AlQDs (at) Ga2O3 solar blind photoelectric detector based on quantum size effect, preparation method and application

Abstract

The invention discloses an AlQDs (at) Ga2O3 solar blind photoelectric detector based on a quantum size effect, a preparation method and application, and belongs to the technical field of photoelectric detection. The solar blind photoelectric detector comprises a substrate, a Ga2O3 layer, a quantum dot material layer and an electrode, the Ga2O3 layer is arranged on the surface of the substrate, and the quantum dot material layer is arranged on the surface of the Ga2O3 layer and incompletely covers the Ga2O3 layer; the electrodes comprise an electrode I and an electrode II; the electrode I and the electrode II are arranged on the Ga2O3 layer or the quantum dot material layer; the electrode I and the electrode II are not positioned on the same material layer at the same time; and the quantum dot material layer comprises aluminum quantum dots (AlQDs). According to the invention, the solar blind detector is prepared by combining AlQDs with continuously adjustable optical band gaps in the solar blind band and Ga2O3 with adaptive band gap values in the solar blind band, and the detector has excellent wavelength selectivity, provides a new idea for high-resolution single-pixel imaging, ultra-low power consumption remote sensing and ultraviolet multispectral photoelectric detection application, and has wide application prospects. Meanwhile, the method can be used for deep ultraviolet anti-interference imaging.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detection, and in particular relates to an AlQDs@Ga2O3 solar-blind photoelectric detector based on quantum size effect, a preparation method and an application thereof. Background Art

[0002] Due to the strong absorption of UVC band ultraviolet radiation by the ozone layer in the atmosphere, photons in this band are usually unable to penetrate the atmosphere, so it is called the solar blind zone. This feature ensures that deep ultraviolet solar blind detection is free from interference from the background of sunlight, and has outstanding advantages such as high precision and high signal-to-noise ratio. Therefore, solar blind ultraviolet photodetectors are indispensable key components in civil fields such as sterilization, water purification, environmental monitoring and ultraviolet curing technology, scientific research fields such as medicine and biology, and military fields such as battlefield covert communications.

[0003] Commercial UV detection mainly relies on photomultiplier tubes or UV-enhanced silicon photodiodes, but these technologies are limited by low-temperature operation requirements, high power consumption, low sensitivity, and the need for optical filtering systems. Third-generation wide-bandgap semiconductors (WBS), such as AlN, GaN, SiC, Ga2O3, ZnO, and diamond, offer a promising alternative for deep UV detection due to their stability, high thermal conductivity, and suitable cutoff wavelengths. Among them, monoclinic gallium oxide (β-Ga2O3) has been widely studied; however, high dark current and slow response time caused by neutral oxygen vacancy photoionization limit its performance. To overcome these problems, epitaxial semiconductor films, organic conducting polymers, and transition metal dichalcogenides (TMDs) have been used for heterojunction fabrication. However, these approaches still encounter obstacles, including complex manufacturing processes, large dark current density, and poor spectral selectivity. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides an AlQDs@Ga2O3 solar-blind photodetector based on quantum size effect, a preparation method and application. The present invention prepares AlQDs with continuously adjustable optical band gap in the solar-blind band, and combines it with Ga2O3 with a matching band gap value in the solar-blind band to prepare an AlQDs@Ga2O3 heterojunction solar-blind detector, and utilizes the ultra-narrow-band optical response of the detector in the solar-blind band to realize its deep ultraviolet anti-interference imaging application, and further realizes the preparation of AlQDs of different particle sizes by changing the relative molar ratio of the metal precursor and the reducing agent, and utilizes the quantum confinement effect to realize the continuous adjustable optical band gap in the deep ultraviolet solar-blind band, and realizes the preparation of a heterojunction with a cascaded energy band structure distribution. The ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on the quantum size effect prepared by the present invention provides a new idea for high-resolution single-pixel imaging, ultra-low power remote sensing and ultraviolet multi-spectral photoelectric detection applications.

[0005] The technical solution of the present invention is as follows:

[0006] The first aspect of the present invention provides an ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on quantum size effect, comprising a substrate, a Ga2O3 layer, a quantum dot material layer, and an electrode; the Ga2O3 layer is arranged on the surface of the substrate, the quantum dot material layer is arranged on the surface of the Ga2O3 layer, and does not completely cover the Ga2O3 layer; the electrode comprises electrode I and electrode II; the electrode I and the electrode II are arranged on the Ga2O3 layer or the quantum dot material layer, and the electrode I and the electrode II are not located in the same material layer; the quantum dot material layer comprises AlQDs quantum dots.

[0007] Preferably, the Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; and the quantum dot material layer includes at least one layer of quantum dot material layer.

[0008] Preferably, the quantum dot material layer comprises two or more layers of AlQDs quantum dot material layers having different particle sizes.

