A metal nanoparticle modified gallium oxide thin film solar blind ultraviolet detector and a preparation method thereof

Abstract

The application discloses a metal nanoparticle modified gallium oxide film solar blind ultraviolet detector and a preparation method thereof, and relates to the technical field of surface modification of metal materials. The application replaces traditional noble metal materials with inexpensive metal nanoparticles, utilizes the localized surface plasmon resonance effect of the inexpensive metal nanoparticles in the solar blind ultraviolet band, and combines the interface barrier between the gallium oxide layer to realize synergistic regulation, so that a surface modification function structure is constructed on the surface of the gallium oxide photosensitive layer. The device can realize synergistic optimization of light absorption enhancement, efficient separation and transport of photo-generated carriers and effective suppression of dark current, has good solar blind wave band selection characteristics, and has significantly improved photoelectric detection sensitivity, light and dark current matching characteristics and working stability. The overall preparation process is simple, compatible and controllable in cost, and is suitable for industrialization popularization and practical application of gallium oxide-based deep ultraviolet solar blind detector devices.

Description

Technical Field

[0001] This invention relates to the field of surface modification technology for metal materials, and in particular to a gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles and its preparation method. Background Technology

[0002] Solar-blind ultraviolet light has a wavelength range of 220-280 nm. This band of ultraviolet radiation can be almost completely shielded by the ozone layer, and background interference from the atmospheric environment is close to zero. Thanks to this unique advantage of no background interference, solar-blind ultraviolet photodetectors (PDs) possess the core characteristics of low noise and high sensitivity, showing broad application prospects in both civilian and military fields such as flame monitoring and early warning, space ultraviolet communication, biomedical detection, and missile guidance.

[0003] Solar-blind ultraviolet detectors require wide-bandgap semiconductors as the core photosensitive material. These materials respond only to short-wavelength ultraviolet light in the 220-280 nm range, eliminating the need for additional filter devices, thus effectively reducing costs and simplifying device structure design. Commonly used wide-bandgap semiconductors include AlGaN, MgZnO, diamond, and gallium oxide (Ga2O3). Among them, Ga2O3 has an ultra-wide direct bandgap of approximately 4.9 eV, which is highly matched to the solar-blind ultraviolet band. It also possesses high optical transmittance, excellent thermal stability, and chemical stability, making it suitable for extreme operating environments and the preferred material for fabricating solar-blind ultraviolet detectors.

[0004] Despite breakthroughs in Ga2O3 performance optimization through doping and structural design, inherent defects leading to insufficient device response speed and high dark current remain unresolved, hindering its industrial application. In recent years, the widespread application of surface plasmons (SPs) in photoelectric detection has provided a novel approach to overcoming the performance bottleneck of Ga2O3 solar-blind ultraviolet detectors. Surface plasmons (SPs), also known as surface plasmons, have had their resonance effects systematically studied and have been widely applied in photoelectric detectors, biochemical sensors, and surface-enhanced Raman scattering. This technology, with its unique advantages such as strong localized enhancement of the light field and efficient manipulation of light-matter interactions, provides crucial support for performance breakthroughs and functional expansion of related devices.

[0005] To prepare high-performance Ga2O3 thin films, researchers often use noble metal nanoparticles (Au, Ag, etc.) to excite local surface plasmon resonances to optimize performance. For example, in 2016, An et al. prepared Au-NPs / β-Ga2O3 composite films using magnetron sputtering and found a significant absorption peak near 510 nm, which was attributed to surface plasmon resonances of the gold nanoparticles. Studies showed that the detector's photoresponse rate was significantly higher when irradiated with both 254 nm and 532 nm light than when irradiated with only 254 nm light. However, the plasmon resonance frequency range of most noble metals is concentrated in the visible light region, which does not match the solar-blind ultraviolet response band of Ga2O3 sufficiently, and research on plasmon enhancement in this band remains insufficient.

[0006] Therefore, there is an urgent need for a low-cost gallium oxide surface modification scheme that matches the plasmon excitation wavelength with the solar blind band and can synergistically improve light absorption and suppress dark current. Summary of the Invention

[0007] The purpose of this invention is to provide a gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles and its preparation method, so as to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides the following solution: This invention provides a gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles, wherein a substrate, a gallium oxide photosensitive layer, a metal nanoparticle modification layer, and an electrode are arranged sequentially from bottom to top; or, the substrate, the metal nanoparticle modification layer, the gallium oxide photosensitive layer, and the electrode are arranged sequentially from bottom to top.

