An ultraviolet detector

Abstract

An ultraviolet detector, which comprises a p-i-n structure formed by a p-type semiconductor, an intermediate layer and an n-type semiconductor, the p-type semiconductor is NiO, the n-type semiconductor is TiO2, and the intermediate layer is Bi2O3.In the application, by inserting a layer of Bi2O3 intermediate layer in the p-n structure composed of TiO2 and NiO, the anti-ultraviolet damage ability of the structure is effectively improved, and the signal stability of the detector is improved; secondly, Bi2O3 is inserted between TiO2 and NiO, which improves the responsivity of the device. The responsivity and external quantum efficiency (EQE) of the formal structure ultraviolet detector to 254 nm ultraviolet light respectively reached 162 mA W ‑1 and 79.09%, and the response current of the detector was 0.81 mu A, which was 2.3 times that of the p-n structure ultraviolet detector without Bi2O3.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor detectors, and particularly relates to an ultraviolet detector. BACKGROUND

[0002] The ultraviolet detector has wide applications in the fields of space detection, optical communication, environmental monitoring and chemical and biological sensing. The ultraviolet detector generally has two basic device structures of photoconductive and p-n junction. For example, the document (High-performance solar-blind ultraviolet photodetector based on mixed-phase ZnMgO thin film. Applied Physics Letters, 2014, 105, 011117) adopts the photoconductive device structure to test the current change under the action of an electric field to realize detection, but the technology generally adopts interdigital electrodes as two electrodes, the spacing is small, the light utilization rate is low, the device responsivity is low, and the device needs to work under an electric field, so the dark current is large, and the switching is low. In comparison, the thin film photodiode ultraviolet detector with the p-n structure has advantages of high switching ratio, high responsivity, high sensitivity and fast response, and has wide applications in the fields of national defense and civil use. However, due to the large ultraviolet energy, the p-n junction interface of the detector is damaged to a certain extent, which causes unstable signals of the detector and difficult-to-ensure linearity. SUMMARY

[0003] Based on the above technical problems, the present application aims to provide a p-i-n structure ultraviolet detector containing an intermediate layer. The core structure of the device is a p-n structure in which a Bi2O3 thin film layer is inserted, which improves the anti-ultraviolet damage ability of the detector, ensures the signal stability of the detector, prolongs the service life of the detector, and effectively improves the responsivity of the detector.

[0004] Another object of the present application is to provide a preparation method of the ultraviolet detector.

[0005] The object of the present application is achieved by the following technical solutions.

[0006] An ultraviolet detector, characterized in that the detector comprises a p-i-n structure formed by a p-type semiconductor, an intermediate layer and an n-type semiconductor, the p-type semiconductor is NiO, the n-type semiconductor is TiO2, and the intermediate layer is Bi2O3.

[0007] Further, the semiconductor structure in the detector is divided into formal structure and reverse structure, the formal structure is n-type semiconductor / Bi2O3 / p-type semiconductor from bottom to top, and the reverse structure is p-type semiconductor / Bi2O3 / n-type semiconductor from bottom to top, in the detector, the n-type semiconductor TiO2, the p-type semiconductor is NiO, and the intermediate layer Bi2O3 are all film layer structures, and the thickness ratio is 1-4:1-3:1-2.

[0008] Specifically, the n-type semiconductor TiO2 is a film layer structure with a thickness of 10-40 nm, the p-type semiconductor is NiO which is a film layer structure with a thickness of 10-30 nm, and the intermediate layer Bi2O3 has a thickness of 10-20 nm.

[0009] Further, the n-type semiconductor TiO2 is prepared by dissolving titanium isopropylate in ethanol to prepare a TiO2 precursor solution with a concentration of 0.1-0.2 mol / L, spin coating and then annealing.

[0010] Further, the annealing temperature in the formal structure is 350-500 DEG C, and the annealing time is 20-45 min, the annealing temperature in the reverse structure is 400-450 DEG C, and the annealing time is 10-40 min.

[0011] Further, the p-type semiconductor NiO is prepared by dissolving nickel acetylacetonate or nickel acetate in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.15-0.45 mol / L, spin coating and then annealing.

[0012] Further, the annealing temperature in the formal structure is 300-400 DEG C, and the annealing time is 10-30 min, the annealing temperature in the reverse structure is 400-450 DEG C, and the annealing time is 10-40 min.

[0013] Further, the intermediate layer Bi2O3 is prepared by dissolving bismuth nitrate in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.1-0.2 mol / L, spin coating and then annealing.