[0009] Preferably, the electrode I includes at least one of a Ti electrode and an Au electrode; the electrode II includes at least one of a Ti electrode and an Au electrode.

[0010] The second aspect of the present invention provides a method for preparing the AlQDs@Ga2O3 heterojunction solar-blind photodetector described in the first aspect, comprising the following steps:

[0011] S1: Prepare colloidal AlQDs solution and prepare substrate containing Ga2O3 layer.

[0012] S2: depositing the colloidal AlQDs solution layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer to form an AlQDs@Ga2O3 heterojunction, thereby obtaining a material containing the Ga2O3 layer and the AlQDs layer.

[0013] S3: Electrode I and electrode II are deposited on the Ga2O3 layer and the AlQDs layer respectively by mask evaporation to obtain an AlQDs@Ga2O3 heterojunction solar-blind photodetector.

[0014] In step S2, the AlQDs layer partially covers the Ga2O3 layer.

[0015] Preferably, in step S1, the concentration of the colloidal AlQDs solution is 10-20 mg / mL.

[0016] Preferably, in step S1, the preparation method of the colloidal AlQDs solution is:

[0017] S1-1: Aluminum halide and surfactant are added to solvent I, and the solution is ultrasonicated to change from light yellow to colorless to obtain a precursor solution.

[0018] S1-2: The precursor solution is degassed with argon, heated under anhydrous and oxygen-free conditions, and then the reducing agent solution is added and stirred for reaction. Solvent II is then added and stirred for 5 minutes. The white precipitate is removed by centrifugation, and solvent I is removed by rotary evaporation of the supernatant to obtain crude AlQDs. Solvent III is added and ultrasonically dispersed to obtain a colloidal AlQDs solution.

[0019] Preferably, in step S1-1, the aluminum halide includes at least one of aluminum chloride and aluminum bromide.

[0020] The surfactant includes a quaternary ammonium cationic surfactant; preferably, the surfactant includes at least one of tetraoctylammonium bromide, tetramethylammonium fluoride, and dialkyldimethylammonium chloride; the molar ratio of the aluminum halide to the surfactant is 1:1-32; and the solvent I includes at least one of anhydrous xylene and oleylamine.

[0021] Preferably, in step S1-2, the heating refers to heating to 110-120°C; the reducing agent solution is lithium aluminum hydride solution or ammonia ethanol solution; the reducing agent solution is 2M; the adding rate of the reducing agent solution is 1-4mL / h; the molar ratio of the aluminum halide to the reducing agent is 2:1-1:4; the stirring reaction speed is 700-900r / min, the reaction temperature is 110-130°C, and the time is 3-8h; preferably, the stirring reaction is carried out under the protection of an argon atmosphere; the solvent II includes methanol; the solvent III includes at least one of ethanol and dimethylformamide.

[0022] Preferably, in step S2, the Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; the colloidal AlQDs solution is deposited layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer, and the colloidal AlQDs solution is spin-coated on a portion of the surface of the Ga2O3 substrate, annealed, and repeatedly spin-coated and annealed to form a multilayer AlQDs layer; the number of repetitions is greater than or equal to 0; the spin coating is first at 500 rpm for 10 s, and then at 2000 rpm for 30 s; the annealing temperature is 90°C and the time is 10 min.

[0023] Preferably, in step S3, the electrode I is arranged on the surface of AlQDs; the electrode II is arranged on the Ga2O3 surface not coated with the AlQDs solution; the electrode I includes at least one of a Ti electrode and an Au electrode; the electrode II includes at least one of a Ti electrode and an Au electrode; the electrode materials of the electrode I and the electrode II are the same or different.

[0024] The third aspect of the present invention provides an imaging device, comprising the ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on the quantum size effect as described in the first aspect above or the AlQDs@Ga2O3 heterojunction solar-blind photodetector prepared by the preparation method as described in the second aspect above.

[0025] The beneficial technical effects of the present invention are:

[0026] (1) The AlQDs quantum dot material with continuously adjustable optical band gap prepared by the present invention can be combined with Ga2O3, especially β-Ga2O3, to prepare a heterojunction solar-blind detector with ultra-narrow-band response in the deep ultraviolet band through characteristic absorption of the deep ultraviolet solar-blind light band, which is conducive to its wide application in the field of solar-blind band feature recognition.

[0027] (2) The present invention further realizes the preparation of AlQDs of different particle sizes by changing the relative molar ratio of the metal precursor and the reducing agent, and utilizes the quantum confinement effect to achieve continuous adjustment of the optical band gap in the deep ultraviolet solar-blind band, which helps to realize the preparation of a heterojunction with a cascaded energy band structure distribution.

