A gallium oxide solar blind ultraviolet detector based on a microcavity structure and a preparation method thereof

Abstract

The application discloses a gallium oxide solar blind ultraviolet detector based on a microcavity structure and a preparation method thereof, and comprises the following steps: (1) depositing a high-reflection metal layer on a substrate; (2) depositing a gallium oxide layer on the high-reflection metal layer and performing annealing treatment; (3) depositing a semi-transparent metal layer on the gallium oxide layer; and (4) depositing a first contact electrode and a second contact electrode and performing annealing treatment to complete preparation of the detector. The microcavity enhances the absorption of target ultraviolet light in a relatively thin gallium oxide thin film, thereby improving the detection performance. Meanwhile, the conductive metal thin film has the properties of high reflectivity when the thickness is relatively large, semi-transparency and certain reflectivity when the thickness is relatively small, the upper and lower metal layers are used as reflectors of the microcavity structure and upper and lower conductive electrodes, and the device structure is ingeniously simplified. The gallium oxide solar blind ultraviolet detector based on the microcavity structure has the advantages of simple design and preparation method and low cost, and is favorable for large-scale commercial application.

Description

Technical Field

[0001] This invention relates to a gallium oxide solar-blind ultraviolet detector based on a microcavity structure and its fabrication method. Background Technology

[0002] Photoelectric detection technology plays a vital role in national production and daily life. Compared to common visible light and infrared detection, ultraviolet (UV) detection is also crucial in fields such as missile early warning, UV communication, and fire monitoring. When sunlight reaches the Earth's surface, the shorter wavelength and higher energy portion of UV light is strongly absorbed, making the background noise in this wavelength range negligible during UV detection. Detectors operating in the 200nm-280nm wavelength range are typically called solar-blind UV detectors. Due to their low background noise, solar-blind UV detectors are attracting increasing attention.

[0003] Materials are fundamental; selecting suitable materials is crucial for obtaining high-performance detectors. Silicon-based detectors have a significant advantage due to their mature industrial system; however, silicon's small bandgap and strong response to visible light necessitate additional filters, increasing device cost. Ultra-wide bandgap semiconductor materials, relying on their bandgap advantage, can operate efficiently without filters, offering a clear advantage. Among ultra-wide bandgap semiconductor materials, gallium oxide (bandgap 4.9 eV), a binary compound, is an ideal material for fabricating solar-blind ultraviolet detectors due to its advantages such as not requiring complex doping and growth processes like other ternary compounds, chemical stability, and low growth cost.

[0004] Photodetection is the process of converting light into electricity. Light absorption, as the first step, has a significant impact on the detector's performance. To enhance light absorption, methods such as introducing surface plasmon nanoparticles and superstructures can be employed. However, the introduction of these micro / nano structures not only relies on advanced micro / nano fabrication techniques but also increases the complexity of device fabrication. This increased complexity not only affects the yield of the final product but also increases production time and costs, severely hindering its commercialization.

[0005] Therefore, designing and fabricating a simple and high-performance gallium oxide solar-blind ultraviolet detector is of great significance for promoting its commercial application. Summary of the Invention

[0006] This invention introduces a microcavity structure into a gallium oxide solar-blind ultraviolet detector, providing a simple and high-performance device structure fabrication method. The microcavity is composed of a high-reflectivity metal layer, a semi-transparent metal layer, and a spacer layer that are parallel to each other and spaced at a certain distance.

[0007] The present invention provides a gallium oxide solar-blind ultraviolet detector based on a microcavity structure, comprising a substrate, a highly reflective metal layer, a gallium oxide layer, a semi-transparent metal layer, a first contact electrode, and a second contact electrode.

[0008] This invention provides a method for fabricating a gallium oxide solar-blind ultraviolet detector based on a microcavity structure, comprising the following steps:

[0009] (1) Deposit a highly reflective metal layer on the substrate;

[0010] (2) Deposit a gallium oxide layer on the high-reflectivity metal layer and perform annealing treatment;

[0011] (3) Deposit a semi-transparent metal layer on the gallium oxide layer;

[0012] (4) Deposit the first contact electrode and the second contact electrode and perform annealing to complete the fabrication of the detector device.

[0013] Furthermore, the substrate is a gallium oxide substrate, a sapphire substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, an aluminum substrate, or a copper substrate.

[0014] Furthermore, the deposited high-reflectivity metal layer, semi-transparent metal layer, first contact electrode, and second contact electrode are prepared by any one of the following methods: thermal evaporation, electron beam evaporation, magnetron sputtering, and atomic layer deposition.

[0015] Furthermore, the high-reflectivity metal layer is prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, and Mo, with a thickness of 50 nm to 1000 nm.

[0016] Furthermore, the gallium oxide layer is prepared by any one of the following methods: molecular beam epitaxy, metal-organic chemical vapor deposition, spray chemical vapor deposition, halide vapor deposition, pulsed laser deposition, magnetron sputtering, and atomic layer deposition, with a thickness of 10 nm to 1000 nm.