[0009] In this invention, metal nanoparticles are uniformly distributed on the upper or lower surface of the gallium oxide photosensitive layer. By utilizing the surface plasmon resonance effect, the light absorption and photogenerated carrier separation efficiency of the device are improved, thus forming a surface-modified composite photosensitive structure.

[0010] Furthermore, the substrate is a sapphire substrate.

[0011] Furthermore, the metal is one of Zn, Cu, Mo, and W.

[0012] Furthermore, the electrode is an interdigitated ITO transparent electrode.

[0013] The present invention also provides a method for fabricating a gallium oxide thin film solar-blind ultraviolet detector modified with the above-mentioned metal nanoparticles. When a substrate, a gallium oxide photosensitive layer, a metal nanoparticle modification layer, and an electrode are sequentially arranged from bottom to top, the fabrication method includes the following steps: (1) Deposit the gallium oxide photosensitive layer on the surface of the substrate; (2) A metal layer is deposited on the surface of the gallium oxide photosensitive layer of the device obtained in step (1); (3) Anneal the device obtained in step (2) in an inert atmosphere to allow the metal layer to agglomerate and grow into metal nanoparticles, thus obtaining a metal nanoparticle modified layer. (4) Deposit an electrode on the surface of the metal nanoparticle modified layer of the device obtained in step (3) to obtain the metal nanoparticle modified gallium oxide thin film solar blind ultraviolet detector; When the substrate, metal nanoparticle modification layer, gallium oxide photosensitive layer, and electrode are sequentially arranged from bottom to top, the fabrication method includes the following steps: (1) Deposit a metal layer on the surface of the substrate; (2) Anneal the device obtained in step (1) in an inert atmosphere to allow the metal layer to agglomerate and grow into metal nanoparticles, thus obtaining a metal nanoparticle modified layer. (3) A gallium oxide photosensitive layer is deposited on the surface of the metal nanoparticle modification layer of the device obtained in step (2); (4) An electrode is deposited on the surface of the gallium oxide photosensitive layer of the device obtained in step (3) to obtain the gallium oxide thin film solar-blind ultraviolet detector modified by the metal nanoparticles.

[0014] Furthermore, the annealing temperature is 600-1000℃, and the annealing time is 30-90 minutes.

[0015] Furthermore, the thickness of the metal layer is 10-50 nm.

[0016] The physical mechanism by which the metal layer is transformed into metal nanoparticles through atmospheric thermal annealing is: Solid metal layers are typically in a metastable, condensed state. When this metastable state is disrupted, the metal layer transitions to thermal equilibrium and forms a granular structure. This process is driven by the principle of minimizing surface energy. When the metal layer is thin, this process can occur at temperatures far below the metal's melting point and usually needs to be completed in an inert atmosphere; this process is generally referred to as self-assembly. Depositing a metastable metal layer on a substrate and then annealing it at a specific temperature can drive the self-assembly process. This method can be used for the large-scale preparation of metal nanoparticles. Atmospheric thermal annealing is a simple and economical way to achieve the self-assembly of solid metal layers. Metal nanoparticles formed by the self-assembly of metastable metal layers through atmospheric thermal annealing are characterized by high density, uniform distribution, and no agglomeration. They also offer advantages such as simple operation, controllable particle morphology, and high preparation efficiency, making it the fastest and most economical method for the large-scale preparation of nanoparticles.

[0017] The present invention discloses the following technical effects: This invention uses low-cost metal nanoparticles to replace expensive precious metal materials. It relies on the excellent local surface plasmon resonance characteristics of metal nanoparticles in the solar-blind ultraviolet band, and the excitation wavelength is highly matched with the solar-blind ultraviolet detection band. At the same time, it combines the synergistic regulation effect of the interface barrier between metal nanoparticles and Ga2O3 semiconductor layer to construct an MSM solar-blind ultraviolet detector structure with Ga2O3 modified on the surface of metal nanoparticles.

[0018] This invention leverages the local electric field enhancement effect of surface plasmons to effectively enhance the ultraviolet light absorption efficiency of semiconductor layers, promote the generation, separation, and transport of photogenerated carriers, and, in conjunction with interface barrier modulation, effectively suppress dark current, achieving synergistic optimization of light absorption enhancement, carrier gain, and dark current suppression.