[0028] (3) Compared with the current photodetector structure with a cascade structure mainly used in the mid-infrared band, the present invention innovatively utilizes the quantum confinement effect of quantum dots to prepare a cascade heterojunction solar-blind photodetector. Due to its cascaded band structure arrangement and the existence of a built-in electric field, the dark current of the device is effectively suppressed to achieve ultra-sensitive photodetection. At the same time, its narrow-band response in the solar-blind band can be used to achieve anti-interference deep ultraviolet solar-blind imaging.

[0029] (4) The synthesis route of AlQDs quantum dots of the present invention has the advantages of simple and easy raw materials, simple and easy reaction conditions, simple operation and high product quality. The prepared heterojunction solar-blind ultraviolet photodetector with cascaded energy band structure has excellent anti-interference solar-blind imaging capability and has broad application prospects in ultraviolet missile early warning, ground-based air defense and battlefield non-line-of-sight optical communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Transmission electron micrographs of colloidal aluminum quantum dots with different size distributions prepared in Examples 1-5 of the present invention, wherein the quantum dots prepared when the relative molar ratios of the precursor and the reducing agent are 1:0.5, 1:1, 1:2, 1:3, and 1:4 are marked as AlQDs-0.5, AlQDs-1, AlQDs-2, AlQDs-3, and AlQDs-4, respectively.

[0031] In the figure: a, TEM image of AlQDs-0.5; b, ACTEM image corresponding to AlQDs-0.5; c, TEM image of AlQDs-1; d, ACTEM image corresponding to AlQDs-1; e, TEM image of AlQDs-2; f, ACTEM image corresponding to AlQDs-2; g, TEM image of AlQDs-3; h, ACTEM image corresponding to AlQDs-3; i, TEM image of AlQDs-4; j, ACTEM image corresponding to AlQDs-4.

[0032] Figure 2 Ultraviolet absorption spectra and fluorescence emission spectra of colloidal aluminum quantum dots with different size distributions prepared in Examples 1-5 of the present invention.

[0033] In the figure: a, UV absorption spectrum; b, fluorescence emission spectrum.

[0034] Figure 3 The IV diagram and It diagram of the AlQDs@β-Ga2O3 heterojunction solar-blind photodetector with a cascaded energy band structure prepared in Example 6 of the present invention, as well as a comparison diagram between Example 6 and Example 7.

[0035] In the figure: a is the It comparison diagram of the detector of Example 6; b is the IV diagram of Example 6; c is the comparison diagram of Example 6 and Example 7.

[0036] Figure 4 Ultra-sensitive solar-blind imaging diagram of the cascaded energy band structure AlQDs@β-Ga2O3 heterojunction solar-blind photodetector prepared in Example 6 of the present invention at different light power densities.

[0037] In the figure: (1) is 23nW / cm 2 ; (2) 1.2 μW / cm 2 ; (3) 60μW / cm 2 ; (4) 233 μW / cm 2 ; (5) 6.0 mW / cm 2 .

[0038] Figure 5 The AlQDs@β-Ga2O3 heterojunction solar-blind photodetector with cascaded energy band structure prepared in Example 6 of the present invention corresponds to Figure 4The corresponding photocurrent under different light power densities.

[0039] Figure 6 Anti-interference solar-blind imaging tests of the cascaded band structure AlQDs@β-Ga2O3 heterojunction solar-blind photodetector prepared in Example 6 of the present invention and a commercial silicon detector under different mixed light sources.

[0040] In the figure: a. Solar-blind imaging of the solar-blind photodetector with a cascade energy band structure prepared in Example 6 under different mixed light sources, b. Solar-blind imaging of a commercial silicon detector under different mixed light sources.

[0041] Figure 7 This is a schematic structural diagram of the cascaded energy band structure AlQDs@β-Ga2O3 heterojunction solar-blind photodetector prepared by the present invention.

[0042] In the figure: 1, substrate; 2, Ga2O3 layer; 3, first colloidal AlQDs layer; 4, second colloidal AlQDs layer; 5, electrode. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0044] Based on the problems of the existing technology, it is urgent to provide a new solar-blind detector that can suppress dark current and achieve ultra-sensitive photodetection. The confinement of charge carriers (holes and electrons) in III-V quantum dots (QDs) in three dimensions leads to a strong quantum confinement effect. Compared with bulk materials, they have low-cost solution processing, bandgap regulation through size control, surface chemical engineering and metal co-doping, and high stress and strain resistance, making them easy to integrate into crystalline substrates or flexible substrates. At the same time, improving the external quantum dot efficiency (EQE) of the detector through system band engineering can achieve better photoelectric conversion and suppress the dark current (I d ) to further improve the sensitivity of the device. Therefore, the present invention provides an ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on quantum size effect and its preparation method and application.

