A Strained Quantum Well Laser Based on Antimony-Phosphorus Material System

Abstract

The present invention provides a strain quantum well laser based on an antimony-phosphorus material system, belonging to the technical field of semiconductor lasers; it solves the problems that the valence band offset of the classical InGa(As)Sb-AlGaAsSb type I strain quantum well structure is not large and the confinement ability for holes is not strong, etc.; it includes a substrate, and a buffer layer, a lower confinement layer, a lower waveguide layer, a lower quantum barrier layer, a quantum well, an upper quantum barrier layer, an upper waveguide layer, an upper confinement layer and a protective layer that are sequentially epitaxially grown on the substrate. The substrate and the buffer layer are made of InPSb material, the lower confinement layer and the upper confinement layer are made of InAlPSb material lattice-matched with the substrate material, the lower waveguide layer, the lower quantum barrier layer, the upper quantum barrier layer and the upper waveguide layer are all made of AlGaPSb material lattice-matched with the substrate material, and the quantum well is made of InGaPSb material lattice-mismatched with the substrate material. The present invention introduces phosphorus into the classical structure, that is, adopts an antimony-phosphorus material system, which can effectively improve the valence band offset and thermal conductivity.

Description

Technical Field

[0001] The present invention provides a strain quantum well laser based on an antimony-phosphorus material system, belonging to the technical field of semiconductor lasers. Background Art

[0002] Semiconductor lasers are lasers based on semiconductor materials. They are very important components in modern microelectronics and optoelectronics technologies, and have advantages such as small size, light weight, high efficiency, long life, high reliability, easy integration and modulation. The working principle of semiconductor lasers is based on the energy band structure of semiconductor materials: when an electric current passes through a semiconductor material, electrons transition from low energy levels to high energy levels, and then photons are released through the stimulated emission process; these photons are reflected back and forth in the resonant cavity of the laser, and coherent light, that is, laser light, is generated through the amplification of light. Common semiconductor lasers are composed of an active region, waveguide layers, confinement layers, and mirrors, etc. It can be applied to multiple fields such as optical communication, data storage, industrial processing, medical treatment, medical aesthetics, military defense, sensing, etc.

[0003] At present, semiconductor lasers have been commercially available on a large scale in the visible light band and are gradually expanding to the near-infrared band. However, with the progress of human science and technology, the demand for the use of longer wavelengths is also increasing day by day, and the mid-infrared band has gradually become the forefront of semiconductor lasers.

[0004] Antimonide semiconductor materials are ideal material systems that can cover the mid-infrared band because they have a suitable bandgap width and can regulate the bandgap through ingenious band engineering. Due to the excellent properties of the materials, antimonide semiconductor lasers show great potential in fields such as medical treatment, satellite remote sensing, lidar, gas detection, free space communication, etc. At present, for the 2-3um band, the classical InGa(As)Sb-AlGaAsSb type-I strain quantum well shows certain advantages. It uses InGa(As)Sb as the quantum well, low-Al-component AlGaAsSb as the quantum potential barrier and waveguide layer, and high-Al-component AlGaAsSb as the confinement layer, so as to achieve double confinement of light and electricity to ensure high-quality laser lasing.

[0005] However, the classical InGa(As)Sb-AlGaAsSb type-I strain quantum well is an advantageous material in the 2-3um band and is usually epitaxially grown on a GaSb substrate. The valence band offset of the classical structure is not large, and the band offsets of the confinement layer and the quantum well are about 0.25eV, and the confinement ability of holes is not strong, which limits the improvement of the laser gain. Moreover, the thermal conductivity is not high, which is a challenge to the development of high-power lasers. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a strained quantum well laser based on an antimony-phosphorus material system. Introducing phosphorus into the classical structure, that is, adopting an antimony-phosphorus material system, can effectively improve the valence band offset and thermal conductivity.

[0007] The technical solution adopted by the present invention is: a strained quantum well laser based on an antimony-phosphorus material system, including a substrate, and a buffer layer, a lower confinement layer, a lower waveguide layer, a lower quantum barrier layer, a quantum well, an upper quantum barrier layer, an upper waveguide layer, an upper confinement layer, and a protective layer that are sequentially epitaxially grown on the substrate. The substrate and the buffer layer are made of InPSb material, the lower confinement layer and the upper confinement layer are made of InAlPSb material lattice-matched with the substrate material, the lower waveguide layer, the lower quantum barrier layer, the upper quantum barrier layer, and the upper waveguide layer are all made of AlGaPSb material lattice-matched with the substrate material, and the quantum well is made of InGaPSb material lattice-mismatched with the substrate material.

[0008] Further, the component ratio of InPSb is In z Sb 1-z , where z = 0.57 - 0.85.

[0009] Further, the component ratio of InAlPSb is In x1 Al 1-x1 P y1 Sb 1-y1 , where x1 = 0.34 - 0.45, and satisfies y1 = (0.3438 - 0.611*z - 0.3438*x1) / (0.0739*x1 - 0.685).