[0019] The device of this invention has high detection sensitivity, large light-dark current ratio, excellent selectivity in the solar-blind band, stable switching response, and excellent cycle durability. It avoids the drawbacks of high cost and poor band adaptability of traditional noble metal modification, and provides a new high-performance improvement scheme for gallium oxide-based deep ultraviolet optoelectronic devices that is low-cost, process-compatible, and relies on surface plasmon enhancement. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0021] Figure 1 This is a schematic diagram illustrating the fabrication process of the MSM structure solar-blind ultraviolet detector in Examples 1-3 of the present invention.

[0022] Figure 2 The diagram shows the structure of the MSM structure solar-blind ultraviolet detector in Embodiments 1-3 of the present invention. (a) shows the Zn nanoparticle modification layer on the upper surface of the gallium oxide photosensitive layer, and (b) shows the Zn nanoparticle modification layer on the lower surface of the gallium oxide photosensitive layer.

[0023] Figure 3 The following are scanning electron microscope images of the Ga2O3 thin film in Example 1 of the present invention: (a) No zinc particles deposited; (b) Sputtering time 5 s; (c) Sputtering time 10 s; (d) Sputtering time 15 s.

[0024] Figure 4The following are the current-voltage response curves of different devices in Embodiment 1 of the present invention: (a) photocurrent and dark current; (b) IT response curve; photocurrent to dark current ratio: (c) 0 s; (d) 5 s; (e) 10 s; (f) 15 s.

[0025] Figure 5 The following are the light-dark current ratio, responsivity, external quantum efficiency, and detectivity of the devices with different sputtering times in Embodiment 1 of the present invention: (a) Light-dark current ratio; (b) Detectivity; (c) Responsivity; (d) External quantum efficiency. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0032] The present invention will be further described in detail below with reference to embodiments: Example 1 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Zn target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0033] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Zn film: turn off the RF power supply, switch to the DC sputtering power supply, set the sputtering current to 0.1 A, the sputtering power to 50 W, the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 15 s to deposit Zn film on the surface of gallium oxide film.

[0034] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0035] (5) High-temperature annealing to form Zn nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 800℃ in 40 min and held at this temperature for 60 min to allow the Zn ultrathin film to agglomerate and form uniformly distributed Zn nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0036] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode fabrication is completed after sputtering for 15 min. Thus, a solar-blind ultraviolet detector with a Zn nanoparticle modified gallium oxide composite layer (Zn-NPs / Ga2O3) structure (Zn-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0037] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer, a Zn nanoparticle surface modification layer, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; the Zn nanoparticles are uniformly attached to the surface of the Ga2O3 layer.

[0038] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photocurrent-to-dark-current ratio can reach 9.92 × 10⁻⁶. 4 The responsivity reached 2.89 A / W, and the detectivity was 3.46 × 10⁻⁶. 12 Jones, with an external quantum efficiency of 1417.1%.

[0039] Based on Example 1, the sputtering time in step (3) was further changed to 0s, 10s, and 15s to obtain different MSM structure solar-blind ultraviolet detectors.

[0040] Example 2 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Zn target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0041] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Zn film: turn off the RF power supply, switch to turn on the DC sputtering power supply, set the sputtering current to 0.1 A, the sputtering power to 52 W, the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 5 s to deposit Zn film on the surface of gallium oxide film.

[0042] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0043] (5) High-temperature annealing to form Zn nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 900℃ in 40 min and held at this temperature for 60 min to allow the Zn ultrathin film to agglomerate and form uniformly distributed Zn nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0044] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode is fabricated after sputtering for 15 min. The solar-blind ultraviolet detector with Zn nanoparticle modified gallium oxide composite layer (Zn-NPs / Ga2O3) structure (Zn-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is fabricated.

[0045] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer, a Zn nanoparticle surface modification layer, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; the Zn nanoparticles are uniformly attached to the surface of the Ga2O3 layer.

[0046] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photocurrent-to-dark-current ratio can reach 4.32 × 10⁻⁶. 4 The responsivity reaches 1.33 A / W, and the detectivity is 1.16 × 10⁻⁶. 12 Jones has an external quantum efficiency of 1276.2%.

[0047] Example 3 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Zn target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0048] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Zn film: turn off the RF power supply, switch to turn on the DC sputtering power supply, set the sputtering current to 0.05 A, the sputtering power to 30 W, the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 5 s to deposit Zn film on the surface of gallium oxide film.