[0014] Further, the annealing temperature in the formal structure is 400-500 DEG C, and the annealing time is 20-45 min, the annealing temperature in the reverse structure is 350-450 DEG C, and the annealing time is 30-45 min.

[0015] Further, the detector further comprises a metal nanowire electrode layer on the surface of the p-i-n structure and a protective layer on the surface of the electrode layer, the metal nanowire electrode is preferably a silver nanowire electrode, and the protective layer is a gallium oxide protective layer.

[0016] The preparation method of the p-i-n structure ultraviolet detector containing the intermediate layer, comprising the preparation of a p-i-n semiconductor structure, characterized in that: TiO2 precursor solution prepared by dissolving titanium isopropylate in ethanol as a titanium source is spin-coated and annealed to form an n-type semiconductor TiO2 film, Bi2O3 precursor solution and NiO precursor solution are prepared by dissolving bismuth nitrate in ethylene glycol monomethyl ether, and the intermediate layer Bi2O3 film is formed by spin-coating and annealing, and the p-type semiconductor NiO film is formed by spin-coating and annealing after preparing NiO precursor solution by dissolving nickel acetylacetonate or nickel acetate in ethylene glycol monomethyl ether.

[0017] Further, the p-i-n semiconductor structure is divided into a formal structure and an inverse structure, the formal structure is to prepare TiO2 semiconductor film, intermediate layer Bi2O3 film and NiO semiconductor film on the surface of the substrate in sequence, and the inverse structure is to prepare NiO semiconductor film, intermediate layer Bi2O3 film and TiO2 semiconductor film on the surface of the substrate in sequence.

[0018] Further, the concentration of the n-type semiconductor TiO2 precursor solution is 0.1-0.2 mol / L, the annealing temperature for preparing the formal structure is 350-500 ℃, the annealing time is 20-45 min, the annealing temperature for preparing the inverse structure is 400-450 ℃, and the annealing time is 10-40 min.

[0019] Further, the concentration of the Bi2O3 precursor solution is 0.1-0.2 mol / L, the annealing temperature for preparing the formal structure is 400-500 ℃, the annealing time is 20-45 min, the annealing temperature for preparing the inverse structure is 350-450 ℃, and the annealing time is 30-45 min.

[0020] Further, the concentration of the p-type semiconductor NiO precursor solution is 0.15-0.45 mol / L, the annealing temperature for preparing the formal structure is 300-400 ℃, the annealing time is 10-30 min, the annealing temperature for preparing the inverse structure is 400-450 ℃, and the annealing time is 10-40 min.

[0021] In the preparation of the p-n structure composed of TiO2 and NiO, it is found that under long-term ultraviolet light, the ultraviolet light energy can cause certain photo damage to the p-n structure junction interface, which can lead to unstable detector signal and difficult to guarantee the linearity, and long-term ultraviolet energy can form more interface defects at the interface, further hindering the diffusion of photo-generated electrons to the conductive substrate or metal nanowire electrode, so that a large number of photo-generated electron-hole pairs are lost due to the diffusion.

[0022] In order to solve the above problems, the application increases a layer of Bi2O3 interpenetrating layer in the p-n structure, suppresses the interaction of semiconductor NiO and semiconductor TiO2 under the action of ultraviolet light to form interface defects, improves the ultraviolet damage resistance of the structure, thereby improving the signal stability of the detector, and since Bi2O3 is between TiO2 and NiO, a good energy level matching is formed, as a transition between the p-n structure, balances the transport of photo-generated carriers to both ends, reduces the carrier recombination, and improves the responsivity of the device.

[0023] Most specifically, the preparation method of the above-mentioned p-i-n structure ultraviolet detector containing an intermediate layer is characterized in that it comprises the following steps:

[0024] Preparation of solution:

[0025] Isopropyl titanate is dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.1-0.2 mol / L; bismuth nitrate is dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.1-0.2 mol / L; acetylacetone nickel or nickel acetate is dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.15-0.45 mol / L;

[0026] Device preparation:

[0027] The device preparation is divided into two structures, formal and reverse, the formal device structure is ITO / n-type semiconductor / Bi2O3 / p-type semiconductor / silver nanowire / oxidation protection layer, and the reverse device structure is ITO / p-type semiconductor / Bi2O3 / n-type semiconductor / silver nanowire / oxidation protection layer;

