Method for growing high-quality GaSbBuffer on GaAs substrate by molecular beam epitaxy

Abstract

The invention relates to the technical field of infrared detectors, in particular to a method for growing a high-quality GaSb Buffer on a GaAs substrate by molecular beam epitaxy, which adopts a gradient buffer layer to reduce the problem of lattice mismatching between the GaAs substrate and the GaSb Buffer. The high-quality GaSbBuffer can be grown on the GaAs substrate, the surface quality of the GaSbBuffer grown on the GaAs substrate and the surface quality of the GaSbBuffer grown on the GaSb substrate are compared through measurement of AFM and AOI, it is found that the surface quality of the GaSbBuffer grown on the GaAs substrate and the surface quality of the GaSbBuffer grown on the GaSb substrate are almost equivalent to the surface quality of the GaSbBuffer obtained through homoepitaxy on the GaSb substrate, and the substrate cost in production can be reduced.

Description

Technical Field

[0001] This invention relates to the field of infrared detector technology, and in particular to a method for growing high-quality GaSbBuffer on GaAs substrates using molecular beam epitaxy. Background Technology

[0002] Type-II superlattices are a relatively new technology, but they have already shown great potential in infrared detector applications. Their main advantages are: the ability to fabricate infrared detectors operating in the mid-wave and long-wave infrared regions by adjusting layer thickness and composition; the ability to achieve high quantum efficiency; and the absence of toxic heavy metals such as Cd or Hg.

[0003] However, many problems and challenges still need to be solved. One of them is the manufacturing technology. Type II superlattice devices are composed of many different layers (substrate, buffer layer, electrical contact layer, barrier layer, absorption layer, etc.), which together form a structure whose parameters determine the application scenarios.

[0004] Among various structures, GaAs and GaSb substrates are the most commonly used. GaAs substrates are more affordable than GaSb substrates, and GaAs substrates have low infrared absorption and good thermal properties, making them more advantageous. However, growing GaSbBuffer on GaAs substrates results in a significant lattice mismatch, with a mismatch degree of 7.8%. Summary of the Invention

[0005] The purpose of this invention is to provide a method for growing high-quality GaSbBuffer on GaAs substrates using molecular beam epitaxy, aiming to solve the problem of large lattice mismatch in the growth of GaSbBuffer on GaAs substrates.

[0006] To achieve the above objectives, the present invention provides a method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy, comprising the following steps: The GaAs substrate is deoxidized, and a GaAs thin layer is grown on the deoxidized GaAs substrate. Without interrupting growth, reduce the growth rate of the GaAs layer and adjust the substrate temperature to the GaSb growth temperature to switch the source furnace. A first GaSb layer is grown on a GaAs thin layer. The first GaSb layer is Be-doped and the doping concentration decreases linearly. A second GaSb layer is grown on the first GaSb layer. The second GaSb layer is Be-doped and the doping concentration decreases exponentially. A third GaSbBuffer layer is grown on the second GaSb layer.

[0007] In the section "deoxidizing the GaAs substrate and growing a GaAs thin layer on the deoxidized GaAs substrate", the growth conditions of the GaAs thin layer are: substrate temperature 590℃, growth rate of about 1μm / h, thickness of 200nm, and substrate rotation speed of 30rpm during the growth process.

[0008] In the phrase "reducing the GaAs layer growth rate and adjusting the substrate temperature to the GaSb growth temperature without interrupting growth, and performing source furnace switching," the source furnace switching includes: Maintaining a V / III ratio of approximately 16.67, the GaAs layer growth rate was reduced to approximately 120 nm / h; The substrate temperature was reduced from 590°C to 510°C within 3 minutes; Close the Ga source furnace baffle and maintain the As beam wetted surface for 1 second; Switch the As source to the Sb source and wet the surface with the Sb beam for 1 min.

[0009] In the description of "growing a first GaSb layer on a GaAs thin film, wherein the first GaSb layer is Be-doped and the doping concentration decreases linearly," the growth conditions for the first GaSb layer are: substrate temperature 510℃, Sb beam current to Ga beam current ratio 7.29, Ga growth rate 400 nm / h, thickness 400 nm, and Be doping concentration starting from 1 × 10⁻⁶. 19 cm -3 linear decay to 1×10 18 cm -3 .