[0049] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0050] (5) High-temperature annealing to form Zn nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 800℃ in 40 min and held at this temperature for 60 min to allow the Zn ultrathin film to agglomerate and form uniformly distributed Zn nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0051] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode is fabricated after sputtering for 15 min. A solar-blind ultraviolet detector with a Zn nanoparticle modified gallium oxide composite layer (Zn-NPs / Ga2O3) structure (Zn-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0052] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer, a Zn nanoparticle surface modification layer, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; the Zn nanoparticles are uniformly attached to the surface of the Ga2O3 layer.

[0053] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photocurrent-to-dark-current ratio can reach a maximum of 7.01 × 10⁻⁶. 4 The responsivity reaches 2.01 A / W, and the detectivity is 1.78 × 10⁻⁶. 12 Jones, with an external quantum efficiency of 1382.2%.

[0054] Example 4 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Zn target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0055] (2) DC sputtering deposition of Zn film: Turn on the DC sputtering power supply, set the sputtering current to 0.1 A, the sputtering power to 56 W, the Ar flow rate to 35 sccm, the working pressure to 0.2 Pa, and the sputtering time to 5 s to deposit a Zn film on the substrate surface; (3) High-temperature annealing to form Zn nanoparticles: The sample was transferred into a CVD tube furnace, the vacuum was drawn to 0.08 Pa, and 99.99% high-purity argon gas was introduced at a flow rate of 60 sccm; the temperature was raised to 800 ℃ in 40 min and held at this temperature for 1 h to allow the Zn ultrathin film to agglomerate into uniformly distributed Zn nanoparticles; the sample was then cooled to room temperature with the furnace and removed. (4) Preparation of gallium oxide thin film by radio frequency sputtering: The annealed sample was placed in the vacuum chamber, the substrate was turned on and the argon flow rate was adjusted to 25 sccm to make the vacuum degree reach 0.2 Pa. The radio frequency power supply was turned on and the power was adjusted to 100 W. The sputtering time was 90 min to prepare gallium oxide thin film. (5) Initial forming of composite film: Turn off the RF sputtering power supply to complete the composite film preparation process; (6) Sputtering ITO electrodes to complete detector fabrication: The sample is transferred into a magnetron sputtering instrument, and a high-purity ITO target is used to sputter interdigitated transparent electrodes through a mask; without turning on the substrate rotation, 99.99% high-purity argon gas is introduced at a flow rate of 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the sputtering time is 15 min; the electrode fabrication is completed, and a solar-blind ultraviolet detector with a Zn nanoparticle modified gallium oxide composite layer (Zn-NPs / Ga2O3) structure (Zn-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0056] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer with Zn nanoparticle surface modification, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; wherein the Zn nanoparticles are uniformly attached to the surface of the sapphire substrate.

[0057] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photo-dark current ratio can reach a maximum of 7.35 × 10⁻⁶. 4 The responsivity reaches 2.69 A / W, and the detectivity is 2.38 × 10⁻⁶. 12 Jones, with an external quantum efficiency of up to 1315.2%.

[0058] Example 5 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Mo target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0059] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Mo film: turn off the RF power supply, switch to the DC sputtering power supply, set the sputtering current to 0.15 A, the sputtering power to 60 W, the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 15 s to deposit Mo film on the surface of gallium oxide film.

[0060] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0061] (5) High-temperature annealing to form Mo nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 850℃ in 40 min and held at this temperature for 60 min to allow the Mo ultrathin film to self-assemble and agglomerate, forming uniformly distributed Mo nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0062] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode fabrication is completed after sputtering for 15 min. Thus, a solar-blind ultraviolet detector with a Mo nanoparticle modified gallium oxide composite layer (Mo-NPs / Ga2O3) structure (Mo-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0063] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer, a Mo nanoparticle surface modification layer, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; the Mo nanoparticles are uniformly attached to the surface of the Ga2O3 layer.

[0064] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photocurrent-to-dark-current ratio can reach 9.72 × 10⁻⁶. 4 The responsivity reached 2.91 A / W, and the detectivity was 3.62 × 10⁻⁶. 12 Jones, with an external quantum efficiency of 1486.1%.

