Preparation method of gallium arsenide / beta-phase gallium oxide heterojunction ultraviolet photoelectric detector

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a gallium arsenide / beta-phase gallium oxide heterojunction ultraviolet photoelectric detector and a preparation method thereof. The preparation method comprises the following steps: growing a beta-phase gallium oxide film on a gallium arsenide substrate through PLD; depositing a layer of first metal material on the lower surface of the gallium arsenide substrate; depositing a layer of second metal material on the surface of the beta-phase gallium oxide thin film; and annealing the obtained device to enable the first metal material and the second metal material to form ohmic contact so as to complete the preparation of an electrode, thereby obtaining the beta-Ga2O3-GaAs heterojunction ultraviolet photoelectric detector. According to the Ga2O3 heterojunction ultraviolet detector, the separation capacity of photon-generated carriers is enhanced through the heterojunction, good thin film crystallization quality, few oxygen vacancy defects and good surface flatness are formed, and practical application of the Ga2O3 heterojunction ultraviolet detector is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a method for preparing a gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Solar-blind UV detectors (PDs) can effectively detect electromagnetic waves in the range of 200-280nm, and play an important role in fire detection, UV early warning, deep space exploration, etc. [. Compared with traditional infrared detectors, the strong absorption of 200-280nm solar radiation by stratospheric ozone provides a natural low background noise for solar-blind UV detectors, making solar-blind UV detectors have the characteristics of high signal-to-noise ratio and low error rate.

[0004] Gallium arsenide (GaAs) and β-gallium oxide (β-Ga2O3), as two new semiconductor materials, have gradually shown great potential in the field of ultraviolet photoelectric detection due to their unique physical and chemical properties. β-Ga2O3 has a wide bandgap (about 4.9eV), can achieve efficient detection in the deep ultraviolet band, and has the advantages of high breakdown electric field and good thermal stability. Gallium arsenide (GaAs) has good electron mobility and a relatively mature preparation process.

[0005] By forming a heterojunction structure between gallium arsenide and β-phase gallium oxide, the advantages of both can be utilized to achieve higher photoelectric conversion efficiency and detection performance. The heterojunction structure can not only enhance the electric field strength of the device, but also effectively suppress dark current and improve the detection sensitivity and response speed of the device. Therefore, ultraviolet photodetectors based on gallium arsenide / β-phase gallium oxide heterojunctions have become one of the current research hotspots. However, how to solve the defect state problem caused by the heterojunction interface and improve the crystal quality and interface flatness of the material are still the difficulties in current research. At the same time, how to achieve large-scale manufacturing and integrated applications while ensuring high performance is also an important research topic. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector and a preparation method. By constructing a gallium arsenide / β-phase gallium oxide heterostructure, the separation ability of photogenerated carriers is enhanced, and β-phase gallium oxide with high crystallinity and low oxygen vacancy concentration can be obtained, verifying the potential of the heterojunction structure in deep ultraviolet detection.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, a gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector and a preparation method thereof include the following steps:

[0009] S1. Growing a β-phase gallium oxide thin film on a GaAs substrate using a pulsed laser deposition process (PLD);

[0010] S2, depositing a layer of a first metal material on the lower surface of the gallium arsenide substrate, and depositing a layer of a second metal material on the surface of the β-phase gallium oxide film;

[0011] S3. Annealing the obtained device to form an ohmic contact between the first metal material and the second metal material to complete the preparation of the electrode, thereby obtaining the gallium arsenide / β-phase gallium oxide ultraviolet photodetector.

[0012] Preferably, in step S1, the substrate is a GaAs n-type Si-doped (100) surface substrate, and the substrate is pre-treated by ultrasonic cleaning using anhydrous ethanol as a cleaning agent and then drying.

[0013] Preferably, in step S1, the conditions of the pulsed laser deposition process are controlled as follows: the laser uses a KrF excimer laser with an energy of 250mJ, the growth mode is set to the EGY NGR mode, the substrate growth temperature is 500-700°C, the growth time is 120min, and the oxygen is introduced to maintain the pressure at 0.85Pa; the target material used is a 99.99% high-purity gallium oxide target material, and the distance between the substrate and the gallium oxide target material is 40mm.

[0014] More preferably, the substrate growth temperature is 700° C. Under this temperature condition, the flatness and crystal quality of the β-phase gallium oxide film are better, and the oxygen vacancy defects are less.

[0015] Preferably, in step S2, the method of growing the first metal material and the second metal material is magnetron sputtering, the temperature is room temperature, the first metal material is Au, and the second metal material is Ti / Au (lower layer Au, upper layer Ti structure).

[0016] Preferably, in step S3, the annealing temperature is 500° C., the time is 60 seconds, and the annealing atmosphere is a nitrogen atmosphere.

[0017] In a second aspect, a gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector is obtained by the preparation method described in the first aspect.

