WO2021104528A1

WO2021104528A1 - Solar-blind ultraviolet photoelectrochemical light detector and product thereof

Info

Publication number: WO2021104528A1
Application number: PCT/CN2020/136491
Authority: WO
Inventors: 孙海定; 汪丹浩; 黄晨; 张昊宸
Original assignee: 中国科学技术大学
Priority date: 2019-11-29
Filing date: 2020-12-15
Publication date: 2021-06-03
Also published as: CN112880823A; CN112880823B

Abstract

A solar-blind ultraviolet photoelectrochemical light detector (400), comprising a photoelectrode, wherein the photoelectrode comprises a substrate (110) and also comprises a p-type/n-type doped Gallium Nitride (GAN)-based nanowire (120) grown on the surface of the substrate. Additionally, the GaN-based nanowire (120) is modified with catalytic promoter nanoparticles (210), thereby optimizing the absorption and desorption process of molecules and improving the redox reaction speed of the photoelectrode in a solution. In addition, further optimizing the design of a photoelectrochemical apparatus improves the electrolyte solution environment, and ultimately allows for a new, highly responsive, highly sensitive solar-blind ultraviolet photoelectrochemical light detector (400) that is quick-responding, economic and environmentally friendly, and self-powered (without the need for additional electric power). Applying a gallium nitride-based nanowire (120) to the research of photoelectrochemical light detectors is significant.

Description

Solar-blind ultraviolet photoelectrochemical photodetector and its products

Technical field

The present disclosure relates to the technical field of photoelectrochemical photodetectors, in particular to a solar-blind ultraviolet photoelectrochemical photodetector and products thereof.

Background technique

Photodetectors (ie, light detectors), that is, devices that capture light signals and convert them into electrical signals, are widely used in imaging, communication, sensing, computing, emerging wearable devices, and detection in the space field. Optical detectors are widely used in various fields of military and national economy.

Most of today's photodetectors are based on simple Metal-Semiconductor-Metal (MSM) structure. MSM structured photodetectors need to apply an external bias when working, which not only consumes electricity, but also in terms of responsivity and response speed. Other aspects need to be improved. Compared with photodetectors composed of traditional MSM semiconductor Schottky junctions and pn/nn junctions, photoelectrochemical photodetectors have the following advantages: no additional electrical energy is required; higher photoresponse, adjustable response time; simple manufacturing process And the cost is low.

Although photoelectrochemical photodetectors have great technical advantages over traditional photodetectors, they are still in their infancy. Photoelectrochemical photodetectors are developed from photoelectrochemical reactions. At present, the research hotspot of photoelectrochemical reactions is mainly artificial photosynthesis, that is, simulating redox reactions under sunlight (visible light band) for photoelectrocatalysis research. However, there is not much research on photoelectrochemical photodetectors, including infrared and ultraviolet photoelectrochemical photodetectors, while photoelectrochemical photodetectors in solar-blind ultraviolet bands are even more lacking.

The existing photoelectrochemical photodetector preparation materials are mainly powder materials or nanosheet materials, with poor crystal quality, slow oxidation-reduction reaction rate, and poor optical detection effect, such as gallium oxide nanomaterials. Therefore, it is very important to prepare high crystal quality semiconductors suitable for photoelectrochemical photodetectors and apply them to the significant solar-blind ultraviolet light detection field.

Summary of the invention

One aspect of the present disclosure proposes a new solar-blind ultraviolet photoelectrochemical photodetector, which includes a photoelectrode, the photoelectrode includes a substrate, and also includes gallium nitride (GaN)-based nanowires grown on the surface of the substrate , GaN-based nanowires include n-type GaN-based nanowires and p-type GaN-based nanowires.

According to an embodiment of the present disclosure, the GaN-based nanowire has a length of 10 nm-5000 nm and a diameter of 5 nm-5000 nm.

According to an embodiment of the present disclosure, the coverage density (or filling rate) of the GaN-based nanowires is 1%-99%.

According to an embodiment of the present disclosure, the substrate includes any solid-state substrate that can conduct electricity, including metal, conductive silicon, and a substrate covered with a metal thin film on silicon, silicon carbide, gallium nitride, gallium oxide, diamond, graphene, ITO ( Indium tin oxide) material substrate, or other solid semiconductor conductive substrate or any solid substrate material covered with a conductive layer can be used as the conductive substrate of the present disclosure. According to the embodiment of the present disclosure, the conductive substrate includes a standard low-resistance silicon substrate. The size of the silicon substrate may be 1 cm×1 cm. The specific size depends on the size of the photoelectrode, which is not limited in the present disclosure.

According to an embodiment of the present disclosure, the silicon substrate includes an n-type silicon substrate, which is an n-type silicon substrate with any crystal plane, such as a Si(111) surface substrate; also includes a p-type silicon substrate, p The type silicon substrate is a p-type silicon substrate with any crystal plane, for example, a Si (100) plane substrate.

According to an embodiment of the present disclosure, the photoelectrode includes a photoanode formed of n-type GaN-based nanowires and a photocathode formed of p-type GaN-based nanowires, and also includes promoter nanoparticles distributed on the surface thereof.

According to an embodiment of the present disclosure, the GaN-based nanowire is an n-type GaN-based nanowire, and the surface of the photoelectrode further includes a protective layer formed on the surface of the n-type GaN-based nanowire, and the thickness of the protective layer is less than or equal to 10 nm.

According to an embodiment of the present disclosure, the photoelectrode further includes co-catalyst nanoparticles modified on the surface of the GaN-based nanowires, and the size of the co-catalyst nanoparticles is 0.1 nm-1000 nm.

According to an embodiment of the present disclosure, the co-catalyst nanoparticles include metal particles active in water oxidation reaction or reduction reaction.

According to an embodiment of the present disclosure, the promoter nanoparticles include metal particles with water oxidation or reduction reaction activity, including platinum, rhenium, palladium, iridium, rhodium, iron, cobalt, or nickel, etc., or their multiple alloys; Metal particles active in water oxidation reaction include iridium, iron, cobalt, nickel or ruthenium, etc., or their multiple alloys.