[0045] The first aspect of the present invention provides an ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on quantum size effect, such as Figure 7 As shown, it includes a substrate 1, a Ga2O3 layer 2, a quantum dot material layer, and an electrode 5. The quantum dot material layer has one or more layers. For example, Figure 7As shown, it includes a first layer of colloidal AlQDs 3 and a second layer of colloidal AlQDs 4; the Ga2O3 layer is arranged on the surface of the substrate 1, and the quantum dot material layer is arranged on the surface of the Ga2O3 layer 2 and does not completely cover the Ga2O3 layer 2; the electrode 5 includes electrode I and electrode II.

[0046] In some embodiments, the electrode I and the electrode II are disposed in a Ga2O3 layer or a quantum dot material layer; and the electrode I and the electrode II are not located in the same material layer at the same time.

[0047] In some embodiments, the electrode I and the electrode II are disposed on the Ga2O3 layer, and the electrode II is disposed on the Ga2O3 layer; and the quantum dot material layer includes AlQDs quantum dots.

[0048] It can be understood that the present invention combines AlQDs with continuously adjustable optical band gap with Ga2O3, especially β-Ga2O3, and prepares a heterojunction solar-blind detector with ultra-narrow-band response in the deep ultraviolet band through characteristic absorption of the deep ultraviolet solar-blind light band.

[0049] In some embodiments, the Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; preferably β-Ga2O3. The quantum dot material layer is disposed on the entire or partial surface of the Ga2O3 layer; the quantum dot material layer includes at least one quantum dot material layer; preferably, the quantum dot material layer includes more than two layers of AlQDs quantum dot material layers with different particle sizes. Among them, quantum dot materials with different particle sizes can be achieved by changing the ratio of the metal precursor to the reducing agent.

[0050] It is understandable that when the quantum dot material layer includes 2 or more layers of AlQDs quantum dot layers with different particle sizes (constructing AlQDs quantum dots with different band gaps), a cascade structure of energy band arrangement can be formed, which promotes the effective separation of photogenerated carriers through the Fermi level difference, resulting in energy band bending and the formation of a built-in electric field. The built-in electric field promotes the transmission of photogenerated electrons from the Ga2O3 side to the gradient AlQDs side, while suppressing radiative recombination, thereby improving the light detection efficiency and extending the carrier diffusion length. In addition, the band offset between different layers reduces electron tunneling, helps to suppress dark current, and achieves ultra-sensitive photodetection.

[0051] It can be understood that the cascade heterojunction solar-blind photodetector prepared by the present invention using the quantum confinement effect of quantum dots, due to its cascaded energy band structure arrangement and the existence of the built-in electric field, the dark current of the device is effectively suppressed to achieve ultra-sensitive photodetection, and at the same time, the narrow-band response of its solar-blind band can be used to achieve the application of anti-interference deep ultraviolet solar-blind imaging. The prepared heterojunction solar-blind ultraviolet photodetector has excellent anti-interference solar-blind imaging capabilities and has broad application prospects in ultraviolet missile early warning, ground-based air defense, and battlefield non-line-of-sight optical communications.

[0052] The electrode I includes at least one of a Ti electrode and an Au electrode; the electrode II includes at least one of a Ti electrode and an Au electrode.

[0053] The second aspect of the present invention provides a method for preparing the AlQDs@Ga2O3 heterojunction solar-blind photodetector described in the first aspect, comprising the following steps:

[0054] S1: Prepare colloidal AlQDs solution and prepare substrate containing Ga2O3 layer.

[0055] S2: depositing the colloidal AlQDs solution layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer to form an AlQDs@Ga2O3 heterojunction, thereby obtaining a material containing the Ga2O3 layer and the AlQDs layer.

[0056] S3: Electrode I and electrode II are deposited on the Ga2O3 layer and the AlQDs layer respectively by mask evaporation to obtain an AlQDs@Ga2O3 heterojunction solar-blind photodetector.

[0057] In some embodiments, in step S1, the concentration of the colloidal AlQDs solution is 10-20 mg / mL.

[0058] In some embodiments, in step S1, the colloidal AlQDs solution is prepared by:

[0059] S1-1: Aluminum halide and surfactant are added to solvent I, and the solution is ultrasonicated to change from light yellow to colorless to obtain a precursor solution.

[0060] S1-2: The precursor solution is degassed with argon, heated under anhydrous and oxygen-free conditions, and then the reducing agent solution is added and stirred for reaction. Solvent II is then added and stirred for 5 minutes. The white precipitate is removed by centrifugation, and solvent I is removed by rotary evaporation of the supernatant to obtain crude AlQDs. Solvent III is added and ultrasonically dispersed to obtain a colloidal AlQDs solution.