[0018] Preferably, the thickness of the β-phase gallium oxide film is 60-120 nm. If the film is too thick, it may cause stress cracking, reduced crystal quality (introducing more defects and dislocations), deterioration of interface performance (increase in interface defects, affecting carrier separation and transmission efficiency), reduced optical performance, reduced thermal stability, and other problems.

[0019] Preferably, the thickness of the first metal material Au is 10-20 nm, the thickness of the Ti electrode of the second metal material is 4-6 nm, and the thickness of the Au electrode is 6-8 nm.

[0020] The present invention has the following beneficial effects:

[0021] The gallium arsenide / β-phase gallium oxide heterojunction structure prepared by the present invention can help separate photogenerated electrons and holes, reduce the oxygen vacancy concentration at the interface, and has fewer oxygen vacancy defects; the gallium oxide film is polycrystalline, has higher crystal quality and better surface flatness.

[0022] The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector of the present invention has a simple preparation process, is easy to operate, has a cost advantage, and is easy to realize large-scale manufacturing and integrated application.

[0023] In summary, the present invention is based on a pulsed laser deposition process, combined with process parameter optimization, substrate material selection, and film thickness control, to effectively solve the defect state problem existing at the gallium arsenide / β-phase gallium oxide heterojunction interface, and improve the crystal quality of the material and the interface flatness problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 Schematic diagram of the structure of the gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector in Example 1-3;

[0026] Figure 2 This is the XRD-2Theta diagram of the β-phase gallium oxide thin film on the gallium arsenide substrate in Example 1-3, where the abscissa is the 2Theta angle and the ordinate is the diffraction line intensity.

[0027] Figure 3 The surface flatness test results of the β-phase gallium oxide film in Examples 1-3.

[0028] Figure 4 These are the test results of oxygen and arsenic content in the gallium arsenide / β-phase gallium oxide heterojunction in Examples 1-3.

[0029] Figure 5It curve of the gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector in Example 1 in the dark and under 255nm, 0.77mW / cm2 illumination. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0031] Example 1

[0032] First, the gallium arsenide substrate was cleaned with anhydrous ethanol in an ultrasonic oscillator for 5 minutes and dried with high-purity nitrogen to obtain a pre-treated gallium arsenide substrate. A β-phase gallium oxide film was grown on the substrate by pulsed laser deposition; the substrate temperature was 700°C; the deposition time was 120 minutes; the thickness was 120nm; the laser mode was EGY NGR250mJ; oxygen was introduced to maintain the vacuum environment at 0.85Pa; a high-purity 99.99% gallium oxide target was used; and the distance between the substrate and the target was 40mm.

[0033] The device prepared in the previous step is placed in a magnetron sputtering growth chamber by magnetron sputtering and evacuated to a pressure below normal pressure. The lower surface of the gallium arsenide substrate is plated with Au having a thickness of 10-20 nm by magnetron sputtering, and the surface of the β-phase gallium oxide film is plated with Au having a thickness of 6-8 nm and Ti having a thickness of 4-6 nm in turn. The sputtering targets used are high-purity Au and Ti. The sputtering temperature is room temperature.

[0034] Annealing was performed at 500°C for 60 seconds in a nitrogen atmosphere to form an ohmic contact between metal Au and metal Ti to form an electrode, and a structure such as Figure 1 The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector shown.

[0035] Example 2

[0036] First, the gallium arsenide substrate was cleaned with anhydrous ethanol in an ultrasonic oscillator for 5 minutes and dried with high-purity nitrogen to obtain a pre-treated gallium arsenide substrate. A β-phase gallium oxide film was grown on the substrate by pulsed laser deposition; the substrate temperature was 600°C; the deposition time was 120 minutes; the thickness was 120nm; the laser mode was EGY NGR250mJ; oxygen was introduced to maintain the vacuum environment at 0.85Pa; a high-purity 99.99% gallium oxide target was used; and the distance between the substrate and the target was 40mm.

[0037] The device prepared in the previous step is placed in a magnetron sputtering growth chamber by magnetron sputtering and evacuated to a pressure below normal pressure. The lower surface of the gallium arsenide substrate is plated with Au having a thickness of 10-20 nm by magnetron sputtering, and the surface of the β-phase gallium oxide film is plated with Au having a thickness of 6-8 nm and Ti having a thickness of 4-6 nm in turn. The sputtering targets used are high-purity Au and Ti. The sputtering temperature is room temperature.

[0038] Annealing was performed at 500°C for 60 seconds in a nitrogen atmosphere to form an ohmic contact between metal Au and metal Ti to form an electrode, and a structure such as Figure 1 The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector shown.