According to an embodiment of the present disclosure, the photoelectrochemical photodetector further includes: a wire arranged in the conductive area of the substrate, the wire and the photoelectrode are covered and fixed, and the cured and coated structure of the GaN-based nanowire of the photoelectrode is exposed.

According to an embodiment of the present disclosure, the wire material includes gold, silver, and copper, and the size of the wire is selected to match the size of the substrate.

According to an embodiment of the present disclosure, the material of the cured coating structure includes a liquid material that is curable and has insulating properties after curing, and the cured coating structure is an epoxy resin.

According to an embodiment of the present disclosure, a liquid alloy disposed on the conductive area of the substrate and a conductive glue disposed on the surface of the wire opposite to the liquid alloy are further included between the wire and the substrate;

According to the embodiment of the present disclosure, the liquid alloy is a liquid gallium indium (GaIn) alloy, and the purity of the liquid gallium indium (GaIn) alloy is 90-99.99999%; the conductive glue is a silver glue.

According to an embodiment of the present disclosure, the photoelectrochemical photodetector further includes: an electrolyte solution in contact with the photoelectrode, and a reference electrode and a counter electrode in contact with the electrolyte solution, and a certain distance is maintained between the reference electrode, the counter electrode and the photoelectrode ; Among them, the reference electrode, the counter electrode and the photoelectrode are respectively connected with an electrochemical workstation with current monitoring function.

According to an embodiment of the present disclosure, the electrolyte solution is an acidic or neutral electrolyte solution, the acidic electrolyte solution includes sulfuric acid, hydrochloric acid, and perchloric acid, the neutral electrolyte solution is sodium sulfate, and the concentration of the electrolyte solution is 0.01-5 mol/L; the reference electrode It is a silver/silver chloride electrode; the counter electrode includes platinum electrode and carbon electrode.

Another aspect of the present disclosure proposes a new solar-blind ultraviolet photoelectrochemical photodetector product. The product includes the above-mentioned photodetector and a packaging structure for packaging the photodetector. The packaging structure includes coating the photoelectrochemical photodetector with The shell structure that encapsulates it; an optical window is opened on the surface of the shell structure, and a light-transmitting surface that matches the optical window for sealing the optical window is provided. The distance between the light-transmitting surface and the surface of the photoelectrode with GaN-based nanowires It is greater than or equal to 0.01mm, used for solar-blind ultraviolet light to irradiate the photoelectrode through the light-transmitting surface to modify the GaN-based nanowires with promoter nanoparticles.

According to an embodiment of the present disclosure, the light-transmitting surface includes a transparent material with limited ability to absorb solar-blind ultraviolet light; the shell structure includes a shell structure formed of a polytetrafluoroethylene material;

According to an embodiment of the present disclosure, one surface of the housing structure is provided with a sealable/openable injection hole, an exhaust hole, and at least three electrode holes for setting a reference electrode, a counter electrode, and a photoelectrode, respectively.

Description of the drawings

FIG. 1A is a schematic diagram of AlGaN nanowires in an embodiment of the present disclosure;

1B is a scanning electron microscope image of AlGaN nanowires in an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of modified co-catalyst nano-Pt particles in AlGaN nanowires in an embodiment of the present disclosure;

3A is a schematic diagram of a package cross-sectional view of an AlGaN nanowire photocathode in an embodiment of the present disclosure;

FIG. 3B is a schematic diagram of packaging the AlGaN nanowire photocathode in an embodiment of the present disclosure;

4 is a schematic diagram of the preparation of a novel solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure;

5 is a schematic diagram of a product of a novel solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure;

Fig. 6 is a schematic flow chart of a preparation method of a photoelectrochemical photodetector in an embodiment of the present disclosure;

FIG. 7 is a simple comparison diagram of the spectra of the photoelectrochemical photodetector in an embodiment of the present disclosure;

8A is a schematic diagram of an AlGaN nanohole array of solar-blind ultraviolet photoelectrochemical photodetectors in an embodiment of the present disclosure;

FIG. 8B is a schematic diagram of an AlGaN nanohole array with modified promoter nanoparticles in a solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure; FIG.

FIG. 9 is a schematic diagram of a method for preparing a solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure;

10A is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10B is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10C is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10D is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10E is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10F is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10G is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure;

10H is a schematic diagram of the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure.

Detailed ways

The photoelectrochemical photodetector is derived from the photoelectrochemical reaction. Taking p-type semiconductor as an example, the photoelectrochemical reaction means that the semiconductor generates photoelectrons and holes when exposed to light. The electrons undergo a reduction reaction at the semiconductor electrode, and the holes flow through the external circuit to the counter electrode to undergo oxidation reaction (the opposite is true for n-type semiconductors). The performance indicators tested in this process, the ratio of light/dark current, and the response time are directly related to the intensity of light and the wavelength of light, and a photoelectrochemical device dedicated to light detection is gradually derived from this. In the field of photoelectrochemical research, most researches focus on photoelectrocatalytic oxidation-reduction reactions under visible light conditions. There are few researches on photoelectrochemical photodetectors, and very few researches on photoelectrochemical photodetectors in the infrared and ultraviolet bands. , This can be said to be a brand new direction. Specifically, photoelectrochemical catalysis focuses on the study of chemical reaction mechanisms, such as studying the amount of hydrogen produced by semiconductor materials during the photoelectric catalytic reaction, how to increase the amount of hydrogen produced, and how to design reaction sites. The photoelectrochemical photodetector mainly studies the photo-dark current signal generated in the above photoelectrochemical reaction process to reflect the relevant parameters of the detection light, and then realize various photoelectric detection functions.