[0061] In some embodiments, in step S1-1, the aluminum halide includes at least one of aluminum chloride and aluminum bromide; the surfactant includes a quaternary ammonium cationic surfactant. Preferably, the surfactant includes at least one of n-tetraoctylammonium bromide, tetramethylammonium fluoride, and dialkyldimethylammonium chloride.

[0062] In some embodiments, the molar ratio of the aluminum halide to the surfactant is 1:1-3; and the solvent I includes at least one of anhydrous xylene and oleylamine.

[0063] In some embodiments, in step S1-2, the heating refers to heating to 110-120°C.

[0064] It is understandable that if the heating temperature is too high, it will exceed the boiling point of the solvent, and if the heating temperature is too low, it will affect the quality of the crystallization.

[0065] In some embodiments, in step S1-2, the reducing agent solution is ethanolamine or lithium aluminum hydride solution, preferably lithium aluminum hydride solution; the reducing agent solution concentration is 2M; the adding rate of the reducing agent solution is 1-4mL / h; the molar ratio of the aluminum halide to the reducing agent is 2:1-1:4. The molar volume ratio of the aluminum chloride to the solvent I is 1 mol:100mL.

[0066] It can be understood that the present invention realizes the preparation of AlQDs of different particle sizes by changing the relative molar ratio of the metal precursor and the reducing agent, and utilizes the quantum confinement effect to realize the continuous adjustment of its optical band gap in the deep ultraviolet solar-blind band, which helps to realize the preparation of a heterojunction with a cascaded energy band structure distribution.

[0067] In some embodiments, in step S1-2, the stirring reaction speed is 700-900 r / min, the reaction temperature is 110-120° C., and the time is 3-8 h; preferably, the stirring reaction is carried out under the protection of an argon atmosphere.

[0068] In some embodiments, in step S1-2, the solvent I includes at least one of xylene and oleylamine; the solvent II includes methanol; and the solvent III includes at least one of ethanol and dimethylformamide.

[0069] In some embodiments, in step S2, the Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; preferably β-Ga2O3.

[0070] In some embodiments, the colloidal AlQDs solution is deposited layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer by spin coating the colloidal AlQDs solution on a portion of the surface of the Ga2O3 substrate, annealing, repeating the spin coating, and annealing to form a multilayer AlQDs layer; the number of repetitions is greater than or equal to 0.

[0071] In some embodiments, the spin coating is first performed at 500 rpm for 10 s, and then at 2000 rpm for 30 s.

[0072] In some embodiments, the annealing temperature is 90° C. and the time is 10 min.

[0073] In some embodiments, in step S3, depositing electrode I and electrode II on the Ga2O3 layer and the AlQDs layer respectively by mask evaporation includes depositing electrode I on the Ga2O3 layer and electrode II on the AlQDs layer, or depositing electrode I on the AlQDs layer and electrode II on the Ga2O3 layer.

[0074] In some embodiments, in step S3, the electrode I is disposed on the surface of the AlQDs; and the electrode II is disposed on the Ga2O3 surface that is not coated with the AlQDs solution.

[0075] The electrode I includes at least one of a Ti electrode and an Au electrode; the electrode II includes at least one of a Ti electrode and an Au electrode; the electrode materials of the electrode I and the electrode II are the same or different.

[0076] In some embodiments, the layer thickness of the electrode I is 10 nm; and the layer thickness of the electrode II is 100 nm.

[0077] The third aspect of the present invention provides an imaging device, comprising the ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on the quantum size effect as described in the first aspect above or the AlQDs@Ga2O3 heterojunction solar-blind photodetector prepared by the preparation method as described in the second aspect above.

[0078] It is understandable that in the embodiments of the present invention, before the experiment begins, all glassware used must be placed in an oven for high-temperature drying to remove moisture, and then naturally cooled to room temperature before use.

[0079] The present invention will be further described below by way of examples and the like.

[0080] Embodiment 1:

[0081] A colloidal AlQDs with continuously adjustable optical band gap, the synthesis method of which comprises the following steps:

[0082] (1) Using an electronic analytical balance, 2 mmol of tetraoctylammonium bromide and 1 mmol of aluminum chloride were weighed and added to 100 mL of anhydrous xylene for ultrasonic dispersion. The color of the solution gradually changed from light yellow to a clear, transparent, colorless solution to obtain the precursor solution required for the reaction.

[0083] (2) The prepared precursor solution was transferred to a double-row tube reaction system for dehydration and deoxygenation, and then the reaction system was degassed with argon for 20 minutes; the degassed solution was gradually heated to 120° C., and then a microfluidic injection pump was used to slowly add lithium aluminum hydride solution to the solution at a rate of 1 mL / h, so that the molar ratio of aluminum chloride to lithium aluminum hydride was 1:1.

[0084] (3) After the injection of the reducing agent lithium aluminum hydride solution was completed, the reaction solution was continued to be magnetically stirred at 800 r / min at a high temperature of 120° C. for 4 hours. The entire experiment was carried out under the protection of an argon atmosphere.