[0028] (1) Formal structure: ITO glass as substrate, spin-coating TiO2 precursor solution on the surface of ITO glass, after spin-coating, annealing at 350-500 DEG C for 20-45 min, preparing TiO2 film with a thickness of 10-40 nm; then continue to spin-coating Bi2O3 precursor solution on the surface of TiO2 film, after spin-coating, annealing at 400-500 DEG C for 20-45 min, preparing Bi2O3 film with a thickness of 10-20 nm; then spin-coating NiO precursor solution on the surface of Bi2O3 film, after spin-coating, annealing at 300-400 DEG C for 10-30 min, preparing NiO film with a thickness of 10-30 nm; spin-coating a layer of silver nanowire film with a sheet resistance of 4-20 Ω / sq on the surface of NiO film; finally, covering a mask on the surface of silver nanowire film, depositing a layer of gallium oxide protection layer by sputtering method, with a thickness of 20-60 nm;

[0029] (2) Reverse structure: taking ITO glass as a substrate base sheet, NiO precursor liquid is spin-coated on the surface of the ITO glass, after spin-coating, annealing at 300-400 DEG C for 20-45 min, NiO film with a thickness of 10-30 nm is prepared; Bi2O3 precursor liquid is spin-coated on the surface of the NiO film, after spin-coating, annealing at 350-450 DEG C for 30-45 min, Bi2O3 film with a thickness of 10-20 nm is prepared; TiO2 precursor liquid is spin-coated on the surface of the Bi2O3 film, after spin-coating, annealing at 350-450 DEG C for 10-40 min, TiO2 film with a thickness of 10-40 nm is prepared; finally, a layer of silver nanowire film is spin-coated on the surface of the TiO2 film as an electrode; a mask is covered on the surface of the silver nanowire film, and a gallium oxide protective layer with a thickness of 20-60 nm is deposited by sputtering method.

[0030] The present application has the following technical effects:

[0031] In the present application, by inserting a layer of Bi2O3 intermediate layer in the p-n structure composed of TiO2 and NiO, the anti-ultraviolet damage ability of the structure is effectively improved, and the signal stability of the detector is improved; secondly, Bi2O3 is inserted between TiO2 and NiO, the energy level matching between them is realized, the transport of photo-generated carriers to both ends is balanced, the carrier recombination is reduced, and the responsivity of the device is improved. The responsivity and external quantum efficiency (EQE) of the formal structure of the ultraviolet detector to 254 nm ultraviolet light are 162 mA W -1 and 79.09%, which are significantly higher than 71 mA W -1 and 34.78% of the p-n structure ultraviolet detector without Bi2O3 intermediate layer. The response current of the detector prepared in the present application is 0.81 mu A, which is 2.3 times of the p-n structure ultraviolet detector without Bi2O3. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 : The formal structure of the p-i-n structure ultraviolet detector with Bi2O3 as the intermediate layer in the present application is shown in the structure diagram.

[0033] Figure 2 : The reverse structure of the p-i-n structure ultraviolet detector with Bi2O3 as the intermediate layer in the present application is shown in the structure diagram.

[0034] Figure 3 : The current-time response curve comparison of the p-i-n structure ultraviolet detector with Bi2O3 intermediate layer prepared in the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer.

[0035] Figure 4The p-i-n structure ultraviolet detector prepared in Embodiment 1 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of response to different wave bands of ultraviolet light.

[0036] Figure 5 The p-i-n structure ultraviolet detector prepared in Embodiment 1 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of responsivity to different wave bands of ultraviolet light.

[0037] Figure 6 The p-i-n structure ultraviolet detector prepared in Embodiment 1 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of external quantum efficiency (EQE) to different wave bands of ultraviolet light.

[0038] Figure 7 The p-i-n structure ultraviolet detector prepared in Embodiment 2 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of current-time response curve.

[0039] Figure 8 The p-i-n structure ultraviolet detector prepared in Embodiment 2 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of response to different wave bands of ultraviolet light.

[0040] Figure 9 The p-i-n structure ultraviolet detector prepared in Embodiment 1 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of response to different wave bands of ultraviolet light.

[0041] Figure 10 The p-i-n structure ultraviolet detector prepared in Embodiment 1 of the present application and the p-n structure ultraviolet detector without Bi2O3 intermediate layer are compared in terms of responsivity to different wave bands of ultraviolet light. DETAILED DESCRIPTION

[0042] The present application will be described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application.