[0010] Further, the component ratio of AlGaPSb is Al x2 Ga 1-x2 P y2 Sb 1-y2 , where x2 = 0.17 - 1.0, and satisfies y2 = (0.0401*x2 + 0.611*z - 0.3839) / (0.0396*x2 + 0.6449).

[0011] Further, the lattice mismatch between the quantum well and the substrate material is between 0 and 2.0%. The component ratio of InGaPSb is In x3 Ga 1-x3 P y3 Sb 1-y3 , where x3 = 0 - 0.15, and when the lattice mismatch between the quantum well and the substrate material is 0, it satisfies y3 = (0.3839 - 0.3839*x3 - 0.611*z) / (0.0343*x3 - 0.645).

[0012] Further, the number of quantum wells is 1 - 5, and the thickness of the quantum wells is 5 - 15 nm.

[0013] Further, the conductive type of the substrate, buffer layer, and lower confinement layer is N-type, and the conductive type of the upper confinement layer and the protective layer is P-type.

[0014] Further, a first composition transition layer is provided between the buffer layer and the lower confinement layer.

[0015] Further, a second composition transition layer is provided between the protective layer and the upper confinement layer.

[0016] Further, a composition graded layer or a doping graded layer is provided between the confinement layer and the waveguide layer.

[0017] The beneficial effects of the present invention compared with the prior art are as follows: The valence band offset of the classical structure is not large, and the binding ability to holes is not strong, which limits the improvement of the laser gain, and the thermal conductivity is not high. The present invention adopts an antimony-phosphorus material system, which can effectively increase the valence band offset and thermal conductivity, which is beneficial to the development of high-gain, high-power mid-infrared and near-infrared lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following further describes the present invention with reference to the drawings:

[0019] Figure 1 is a schematic diagram of the epitaxial structure of a strained quantum well laser based on an antimony-phosphorus material system according to the present invention;

[0020] Figure 2 is the flat band energy band diagram of a strained quantum well laser based on an antimony-phosphorus material system according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] As Figure 1 and 2 shown, the present invention provides a strained quantum well laser based on an antimony-phosphorus material system, and its basic structure is as follows:

[0022] (1) Using InP z Sb 1-z material as the epitaxial substrate (z = 0.57 - 0.85), with an N-type conductive type and a doping concentration of 1E17 to 1E18 cm -3 ; (A relaxed InP z Sb 1-z thick film can be grown on a conventional compound substrate to epitaxially grow the device thin film);

[0023] (2) Buffer layer: The material is InP z Sb 1-z (z = 0.57 - 0.85, the same as the substrate, homoepitaxy), N-type, with a doping concentration of 5E17 to 1E18 cm-3 , with a thickness of 250 - 650 nm;

[0024] (3) Lower confinement layer: The material is In x1 Al 1-x1 P y1 Sb 1-y1 (x1 = 0.34 - 0.45), lattice-matched with the InP z Sb 1-z substrate, and x1, y1, and z satisfy the following relationship: y1 = (0.3438 - 0.611*z - 0.3438*x1) / (0.0739*x1 - 0.685). N-type, with a doping concentration of 5E17 to 1E18 cm -3 , with a thickness of 1000 - 3000 nm;

[0025] (4) Lower waveguide layer: The material is Al x2 Ga 1-x2 P y2 Sb 1-y2 (x2 = 0.17 - 1.0), lattice-matched with the InP z Sb 1-z substrate, and x2, y2, and z satisfy the following relationship: y2 = (0.0401*x2 + 0.611*z - 0.3839) / (0.0396*x2 + 0.6449). Not intentionally doped. The width of the waveguide layer is 100 - 600 nm;

[0026] (5) Lower quantum barrier layer: The material is Al x2 Ga 1-x2 P y2 Sb 1-y2 , lattice-matched with the InP z Sb 1-z substrate, and x2, y2, and z satisfy the following relationship: y2 = (0.0401*x2 + 0.611*z - 0.3839) / (0.0396*x2 + 0.6449). Not intentionally doped. The barrier width is 15 - 30 nm;

[0027] (6) A quantum well with In x3 Ga 1-x3 P y3 Sb 1-y3 as the active region (x3 = 0 - 0.15), lattice-matched with the InP z Sb 1-zThe lattice mismatch is between 0 and 2.0%; when the mismatch is 0, x3, y3, and z satisfy the following relationship: y3 = (0.3839 - 0.3839 * x3 - 0.611 * z) / (0.0343 * x3 - 0.645). There is no intentional doping. The thickness of the quantum well is 5 - 15 nm and can be selected according to the target lasing wavelength and power. The number of quantum wells is 1 - 5;