[0085] (4) Add 3 mL of low-temperature methanol solvent to step (3) to destroy the reverse micelle synthesis system, and then add 10 mL of deionized water to separate the excess surfactant. Centrifuge the reaction solution and save the supernatant.

[0086] (5) The supernatant of step (4) was subjected to rotary evaporation to remove the organic solvent xylene to obtain the primary product of AlQDs quantum dots, and then dimethylformamide was added for ultrasonic dispersion to obtain a colloidal AlQDs solution, which was stored for subsequent research.

[0087] Embodiment 2:

[0088] A colloidal AlQDs with continuously adjustable optical band gap, the synthesis method of which is substantially the same as that of Example 1. The only difference is that in step (2), the molar ratio of aluminum chloride to lithium aluminum hydride is 1:2.

[0089] Embodiment 3:

[0090] A colloidal AlQDs with continuously adjustable optical band gap, the synthesis method of which is substantially the same as that of Example 1. The only difference is that in step (2), the molar ratio of aluminum chloride to lithium aluminum hydride is 1:3.

[0091] Embodiment 4:

[0092] A colloidal AlQDs with continuously adjustable optical band gap, the synthesis method of which is substantially the same as that of Example 1. The only difference is that in step (2), the molar ratio of aluminum chloride to lithium aluminum hydride is 1:4.

[0093] Example 5

[0094] A colloidal AlQDs with continuously adjustable optical band gap, the synthesis method of which is the same as that of Example 1. The only difference is that in step (2), the molar ratio of aluminum chloride to lithium aluminum hydride is 1:0.5.

[0095] Example 6

[0096] An ultra-sensitive cascade AlQDs@β-Ga2O3 heterojunction solar-blind photodetector based on quantum size effect, the structural schematic diagram of which is shown in the figure Figure 7 As shown, the preparation method comprises the following steps:

[0097] (1) Specifically, the commercial β-Ga2O3 substrate used was first ultrasonically treated in acetone, isopropanol, and deionized water for 5 min respectively to remove organic matter and contaminants on the substrate surface.

[0098] (2) The colloidal AlQDs solutions prepared in Example 2 and Example 4 are respectively deposited layer by layer on the β-Ga2O3 substrate by spin coating, and the colloidal AlQDs solution does not completely cover the β-Ga2O3 layer. The specific spin coating parameters are 500rpm, 10s; 2000rpm 30s. In order to make the quantum dots form a uniform film, annealing treatment is required after each spin coating of AlQDs, specifically annealing at a temperature of 90°C for 10 minutes before the next spin coating operation. That is to say, the colloidal AlQDs solution of Example 2 is first spin coated, then annealed, and then the colloidal AlQDs solution prepared in Example 4 is spin coated, and annealed again to form a multilayer colloidal AlQDs quantum dot layer.

[0099] (4) A customized shadow mask was used to cover the transfer onto a heterojunction solar-blind detector with a semi-covered structure. A nitrogen gun was used to purge for 30 seconds to remove surface dust. Then, a Ti / Au electrode was deposited using a magnetron sputtering machine, wherein the Ti layer was deposited on the surface of the β-Ga2O3 layer with a thickness of 10 nm, and the Au layer was deposited on the surface of the AlQDs quantum dot layer with a thickness of 100 nm. After the evaporation was completed, the shadow mask was removed to obtain an AlQDs@β-Ga2O3 heterojunction solar-blind photodetector with a prepared cascade band structure.

[0100] Example 7

[0101] An ultra-sensitive cascade AlQDs@β-Ga2O3 heterojunction solar-blind photodetector based on quantum size effect, whose structure and preparation method are basically the same as those of Example 6. The only difference is that in step (2), only the colloidal AlQDs solution prepared in Example 2 is deposited on β-Ga2O3, and then annealed to obtain a single-layer AlQDs thin film layer. It can be seen from the experiment that compared with the detector of this embodiment, the performance of the detector with cascade heterojunction structure is enhanced.

[0102] Application test examples:

[0103] (1) Characterization of colloidal AlQDs

[0104] The surface morphology of the colloidal AlQDs quantum dots with different optical band gaps synthesized in Examples 1-5 was analyzed by TEM and ACTEM. The results are as follows: Figure 1 As shown in the figure, the particle size of AlQDs gradually decreases with the increase of reducing agent concentration. Considering the quantum confinement effect of quantum dots, its absorption and photoluminescence spectra will also undergo a significant blue shift.