In addition, the research direction of group III and V nitride semiconductor materials is mainly focused on light-emitting diodes (Light Emitting Diode, or LED) and power devices, and the cost of preparing nitrides is extremely high due to, for example, molecular beam epitaxy (MBE). The use of nitride nanomaterials for photoelectrochemical catalysis research is still in its infancy, not to mention the use of group III-V nitride materials as photoelectrochemical photodetectors. Generally, ultraviolet light detection (non-blind band) selects chemically prepared powder samples (such as zinc oxide ZnO, titanium dioxide TiO ₂ etc.). Due to the poor quality of the crystals, many defects, photo-generated electron-hole pairs are easy to recombine, directly This results in poor light detection performance. The present disclosure creatively proposes a GaN-based nanowire/nanopore structure, which is applied to a photoelectrochemical photodetector, which overcomes technical problems in the field and achieves breakthrough technical effects.

In order to make the objectives, technical solutions, and advantages of the present disclosure clearer, the following further describes the present disclosure in detail in conjunction with specific embodiments and with reference to the accompanying drawings.

Example 1:

In order to prepare high crystalline quality semiconductor materials or structures for application in the field of solar-blind ultraviolet light detection, the present invention proposes a novel solar-blind ultraviolet photoelectrochemical photodetector and its products.

One aspect of the present disclosure proposes a novel solar-blind ultraviolet photoelectrochemical photodetector. FIG. 1A is a schematic diagram of an AlGaN nanowire in an embodiment of the present disclosure. The new solar-blind ultraviolet photoelectrochemical photodetector includes a photocathode. The photocathode includes a substrate 110 and also includes AlGaN nanowires 120 grown on the surface of the substrate 110, thereby forming the new photoelectrochemical photodetector photocathode proposed in the present disclosure. The basic structure of 100. Among them, GaN-based nanowires include n-type GaN-based nanowires and p-type GaN-based nanowires. Those skilled in the art should understand that the nanowire structure can be a regular arrangement, such as a nanowire structure prepared by directional growth, or it can also include an irregularly arranged nanowire structure. The so-called "regular" can be understood as whether the nanowire arrangement has Periodicity; correspondingly, the so-called "irregularity" can be understood as whether the arrangement of nanowires is not periodic, it can also be understood as the length and diameter of the nanowires, the distance between any adjacent nanowires, and the growth angle of the nanowires Inconsistent (relative to the substrate), no rules to follow. In addition, the gallium nitride-based material can be selected as AlGaN in the present disclosure. AlGaN is only a symbolic expression of the material, and does not represent the standard chemical formula of the material. Specifically, the chemical formula of the GaN-based material can be Al _x Ga _{1 -x} N, B _x Al _y Ga _1-xy N or In _x Al _y Ga _1-xy N, 0≤x<1, 0≤y≤1. That is, the gallium nitride-based material may be AlGaN or InGaN, or a gallium nitride-based material such as AlInGaN, which is not limited in the present disclosure.

The photoelectrode mentioned in the claims in the present disclosure can be a photocathode or a photoanode, and can be specifically distinguished by its doping component (such as magnesium doping or silicon doping), which corresponds to the reduction in the present disclosure. Reaction or oxidation reaction. In order to clearly express the function of the photoelectrode in the present disclosure, the present disclosure mainly uses the AlGaN photocathode as an example for description. Those skilled in the art should understand that it is not a limitation on the photoanode, nor is it a limitation on the non-AlGaN photoelectrode. As an embodiment of the present disclosure, the AlGaN nanowires 120 grown on the surface of the substrate 110 can be obtained by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) , The conventional chemical vapor deposition method, halide vapor phase epitaxy or pulsed laser deposition and other methods are used for preparation, which are not specifically limited in the present disclosure. At the same time, in order to express the AlGaN nanowire 120 of the present disclosure more clearly, the following mainly uses molecular beam epitaxy (MBE) as a basic preparation method to introduce.

The AlGaN nanowire 120 of the present disclosure has the advantages of high stability, high crystal quality, and adjustable band gap height compared with ordinary oxide and nitride nanomaterials (such as gallium oxide nanostructures). It has excellent water reduction performance under blind light irradiation, which is reflected in excellent light detection performance. In addition, for Al _x Ga _1-x N materials, the band gap can be changed with the doping of the composition, specifically:

Eg=3.42eV+x*2.86eV-x(1-x)*1.0eV...(1)

Among them, Eg is the semiconductor forbidden band width, corresponding to the absorption wavelength of different optical wavelength bands.

Therefore, according to formula (1), by controlling the proportions of Al and Ga components in the preparation process, the band gap of the prepared photocathode can be precisely adjusted to achieve light absorption in the solar-blind ultraviolet band. Correspondingly, for _{GaN-based materials in B x} Al _y Ga _1-xy N or In _x Al _y Ga _1-xy N (0≤x＜1, 0≤y≤1), the corresponding wavelength is calculated The formula can be changed accordingly, and the actual preparation requirements shall prevail, which is not limited in this disclosure.

In addition, the AlGaN nanowires with high crystal quality prepared in the present disclosure may be p-type doped materials, specifically, Mg atoms may be doped. When a p-type semiconductor is in contact with an aqueous solution, electron exchange occurs. The final result is that the Fermi energy level of the water-semiconductor system is the same, and the p-type semiconductor energy band is bent downward, causing electrons to move to the contact surface, and the surface is rich in electrons. The process will not cause any impact on AlGaN nanomaterials or structures. Compared with oxide nanomaterials that have not yet achieved p-type doping (such as gallium oxide nanostructures), the stability is very high, and it can be used as a photocathode. Correspondingly, as another embodiment of the present disclosure, it is also possible to change it to n-type doped AlGaN nanowires and apply a certain protective layer to use it as a photoanode.

As an optional embodiment, the substrate 110 includes a conductive substrate, and the conductive substrate includes a standard low-resistance silicon substrate, such as a silicon wafer with overall conductivity. The size of the silicon substrate may be 1cm×1cm, and the specific size depends on The size of the photoelectrode is required, which is not limited in this disclosure.