[0043] Embodiment 1

[0044] A preparation method of a p-i-n structure ultraviolet detector with an intermediate layer, the structure of which is formal structure, comprises the following steps:

[0045] Prepare a solution:

[0046] Isopropyl titanate is dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.17 mol / L; bismuth nitrate is dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.13 mol / L; and nickel acetate is dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.3 mol / L;

[0047] Device preparation:

[0048] The formal device structure is ITO / n-type semiconductor TiO2 / Bi2O3 / p-type semiconductor NiO / silver nanowire / oxidation protective layer, specifically, ITO glass is used as a substrate, TiO2 precursor solution is spin-coated on the surface of the ITO glass, after spin-coating, annealing is performed at 450 DEG C for 30 min to prepare a TiO2 film with a thickness of about 30 nm; then Bi2O3 precursor solution is spin-coated on the surface of the TiO2 film, after spin-coating, annealing is performed at 450 DEG C for 30 min to prepare a Bi2O3 film with a thickness of about 15 nm; then NiO precursor solution is spin-coated on the surface of the Bi2O3 film, after spin-coating, annealing is performed at 300 DEG C for 15 min to prepare a NiO film with a thickness of about 16 nm; a silver nanowire film with a sheet resistance of 6 Ω / sq is spin-coated on the surface of the NiO film; finally, a mask is placed on the surface of the silver nanowire film, and a gallium oxide protective layer with a thickness of about 50 nm is deposited by sputtering.

[0049] The structural diagram of the formal structure of the p-i-n structure ultraviolet detector in the application is shown in Figure 1 .

[0050] Figure 3 The current-time response curve comparison of the p-i-n structure ultraviolet detector with a Bi2O3 intermediate layer prepared in Example 1 and the p-n structure ultraviolet detector without a Bi2O3 intermediate layer is shown in the figure. As can be seen from the figure, the photocurrent of the p-i-n structure ultraviolet detector with a Bi2O3 intermediate layer remains constant at 0.81 μA after 1000 s under the test of ultraviolet light with a wavelength of 254 nm and a light power of 5 μW cm -2 . The photocurrent of the p-n structure ultraviolet detector without a Bi2O3 intermediate layer gradually decreases from the initial 0.36 μA to 0.32 μA after 1000 s under the same test conditions. It is shown that the p-i-n structure ultraviolet detector with a Bi2O3 intermediate layer is superior to the p-i-n structure ultraviolet detector without a Bi2O3 intermediate layer in terms of signal and response signal intensity.

[0051] Figure 4The response of the UV detector with Bi2O3 intermediate layer p-i-n structure prepared in Example 1 to different waveband UV light is compared with that of the UV detector without Bi2O3 intermediate layer p-n structure. Figures 5-6 The response of the UV detector with Bi2O3 intermediate layer p-i-n structure prepared in Example 1 to different waveband UV light is compared with that of the UV detector without Bi2O3 intermediate layer p-n structure. Figure 4 The calculated response of the UV detector with Bi2O3 intermediate layer p-i-n structure to different waveband UV light is compared with that of the UV detector without Bi2O3 intermediate layer p-n structure. The response spectrum range of the UV detector with Bi2O3 intermediate layer p-i-n structure is consistent with that of the UV detector without Bi2O3 intermediate layer p-i-n structure, i.e. the UV detector has response to short-wave UV at 254 nm and 310 nm, and has almost no response to long-wave UV at 365 nm and 420 nm, indicating that the Bi2O3 intermediate layer does not change the response range of the spectrum. In the entire spectral response range, the response and external quantum efficiency (EQE) of the UV detector with Bi2O3 intermediate layer p-i-n structure are higher than those of the UV detector without Bi2O3 intermediate layer p-n structure. For example, the response and external quantum efficiency (EQE) of the UV detector with Bi2O3 intermediate layer p-i-n structure to 254 nm UV light reach 162 mA W -1 and 79.09% respectively, which are significantly higher than 71 mA W -1 and 34.78% of the UV detector without Bi2O3 intermediate layer p-n structure.

[0052] Comparative Example 1

[0053] The preparation method of the UV detector in Example 1 is used to prepare a p-i-n structure detector with Sb2O3 instead of Bi2O3 intermediate layer, and the specific structure is ITO / n-type semiconductor TiO2 / Sb2O3 / p-type semiconductor NiO / silver nanowire / oxidation protection layer. It is found that compared with the p-n structure detector without any intermediate layer, the stability of the detector is not improved, indicating that the anti-ultraviolet damage performance is not obviously improved, and the response is not changed too much.

[0054] Comparative Example 2

[0055] The preparation method of the UV detector in Example 1 is used to prepare a UV photodetector with the structure of ITO / n-type semiconductor TiO2 / Bi2O3 / silver nanowire / oxidation protection layer by removing the p-type semiconductor NiO layer. The UV detector with NiO layer in Example 1 has a photocurrent of 0.80 μA under the test of UV light with a wavelength of 254 nm and a light power of 5 μW cm -2 , while the UV detector without NiO layer in Comparative Example 2 has a photocurrent of only 0.07 μA.