[0028] (7) Upper quantum barrier layer: The material is Al x2 Ga 1-x2 P y2 Sb 1-y2 , lattice-matched with the substrate InP z Sb 1-z , x2, y2, and z satisfy the following relationship: y2 = (0.0401 * x2 + 0.611 * z - 0.3839) / (0.0396 * x2 + 0.6449), and the barrier width is 15 - 30 nm;

[0029] (8) Upper waveguide layer: The material is Al x- Ga 1-x2 P y2 Sb 1-y2 (x2 = 0.17 - 1.0), lattice-matched with the substrate InP z Sb 1-z , x2, y2, and z satisfy the following relationship: y2 = (0.0401 * x2 + 0.611 * z - 0.3839) / (0.0396 * x2 + 0.6449), and the width of the waveguide layer is 100 - 600 nm;

[0030] (9) Upper confinement layer: The material is In x1 Al 1-x1 P y1 Sb 1-y1 (x1 = 0.34 - 0.45), lattice-matched with the substrate, x1, y1, and z satisfy the following relationship: y1 = (0.3438 - 0.611 * z - 0.3438 * x1) / (0.0739 * x1 - 0.685). P-type, the doping concentration is 5E17 to 1E18 cm -3 , and the thickness is 1000 - 3000 nm;

[0031] (10) Capping layer (protective layer): The material is InP z Sb 1-z (consistent with the substrate), P-type, the doping concentration is 1E18 to 1E19 cm -3 , and the thickness is 150 - 350 nm.

[0032] Based on the above structure, the components of each functional layer can be changed within a given range. A component transition layer can be added between the protective layer and the upper confinement layer. A compositionally graded layer or a doping graded layer can be added between the confinement layer and the waveguide layer. The compositionally graded layer can be achieved by pausing the growth, changing the source furnace temperature, or by using the digital alloy method for growth. A component transition layer can be added between the buffer layer and the lower confinement layer.

[0033] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 strained quantum well laser based on an antimony-phosphorus material system, comprising a substrate, and a buffer layer, a lower confinement layer, a lower waveguide layer, a lower quantum barrier layer, a quantum well, an upper quantum barrier layer, an upper waveguide layer, an upper confinement layer and a protective layer epitaxially grown in sequence on the substrate, characterized in that: The substrate and buffer layer are made of InPSb material, the lower confinement layer and the upper confinement layer are made of InAlPSb material lattice-matched with the substrate material, the lower waveguide layer, the lower quantum barrier layer, the upper quantum barrier layer, and the upper waveguide layer are all made of AlGaPSb material lattice-matched with the substrate material, and the quantum well is made of InGaPSb material lattice-mismatched with the substrate material.

2. The strained quantum well laser based on the antimony-phosphorus material system according to claim 1, characterized in that: The composition ratio of InPSb is InP z Sb 1-z , where z=0.57-0.

85.

3. The strained quantum well laser based on the antimony-phosphorus material system according to claim 2, characterized in that: The composition ratio of InAlPSb is In x1 Al 1-x1 P y1 Sb 1-y1 ; Where x1=0.34-0.45, and satisfies y1=(0.3438-0.611*z-0.3438*x1) / (0.0739*x1-0.685).

4. The strained quantum well laser based on the antimony-phosphorus material system according to claim 2, characterized in that: The composition ratio of AlGaPSb is Al x2 Ga 1-x2 P y2 Sb 1-y2 , where x2=0.17-1.0, and satisfies y2=(0.0401*x2+0.611*z-0.3839) / (0.0396*x2+0.6449).

5. The strained quantum well laser based on the antimony-phosphorus material system according to claim 2, characterized in that: The lattice mismatch between the quantum well and the substrate material is between 0 and 2.0%; The composition ratio of InGaPSb is In x3 Ga 1-x3 P y3 Sb 1-y3 , where x3=0-0.15, and when the lattice mismatch between the quantum well and the substrate material is 0, y3=(0.3839-0.3839*x3-0.611*z) / (0.0343*x3-0.645) is satisfied.

6. The strained quantum well laser based on the antimony-phosphorus material system according to claim 5, characterized in that: The number of quantum wells is 1-5, and the thickness of the quantum well is 5-15 nm.

7. The strained quantum well laser based on the antimony-phosphorus material system according to claim 6, characterized in that: The conductivity types of the substrate, the buffer layer and the lower limiting layer are N-type, and the conductivity types of the upper limiting layer and the protective layer are P-type.

8. A strained quantum well laser based on an antimony-phosphorus material system according to any one of claims 1 to 7, characterized in that: A first component transition layer is arranged between the buffer layer and the lower limiting layer.

9. A strained quantum well laser based on an antimony-phosphorus material system according to any one of claims 1 to 7, characterized in that: A second component transition layer is arranged between the protection layer and the upper limiting layer.

10. A strained quantum well laser based on an antimony-phosphorus material system according to any one of claims 1 to 7, characterized in that: A composition gradient layer or a doping gradient layer is arranged between the confinement layer and the waveguide layer.

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