Ga2O3 / MgO / Si avalanche heterojunction design

Abstract

The invention relates to a Ga2O3 / MgO / Si avalanche heterostructure and preparation thereof, and belongs to the technical field of semiconductor devices. In order to improve the epitaxial quality of a Ga2O3 film on the Si substrate, guarantee good energy band arrangement and charge transmission and improve the avalanche gain of the Ga2O3 / Si heterojunction, the invention provides a Ga2O3 / MgO / Si avalanche heterojunction design which is focused on the fact that Si and Ga2O3 are combined to form the heterojunction, and the avalanche gain of the Ga2O3 / MgO / Si avalanche heterojunction is improved. The integration level and the universality of the Ga2O3-based solar-blind ultraviolet photoelectric detector are enhanced, and avalanche gain is provided for the detector by adding the MgO barrier layer. The preparation is simple, the optical gain and the sensitivity are ideal, and Si is used as a substrate, so that the integration and the processing of a subsequent CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process are facilitated.

Description

Technical Field

[0001] The invention relates to a Ga2O3 / MgO / Si avalanche heterostructure and preparation thereof, belonging to the technical field of semiconductor devices. Background Art

[0002] Solar-blind ultraviolet light (wavelength 200-280nm) is absorbed by ozone in the atmosphere, making it an ideal spectral window without background noise. Traditional silicon-based photodetectors have poor response to this band due to the limited bandgap width, and often need to be used in conjunction with filters, resulting in increased system complexity and cost. Gallium oxide (Ga2O3), as a third-generation wide-bandgap semiconductor material, has become an ideal material choice for solar-blind ultraviolet detectors with its high breakdown voltage (8MV / cm), high thermal stability, large bandgap width (4.6-4.9eV), and excellent ultraviolet light absorption ability. It provides great application value in missile warning, maritime search and rescue, forest fire warning, ultraviolet communication, etc.

[0003] In recent years, researchers have used heterojunction structures, such as the combination of Ga2O3 and Si, to manufacture solar-blind ultraviolet photodetectors. Heterojunction design can take advantage of the energy band matching advantages of different materials to improve carrier transmission and light absorption efficiency, making it have the advantages of large response coefficient and high sensitivity. In the prior art, many works have been carried out around gallium oxide-based solar-blind ultraviolet detectors. For example, "A Silicon-Based Gallium Oxide Heterogeneous Solar-Blind Photoelectric Sensor Structure" reported a silicon-based gallium oxide heterogeneous PIN-type photodetector. The sensor designed in this scheme consists of a silicon substrate, a multidimensional silicon nanocone structure, a gallium oxide film, a P-type doped region, an N-type doped region, an ohmic contact, and a gold electrode, forming a PIN-type heterostructure. The photogenerated electron-hole pairs are collected through the multiplication absorption of solar-blind ultraviolet light by the gallium oxide film, thereby achieving effective detection of solar-blind ultraviolet light.

[0004] In the prior art, although certain progress has been made in the field of gallium oxide-based solar-blind ultraviolet detectors, most of them are concentrated on a single material structure or a simple heterojunction design. However, a single Ga2O3-based detector has limitations in integration, quantum efficiency, and process compatibility. In addition, there are many oxygen defects in the Ga2O3 material, lattice mismatch with other materials, difficulty in film formation, low carrier mobility, and difficulty in conduction. These problems will limit and reduce the performance and efficiency of the device, and increase the complexity of the preparation process of Ga2O3-based solar-blind ultraviolet photodetectors, which ultimately leads to an increase in production costs. Therefore, further research is needed in the preparation of high-quality films and obtaining high response. How to achieve a high-quality heterojunction interface, improve the quality of Ga2O3 film epitaxy on Si substrates, and ensure good band alignment and charge transfer are still technical difficulties. In addition, there are few studies on Ga2O3 / Si avalanche heterojunctions, and the responsivity and detection rate of the photodetector can be increased through the avalanche effect. Therefore, research based on Ga2O3 is very meaningful, and there is an urgent need for a Ga2O3-based heterojunction with Si as a substrate and capable of avalanche gain. Summary of the invention

[0005] To solve the above problems, the present invention provides a Ga2O3 / MgO / Si avalanche heterojunction design, focusing on combining Si and Ga2O3 to form a heterojunction, enhancing the integration and versatility of Ga2O3-based solar-blind ultraviolet photodetectors, and providing avalanche gain for the detector by adding a MgO barrier layer. The preparation is simple and has ideal optical gain and sensitivity, and Si is used as the substrate, which facilitates the integration and processing of subsequent CMOS processes.