[0065] Comparative Example 1 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen; the cleaned sapphire substrate was placed on the sample stage of the vacuum chamber, and a high-purity Ga2O3 ceramic target (purity of 99.99%) was selected as the target material. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0066] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) High temperature annealing: The prepared thin film sample was transferred into a CVD tube furnace, the vacuum was evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm; the temperature was raised to 800℃ in 40 min and held at this temperature for 60 min; then the furnace was cooled to room temperature and the sample was taken out.

[0067] (4) Sputtering ITO electrodes to complete detector fabrication: The cooled sample was placed back into the magnetron sputtering equipment, and a high-purity ITO target with a purity of 99.99% was selected. Interdigitated transparent electrodes were sputtered through a mask. In this step, the substrate rotation was not turned on, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 35 sccm. The vacuum degree was adjusted to 0.2 Pa, and sputtering was carried out for 15 minutes to complete the electrode fabrication, thus obtaining the solar-blind ultraviolet detector. The test results showed that the photocurrent-to-dark-current ratio of the device was 2.43 × 10⁻⁶ under ultraviolet light irradiation at a wavelength of 254 nm with a bias voltage of 10 V. 3 The responsivity is 0.16 A / W, and the detectivity is 2.54 × 10⁻⁶. 11 Jones, with an external quantum efficiency of 82.9%.

[0068] Comparative Example 2 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Ag target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0069] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Ag film: turn off the RF power supply, switch to turn on the DC sputtering power supply, set the sputtering current to 0.1 A, the sputtering power to 45 W, the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 15 s to deposit an Ag film on the surface of the gallium oxide thin film.

[0070] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0071] (5) High-temperature annealing to form Ag nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 800℃ in 40 min and held at this temperature for 60 min to allow the Ag ultrathin film to agglomerate and form uniformly distributed Ag nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0072] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode fabrication is completed after sputtering for 15 min. Thus, a solar-blind ultraviolet detector with an Ag nanoparticle modified gallium oxide composite layer (Ag-NPs / Ga2O3) structure (Ag-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0073] The fabricated MSM structure solar-blind ultraviolet detector consists of a sapphire substrate, a Ga2O3 photosensitive layer, an Ag nanoparticle surface modification layer, and an ITO interdigitated electrode, forming a four-layer stacked structure from bottom to top; the Ag nanoparticles are uniformly attached to the surface of the Ga2O3 layer.

[0074] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device's photocurrent-to-dark-current ratio is 1.15 × 10⁻⁶. 4 The responsivity is 0.53 A / W, and the detectivity is 9.31 × 10⁻⁶. 10 Jones, with an external quantum efficiency of 542.9%.

[0075] Comparative Example 3 (1) Substrate and target clamping and vacuum pretreatment: The single-polished sapphire c-(001) substrate was first ultrasonically cleaned in ethanol for 15 min, then ultrasonically cleaned in deionized water for 15 min, and finally dried with nitrogen. The cleaned sapphire substrate was placed on the sample stage of the vacuum chamber. High-purity Ga2O3 ceramic target (purity of 99.99%) and high-purity Zn target (purity of 99.99%) were selected as the target materials. The vacuum chamber was evacuated to 5×10 -3 Pa, open the flow limiting valve and introduce high-purity argon gas with a purity of 99.99%.

[0076] (2) Preparation of gallium oxide thin film by radio frequency sputtering: turn on the substrate rotation function, adjust the argon flow rate to 25 sccm, and stabilize the vacuum at 0.2 Pa; turn on the radio frequency power supply, adjust the power to 100 W, and sputter continuously for 90 min to prepare gallium oxide thin film; (3) DC sputtering deposition of Zn film: turn off the RF power supply, switch to turn on the DC sputtering power supply, set the sputtering current to 0.1 A, the sputtering power to 62 W, ​​the argon flow rate to 35 sccm, the working pressure to 0.2 Pa, and control the sputtering time to 5 s to deposit Zn film on the surface of gallium oxide film.

[0077] (4) Initial forming of composite film: Turn off the DC sputtering power supply and complete the preparation process of composite film.

[0078] (5) High-temperature annealing to form Zn nanoparticles: The prepared thin film sample was transferred into a CVD tube furnace, evacuated to 0.08 Pa, and high-purity argon gas with a purity of 99.99% was introduced at a flow rate of 60 sccm. The temperature was raised to 300℃ in 40 min and held at this temperature for 10 min to allow the Zn ultrathin film to agglomerate and form uniformly distributed Zn nanoparticles. The sample was then cooled to room temperature with the furnace and removed.