[0056] Comparative Example 3

[0057] Using the preparation method of the ultraviolet detector of Example 1, the n-type semiconductor TiO2 layer was removed, and an ultraviolet photodetector with the structure of ITO / Bi2O3 / p-type semiconductor NiO / silver nanowire / oxidation protective layer was prepared.

[0058] The ultraviolet detector containing the NiO layer in Example 1 has a photocurrent of 0.80 μA under the test of ultraviolet light with a wavelength of 254 nm and a light power of 5 μW cm -2 , while the photocurrent of the ultraviolet detector without the TiO2 layer in Comparative Example 3 is almost zero.

[0059] Comparative Examples 2 and 3 show that the introduced Bi2O3 layer cannot replace the n-type semiconductor or the p-type semiconductor and cannot form a p-n heterojunction with NiO or TiO2. The Bi2O3 layer in the present application plays a role in improving the responsivity of the p-n junction structure ultraviolet detector and the stability of the response signal under ultraviolet light.

[0060] Example 2

[0061] A preparation method of a p-i-n structure ultraviolet detector containing an intermediate layer, which has a transverse structure, comprises the following steps:

[0062] Preparation of solutions:

[0063] Isopropyl titanate is dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.1 mol / L; bismuth nitrate is dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.2 mol / L; and nickel acetylacetate is dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.4 mol / L;

[0064] Device preparation:

[0065] The transverse device structure is ITO / p-type semiconductor NiO / Bi2O3 / n-type semiconductor TiO2 / silver nanowire / oxidation protective layer. Specifically, ITO glass is used as a substrate wafer, NiO precursor solution is spin-coated on the surface of the ITO glass, and after spin-coating, the wafer is annealed at 350 ℃ for 30 min to prepare a NiO thin film with a thickness of about 30 nm; Bi2O3 precursor solution is spin-coated on the surface of the NiO thin film, and after spin-coating, the wafer is annealed at 350 ℃ for 45 min to prepare a Bi2O3 thin film with a thickness of about 10 nm; TiO2 precursor solution is spin-coated on the surface of the Bi2O3 thin film, and after spin-coating, the wafer is annealed at 350 ℃ for 20 min to prepare a TiO2 thin film with a thickness of 10 nm; finally, a silver nanowire thin film with a sheet resistance of 10 Ω / sq is spin-coated on the surface of the TiO2 thin film; a mask is placed on the surface of the silver nanowire thin film, and a gallium oxide protective layer with a thickness of about 20 nm is deposited on the mask by sputtering.

[0066] The schematic diagram of the prepared p-i-n structure ultraviolet detector reverse structure is shown in Figure 2 .

[0067] Figure 7 is the current-time response curve comparison of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer prepared in Example 2 and the p-n structure ultraviolet detector without Bi2O3 intermediate layer. As can be seen from the figure, the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer has a constant photocurrent of 0.18 μA after 1000 s under the test of ultraviolet light with a wavelength of 254 nm and a light power of 5 μW cm -2 . While the photocurrent of the p-n structure ultraviolet detector without Bi2O3 intermediate layer gradually decreases from 0.13 μA to 0.10 μA after 1000 s under the same test conditions. It shows that the stability and response signal intensity of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer in the reverse structure are also better than those of the p-i-n structure ultraviolet detector without Bi2O3 intermediate layer.

[0068] Figure 8 is the response comparison of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer prepared in Example 2 and the p-n structure ultraviolet detector without Bi2O3 intermediate layer to different waveband ultraviolet light. Figures 9-10 is the calculated response of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer and the p-n structure ultraviolet detector without Bi2O3 intermediate layer to different waveband ultraviolet light. Figure 8 The responsivity and external quantum efficiency (EQE) of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer are higher than those of the p-n structure ultraviolet detector without Bi2O3 intermediate layer. For example, the responsivity and external quantum efficiency (EQE) of the p-i-n structure ultraviolet detector containing Bi2O3 intermediate layer to 310 nm ultraviolet light reach 87.0 mA W -1 and 34.80%, which are significantly higher than 32.3 mA W -1 and 12.92% of the p-n structure ultraviolet detector without Bi2O3 intermediate layer.

[0069] Example 3

[0070] A preparation method of a p-i-n structure ultraviolet detector containing an intermediate layer, the structure of which is a formal structure, comprising the following steps:

[0071] Solution preparation

[0072] Isopropyl titanate was dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.1 mol / L; bismuth nitrate was dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.2 mol / L; nickel acetylacetone was dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.45 mol / L.

