MSM structure ultraviolet photoelectric detector based on p-Si / Ga2O3 / ZnO and preparation method thereof

Abstract

The invention relates to the technical field of ultraviolet photoelectric detectors, in particular to an MSM structure ultraviolet photoelectric detector based on p-Si / Ga2O3 / ZnO and a preparation method of the MSM structure ultraviolet photoelectric detector. Comprising a p-Si substrate; the Ga2O3 thin film layer is arranged on the p-Si substrate; the ZnO thin film layer is arranged on the Ga2O3 thin film layer; and the interdigital electrode is arranged on the ZnO thin film layer. The interdigital electrode is a Ti interdigital electrode, the width of the interdigital electrode is 50-100 m, the length of the interdigital electrode is 600-1000 m, and the electrode interval is 50-100 m; and the p-Si substrate is a double-surface polished boron-doped p-Si substrate. In the preparation process, magnetron sputtering and thermal evaporation deposition are adopted to prepare the photoelectric detector. The method has the advantages that manufacturing cost is reduced; the suppression ratio of UV / Vis-NIR light is improved, so that the device has higher spectral selectivity; the detection wavelength range is widened, and sensitive detection of UVA-UVC is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of ultraviolet photoelectric detectors, and in particular to an ultraviolet photoelectric detector with an MSM structure based on p-Si / Ga2O3 / ZnO and a preparation method thereof. Background Art

[0002] Silicon (Si)-based photodetectors are key components in optical communications, optical interconnects, and silicon-photonic integrated systems. Due to their high compatibility with silicon-based microelectronics, they offer irreplaceable advantages in integrated applications. However, due to the low bandgap of Si (~1.12 eV), Si exhibits high responsivity in the visible (Vis) to near-infrared (NIR) bands, but exhibits poor responsivity in the ultraviolet (UV) band, making it difficult to meet the demand for UV light detection.

[0003] In recent years, with the rapid development of third- and fourth-generation semiconductor material technologies, wide-bandgap semiconductor materials have shown great potential in the research and development of UV photodetectors. These materials include ZnO, Ga2O3, GaN, SiC, and TiO2. Among them, ZnO has become an ideal UV detection material due to its following advantages: (1) an optical bandgap of 3.37 eV, suitable for UV-band light detection; (2) high exciton binding energy, which ensures efficient photoresponse at room temperature; (3) simple preparation process, mild growth conditions, non-toxicity, and low cost. In particular, p-Si / ZnO heterojunction photodetectors have attracted widespread attention because they combine the excellent UV photoresponse characteristics of ZnO with the high integration characteristics of p-Si.

[0004] However, existing p-Si / ZnO photodetectors still have the following problems: (1) The UV response has a poor suppression effect on the Vis-NIR band response, which limits its spectral selectivity; (2) The device's light response band is concentrated in the long-wave UVA region, making it impossible to achieve ultraviolet dual-band detection; (3) The overall light response intensity is low, which affects its performance in practical applications.

[0005] To overcome these issues, researchers have attempted to deposit barrier layers of wide-bandgap materials such as BeO, MgO, and LaAlO3 onto p-Si thin films to suppress the Vis-NIR photoresponse. While these methods have improved device performance to some extent, they still fail to achieve effective detection across the entire UV range and fail to significantly enhance the photoresponse intensity. Therefore, further optimizing the structure and performance of ZnO / p-Si heterojunction photodetectors has become a critical and pressing issue in the current technology landscape. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO and a preparation method thereof.

[0007] The first object of the present invention is to provide a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector, comprising: p-Si substrate; A Ga2O3 thin film layer provided on a p-Si substrate; A ZnO thin film layer disposed on the Ga2O3 thin film layer; The interdigital electrodes are arranged on the ZnO thin film layer.

[0008] Preferably, the interdigital electrodes are Ti interdigital electrodes; and the p-Si substrate is a double-surface polished boron-doped p-Si substrate with a resistivity of 1-10Ω·cm.

[0009] Preferably, the width of the interdigitated electrodes is 50-100 μm, the length is 600-1000 μm, and the electrode spacing is 50-100 μm.

[0010] Preferably, the thickness of the Ga2O3 thin film layer is 350-950 nm; the thickness of the ZnO thin film layer is 300-400 nm.