As an optional embodiment, the silicon substrate includes an n-type silicon substrate, and the n-type silicon substrate is an n-type silicon substrate with any crystal plane, for example, a Si(111) surface substrate; it also includes a p-type silicon substrate, p The type silicon substrate is a p-type silicon substrate with any crystal plane, for example, a Si (100) plane substrate. GaN-based nanowires with high crystal quality can be stably formed on the substrate. Specifically, the silicon substrate is only an optional substrate in the present disclosure. In the present disclosure, the substrate includes any conductive solid substrate (which can be understood as a substrate with a conductive layer grown on the surface), including metal, conductive silicon, and silicon. A substrate covered with a metal film, silicon carbide, gallium nitride, gallium oxide, diamond, graphene, ITO (indium tin oxide) material, or other solid semiconductor conductive substrate or any solid substrate material covered with a conductive layer.

FIG. 1B is a scanning electron microscope image of AlGaN nanowires in an embodiment of the present disclosure. As an optional embodiment, the average length of a single nanowire of the AlGaN nanowire 120 is 10 nm-5000 nm, optionally in the range of 300 nm-400 nm; the average diameter of a single nanowire is 5 nm-5000 nm, optionally 60 nm-80 nm. This makes the specific surface area of the nanowire larger, and at the same time increases the rate of the redox reaction in the photodetection process.

As an optional embodiment, the coverage (or filling rate) of the AlGaN nanowire 120 is 1%-99%, and may be about 70%. The coverage density is equivalent to the percentage of the total area of the upper surface of the nanowires to the surface area of the entire substrate, which is used to reflect the distance between the nanowires, the number of nanowires per unit surface, and so on.

As an optional embodiment, the photoelectrode includes a photoanode formed by n-type GaN-based nanowires and a photocathode formed by p-type GaN-based nanowires, and also includes promoter nanoparticles distributed on the surface thereof.

As an optional embodiment, the GaN-based nanowires are n-type GaN-based nanowires, and the surface of the photoelectrode further includes a protective layer formed on the surface of the n-type GaN-based nanowires, and the thickness of the protective layer is less than or equal to 10 nm. It is used to prevent the occurrence of photo-corrosion of GaN-based nanowires, and the protective layer is titanium dioxide (TiO ₂ ) or other protective materials.

FIG. 2 is a schematic diagram of modified co-catalyst nano-Pt particles in AlGaN nanowires in an embodiment of the present disclosure. As an optional embodiment, in the modified cocatalyst nanoparticle AlGaN nanostructure 200 shown in FIG. 2, the photocathode further includes cocatalyst nanoparticles 210 modified on the surface of the nanowire in the AlGaN nanowire 120, and the cocatalyst nanoparticle The size of 210 is 0.1nm-1000nm. Correspondingly, the corresponding n-type gallium nitride-based nanowires in the present disclosure (such as AlGaN or InGaN nanowires, etc., which are not limited here, and are subject to the protection scope defined by the claims) can be used as the optoelectronics in the present disclosure. For the photoanode of the chemical photodetector, the n-type nanowire can optionally form at least one protective layer on the surface of the nanowire before modifying the co-catalyst nanoparticles. The protective layer can be a protective layer made of the aforementioned titanium dioxide and other materials. To prevent the photo-corrosion phenomenon of n-type GaN-based nanowires, it will not be repeated here.

On the nanowires of AlGaN nanowires 120, photodeposition, or atomic layer deposition (Atomic Layer Deposition, ALD), electrodeposition (chemical loading method), and immersion method (chemical loading method) are used to modify the co-catalyst nanoparticles on the nanowires. Nanowire surface.

Specifically, when solar-blind ultraviolet light corresponding to the band gap of the AlGaN nanowire 120 is used to irradiate the AlGaN nanowire 120 in the photodeposition process, in the case of the semiconductor photoelectric effect, the nanowire of the AlGaN nanowire 120 absorbs photons and produces photogenerated Electron-hole pairs. Then the photogenerated electrons diffuse to the surface of the nanowires. Because the energy of the photogenerated electrons is greater than the reduction potential of the cocatalyst precursor groups in the solution, the photogenerated electrons diffused to the surface of the nanowires will reduce and modify the cocatalyst precursor groups on the surface of the AlGaN nanowires , Thereby forming modified nanoparticles 210 on the surface of the AlGaN nanowire 120. The particle size diameter can be 0.1nm-1000nm, 5nm can be selected, and modified on the surface of the nanowire. In the subsequent photodetection process, the co-catalyst significantly enhances the reduction reaction activity of the system, accelerates the reaction rate, and improves the photoresponse performance.

As an optional embodiment, the promoter nano-particles 210 include metal particles active in water reduction reaction. As an optional embodiment, the metal particle material includes platinum, rhenium, palladium, iridium, rhodium, iron, cobalt, or nickel, etc., or multiple alloys thereof. The alloy uses two metals at the same time, such as RuFe and RuCo. In the present disclosure, platinum (Pt) is optional. The promoter nanoparticle 210 needs to have proper adsorption energy for water molecules and reduction products, and has a higher water reduction activity, which makes the reduction reaction stronger and the photocurrent signal stronger during the photodetection process. Correspondingly, for the photoanode, its promoter nano particles can include metal particles with water oxidation reaction activity, including iridium, iron, cobalt, nickel or ruthenium, etc., or their multi-component alloys, which have correspondingly higher Water oxidation is active, and the oxidation reaction is more intense. Those skilled in the art should understand that the introduction of the cocatalyst modification material in this embodiment is not a limitation of the protection scope of the present disclosure, but merely an embodiment of the present disclosure.