[0073] Device fabrication:

[0074] The formal device structure is ITO / n-type semiconductor TiO2 / Bi2O3 / p-type semiconductor NiO / silver nanowires / oxide protective layer. Specifically, ITO glass is used as the substrate. TiO2 precursor solution is spin-coated onto the surface of the ITO glass. After spin-coating, it is annealed at 500 °C for 20 min to prepare a TiO2 film with a thickness of 10 nm. Then, Bi2O3 precursor solution is spin-coated onto the TiO2 film. After spin-coating, it is annealed at 400 °C for 45 min to prepare a Bi2O3 film with a thickness of 20 nm. Next, NiO precursor solution is spin-coated onto the Bi2O3 film. After spin-coating, it is annealed at 400 °C for 30 min to prepare a NiO film with a thickness of 30 nm. A silver nanowire film with a sheet resistance of 4 Ω / sq is spin-coated onto the NiO film. Finally, a mask is placed on the surface of the silver nanowire film, and a gallium oxide protective layer with a thickness of about 60 nm is deposited by sputtering.

[0075] The ultraviolet detector prepared in this embodiment has an optical power of 5 μW cm⁻¹ at a wavelength of 254 nm. -2 Under ultraviolet light testing, the photocurrent remained constant at 0.76 μA after 1000 s, and its responsivity to 254 nm ultraviolet light and external quantum efficiency (EQE) reached 152 mA W. -1 And 74.20%.

[0076] Example 4

[0077] A method for fabricating a pin-structured ultraviolet detector with an intermediate layer, the structure of which is a formal structure, includes the following steps:

[0078] Solution preparation:

[0079] Isopropyl titanate was dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.2 mol / L; bismuth nitrate was dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.1 mol / L; nickel acetate was dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.15 mol / L.

[0080] Device fabrication:

[0081] The formal device structure is ITO / n-type semiconductor TiO2 / Bi2O3 / p-type semiconductor NiO / silver nanowire / oxidation protective layer, specifically, ITO glass is used as a substrate, TiO2 precursor solution is spin-coated on the surface of the ITO glass, and after spin-coating, the TiO2 film with a thickness of 40 nm is prepared by annealing at 350 ℃ for 45 min; then Bi2O3 precursor solution is spin-coated on the surface of the TiO2 film, and after spin-coating, the Bi2O3 film with a thickness of 10 nm is prepared by annealing at 500 ℃ for 20 min; then NiO precursor solution is spin-coated on the surface of the Bi2O3 film, and after spin-coating, the NiO film with a thickness of 10 nm is prepared by annealing at 350 ℃ for 10 min; a silver nanowire film with a sheet resistance of 20 Ω / sq is spin-coated on the surface of the NiO film; finally, a mask is covered on the surface of the silver nanowire film, and a 40 nm thick gallium oxide protective layer is deposited on the surface of the silver nanowire film by sputtering.

[0082] The ultraviolet detector prepared in this embodiment has a constant photocurrent of 0.74 μA after 1000 s under the test of 5 μW cm -2 of ultraviolet light with a wavelength of 254 nm and a light power, and the responsivity and external quantum efficiency (EQE) of the ultraviolet detector to 254 nm ultraviolet light reach 148 mA W -1 and 72.25%, respectively.

[0083] Example 5

[0084] A preparation method of a p-i-n structure ultraviolet detector containing an intermediate layer, the structure of which is a reverse structure, comprising the following steps:

[0085] Solution preparation:

[0086] Isopropyl titanate is dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.2 mol / L; bismuth nitrate is dissolved in ethylene glycol methyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.1 mol / L; and nickel acetate is dissolved in ethylene glycol methyl ether to prepare a NiO precursor solution with a concentration of 0.15 mol / L;

[0087] Device preparation:

[0088] The trans device structure is ITO / p-type semiconductor NiO / Bi2O3 / n-type semiconductor TiO2 / silver nanowire / oxidation protective layer, specifically, ITO glass is used as a substrate sheet, NiO precursor solution is spin-coated on the surface of the ITO glass, after spin-coating, the NiO film with a thickness of 10 nm is prepared by annealing at 300 DEG C for 45 min; Bi2O3 precursor solution is spin-coated on the surface of the NiO film, after spin-coating, the Bi2O3 film with a thickness of 20 nm is prepared by annealing at 450 DEG C for 30 min; TiO2 precursor solution is spin-coated on the surface of the Bi2O3 film, after spin-coating, the TiO2 film with a thickness of 40 nm is prepared by annealing at 400 DEG C for 40 min; finally, a silver nanowire film with a sheet resistance of 4 Ω / sq is spin-coated on the surface of the TiO2 film; a mask is covered on the surface of the silver nanowire film, and a gallium oxide protective layer is deposited on the surface of the silver nanowire film by sputtering.