[0010] In the statement "A second GaSb layer is grown on the first GaSb layer, and the second GaSb layer is Be-doped with an exponentially decreasing doping concentration," the thickness of the second GaSb layer is 40 nm, and the Be doping concentration decreases from 1 × 10⁻⁶. 18 cm -3 Exponential decay to 1×10 17 cm -3 .

[0011] In the process of "growing a third GaSbBuffer layer on the second GaSb layer", the thickness of the third GaSbBuffer layer is 1600 nm, and it is grown under the same conditions as the first GaSb layer.

[0012] This invention discloses a method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy. The invention employs a gradient buffer layer to reduce the lattice mismatch between the GaAs substrate and the GaSbBuffer. High-quality GaSbBuffer can be grown on a GaAs substrate. By measuring AFM and AOI to compare the surface quality of GaSbBuffer grown on a GaAs substrate using this method and GaSbBuffer grown on a GaSb substrate, it was found that the surface quality of the former is nearly equivalent to that of the latter, while also reducing substrate costs in production. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a simplified diagram of the growth structure.

[0015] Figure 2 This is the AFM of the GaSbBuffer heteroepitaxially grown according to the present invention.

[0016] Figure 3 It is the AFM of GaSbBuffer homoepitaxially grown on a GaSb substrate.

[0017] Figure 4 This is the AOI of the GaSbBuffer heteroepitaxially grown according to the present invention.

[0018] Figure 5 It is an AOI of GaSbBuffer homoepitaxially grown on a GaSb substrate.

[0019] Figure 6 This is a flowchart of the method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy provided by the present invention. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] Please see Figures 1 to 6This invention provides a method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy, comprising the following steps: S1 performs deoxidation treatment on the GaAs substrate and grows a GaAs thin layer on the deoxidized GaAs substrate. The growth conditions for the GaAs thin layer are: substrate temperature 590℃, growth rate of about 1μm / h, thickness of 200nm, and substrate rotation speed of 30rpm during the growth process.

[0022] Specifically, the GaAs substrate was deoxidized, and a 200 nm GaAs thin layer was grown at a temperature of 590 °C and a growth rate of approximately 1 μm / h. During the growth process, the substrate rotation speed was 30 rpm, and the heating and cooling rates of the substrate were both 20 °C / min.

[0023] S2 reduces the GaAs layer growth rate and adjusts the substrate temperature to the GaSb growth temperature without interrupting growth, and switches the source furnace. The source furnace switching includes: Maintaining a V / III ratio of approximately 16.67, the GaAs layer growth rate was reduced to approximately 120 nm / h; The substrate temperature was reduced from 590°C to 510°C within 3 minutes; Close the Ga source furnace baffle and maintain the As beam wetted surface for 1 second; Switch the As source to the Sb source and wet the surface with the Sb beam for 1 min.

[0024] Specifically, without interrupting GaAs layer growth, the V / III ratio was maintained at approximately 16.67, and both the Ga and As beam currents were reduced to lower the GaAs layer growth rate to approximately 120 nm / h. Subsequently, the substrate temperature was lowered from 590°C to 510°C (the optimal temperature for growing GaSb layers) over 3 minutes. After reaching 510°C, the Ga source furnace baffle was closed to stop GaAs layer growth, and the As beam was used to wet the surface for 1 second. Then, the As source was switched to the Sb source required for growing GaSb layers, and the surface was wetted with the Sb source for another 1 minute.

[0025] S3 grows a first GaSb layer on a GaAs thin layer. The first GaSb layer is Be-doped and the doping concentration decreases linearly. The growth conditions for the first GaSb layer were: substrate temperature 510℃, Sb beam current to Ga beam current ratio 7.29, Ga growth rate 400 nm / h, thickness 400 nm, and Be doping concentration from 1 × 10⁻⁶. 19 cm -3 linear decay to 1×10 18 cm -3 .

[0026] Specifically, 400 nm GaSb:Be was grown using optimal GaSb growth conditions, with a Be doping concentration ranging from 1 × 10⁻⁶. 19 cm -3 It decays linearly to 1×10 18 cm -3 The optimal conditions for GaSb are a substrate temperature of 510℃, SbFlux:GaFlux = 7.29, and a Ga growth rate of 400 nm / h.