[0011] Preferably, the thickness of the Ga2O3 thin film layer is 700nm; the thickness of the ZnO thin film layer is 310nm. The second object of the present invention is to provide a method for preparing an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO, which specifically includes the following steps: S1. Select a substrate and ultrasonically clean it with acetone, isopropyl alcohol, and deionized water, followed by drying with nitrogen. S2. depositing a Ga2O3 thin film layer on the substrate by radio frequency magnetron sputtering; S3. depositing a ZnO thin film layer on the Ga2O3 thin film layer by radio frequency magnetron sputtering; S4. Deposit interdigitated electrodes on the ZnO thin film layer by thermal evaporation to obtain an MSM structure UV photodetector based on p-Si / Ga2O3 / ZnO.

[0012] Preferably, the sputtering power in step S2 is 120-160 W; the sputtering pressure in step S3 is 2-6 Pa, and the sputtering time is 25-80 min.

[0013] Preferably, the sputtering parameters in step S2 are as follows: the vacuum degree is 5×10 -4 Pa, the sputtering pressure was 1 Pa, the sputtering power was 140 W, the O2 / Ar flow ratio was 0:30, and the sputtering time was 60 min.

[0014] Preferably, in step S3, the sputtering pressure is 4 Pa, the sputtering power is 100 W, the O2 / Ar flow ratio is 10:40, and the sputtering time is 60 minutes.

[0015] Preferably, step S4 specifically includes: spin coating photoresist on the surface of the ZnO thin film layer, forming a patterned photoresist layer by exposure and development; then forming interdigitated electrodes by thermal evaporation deposition on the photoresist layer; after deposition, the photoresist layer is peeled off by a lift-off process to obtain an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. Improved UV light response performance: (1) The heterojunction structure of ZnO and Ga2O3 optimizes the separation efficiency of photogenerated electron-hole pairs, significantly enhancing the detector's light response intensity in both the UVA and UVB bands. (2) The wide bandgap characteristics of the Ga2O3 thin film layer effectively prevent the transmission of holes generated by Vis-NIR light, suppressing the Vis-NIR light response and thus improving the UV / Vis-NIR light suppression ratio.

[0017] 2. Realize dual-band ultraviolet detection: Traditional p-Si / ZnO photodetectors are mainly concentrated in the long-wave UVA region. The present invention introduces a Ga2O3 layer between ZnO and p-Si to broaden the detection wavelength range and achieve sensitive detection of UVA-UVC.

[0018] 3. Optimizing spectral selectivity: The p-Si / Ga2O3 / ZnO MSM detector designed in the present invention has a significantly higher response intensity in the UV band than in the Vis-NIR band. Compared with the existing technology, the UV / Vis-NIR suppression ratio is significantly improved, giving the device higher spectral selectivity.

[0019] 4. Improved device stability and adaptability: (1) By optimizing the process conditions of magnetron sputtering and thermal evaporation, the device exhibits excellent stability in different environments (temperature, humidity), making it suitable for a variety of complex application scenarios. (2) With a reasonable device structure design and optimized electrode size and film thickness, the stability and reproducibility of its photoelectric response are significantly enhanced, ensuring the feasibility of large-scale production.

[0020] 5. Reduce manufacturing costs: The present invention uses ZnO and Ga2O3 materials, which have the advantages of being non-toxic, environmentally friendly and low-cost. At the same time, radio frequency magnetron sputtering and thermal evaporation technology are used to complete film growth and electrode preparation at a lower temperature, thereby reducing the overall manufacturing cost.

[0021] 6. Expanded Application Areas: (1) The p-Si / Ga2O3 / ZnO MSM detector of the present invention has broad application prospects in the fields of photoelectric detection, environmental monitoring, UV imaging, military reconnaissance, and optical communications. (2) Its excellent UV detection performance and high UV / Vis-NIR suppression ratio provide a powerful reference and choice for the next generation of silicon-based UV photodetectors for integrated military and civilian applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the overall structure of an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO provided according to an embodiment of the present invention.

[0023] Figure 2 The figure is a flow chart of the preparation of an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO according to an embodiment of the present invention.

[0024] Figure 3 1 is a responsivity curve of an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO provided in an embodiment of the present invention under different bias voltages.

[0025] Figure 4 1 is a response curve of a p-Si / ZnO-based ultraviolet photodetector under different bias voltages provided in a comparative example of the present invention.

[0026] Figure 5 This is a comparison of the response wavelength range of two ultraviolet photodetectors under a 50V bias.