[0079] (6) Sputtering ITO electrodes to complete detector fabrication: After cooling, the sample is placed back into the magnetron sputtering equipment. A high-purity ITO target with a purity of 99.99% is selected, and interdigitated transparent electrodes are sputtered through a mask. In this step, the substrate rotation is not turned on. High-purity argon gas with a purity of 99.99% is introduced, the flow rate is set to 35 sccm, the vacuum degree is adjusted to 0.2 Pa, and the electrode fabrication is completed after sputtering for 15 min. Thus, a solar-blind ultraviolet detector with a Zn nanoparticle modified gallium oxide composite layer (Zn-NPs / Ga2O3) structure (Zn-NPs / Ga2O3MSM structure solar-blind ultraviolet detector) is obtained.

[0080] Test results show that, under 10V bias and 254nm wavelength ultraviolet light irradiation, the device has a photocurrent-to-dark-current ratio of 1.09, a responsivity of 4.6 A / W, and a detectivity of 8.37 × 10⁻⁶. 9 Jones, with an external quantum efficiency of 224.7%.

[0081] The Zn nanoparticle-modified Ga2O3-based MSM solar-blind ultraviolet photodetector prepared in this invention exhibits excellent performance: the photocurrent-to-dark-current ratio can reach up to 9.92 × 10⁻⁶. 4 This is 40.8 times that of an intrinsic Ga2O3 detector; the responsivity reaches 2.89 A / W, and the detectivity is 3.46 × 10⁻⁶. 12 Jones boasts an external quantum efficiency of up to 1417.1%. Furthermore, the detector exhibits excellent switching response characteristics and cyclic stability, effectively suppressing dark current. Its comprehensive performance meets the practical application requirements for solar-blind ultraviolet detection.

[0082] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A gallium oxide thin-film solar-blind ultraviolet detector modified with metal nanoparticles, characterized in that: From bottom to top, the substrate, gallium oxide photosensitive layer, metal nanoparticle modification layer, and electrode are arranged sequentially. Alternatively, the substrate, metal nanoparticle modification layer, gallium oxide photosensitive layer, and electrode can be arranged sequentially from bottom to top.

2. The gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles according to claim 1, characterized in that, The substrate is a sapphire substrate.

3. The gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles according to claim 1, characterized in that, The metal is one of Zn, Cu, Mo, and W.

4. The gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles according to claim 1, characterized in that, The electrode is an interdigitated ITO transparent electrode.

5. The method for preparing a gallium oxide thin film solar-blind ultraviolet detector modified with metal nanoparticles as described in claim 1, characterized in that, When the substrate, gallium oxide photosensitive layer, metal nanoparticle modification layer, and electrode are sequentially arranged from bottom to top, the fabrication method includes the following steps: (1) Deposit the gallium oxide photosensitive layer on the surface of the substrate; (2) A metal layer is deposited on the surface of the gallium oxide photosensitive layer of the device obtained in step (1); (3) Anneal the device obtained in step (2) in an inert atmosphere to allow the metal layer to agglomerate and grow into metal nanoparticles, thus obtaining a metal nanoparticle modified layer. (4) Deposit an electrode on the surface of the metal nanoparticle modified layer of the device obtained in step (3) to obtain the metal nanoparticle modified gallium oxide thin film solar-blind ultraviolet detector; When the substrate, metal nanoparticle modification layer, gallium oxide photosensitive layer, and electrode are sequentially arranged from bottom to top, the fabrication method includes the following steps: (1) Deposit a metal layer on the surface of the substrate; (2) Anneal the device obtained in step (1) in an inert atmosphere to allow the metal layer to agglomerate and grow into metal nanoparticles, thus obtaining a metal nanoparticle modified layer. (3) A gallium oxide photosensitive layer is deposited on the surface of the metal nanoparticle modification layer of the device obtained in step (2); (4) An electrode is deposited on the surface of the gallium oxide photosensitive layer of the device obtained in step (3) to obtain the gallium oxide thin film solar-blind ultraviolet detector modified by the metal nanoparticles.

6. The preparation method according to claim 5, characterized in that, The annealing temperature is 600-1000℃, and the annealing time is 30-90 minutes.

7. The preparation method according to claim 5, characterized in that, The thickness of the metal layer is 10-50 nm.

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