FIG. 3A is a schematic view of the packaging of the AlGaN nanowire photocathode 300 in an embodiment of the present disclosure; FIG. 3B is a schematic view of the packaging of the AlGaN nanowire photocathode 300 in an embodiment of the present disclosure. As an optional embodiment, in order to successfully encapsulate the AlGaN nanowire 120 of the photocathode mentioned above, the photoelectrochemical photodetector further includes: a wire 310 arranged in the conductive area of the substrate 110, and the wire 310 and the photocathode are covered and fixed, The cured coating structure 320 of the AlGaN nanowire 120 of the photocathode is exposed. As shown in FIG. 3B, a curing window 321 can be formed on the surface of the cured structure of the cured coating structure 320, through which the AlGaN nanowires 120 are exposed, so that in the subsequent light detection process, solar-blind ultraviolet light applied from the outside can directly pass through The curing window 321 is irradiated onto the AlGaN nanowire 120. The optional substrate 110 material here can be a p-type Si (100) surface silicon wafer with an area size of 1 cm×1 cm and a thickness between 0.01 mm and 1000 mm. At this time, the conductive area nanowires are arranged on the back of the substrate 110. As shown in Figure 3A. The wires are arranged on the back of the substrate. Wherein, the conductive area may be a certain area other than the nanowires that is scraped off by a diamond pen on the back or front of the silicon wafer, which is not specifically limited in the present disclosure.

As an optional embodiment, the material of the wire 310 includes gold, silver, copper, etc., and the size of the wire 310 is selected to match the size of the substrate 110. For example, a wire 310 with a width of about 1.2 cm and a length of 5 cm may be selected, and the material may be copper Cu. Conductive copper tape can also be used.

As an optional embodiment, the material of the cured coating structure 320 includes a liquid material that is curable and has insulating properties after curing, and the cured coating structure 320 is epoxy resin or the like, which has a wrapping and insulating effect.

As an optional embodiment, between the wire 310 and the substrate 110, a liquid alloy 330 disposed on the conductive area of the substrate and a conductive glue 340 disposed on the surface of the wire 310 opposite to the liquid alloy 330 are further included. As an optional embodiment, the liquid alloy 330 is a liquid gallium indium (GaIn) alloy, and the purity of the liquid gallium indium (GaIn) alloy is optional between 90% and 99.99999%; and the conductive glue 340 is a silver glue. Specifically, the liquid alloy 330 can directly contact the conductive surface of the substrate to form an ohmic contact, which can achieve better conductive characteristics and current stability. The conductive glue that also fixes the wire 310 and the substrate 110 and fixes the liquid alloy 330 together between the wire 310 and the substrate 110, not only plays a role of fixing and wrapping, but also has better conductive characteristics and Current stability. In addition, based on the above packaging method, a packaged photoelectrode with ohmic contact characteristics is prepared, which can better avoid the Schottky barrier formed by the direct contact between the surface of the conductive area of the substrate and the metal wire, so as to facilitate current conduction.

Fig. 4 is a schematic diagram of the preparation of a novel solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure. As an optional embodiment, the photoelectrochemical photodetector 400 further includes: an electrolyte solution (not shown in the figure) in contact with the photocathode structure 300, and a reference electrode 420 and a counter electrode 430 in contact with the electrolyte solution. The electrode 420, the counter electrode 430, and the photocathode 300 are kept at a certain distance, and they are contained together by a light-transmitting container 410 having at least limited solar-blind ultraviolet light absorption capacity; among them, the reference electrode 420, the counter electrode 430 and the photocathode 300 They are respectively connected to an electrochemical workstation 440 with a current monitoring function. The electrochemical workstation 440 has a photocurrent monitoring function. Therefore, a photoelectrochemical photodetector based on a simple water reduction reaction as the photoelectric reaction mechanism is basically constituted. The preparation conditions are simple, the purity requirements are low, and the working process has almost no effect on the electrode materials.

As an optional embodiment, the electrolyte solution is an acidic or neutral electrolyte solution, the acidic electrolyte solution includes sulfuric acid, hydrochloric acid, and perchloric acid, the neutral electrolyte solution is sodium sulfate, and the concentration of the electrolyte solution is 0.5 mol/L; the reference electrode is Silver/silver chloride electrode; counter electrode includes platinum electrode and carbon electrode. A complete new solar-blind ultraviolet photoelectrochemical photodetector is formed by the above-mentioned components and the above-mentioned AlGaN nanowire photocathode 300. The new solar-blind ultraviolet photoelectrochemical photodetector can further optimize the photodetection responsivity by modifying the co-catalyst.

Another aspect of the present disclosure proposes a new solar-blind ultraviolet photoelectrochemical photodetector product. FIG. 5 is a schematic diagram of a new solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure. The product includes the above-mentioned photoelectrochemical photodetector and a packaging structure 500 for packaging the photoelectrochemical photodetector. The packaging structure 500 includes a housing structure 510 covering the photoelectrochemical photodetector to encapsulate it; the surface of the housing structure 510 is provided with optical The window 511 is provided with a light-transmitting surface 520 matching the optical window 511 for sealing the optical window 511. The distance between the light-transmitting surface 520 and the photocathode surface with the AlGaN nanowire 120 is greater than or equal to 0.01 mm, and the distance can be Choose 0.2cm, but there is no restriction on the specific spacing. The AlGaN nanowires 120 modified with co-catalyst nanoparticles are used to irradiate solar-blind ultraviolet light on the photocathode 300 through the transparent surface 520. The structure is simple, and the preparation materials are easy to obtain.

As an optional embodiment, the light-transmitting surface 520 includes a transparent material with limited ability to absorb solar-blind ultraviolet light; the shell structure 510 includes a shell structure formed of a polytetrafluoroethylene material. As an optional embodiment, one surface of the housing structure 510 is provided with a sealable/openable injection hole 530, an exhaust hole 540, and at least three electrode holes 550 for setting a photocathode, a reference electrode, and a counter electrode. , 560, 570. The manufacturing process has low requirements and low cost.