[0027] Figure 6 These are cross-sectional SEM photos of p-Si / Ga2O3 / ZnO-based MSM structure UV photodetectors with different thicknesses of Ga2O3 thin film layers; (a) indicates a Ga2O3 thin film layer with a thickness of 355nm; (b) indicates a Ga2O3 thin film layer with a thickness of 700nm; and (c) indicates a Ga2O3 thin film layer with a thickness of 920nm.

[0028] Figure 7 These are the response test results of the p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector with different thicknesses of Ga2O3 thin film layers under different bias voltages; (a) represents the Ga2O3 thin film layer thickness of 355nm; (b) represents the Ga2O3 thin film layer thickness of 700nm; (c) represents the Ga2O3 thin film layer thickness of 920nm.

[0029] Reference numerals: 1. substrate; 2.Ga2O3 thin film layer; 3. ZnO thin film layer; 4. Interdigitated electrodes. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0032] The present invention provides an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO, comprising: a substrate; a Ga2O3 thin film layer arranged on the substrate; a ZnO thin film layer arranged on the Ga2O3 thin film layer; and interdigital electrodes arranged on the ZnO thin film layer. Specifically, the substrate is a double-surface polished boron-doped p-Si substrate with a resistivity of 1-10Ω·cm; Specifically, the interdigital electrodes are Ti interdigital electrodes; the width of the interdigital electrodes is 50-100µm, the length is 600-1000µm, and the electrode spacing is 50-100µm; in a specific embodiment, the width of the interdigital electrodes is 50µm, the length is 800µm, and the electrode spacing is 80µm.

[0033] Specifically, the thickness of the Ga2O3 thin film layer is 350-950 nm; the thickness of the ZnO thin film layer is 300-400 nm.

[0034] In a specific embodiment, the thickness of the Ga2O3 thin film layer is 355 nm, 700 nm, or 920 nm; the thickness of the ZnO thin film layer is 310 nm; and the thickness of the interdigital electrode is 100 nm.

[0035] The preparation method of the p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector specifically comprises the following steps: S1. Select a substrate and ultrasonically clean it with acetone, isopropyl alcohol, and deionized water, followed by drying with nitrogen. S2. depositing a Ga2O3 thin film layer on the substrate by radio frequency magnetron sputtering; The vacuum degree of the RF magnetron sputtering system is 5×10 -4 Pa; the sputtering parameters are as follows: sputtering pressure 1 Pa, sputtering power 120~160W, O2 / Ar flow ratio 0:30, sputtering time 60 minutes; In a specific embodiment, the sputtering power is 140W; S3. depositing a ZnO thin film layer on the Ga2O3 thin film layer by radio frequency magnetron sputtering; The sputtering parameters were as follows: sputtering pressure 2–6 Pa, sputtering power 100 W, O / Ar flow ratio 10:40, and sputtering time 60 min; In a specific embodiment, the sputtering pressure is 4 Pa; S4. Deposit interdigitated electrodes on the ZnO thin film layer by thermal evaporation to obtain an MSM structure UV photodetector based on p-Si / Ga2O3 / ZnO.

[0036] Specifically, photoresist is spin-coated on the surface of the ZnO thin film layer, and a patterned photoresist layer is formed by exposure and development; then, interdigital electrodes are formed on the photoresist layer by thermal evaporation deposition; after deposition, the photoresist layer is stripped by a lift-off process to obtain an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO.

[0037] Example 1 See also Figure 1-Figure 2 This embodiment provides a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector, comprising: a substrate 1; a Ga2O3 thin film layer 2 disposed on the substrate; a ZnO thin film layer 3 disposed on the Ga2O3 thin film layer 2; and interdigital electrodes 4 disposed on the ZnO thin film layer 3. Substrate 1 is a double-surface polished boron-doped p-Si substrate with a resistivity of 1-10Ω·cm; The interdigital electrodes 4 have a width of 50 μm, a length of 800 μm, and an electrode spacing of 80 μm; The thickness of the Ga2O3 thin film layer 2 is 700 nm; the thickness of the ZnO thin film layer 3 is 310 nm.