[0039] Example 3

[0040] First, the gallium arsenide substrate was cleaned with anhydrous ethanol in an ultrasonic oscillator for 5 minutes and dried with high-purity nitrogen to obtain a pre-treated gallium arsenide substrate. A β-phase gallium oxide film was grown on the substrate by pulsed laser deposition; the substrate temperature was 500°C; the deposition time was 120 minutes; the thickness was 120nm; the laser mode was EGY NGR250mJ; oxygen was introduced to maintain the vacuum environment at 0.85Pa; a high-purity 99.99% gallium oxide target was used; and the distance between the substrate and the target was 40mm.

[0041] The device prepared in the previous step is placed in a magnetron sputtering growth chamber by magnetron sputtering and evacuated to a pressure below normal pressure. The lower surface of the gallium arsenide substrate is plated with Au having a thickness of 10-20 nm by magnetron sputtering, and the surface of the β-phase gallium oxide film is plated with Au having a thickness of 6-8 nm and Ti having a thickness of 4-6 nm in turn. The sputtering targets used are high-purity Au and Ti. The sputtering temperature is room temperature.

[0042] Annealing was performed at 500°C for 60 seconds in a nitrogen atmosphere to form an ohmic contact between metal Au and metal Ti to form an electrode, and a structure such as Figure 1 The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector shown.

[0043] Performance Test:

[0044] 1) The crystal quality of the β-phase gallium oxide films of Examples 1, 2 and 3 was tested by X-ray diffractometer. The results are shown in Figure 2. It can be concluded that under the condition of large lattice mismatch and thermal mismatch between gallium oxide and gallium arsenide, the prepared gallium oxide film is polycrystalline, indicating that the film still has a high crystal quality. In the figure, the diffraction line intensity of the gallium oxide film is the highest at 700°C, that is, the gallium oxide film of Example 1 has the best crystal quality.

[0045] 2) The surface roughness of the β-phase gallium oxide films of Examples 1, 2 and 3 was tested. The results are as follows: Figure 3As shown, it can be concluded that the surface roughness is small and the flatness is good, among which Example 1 has the smallest roughness of 0.402nm and the best flatness. From the surface appearance in the figure, Example 1 has more and more uniform peaks, and has better crystallization quality than Examples 1 and 2.

[0046] 3) The oxygen and arsenic contents in the gallium arsenide / β-phase gallium oxide heterojunctions of Examples 1, 2 and 3 were tested. The results are as follows: Figure 4 As shown, the embodiment has a higher oxygen content, and as the temperature increases, the oxygen content increases, reflecting that the oxygen vacancy concentration is small. The present invention effectively improves the defect state problem of the heterojunction.

[0047] 4) The device prepared in Example 1 was tested for IV characteristics, and the results were as follows: Figure 5 As shown in the figure, it can be concluded that the light-dark ratio of photocurrent to dark current at 1 V is 1.64, and the detection rate is 1.07×10 21 , can be used as an ultraviolet photodetector. This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims of the present invention, will be protected by the patent law.

Claims

1. A method for preparing a gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector, characterized in that: The following steps are involved: S1. Growing a β-phase gallium oxide thin film on a GaAs substrate using a pulsed laser deposition process; S2, depositing a layer of a first metal material on the lower surface of the gallium arsenide substrate, and depositing a layer of a second metal material on the surface of the β-phase gallium oxide film; S3. Annealing the obtained device to form an ohmic contact between the first metal material and the second metal material to complete the preparation of the electrode, thereby obtaining the gallium arsenide / β-phase gallium oxide ultraviolet photodetector.

2. The preparation method according to claim 1, characterized in that: In step S1, the GaAs substrate is an n-type Si-doped (100)-plane substrate, and the substrate is ultrasonically cleaned with anhydrous ethanol for 5 minutes and then blown dry with high-purity nitrogen.

3. The preparation method according to claim 1, characterized in that: In step S1, the conditions of the pulsed laser deposition process are controlled as follows: the substrate growth temperature is 500-700°C, the growth time is 120min, and the oxygen pressure is maintained at 0.85Pa; the target material used is a 99.99% high-purity gallium oxide target material, and the distance between the substrate and the gallium oxide target material is 40mm.

4. The preparation method according to claim 3, characterized in that: The substrate growth temperature is 700°C.

5. The preparation method according to claim 1, characterized in that: In step S2, the method of growing the first metal material and the second metal material is magnetron sputtering, the temperature is room temperature, the first metal material is Au, and the second metal material is Ti / Au.

6. The preparation method according to claim 1, characterized in that: In step S3, the annealing temperature is 500° C., the time is 60 seconds, and the annealing atmosphere is a nitrogen atmosphere.

7. A gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 6.

8. The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector according to claim 7, characterized in that: The thickness of the β-phase gallium oxide film is 60-120 nm.

9. The gallium arsenide / β-phase gallium oxide heterojunction ultraviolet photodetector according to claim 7, characterized in that: The thickness of the first metal material is 10-20 nm, the thickness of the Ti electrode in the second metal material is 4-6 nm, and the thickness of the Au electrode is 6-8 nm.

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