[0006] A Ga2O3 / MgO / Si avalanche heterojunction design is as follows:

[0007] S1: growing a MgO barrier layer on the surface of a Si substrate, wherein the Si substrate is n-type doped Si;

[0008] S2: growing a Ga2O3 film on the surface of the MgO barrier layer;

[0009] S3: depositing Ti / Au electrodes on the surface of Ga2O3 thin film layer;

[0010] Furthermore, a Ti / Au electrode was deposited on the back of the Si substrate. Finally, a Ga2O3 / MgO / Si nBn-type avalanche heterojunction was obtained. From bottom to top, it includes a cathode ohmic metal layer, an n-type Si substrate, a MgO barrier layer, an n-type Ga2O3 layer, and an anode ohmic metal layer.

[0011] The beneficial effects of the present invention are:

[0012] A Ga2O3 / MgO / Si avalanche heterojunction structure is provided, which uses the avalanche effect as the main working mode. Compared with a single-structure gallium oxide-based heterojunction, it has higher carrier multiplication gain and lower dark current, and has higher responsiveness, signal-to-noise ratio and sensitivity.

[0013] The present invention provides a Ga2O3 / MgO / Si avalanche heterojunction structure, in which MgO is added between gallium oxide and silicon as a barrier layer, thereby improving the problems of gallium oxide being difficult to grow on the surface of a silicon substrate and having poor film quality, and increasing the barrier height between the two, thereby increasing the breakdown voltage and further increasing the avalanche gain. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram of the Ga2O3 / MgO / Si avalanche heterojunction structure, where 1 is the Au / Ti electrode, 2 is the Ga2O3 layer, 3 is the MgO barrier layer, 4 is the Si substrate, and 5 is the Au / Ti electrode. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0016] S1: Prepare 10x10mm 2 The size and thickness of the substrate are 290 μm and the crystal orientation is (100) n-type doped Si single crystal substrate.

[0017] S2: A 25 nm thick MgO barrier layer was grown on the divided Si substrate by laser molecular beam epitaxy using atomic layer deposition. The temperature of the Mg source was 95 °C, the growth environment was 200 °C, and the growth rate was

[0018] S3: Define a 7 mm × 7 mm square area on the MgO / Si substrate using standard photolithography techniques.

[0019] Furthermore, Ga2O3 is deposited on the region by magnetron sputtering. The parameters of magnetron sputtering are as follows: argon gas flow rate: 40 sccm, sputtering speed: Radio frequency: 150W, gas pressure: 2Pa, preparation temperature: room temperature, film thickness: 200nm.

[0020] Finally, we get Figure 1 The Ga2O3 / MgO / Si avalanche heterojunction shown.

[0021] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a Ga2O3 / MgO / Si avalanche heterojunction, characterized in that: The heterojunction can be used to detect solar-blind ultraviolet light and has avalanche gain. The heterojunction includes a cathode ohmic metal layer, an n-type Si substrate, an MgO barrier layer, an n-type Ga2O3 layer, and an anode ohmic metal layer from bottom to top. The preparation method specifically includes the following steps: S1: Select an n-type doped Si single crystal substrate with a (100) crystal orientation; S2: A MgO barrier layer was grown on the divided Si substrate by laser molecular beam epitaxy using atomic layer deposition, where the temperature of the Mg source was 95°C and the growth environment was 200°C; S3: Ga2O3 was deposited on a MgO / Si substrate by magnetron sputtering at room temperature.

2. A Ga2O3 / MgO / Si avalanche heterojunction design according to claim 1, characterized in that: The barrier layer includes a MgO layer, which is located between the Ga2O3 layer and the Si layer, and the thickness of the barrier layer is 20-80nm.

3. A Ga2O3 / MgO / Si avalanche heterojunction design according to claim 1, characterized in that: The absorption layer comprises a Ga2O3 layer, which is located on the surface of the MgO barrier layer, and the thickness of the absorption layer is 50-200nm.

4. A Ga2O3 / MgO / Si avalanche heterojunction, characterized in that: The heterojunction includes a MgO barrier layer structure, and the heterojunction is prepared by the method as claimed in any one of claims 1 to 3.

Images