[0038] The preparation method specifically comprises the following steps: S1. Select substrate 1 and ultrasonically clean it with acetone, isopropanol, and deionized water, then dry it with nitrogen. S2. Deposit Ga2O3 thin film layer 2 on substrate 1 by radio frequency magnetron sputtering; the vacuum degree of the radio frequency magnetron sputtering system is 5×10 -4 Pa; the sputtering parameters are as follows: sputtering pressure 1 Pa, sputtering power 140 W, O2 / Ar flow ratio 0:30, sputtering time 60 min; S3. Depositing a ZnO thin film layer 3 on the Ga2O3 thin film layer 2 by RF magnetron sputtering; sputtering parameters are as follows: sputtering pressure 4 Pa, sputtering power 100 W, O2 / Ar flow ratio 10:40, and sputtering time 60 min; S4. Spin-coat photoresist on the surface of the ZnO thin film layer 3 and form a patterned photoresist layer through exposure and development. Then, thermal evaporation deposition is performed on the photoresist layer to form interdigital electrodes 4. After deposition, the photoresist layer is stripped off through a lift-off process to obtain an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO.

[0039] Comparative Example 1 This comparative example provides a method for preparing a p-Si / ZnO-based ultraviolet photodetector, which specifically includes the following steps: S1. Select a p-Si substrate and ultrasonically clean it with acetone, isopropyl alcohol, and deionized water, followed by drying with nitrogen gas. S2. A ZnO thin film was deposited on substrate 1 by RF magnetron sputtering; the sputtering parameters were as follows: sputtering pressure 4 Pa, sputtering power 100 W, O2 / Ar flow ratio 10:40, and sputtering time 60 min; S4. Spin-coat photoresist on the surface of the ZnO thin film layer, and form a patterned photoresist layer through exposure and development. Then, thermal evaporation deposition is performed on the photoresist layer to form interdigital electrodes. After deposition, the photoresist layer is peeled off through a lift-off process to obtain a p-Si / ZnO-based UV photodetector.

[0040] The performance of the photodetectors prepared in Example 1 and Comparative Example 1 was tested, and the photoelectric response characteristics of the photodetectors were measured using a spectral response test system. The light response intensity, response time, and UV / Vis-NIR suppression ratio of the two devices in the UV and Vis-NIR bands were tested and compared. The results are shown in Figure 2. Figure 3-Figure 5 As shown. Figure 3-Figure 5 It can be seen from the results that when different bias voltages of 10V to 50V are applied to the device, the MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO of the present invention shows significant light response enhancement in the UVA and UVB bands and a greatly improved UV / Vis-NIR suppression ratio; the ultraviolet photodetector based on p-Si / ZnO prepared in the comparative example has a significantly higher light response in the Vis-NIR band than in the UV band, and a relatively low UV / Vis-NIR suppression ratio, and the device performance is inferior to the photodetector of the present invention.

[0041] Example 2 The effects of different preparation conditions on the device performance of the photodetector are studied as follows: 1. Effect of different magnetron sputtering conditions on the device performance of photodetectors (1) While keeping other parameters unchanged, the sputtering power in step S2 was adjusted (120 W, 130 W, 140 W, 150 W, and 160 W). The changes in the UV / Vis-NIR suppression ratio of the devices prepared at different sputtering powers were observed, and the crystal quality, surface morphology, and device performance of the films under different sputtering conditions were compared.

[0042] (2) While keeping other parameters unchanged, the sputtering pressure in step S3 was adjusted (2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa) to test the effect of the devices prepared under different sputtering pressures on the UV light response.

[0043] Results: After the magnetron sputtering conditions were optimized, the device exhibited the highest UV / Vis-NIR suppression ratio when the sputtering power of the Ga2O3 thin film layer was 140 W and the sputtering pressure of the ZnO thin film layer was 4 Pa.

[0044] 2. Effect of different interdigital electrode sizes on the device performance of photodetectors The widths of the interdigital electrodes (50µm, 80µm, 100µm), lengths (600µm, 800µm, 1000µm), and electrode spacings (50µm, 80µm, 100µm) were set. Photodetectors with different interdigital electrode sizes were prepared, and the effects of different electrode designs on photocurrent density and response time were analyzed.

[0045] Results: When the width of the interdigital electrode is 50µm, the length is 800µm, and the electrode spacing is 80µm, the light response intensity and response time reach the best balance.

