas detection, free space communication, etc. Its core is antimonide semiconductor materials. This type of material is an ideal material system for covering the mid-infrared band because it has a suitable bandgap width and can be regulated by clever band engineering. At present, for the 2-3um band, the classic InGa(As)Sb-AlGaAsSb I type strained quantum well shows certain advantages. It is epitaxially grown on a commercial GaSb substrate, using InGa(As)Sb as a quantum well, AlGaAsSb with a low Al component as a quantum barrier and waveguide layer, and AlGaAsSb with a high Al component as a confinement layer, thereby achieving dual confinement of light and electricity to ensure higher quality laser lasing.

[0003] The classic InGa(As)Sb-AlGaAsSb type I strained quantum well contains three group III elements, In, Ga, and Al, and two group V elements, As and Sb. The valence band order of this structure is relatively small, and the ability to bind holes is not strong, which limits the gain of the laser and the ability to expand to longer wavelengths. In addition, the Ga element will introduce certain defects to the material. In addition, there is still room for improvement in the limitation of the light field. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention proposes a gallium-free antimonide semiconductor infrared laser. Its functional layer does not contain gallium, has a larger band step, has a stronger ability to bind holes, and improves the gain of the laser and its ability to expand to longer wavelengths.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: 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, 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 Material, 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 also arranged 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 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;

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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-y2Each 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.

[0016] The beneficial effects of the present invention over the prior art are as follows: compared with the classical structure, the band order of the new laser is larger, the carrier binding effect is stronger, which is conducive to improving the gain. The refractive index of the cladding (i.e., the confinement layer) is smaller, and the binding effect on the light field is stronger. The thermal conductivity is greater, which is conducive to the development of high-power lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings:

[0018] Figure 1 It is a schematic diagram of the structure of the laser of the present invention;

[0019] 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

[0020] 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, 0.50≤y1≤0.85 is used to generate different degrees of compressive stress; In is matched with 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 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, where 0.02≤y3≤0.22.

[0021] The laser of the present invention is described in detail below based on specific embodiments.

[0022] Example 1

[0023] The specific structure is as follows:

[0024] It includes the substrate, lower cladding, lower waveguide layer, active area, upper waveguide layer, upper cladding and protective layer from bottom to top. It adopts GaSb substrate with N-type conductivity. The lower cladding material is InAs 0.2 Sb 0.8 , the conductivity type is N type; the lower waveguide layer material is In 0.5 Al 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 , 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.

[0025] Example 2

[0026] On the basis of Example 1, components or doping gradient layers are added between the functional layers, and the specific structure is as follows:

[0027] (1) GaSb is used as the substrate, the conductivity type is N-type, and the carrier concentration is 2E17-2E18cm -3 ;

[0028] (2) Buffer layer: material is GaSb, conductivity type is N-type, carrier concentration is 2E17-2E18cm -3 , thickness is 450-550um;

[0029] (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;

[0030] (4) Transition layer A: realizes the compositional transition 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;

[0031] (5) Lower waveguide layer: material is In 0.5 Al 0.5 As0.474 Sb 0.526 , lattice matching with the substrate, with a thickness of 200-400nm;

[0032] (6) Transition layer B: realizes the gradual transition of composition between the lower cladding layer and the lower waveguide layer, with a thickness of 40-60nm;

[0033] (7) Active region: 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 potential barrier). Each quantum well is sandwiched by two quantum potential barriers. The thickness of the quantum well is 6-15nm, and the number is 1-5. The thickness of the quantum barrier is 15-40nm.

[0034] (8) Upper waveguide layer: material: In 0.5 Al 0.5 As 0.474 Sb 0.526 , lattice matching with the substrate, with a thickness of 200-400nm;

[0035] (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;

[0036] (10) Transition layer C: realizes the gradual transition of composition between the upper cladding layer and the upper waveguide layer, with a thickness of 40-60 nm;

[0037] (11) Protective layer: material is GaSb, conductivity type is P type, carrier concentration is 6E18-2E19cm -3 , thickness is 100-300nm;

[0038] (12) Transition layer D: realizes the 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 , thickness is 40-60nm.

[0039] The present invention can effectively solve the defects brought by Ga element to the material and the problem of small band step of the valence band of the material, thereby improving the performance of the laser.

[0040] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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. An antimonide semiconductor infrared laser having a gallium-free functional layer, 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium according to claim 2, characterized in that: A buffer layer is also arranged between the GaSb substrate and the transition layer A.

4. An antimonide semiconductor infrared laser having a functional layer free of gallium 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 .

5. The antimonide semiconductor infrared laser whose functional layer does not contain gallium 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 ; 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium 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 antimonide semiconductor infrared laser whose functional layer does not contain gallium 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. An antimonide semiconductor infrared laser having a functional layer free of gallium 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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