[0027] S4 grows a second GaSb layer on the first GaSb layer. The second GaSb layer is Be-doped and the doping concentration decreases exponentially. The second GaSb layer has a thickness of 40 nm, and the Be doping concentration is from 1 × 10⁻⁶. 18 cm -3 Exponential decay to 1×10 17 cm -3 .

[0028] Specifically, a subsequent 40nm Be doping layer is grown, with the concentration increasing exponentially from 1×10⁻⁶. 18 cm -3 Decay to 1×10 17 cm -3 .

[0029] S5 grows a third GaSbBuffer layer on the second GaSb layer.

[0030] The thickness of the third GaSbBuffer layer is 1600 nm, and it is grown under the same conditions as the first GaSb layer.

[0031] Specifically, using the above-mentioned optimal GaSb growth conditions, a 1600nm GaSbBuffer layer was grown.

[0032] In this invention, all layers are deposited and grown using an MBE device, which is equipped with source furnaces for In, Al, Ga, As, and Sb. All beams used are tested using the BFM (Beam Flux Monitor) built into the MBE device.

[0033] The above-disclosed method is merely a preferred embodiment of the method for growing high-quality GaSbBuffer on GaAs substrate using molecular beam epitaxy according to the present invention. Of course, it should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the process of implementing the above embodiments and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy, characterized in that, Includes the following steps: The GaAs substrate is deoxidized, and a GaAs thin layer is grown on the deoxidized GaAs substrate. Without interrupting growth, reduce the growth rate of the GaAs layer and adjust the substrate temperature to the GaSb growth temperature to switch the source furnace. A first GaSb layer is grown on a GaAs thin layer. The first GaSb layer is Be-doped and the doping concentration decreases linearly. A second GaSb layer is grown on the first GaSb layer. The second GaSb layer is Be-doped and the doping concentration decreases exponentially. A third GaSbBuffer layer is grown on the second GaSb layer.

2. The method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy as described in claim 1, characterized in that, In the process of "deoxidizing a GaAs substrate and growing a GaAs thin layer on the deoxidized GaAs substrate", the growth conditions of the GaAs thin layer are as follows: substrate temperature 590℃, growth rate of about 1μm / h, thickness of 200nm, and substrate rotation speed of 30rpm during growth.

3. The method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy as described in claim 1, characterized in that, In the phrase "reducing the GaAs layer growth rate and adjusting the substrate temperature to the GaSb growth temperature to perform source furnace switching without interrupting growth," the source furnace switching includes: Maintaining a V / III ratio of approximately 16.67, the GaAs layer growth rate was reduced to approximately 120 nm / h; The substrate temperature was reduced from 590°C to 510°C within 3 minutes; Close the Ga source furnace baffle and maintain the As beam wetted surface for 1 second; Switch the As source to the Sb source and wet the surface with the Sb beam for 1 min.

4. The method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy as described in claim 1, characterized in that, In the description of "Growing a first GaSb layer on a GaAs thin film, the first GaSb layer being Be-doped with a linearly decreasing doping concentration," the growth conditions for the first GaSb layer are: substrate temperature 510℃, Sb beam current to Ga beam current ratio 7.29, Ga growth rate 400 nm / h, thickness 400 nm, and Be doping concentration starting from 1 × 10⁻⁶. 19 cm -3 linear decay to 1×10 18 cm -3 .

5. The method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy as described in claim 1, characterized in that, In the description of "growing a second GaSb layer on a first GaSb layer, the second GaSb layer being Be-doped with an exponentially decreasing doping concentration", the thickness of the second GaSb layer is 40 nm, and the Be doping concentration starts from 1 × 10⁻⁶. 18 cm -3 Exponential decay to 1×10 17 cm -3 .

6. The method for growing high-quality GaSbBuffer on a GaAs substrate using molecular beam epitaxy as described in claim 1, characterized in that, In "Growing a third GaSbBuffer layer on the second GaSb layer", the thickness of the third GaSbBuffer layer is 1600 nm, and the same growth conditions as the first GaSb layer are used.

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