[0017] Furthermore, the deposited gallium oxide layer is subjected to post-annealing treatment. The annealing atmosphere is any one or more of nitrogen, argon, and oxygen. The annealing temperature is 100℃~1200℃ and the annealing time is 10s~3600s.

[0018] Furthermore, the translucent metal layer is prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, and Mo, with a thickness of 1 nm to 50 nm.

[0019] Furthermore, the first contact electrode and the second contact electrode are prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, Mo, ITO, and AZO, with a thickness of 20 nm to 1000 nm. The first contact electrode and the second contact electrode can be the same or different.

[0020] Furthermore, the first contact electrode and the second contact electrode are located on the same side or both sides of the detector.

[0021] Furthermore, the deposited first and second contact electrodes are subjected to rapid thermal annealing. The annealing atmosphere is any one or more of nitrogen and argon, the annealing temperature is 60℃~800℃, and the annealing time is 1s~1200s.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The present invention enhances the absorption of target ultraviolet light in a thin gallium oxide film by introducing a metal microcavity composed of a high reflective metal layer, a semi-transparent metal layer and a spacer layer that are parallel to each other and spaced at a certain distance, which is beneficial to improving the detection performance of the ultraviolet detector.

[0024] (2) This invention utilizes the properties of conductive metal thin films, which have high reflectivity when thick and semi-transparent and have a certain reflectivity when thin, to make the upper and lower metal layers serve as both the reflector of the microcavity structure and the upper and lower conductive electrodes, thus ingeniously simplifying the device structure.

[0025] (3) The present invention uses a semi-transparent metal layer, which greatly increases the light-receiving area of ​​the detector, thereby improving the detection performance.

[0026] (4) The gallium oxide solar-blind ultraviolet detector designed and prepared in this invention has a simple structure and low cost, and does not require complex micro-nano fabrication technology, which makes it possible for it to move towards large-scale mature commercial application. Attached Figure Description

[0027] Figure 1 This is a structural schematic diagram of the product in Example 1;

[0028] Figure 2 This is a structural schematic diagram of the product in Example 3.

[0029] In the figure, 1-first contact electrode, 2-substrate, 3-high reflective metal layer, 4-gallium oxide layer, 5-semi-transparent metal layer, 6-second contact electrode. Detailed Implementation

[0030] To more clearly illustrate the technical solutions in this invention and / or the prior art, specific embodiments of the invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without any creative effort.

[0031] Example 1

[0032] A Ti (50 nm thick) / Au (150 nm thick) high-reflectivity metal layer was deposited on a gallium oxide substrate by thermal evaporation. A gallium oxide layer of 50 nm to 100 nm was deposited by magnetron sputtering with a gallium oxide ceramic target at a sputtering power of 80 W and an argon atmosphere. The substrate was then annealed at 850 °C in a tube furnace with an oxygen atmosphere for 600 s. Au (1 nm to 50 nm thick) was deposited on the gallium oxide layer as a semi-transparent metal layer by thermal evaporation. Ti (50 nm thick) / Au (100 nm thick) was deposited on the back side of the gallium oxide substrate by thermal evaporation as the first contact electrode. The electrode shape, with a size of 50 μm × 50 μm, was etched on the semi-transparent metal layer by photolithography. Ni (50 nm thick) / Au (150 nm thick) was then thermally evaporated as the second contact electrode and rapidly annealed at 600 °C for 30 s in a nitrogen atmosphere. At this point, the simple and high-performance gallium oxide solar-blind ultraviolet detector has been fabricated, as shown in the schematic diagram below. Figure 1 As shown.

[0033] Example 2

[0034] A Ni (50 nm thick) / Au (150 nm thick) high-reflectivity metal layer was deposited on a gallium oxide substrate by electron beam evaporation. A gallium oxide layer of 50 nm to 100 nm was deposited by atomic layer deposition at a deposition temperature of 280 °C, with trimethylgallium and ozone as precursor sources. The substrate was then annealed at 850 °C in a tube furnace under an oxygen atmosphere for 600 s. A Ni (1 nm to 50 nm thick) semi-transparent metal layer was deposited on the gallium oxide layer by thermal evaporation. Ti (50 nm thick) / Au (100 nm thick) was deposited on the back side of the gallium oxide substrate by electron beam evaporation as the first contact electrode. The electrode shape, with a size of 50 μm × 50 μm, was etched on the semi-transparent metal layer by photolithography. A Ni (50 nm thick) / Au (150 nm thick) second contact electrode was then deposited by thermal evaporation and rapidly thermally annealed at 600 °C for 30 s under a nitrogen atmosphere. At this point, the simple structure and high performance of the gallium oxide solar-blind ultraviolet detector have been completed.