[0046] 3. Effect of different Ga2O3 film thicknesses on the device performance of photodetectors Three groups of p-Si / Ga2O3 / ZnO-based MSM structure UV photodetector samples were prepared according to the method of Example 1. Among them, the ZnO thin film layer thickness was 310nm, and the Ga2O3 thin film layer thickness was different: the Ga2O3 thin film layer thickness of group a was 355nm, the Ga2O3 thin film layer thickness of group b was 700nm, and the Ga2O3 thin film layer thickness of group c was 920nm. SEM photos are shown in Figure 6 The photoelectric response characteristics of three groups of photodetectors were measured using a spectral response test system. The results are shown in Figure 7 ; The results in the figure show that when the thickness of the Ga2O3 thin film layer is 700nm, the response test results under different bias voltages are best.

[0047] Example 3 A p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector was prepared according to the method of Example 1. Its performance was tested under different temperature (-20°C to 80°C) and humidity (10% to 90% RH) environments. After the device was continuously powered on for 200 hours, its photoresponse stability was tested.

[0048] Test results: The MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO maintains stable photoelectric response performance under harsh environments, proving its good reliability and adaptability.

[0049] In summary, the present invention proposes an ultraviolet photodetector based on a p-Si / Ga2O3 / ZnO metal-semiconductor-metal (MSM) structure. By introducing a Ga2O3 layer, the UV light response capability is effectively improved and the Vis-NIR response is significantly suppressed. The detector is suitable for application scenarios such as ultraviolet light communication, environmental monitoring, ultraviolet imaging, and military reconnaissance.

[0050] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0051] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A p-Si / Ga2O3 / ZnO based MSM structure ultraviolet photodetector, characterized in that: include: p-Si substrate; A Ga2O3 thin film layer provided on a p-Si substrate; A ZnO thin film layer disposed on the Ga2O3 thin film layer; The interdigital electrodes are arranged on the ZnO thin film layer.

2. The p-Si / Ga2O3 / ZnO MSM structure ultraviolet photodetector according to claim 1, characterized in that: The interdigital electrodes are Ti interdigital electrodes; the p-Si substrate is a double-surface polished boron-doped p-Si substrate with a resistivity of 1-10Ω·cm.

3. The p-Si / Ga2O3 / ZnO MSM structure ultraviolet photodetector according to claim 2, characterized in that: The width of the interdigital electrodes is 50-100 μm, the length is 600-1000 μm, and the electrode spacing is 50-100 μm.

4. The p-Si / Ga2O3 / ZnO MSM structure ultraviolet photodetector according to claim 1, characterized in that: The thickness of the Ga2O3 thin film layer is 350-950 nm; the thickness of the ZnO thin film layer is 300-400 nm.

5. The p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to claim 4, characterized in that: The thickness of the Ga2O3 thin film layer is 700nm; the thickness of the ZnO thin film layer is 310nm.

6. The method for preparing a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to any one of claims 1 to 5, characterized in that: The specific steps include: S1. Select a substrate and ultrasonically clean it with acetone, isopropyl alcohol, and deionized water, followed by drying with nitrogen gas. S2. depositing a Ga2O3 thin film layer on the substrate by radio frequency magnetron sputtering; S3. depositing a ZnO thin film layer on the Ga2O3 thin film layer by radio frequency magnetron sputtering; S4. Deposit interdigitated electrodes on the ZnO thin film layer by thermal evaporation to obtain an MSM structure UV photodetector based on p-Si / Ga2O3 / ZnO.

7. The method for preparing a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to claim 6, characterized in that: The sputtering power in step S2 is 120-160 W; the sputtering pressure in step S3 is 2-6 Pa, and the sputtering time is 25-80 min.

8. The method for preparing a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to claim 7, characterized in that: The sputtering parameters in step S2 are as follows: the vacuum degree is 5×10 -4 Pa, the sputtering pressure was 1 Pa, the sputtering power was 140 W, the O2 / Ar flow ratio was 0:30, and the sputtering time was 60 min.

9. The method for preparing a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to claim 7, characterized in that: In step S3, the sputtering pressure is 4 Pa, the sputtering power is 100 W, the O2 / Ar flow ratio is 10:40, and the sputtering time is 60 minutes.

10. The method for preparing a p-Si / Ga2O3 / ZnO-based MSM structure ultraviolet photodetector according to claim 6, characterized in that: The step S4 specifically includes: spin coating photoresist on the surface of the ZnO thin film layer, forming a patterned photoresist layer through exposure and development; then forming interdigital electrodes on the photoresist layer by thermal evaporation deposition; after deposition, the photoresist layer is stripped by a lift-off process to obtain an MSM structure ultraviolet photodetector based on p-Si / Ga2O3 / ZnO.

Images