It can be seen from the above embodiments that the new solar-blind ultraviolet photoelectrochemical photodetector proposed in the present disclosure has high crystal quality p-type/n-type doped GaN-based nanowires grown on a substrate and has a large surface area. /Volume ratio, more interface contact with the electrolyte solution, which is beneficial to the separation and transportation of photo-generated carriers. In addition, the modification of co-catalyst nanoparticles (such as Pt) on the GaN-based nanowires optimizes the molecular absorption and desorption process, improves the water reduction reaction rate of the photoelectrode in the solution, ensures the photoelectric conversion efficiency, and obtains greater photoelectricity. Response current, higher light response, response time can be accurately adjusted according to actual needs. At the same time, further optimize the design of the photoelectrochemical device, change the electrolyte solution environment, and finally realize a new solar-blind UV detector with high responsiveness, high sensitivity, rapid response, economic and environmental protection, and self-powered (no need for additional electrical energy). The pioneering application of gallium nitride-based nanowires in the research of photoelectrochemical photodetectors has very important significance.

The novel solar-blind ultraviolet photoelectrochemical photodetector product proposed in the present disclosure has simple structure, low manufacturing process requirements, and low cost due to the above-mentioned photoelectrochemical photodetector, and the product has a very simple packaging structure, which is convenient for practical applications. It is easy to produce on a large scale, and can realize the commercialization of the gallium nitride-based nanowire solar-blind ultraviolet photoelectrochemical photodetector of the present invention.

Example 2:

The present disclosure proposes a gallium nitride-based material nanowire structure to be applied to a photodetector, and accordingly proposes a preparation method of the material structure, which overcomes technical problems in the field and achieves a breakthrough unexpected technology effect. Among them, those skilled in the art should understand that the nanowire structure can be a regular arrangement, such as a nanowire structure prepared by directional growth, or it can also include an irregularly arranged nanowire structure. The so-called "regular" can be understood as an arrangement of nanowires. It has periodicity; the so-called "irregularity" can be understood as the arrangement of the nanowires does not have periodicity, and can also be understood as the length and diameter of the nanowires, the distance between adjacent nanowires, and the nanowires on the same substrate. The growth angle of the line (relative to the substrate) is inconsistent, and there is no rule to follow. In addition, in the introduction of gallium nitride-based materials in the present disclosure, for example, AlGaN or InGaN is only a symbolic expression of this material, and does not represent the standard chemical formula of this material. Accordingly, the chemical formula of AlGaN may be Al _x Ga _{1- x} N, one of B _x Al _y Ga _1-xy N or In _x Al _y Ga _1-xy N, 0≤x<1, 0≤y≤1. That is, the gallium nitride-based material may be AlGaN or InGaN, or a gallium nitride-based material such as AlInGaN, which is not limited in the present disclosure.

The photoelectrode mentioned in the claims in the present disclosure can be a photocathode or a photoanode, and can be specifically distinguished by its doping component (such as magnesium doping or silicon doping), which corresponds to the reduction in the present disclosure. Reaction or oxidation reaction. In order to clearly express the function of the photoelectrode in the present disclosure, the present disclosure mainly uses the photoelectrode with the AlGaN or InGaN nanowire structure as an example for description. Those skilled in the art should understand that the AlGaN or InGaN nanowire photocathode mentioned in the specification is not a limitation on the photoanode, nor is it a limitation on the non-AlGaN or InGaN photoelectrode.

As an embodiment of the present disclosure, AlGaN nanowires grown on the surface of the substrate can be grown by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD), which is conventional Chemical vapor deposition, halide vapor phase epitaxy, pulsed laser deposition and other methods are used for preparation, which are not specifically limited in this disclosure. At the same time, in order to express the AlGaN nanowires of the present disclosure more clearly, the following mainly uses molecular beam epitaxy (MBE) as the basic preparation method to introduce.

One aspect of the present disclosure proposes a method for preparing a photoelectrochemical photodetector, as shown in FIG. 6 in a schematic flow chart of a method for preparing a photoelectrochemical photodetector in an embodiment of the present disclosure, the method includes:

S610. Select the AlGaN or InGaN composition according to the wavelength of the light to be detected by the photodetector; in the gallium nitride-based material, by controlling the different composition ratios of aluminum or indium, the corresponding AlGaN or InGaN materials can be obtained, with different composition ratios The band gap of AlGaN or InGaN material changes with the composition ratio of Al/Ga, In/Ga, Al/In/Ga, corresponding to different light absorption wavelengths. In this embodiment, the composition of aluminum in the gallium nitride-based material can be controlled, the composition of indium in the gallium nitride-based material can also be controlled, and the composition of aluminum and indium in the gallium nitride-based material can be controlled at the same time. It is very easy to modify and control the proportion of components, and at the same time it is very accurate. Therefore, the preparation of the nanowire material corresponding to the full-spectrum light wavelength can be better adapted, and the preparation process can be simplified. The above is only the introduction of AlGaN or InGaN in the gallium nitride-based material in the embodiments of the present disclosure. Correspondingly, the aluminum or indium in the gallium nitride-based material can be replaced with boron, and the corresponding composition adjustment can still be applied to the above solution.

S620, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition; as an embodiment of the present disclosure, the gallium nitride-based nanowire structure prepared by the molecular beam epitaxy method is compared with ordinary oxidation Nanomaterials and nitride nanomaterials (such as gallium oxide nanostructures), with high stability, high crystal quality, and adjustable band gap height, which can ensure excellent water reduction/oxidation performance under light irradiation, that is, light detection performance .

S630. Modifying the promoter nanoparticles on the AlGaN nanowires or InGaN nanowires; using a promoter nanoparticle modification method (such as light deposition method) on the AlGaN nanowires or InGaN nanowires, such as atomic layer deposition (Atomic Layer Deposition) Deposition, ALD), electrodeposition (chemical loading method), and dipping method (chemical loading method) modify the co-catalyst nanoparticles on the surface of nanowires.

S640. Encapsulate AlGaN nanowires or InGaN nanowires modified with co-catalyst nanoparticles to obtain photoelectrodes to prevent leakage in the side or back gaps of the substrate. The epitaxy can also be fixed by curing by silver glue and epoxy resin. sheet.