[0035] Example 3

[0036] A Ni (50 nm thick) / Au (150 nm thick) high-reflectivity metal layer was deposited on a sapphire substrate by electron beam evaporation. A gallium oxide layer of 50 nm–100 nm was deposited by magnetron sputtering using a gallium oxide ceramic target at a sputtering power of 80 W in an argon atmosphere. The layer was then annealed at 850 °C in a tube furnace in an oxygen atmosphere for 600 s. Au (1 nm–50 nm thick) was deposited as a semi-transparent metal layer on the gallium oxide layer by thermal evaporation. The final layer was then etched using photolithography and argon-ion reactive ion beam lithography. The semi-transparent metal layer and gallium oxide layer were etched away using an etching method to expose the first contact electrode region. Then, the electrode shape, with a size of 50 μm × 50 μm, was etched onto the highly reflective metal layer using photolithography. Thermally evaporated Ti (50 nm thick) / Au (100 nm thick) was used as the first contact electrode. Similarly, the electrode shape, also with a size of 50 μm × 50 μm, was etched onto the semi-transparent metal layer using photolithography. Thermally evaporated Ni (50 nm thick) / Au (150 nm thick) was used as the second contact electrode. The electrode was then rapidly thermally annealed at 600°C for 30 s in a nitrogen atmosphere. At this point, the simple and high-performance gallium oxide solar-blind ultraviolet detector was fabricated. A schematic diagram of the structure is shown below. Figure 2 As shown.

[0037] Example 4

[0038] A Ti (50 nm thick) / Au (150 nm thick) high-reflectivity metal layer was deposited on a sapphire substrate via thermal evaporation. A gallium oxide layer of 50 nm–100 nm was deposited using atomic layer deposition at 280 °C, with trimethylgallium and ozone as precursor sources. The substrate underwent high-temperature annealing at 850 °C in a tube furnace at an oxygen atmosphere for 600 s. A Ni (1 nm–50 nm thick) semi-transparent metal layer was then deposited on the gallium oxide layer via thermal evaporation. The final layer was etched using photolithography and argon-ion reactive ion beam etching. The method involves etching away the semi-transparent metal layer and the gallium oxide layer to expose the first contact electrode region. Then, the electrode shape, with a size of 50 μm × 50 μm, is etched onto the highly reflective metal layer using photolithography. Thermally evaporated Ti (50 nm thick) / Au (100 nm thick) serves as the first contact electrode. Similarly, the electrode shape, also 50 μm × 50 μm, is etched onto the semi-transparent metal layer using photolithography. Thermally evaporated Ni (50 nm thick) / Au (150 nm thick) serves as the second contact electrode, followed by rapid thermal annealing at 600 °C for 30 s in a nitrogen atmosphere. At this point, a simple and high-performance gallium oxide solar-blind ultraviolet detector is fabricated.

Claims

1. A gallium oxide solar-blind ultraviolet detector based on a microcavity structure, characterized in that, include: Substrate, high-reflectivity metal layer, gallium oxide layer, semi-transparent metal layer, first contact electrode and second contact electrode.

2. A method for fabricating a gallium oxide solar-blind ultraviolet detector based on a microcavity structure, characterized in that, include: (1) Deposit a highly reflective metal layer on the substrate; (2) Deposit a gallium oxide layer on the high-reflectivity metal layer and perform annealing treatment; (3) Deposit a semi-transparent metal layer on the gallium oxide layer; (4) Deposit the first contact electrode and the second contact electrode and perform annealing to obtain the gallium oxide solar-blind ultraviolet detector based on the microcavity structure as described in claim 1.

3. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The substrate is a gallium oxide substrate, a sapphire substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, an aluminum substrate, or a copper substrate.

4. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The high-reflectivity metal layer, the semi-transparent metal layer, the first contact electrode, and the second contact electrode are prepared by any one of the following methods: thermal evaporation, electron beam evaporation, magnetron sputtering, and atomic layer deposition.

5. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The high-reflectivity metal layer is prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, and Mo, with a thickness of 50 nm to 1000 nm.

6. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The gallium oxide layer is prepared by any one of the following methods: molecular beam epitaxy, metal-organic chemical vapor deposition, spray chemical vapor deposition, halide vapor phase epitaxy, pulsed laser deposition, magnetron sputtering, and atomic layer deposition, with a thickness of 10 nm to 1000 nm.

7. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The deposited gallium oxide layer is subjected to post-annealing treatment. The annealing atmosphere is any one or more of nitrogen, argon, and oxygen. The annealing temperature is 100℃~1200℃ and the annealing time is 10s~3600s.

8. The method for fabricating a gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The translucent metal layer is prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, and Mo, with a thickness of 1 nm to 50 nm.

9. The fabrication method of the gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The first contact electrode and the second contact electrode are prepared using any one or more of Ti / Au, Ni / Au, Mg / Au, Ti / Au / Ni, Pt, Ir, Pd, Au, Ti, Ni, Cu, Al, Mo, ITO, and AZO, with a thickness of 20 nm to 1000 nm. The first contact electrode and the second contact electrode can be the same or different.

10. The method for fabricating a gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The first contact electrode and the second contact electrode are on the same side or both sides of the detector.

11. The method for fabricating a gallium oxide solar-blind ultraviolet detector based on a microcavity structure as described in claim 2, characterized in that: The deposited first and second contact electrodes are subjected to rapid thermal annealing. The annealing atmosphere is any one or more of nitrogen and argon, the annealing temperature is 60℃~800℃, and the annealing time is 1s~1200s.

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