[0089] The ultraviolet detector prepared in the embodiment is tested under 5 μW cm-2 of ultraviolet light with a wavelength of 254 nm, and after 1000 s, the photocurrent is constantly kept at 0.14 μA, the responsivity and the external quantum efficiency (EQE) of the ultraviolet detector to 310 nm ultraviolet light are 68 mA W-1 and 27.07%, respectively. -2 -1

[0090] Embodiment 6

[0091] A preparation method of a p-i-n structure ultraviolet detector containing an intermediate layer, the structure of which is a trans structure, comprising the following steps:

[0092] Solution preparation:

[0093] Isopropyl titanate is dissolved in ethanol to prepare TiO2 precursor solution with a concentration of 0.17 mol / L; bismuth nitrate is dissolved in ethylene glycol methyl ether to prepare Bi2O3 precursor solution with a concentration of 0.13 mol / L; and nickel acetylacetate is dissolved in ethylene glycol methyl ether to prepare NiO precursor solution with a concentration of 0.35 mol / L;

[0094] Device preparation:

[0095] ​​The structure of the trans-device is ITO / p-type semiconductor NiO / Bi2O3 / n-type semiconductor TiO2 / silver nanowire / oxidation protective layer. Specifically, ITO glass is used as a substrate, NiO precursor solution is spin-coated on the surface of the ITO glass, and after spin-coating, the ITO glass is annealed at 400 DEG C for 20 min to prepare a NiO film with a thickness of 20 nm; Bi2O3 precursor solution is spin-coated on the surface of the NiO film, and after spin-coating, the ITO glass is annealed at 400 DEG C for 40 min to prepare a Bi2O3 film with a thickness of 15 nm; TiO2 precursor solution is spin-coated on the surface of the Bi2O3 film, and after spin-coating, the ITO glass is annealed at 450 DEG C for 10 min to prepare a TiO2 film with a thickness of 30 nm; finally, a silver nanowire film with a sheet resistance of 20 Ω / sq is spin-coated on the surface of the TiO2 film; a mask is placed on the surface of the silver nanowire film, and a 30 nm thick gallium oxide protective layer is deposited on the surface of the silver nanowire film by sputtering.

[0096] The ultraviolet detector prepared in the embodiment is tested under 5 μW cm -2 of 254 nm wavelength ultraviolet light, and after 1000 s, the photocurrent is constantly kept at 0.16 μA, and the responsivity and external quantum efficiency (EQE) of the ultraviolet detector to 310 nm ultraviolet light are 84 mA W -1 and 33.60%, respectively.

Claims

1. An ultraviolet detector, characterized by: The detector comprises a p-i-n structure formed by a p-type semiconductor, an intermediate layer and an n-type semiconductor, the p-type semiconductor is NiO, the n-type semiconductor is TiO2, and the intermediate layer is Bi2O3.

2. An ultraviolet detector as claimed in claim 1, characterized in that: The semiconductor structure in the detector is a formal structure or an inverse structure, the formal structure is an n-type semiconductor / Bi2O3 / p-type semiconductor from bottom to top, and the inverse structure is a p-type semiconductor / Bi2O3 / n-type semiconductor from bottom to top, wherein the n-type semiconductor TiO2, the p-type semiconductor NiO and the intermediate layer Bi2O3 are all in a film layer structure, and the thickness ratio is 1-4:1-3:1-2.

3. An ultraviolet detector as claimed in claim 1 or 2, characterized in that: The detector further comprises a metal nanowire electrode layer on the surface of the p-i-n structure and a protective layer on the surface of the electrode layer, the metal nanowire electrode is a silver nanowire electrode, and the protective layer is a gallium oxide protective layer.

4. A method for producing an ultraviolet detector as claimed in claim 1 or 2, comprising a method for producing a p-i-n semiconductor structure, characterized by: TiO2 precursor solution prepared by dissolving isopropyl titanate in ethanol is used to spin-coat and anneal to form an n-type semiconductor TiO2 film, Bi2O3 precursor solution prepared by dissolving bismuth nitrate in ethylene glycol dimethyl ether is used to spin-coat and anneal to form an intermediate layer Bi2O3 film, and NiO precursor solution prepared by dissolving nickel acetylacetonate or nickel acetate in ethylene glycol dimethyl ether is used to spin-coat and anneal to form a p-type semiconductor NiO film.