S650, and the use of photoelectrodes to prepare photoelectrochemical photodetectors. The composition of photoelectrochemical photodetectors includes photoelectrodes. After the photoelectrodes are irradiated with light, photogenerated electron-hole pairs are generated to form currents with other components in the photodetectors. In the loop, the generated photocurrent can be detected by the outside world, which can reflect the photoelectric detection capability for applications in military, industrial, and communications fields.

For example, in the preparation process of molecular beam epitaxy, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition in S620 includes: setting aluminum (Al) according to the composition of the corresponding gallium nitride-based material The heating program of the source furnace or the indium (In) source furnace is turned on or off, and the gallium nitride-based nanowires of the corresponding composition are formed on the substrate. According to the embodiments of the present disclosure, using molecular beam epitaxy equipment, each elemental source in the source furnace will generate a corresponding atomic beam under ultra-high vacuum and a certain temperature. At the same time, the on/off and temperature settings of each furnace source can be adjusted to a certain Or the atomic beams generated by multiple furnace sources are precisely controlled to control the generation of gallium nitride-based materials with different compositions. In this embodiment, if the composition of aluminum in the gallium nitride-based material is controlled to grow AlGaN nanowires, it is only necessary to turn on the aluminum furnace source and the gallium source furnace, and turn off the indium furnace source; if the indium is controlled in the gallium nitride-based material To grow InGaN nanowires, you only need to turn on the indium furnace source and the gallium source furnace, and turn off the aluminum furnace source. Therefore, by controlling the temperature of the source furnace to control the volume flow of the atomic beam of each furnace source, and the timing of opening and closing each furnace source, the technical solution of the present disclosure can further accurately control the composition ratio of the nanowire material.

As an optional embodiment, the selection of AlGaN or InGaN components according to the wavelength of the light to be detected by the photodetector includes: determining and determining according to the following formula: Eg=3.42eV+x×2.86eV-x(1-x)1.0eV The AlGaN composition corresponding to the wavelength of the light to be probed; or according to the following formula: Eg=3.42eV-x×2.65eV-x(1-x)2.4eV to determine the InGaN composition corresponding to the wavelength of the light to be probed. Fig. 7 is a simple comparison diagram of the spectra of the photoelectrochemical photodetector in an embodiment of the present disclosure. Generally, the wavelength of light is less than 400nm as the ultraviolet region. Specifically, when the wavelength of light is less than 290nm, the solar-blind ultraviolet region can be reached; visible light The light wavelength is generally between 400nm-700nm; more than 700nm is the infrared light region, and the photoelectrochemical photodetector generally studies the visible light wavelength range. The energy band of the photoelectrode semiconductor material of the photoelectrochemical photodetector is related to the absorption capacity of the material in the corresponding light wavelength range, and the energy band relationship of the photoelectrode semiconductor material is related to the alloy composition ratio of the gallium nitride-based nanomaterial. Therefore, only by controlling the proportion of aluminum or indium when the nanowires are grown, the band gap can be precisely adjusted to achieve full-wavelength absorption of infrared, visible and ultraviolet light.

As an optional embodiment, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition further includes: forming a nanohole array structure on the substrate, and the thickness of the nanohole array structure is less than or equal to 50 nm; The nanoholes are positioned and filled with p-type doped or n-type doped gallium nitride-based materials to form a composite layer, and the nanohole array structure of the composite layer is removed to form gallium nitride-based nanowires on the surface of the substrate.

Specifically, in the embodiments of the present disclosure, the reverse formation principle of nanowires/nanopores can be used to prepare silica nanopore structures on the surface of the substrate, for example, a silica nanopore array layer with a thickness of up to 50 nm, and nanopores. The hole can be directly formed through the silicon dioxide layer with the surface of the substrate as the bottom surface. The gallium nitride-based crystal nucleus can be pre-formed in the nanoholes of the silicon dioxide nanohole structure, and then the nanoholes can be filled by molecular beam epitaxy or MOCVD to form AlGaN nanomaterials or InGaN nanomaterials and fill the nanoholes ; In addition, even if the gallium nitride-based crystal nucleus is not formed in the nanohole, due to the inert nature of silicon dioxide, when the substrate is a silicon substrate or a sapphire substrate, for example, molecular beam epitaxy or MOCVD can also be used directly A gallium nitride-based material is formed on the bottom surface of the nanopore. Silicon dioxide can be removed by chemical etching or optical etching, or it can be retained as an isolation layer. If retained, it may affect the modification of the promoter nanoparticles. Therefore, it is optional to remove the silicon dioxide. Corresponding to the AlGaN nanomaterials or InGaN nanowires forming the nanopore size, the length can be 200nm. Through the above method, the formation of high-quality single-crystal gallium nitride-based nanowires of corresponding wavelengths is faster and simpler, and the shape similarity of adjacent nanowires can also be better achieved. Among them, it should be noted that whether the silicon dioxide layer is removed or not is not the key to this embodiment, and the limiting effect brought about by it restricts the growth of the thin film, so that the present disclosure can control the growth of nanowires in a defined area. In other words, even if the thickness of the silicon dioxide nanohole array layer is only 10-50nm, after filling the nanohole structure on it, the length of the formed AlGaN nanomaterial or InGaN nanowire can still be grown to 200nm.

As another embodiment of the present disclosure, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition further includes: forming a nanohole array structure on the substrate, and the thickness of the nanohole array structure is less than or equal to 50 nm; Positioning and filling the gallium nitride-based material in the nanoholes forms a composite layer, and continues to form gallium nitride-based nanowires on the surface of the composite layer at positions corresponding to the nanoholes. At this time, the composite layer is not removed. On the one hand, the thickness of the composite layer is very small, for example, a 20nm composite layer can be selected; on the other hand, the selective area growth method can directly correspond to the nanopore composite layer along the position of the nanopore. The other parts of the nanowires directly form nanowires. The nanowires will actually protrude from the surface of the composite layer and can reach a size of several hundred nanometers or even micrometers. Therefore, the size of the nanowires will be much larger than the size of the composite layer without removing the composite layer. In this case, it will not affect the function of the nanowire.