[0105] The colloidal AlQDs quantum dots with different optical band gaps synthesized in Examples 1-5 were subjected to UV-visible absorption and photoluminescence fluorescence spectroscopy analysis. The results are as follows: Figure 2 As shown in the figure, AlQDs-0.5, AlQDs-1, AlQDs-2, AlQDs-3 and AlQDs-4 represent the quantum dots prepared in Example 5, Example 1, Example 2, Example 3 and Example 4, respectively, that is, the colloidal aluminum quantum dots prepared when the relative molar ratio of the precursor to the reducing agent is 1:0.5, 1:1, 1:2, 1:3 and 1:4. Figure 2 It can be seen that the prepared AlQDs have continuously adjustable optical band gap values ​​and have strong photoluminescence in the UVB-UVA band.

[0106] (2) Detector performance characterization

[0107] The detectors prepared in Example 6 and Example 7 were connected to Keithley 2602B respectively to measure the photoelectric response at different wavelengths of 254 nm. Figure 3 Figure a is a comparison diagram of It of the detector in Example 6 under different bias voltages. It can be seen that the photocurrent of the photodetector with a cascaded energy band structure is three times that of a single-layer detector under the same conditions. Figure b is an IV diagram of the photodetector in Example 6; it can be seen from the figure that the detector in the embodiment of the present invention exhibits an ultra-low dark current under a reverse bias voltage, which is beneficial for the device to achieve ultra-sensitive day-blind detection. Figure c is a comparison diagram of Example 6 and Example 7. It can be seen from the figure that the device has excellent linear response and stability of optical power.

[0108] (3) Testing of detectors for anti-interference imaging

[0109] An imaging system was constructed using the AlQDs@β-Ga2O3 heterojunction solar-blind photodetector with a cascaded energy band structure prepared in Example 6, and the anti-interference imaging performance of the detector was measured.

[0110] The imaging system places a solar-blind detector on a focal plane, and then uses a two-axis displacement platform to gradually scan the mask to be tested to obtain imaging images under different light power densities; the imaging system is further used to conduct test research on detective anti-interference imaging.

[0111] In the specific imaging experiment, the detector's ultra-sensitive solar-blind detection in weak-light conditions was first verified, and then its great potential for anti-interference solar-blind imaging in the solar-blind band was verified by using a hybrid light source.

[0112] A. Solar blind detection in low light:

[0113] The specific method is: construct a transmission scanning imaging system according to the above method, adjust the optical power of the 254nm LED, and verify its ultra-sensitive solar blind detection under different light intensities, such as Figure 4 As shown in the figure, (1)-(5) represent the imaging under different light intensities. Figure 5 It can be seen that the solar-blind detector with cascade band structure can be used at as low as 23 nW cm -2 Clear day-blind imaging can still be achieved under low light conditions.

[0114] B. Solar blind detection under mixed light sources:

[0115] The specific method is: construct a transmission scanning imaging system according to the above method, use different light sources, specifically as follows Figure 6 As shown in the figure, the anti-interference experiment in the deep ultraviolet band was verified under the conditions of using a mixed light source of 254nm and 365nm light source, a mixed light source of 254nm and 395nm light source, 254nmLED and white light source, and compared with commercial silicon detectors. The results are shown in Figure 6 As shown in the figure, Figure a shows the solar-blind imaging achieved by the solar-blind photodetector with a cascade energy band structure, and Figure b shows the solar-blind imaging achieved by a commercial silicon detector. By comparison, it can be found that the solar-blind detector with a cascade energy band structure proposed in the present invention can achieve highly selective solar-blind imaging, and has broad application prospects in both military and civilian fields.

[0116] The present invention prepares Al quantum dots (QDs) with continuously adjustable optical band gaps and combines them with β-Ga2O3 to construct a heterojunction solar-blind detector with ultra-narrowband response. The cascaded band structure and built-in electric field of the detector not only effectively suppress dark current, but also greatly improve the sensitivity of photoelectric detection, which is particularly suitable for high-precision imaging in the deep ultraviolet band. Its narrowband response characteristics make it show great potential in anti-interference deep ultraviolet solar-blind imaging.

[0117] The method of the present invention is expected to be widely used in many fields, including high-sensitivity ultraviolet imaging in the fields of space exploration and solar activity monitoring. In addition, in national defense security and industrial detection, systems that rely on deep ultraviolet light detection can take advantage of the solar-blind characteristics of this technology to improve imaging quality and anti-interference capabilities in complex environments. In environmental monitoring, the highly selective detection of deep ultraviolet light can help identify specific gas components and is expected to be used for atmospheric pollutant detection and analysis. Further technical optimization is also likely to promote the use of this detector in medical spectral analysis and high-precision optical sensors.