5. The method for fabricating an ultraviolet detector as described in claim 4, characterized in that: The p-i-n semiconductor structure is a formal structure or an inverse structure, the formal structure is prepared by sequentially preparing a TiO2 semiconductor film, an intermediate layer Bi2O3 film and a NiO semiconductor film on the surface of a substrate, and the inverse structure is prepared by sequentially preparing a NiO semiconductor film, an intermediate layer Bi2O3 film and a TiO2 semiconductor film on the surface of a substrate.

6. A method of fabricating an ultraviolet detector as claimed in claim 4 or 5, wherein: The concentration of the n-type semiconductor TiO2 precursor solution is 0.1-0.2 mol / L, the annealing temperature for preparing the formal structure is 350-500 ℃, and the annealing time is 20-45 min, and the annealing temperature for preparing the inverse structure is 350-450 ℃, and the annealing time is 10-40 min.

7. The method for fabricating an ultraviolet detector as described in claim 6, characterized in that: The concentration of the Bi2O3 precursor solution is 0.1-0.2 mol / L, the annealing temperature for preparing the formal structure is 400-500 ℃, and the annealing time is 20-45 min, and the annealing temperature for preparing the inverse structure is 350-450 ℃, and the annealing time is 30-45 min.

8. The method for fabricating an ultraviolet detector as described in claim 7, characterized in that: The concentration of the p-type semiconductor NiO precursor solution is 0.15-0.45 mol / L, the annealing temperature for preparing the formal structure is 300-400 ℃, and the annealing time is 10-30 min, and the annealing temperature for preparing the inverse structure is 400-450 ℃, and the annealing time is 10-40 min.

9. A method of manufacturing an ultraviolet detector, characterized by, The method comprises the following steps: Preparation of solutions: Isopropyl titanate is dissolved in ethanol to prepare a TiO2 precursor solution with a concentration of 0.1-0.2 mol / L, bismuth nitrate is dissolved in ethylene glycol dimethyl ether to prepare a Bi2O3 precursor solution with a concentration of 0.1-0.2 mol / L, and nickel acetylacetonate or nickel acetate is dissolved in ethylene glycol dimethyl ether to prepare a NiO precursor solution with a concentration of 0.15-0.45 mol / L; Device preparation: The device is prepared as a formal or reverse structure, the formal device structure is ITO / n-type semiconductor / Bi2O3 / p-type semiconductor / silver nanowire / oxidation protective layer, and the reverse device structure is ITO / p-type semiconductor / Bi2O3 / n-type semiconductor / silver nanowire / oxidation protective layer; (1) formal structure: ITO glass is used as a substrate, TiO2 precursor solution is spin-coated on the surface of the ITO glass, after spin-coating, annealing is performed at 350-500 DEG C for 20-45 min, a TiO2 film with a thickness of 10-40 nm is prepared; then Bi2O3 precursor solution is spin-coated on the surface of the TiO2 film, after spin-coating, annealing is performed at 400-500 DEG C for 20-45 min, a Bi2O3 film with a thickness of 10-20 nm is prepared; then NiO precursor solution is spin-coated on the surface of the Bi2O3 film, after spin-coating, annealing is performed at 300-400 DEG C for 10-30 min, a NiO film with a thickness of 10-30 nm is prepared; a silver nanowire film with a sheet resistance of 4-20 Ω / sq is spin-coated on the surface of the NiO film; finally, a mask is covered on the surface of the silver nanowire film, and a layer of gallium oxide protective layer is deposited by sputtering method; (2) reverse structure: ITO glass is used as a substrate, NiO precursor solution is spin-coated on the surface of the ITO glass, after spin-coating, annealing is performed at 300-400 DEG C for 20-45 min, a NiO film with a thickness of 10-30 nm is prepared; Bi2O3 precursor solution is spin-coated on the surface of the NiO film, after spin-coating, annealing is performed at 350-450 DEG C for 30-45 min, a Bi2O3 film with a thickness of 10-20 nm is prepared; then TiO2 precursor solution is spin-coated on the surface of the Bi2O3 film, after spin-coating, annealing is performed at 350-450 DEG C for 10-40 min, a TiO2 film with a thickness of 10-40 nm is prepared; finally, a silver nanowire film is spin-coated on the surface of the TiO2 film as an electrode; a mask is covered on the surface of the silver nanowire film, and a layer of gallium oxide protective layer is deposited by sputtering method.

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