[0118] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. An ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on quantum size effect, characterized in that: It includes a substrate, a Ga2O3 layer, a quantum dot material layer, and an electrode; The Ga2O3 layer is disposed on the surface of the substrate, and the quantum dot material layer is disposed on the surface of the Ga2O3 layer and does not completely cover the Ga2O3 layer; The electrodes include electrode I and electrode II; The electrode I and the electrode II are arranged in a Ga2O3 layer or a quantum dot material layer, and the electrode I and the electrode II are not located in the same material layer; The quantum dot material layer includes AlQDs quantum dots.

2. The AlQDs@Ga2O3 heterojunction solar-blind photodetector according to claim 1, characterized in that: The Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; The quantum dot material layer includes at least one quantum dot material layer; Preferably, the quantum dot material layer comprises two or more layers of AlQDs quantum dot material layers having different particle sizes; The electrode I includes at least one of a Ti electrode and an Au electrode; the electrode II includes at least one of a Ti electrode and an Au electrode.

3. A method for preparing the AlQDs@Ga2O3 heterojunction solar-blind photodetector according to any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: S1: Prepare colloidal AlQDs solution and prepare substrate containing Ga2O3 layer; S2: depositing the colloidal AlQDs solution layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer to form an AlQDs@Ga2O3 heterojunction, thereby obtaining a material containing the Ga2O3 layer and the AlQDs layer; S3: Electrode I and electrode II are deposited on the Ga2O3 layer and the AlQDs layer respectively by mask evaporation to obtain an AlQDs@Ga2O3 heterojunction solar-blind photodetector; In step S2, the AlQDs layer partially covers the Ga2O3 layer.

4. The preparation method according to claim 3, characterized in that: In step S1, the concentration of the colloidal AlQDs solution is 10-20 mg / mL.

5. The preparation method according to claim 1, characterized in that: In step S1, the colloidal AlQDs solution is prepared by: S1-1: Aluminum halide and surfactant are added to solvent I, and the solution color changes from light yellow to colorless to obtain a precursor solution; S1-2: The precursor solution is degassed with argon, heated under anhydrous and oxygen-free conditions, and then the reducing agent solution is added and stirred for reaction. Solvent II is then added and stirred for 5 minutes. The white precipitate is removed by centrifugation, and solvent I is removed by rotary evaporation of the supernatant to obtain crude AlQDs. Solvent III is added and ultrasonically dispersed to obtain a colloidal AlQDs solution.

6. The preparation method according to claim 5, characterized in that: In step S1-1, the aluminum halide includes at least one of aluminum chloride and aluminum bromide; The surfactant includes a quaternary amine cationic surfactant; Preferably, the surfactant includes at least one of n-tetraoctylammonium bromide, tetramethylammonium fluoride, and dialkyldimethylammonium chloride; The molar ratio of the aluminum halide to the surfactant is 1:1-3; The solvent I includes at least one of anhydrous xylene and oleylamine.

7. The preparation method according to claim 5, characterized in that: In step S1-2, the heating refers to heating to 110-120°C; The reducing agent solution is an ammonia ethanol solution or a lithium aluminum hydride solution; the reducing agent solution concentration is 2M; The reducing agent solution is added at a rate of 1-4 mL / h; The molar ratio of the aluminum halide to the reducing agent is 2:1-1:4; The stirring reaction speed is 700-900r / min, the reaction temperature is 110-130°C, and the time is 3-8h; Preferably, the stirring reaction is carried out under the protection of argon atmosphere; The solvent II includes methanol; The solvent III includes at least one of ethanol and dimethylformamide.

8. The preparation method according to claim 3, characterized in that: In step S2, the Ga2O3 includes at least one of β-Ga2O3, α-Ga2O3, γ-Ga2O3, δ-Ga2O3, and ε-Ga2O3; The method of depositing the colloidal AlQDs solution layer by layer on the surface of the Ga2O3 layer of the substrate containing the Ga2O3 layer is to spin-coat the colloidal AlQDs solution on a part of the surface of the Ga2O3 substrate, anneal, repeat the spin coating, and anneal to form a multilayer AlQDs layer; the number of repetitions is greater than or equal to 0; The spin coating is firstly performed at 500 rpm for 10 s, and then at 2000 rpm for 30 s; The annealing temperature is 90° C. and the annealing time is 10 min.

9. The preparation method according to claim 3, characterized in that: In step S3, the electrode I is disposed on the surface of the AlQDs; the electrode II is disposed on the surface of the Ga2O3 that is not coated with the AlQDs solution; The electrode I includes at least one of a Ti electrode and an Au electrode; The electrode II includes at least one of a Ti electrode and an Au electrode; The electrode materials of the electrode I and the electrode II are the same or different.

10. An imaging device, characterized in that: It includes the ultra-sensitive AlQDs@Ga2O3 heterojunction solar-blind photodetector based on quantum size effect as described in any one of claims 1-2 or the AlQDs@Ga2O3 heterojunction solar-blind photodetector prepared by the preparation method as described in any one of claims 3-9.

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