As an optional embodiment, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition, further comprising: forming an AlGaN film or an InGaN film on the substrate; Etching is performed to form the AlGaN nanowires or InGaN nanowires on the surface of the substrate. Specifically, in the embodiments of the present disclosure, an AlGaN film or InGaN film of high crystal quality can be directly formed on the substrate by molecular beam epitaxy or MOCVD method, and then formed on the AlGaN film or InGaN film by micro-nano processing technology. Photoresist, silicon dioxide or small metal islands can be subsequently etched by dry etching methods such as Inductively Coupled Plasma (ICP) or other dry etching methods for AlGaN films or InGaN films. The etching speed of silicon or metal is slower, and the remaining unprotected parts are etched faster to form AlGaN nanowires or InGaN nanowires on the substrate. Wherein, the corresponding substrate can be a silicon wafer or a sapphire substrate. Through the above method, the formation of high-quality single-crystal gallium nitride-based nanowires with corresponding wavelengths is more direct and simple, and the shape similarity of adjacent nanowires is better, the shape of the nanowires is more stable, and the shape is regular and controllable.

As an optional embodiment, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the above composition includes: controlling the doping ratio of magnesium or silicon, and forming p-type doping with corresponding doping ratio on the substrate Or n-type doped AlGaN nanowires or InGaN nanowires. Specifically, as an embodiment of the present disclosure, during the preparation process of the molecular beam epitaxy method, by controlling the switching of the silicon (Si) source furnace and/or the magnesium (Mg) source furnace and the temperature of the source furnace, the nanowire material can be precisely controlled. Doping concentration.

As an optional embodiment, in the preparation process of molecular beam epitaxy, forming AlGaN nanowires or InGaN nanowires on the surface of the substrate according to the composition includes: setting the substrate in the preparation cavity, and at the first temperature Degas the preparation chamber for at least the first time, transfer the substrate set in the preparation chamber to the buffer chamber, degas the buffer chamber at the second temperature for at least the second time, and transfer the substrate in the buffer chamber to the growth chamber. Growth of AlGaN nanowires or InGaN nanowires. Specifically, in this embodiment, taking the formation of AlGaN nanowires as an example, molecular beam epitaxy (MBE) equipment can be used, and a p-type Si (100) substrate (ie, silicon wafer) is used as the substrate to transfer the silicon wafer The MBE equipment preparation cavity (for example, load lock cavity) is used for degassing preparation, so that the MBE equipment reaches the corresponding vacuum degree, for example, the vacuum degree can reach 10 ^-9 , and the baking and degassing time is at least satisfied at the first temperature of 200 ℃. The first time is 1 hour, after that, the silicon wafers in the preparation chamber are sent to the buffer chamber, and the baking and degassing time is maintained at the second temperature of 600℃ for at least 2 hours in the second time to remove the water in the buffer chamber as much as possible And the adsorption of gas molecules to silicon wafers. After the degassing is completed, the silicon wafer is transferred to the growth chamber for the growth of AlGaN nanowires.

As an optional embodiment, during the preparation process of molecular beam epitaxy, the aluminum (Al) source furnace or the indium (In) source furnace is controlled to be turned on or off, and the temperature rise program of the source furnace is controlled according to the corresponding AlGaN or InGaN group. The formation of AlGaN nanowires or InGaN nanowires of the corresponding composition on the substrate includes: after the substrate is transferred to the growth chamber, controlling the opening of the gallium (Ga) source furnace connected to the growth chamber to achieve the first equivalent The pressurized gallium beam is used as the gallium source and the plasma nitrogen of the first volume flow rate is used as the nitrogen source, and maintained at the third temperature for at least a third time to form a GaN seed crystal on the surface of the substrate. Specifically, in this embodiment, molecular beam epitaxy (MBE) equipment can be used, with a p-type Si (100) substrate (ie silicon wafer) as the substrate, and after the silicon wafer enters the growth chamber, the opening and the growth chamber are controlled to be opened. The connected gallium source furnace uses the first equivalent pressure (BEP) 6.0×10 ^-8 Torr gallium beam as the gallium source and the first volume flow rate of 1sccm plasma nitrogen to form high-brightness nitrogen plasma as the nitrogen source. Keep the temperature at 500℃ for at least the third time for 1 minute to form GaN seed crystals on the surface of the silicon wafer, increase the possibility of nucleation, and form the basis for the growth of nanowires on the silicon wafer, so that higher crystal quality can be grown on the silicon wafer Of nanowires.

As an optional embodiment, during the preparation process of molecular beam epitaxy, the aluminum (Al) source furnace or the indium (In) source furnace is controlled to be turned on or off, and the temperature rise program of the source furnace is controlled according to the corresponding AlGaN or InGaN group. In addition, forming the AlGaN nanowires or InGaN nanowires of the corresponding composition on the substrate further includes: controlling to turn on the aluminum source furnace or the indium source furnace, and under the condition that the plasma nitrogen of the first volume flow rate is used as the nitrogen source, At four temperatures, the aluminum beam with the second equivalent pressure or the indium beam with the third equivalent pressure is matched with the gallium beam with the fourth equivalent pressure to form AlGaN nanowires or InGaN nanowires of the corresponding composition on the surface of the substrate line. Specifically, in this embodiment, taking the formation of AlGaN nanowires as an example, the aluminum source furnace is controlled to open, and under the condition that the first volume flow rate of 1sccm plasma nitrogen is used as the nitrogen source, the second temperature is maintained at 610°C. equivalent pressure 2.0 × 10 ^-8 Torr aluminum beam, with the fourth equivalent pressure 3.0 × 10 ^-8 Torr gallium beam, an AlGaN nanowire corresponding components in the silicon surface. If InGaN nanowires are formed, due to the difference between aluminum and indium, it is necessary to turn on the indium furnace source and keep the aluminum furnace source closed, and replace the corresponding aluminum beam current parameters with an indium beam with ^{a third equivalent pressure of 4.0×10 -8 Torr} , Other steps need not be modified. Therefore, the proportion of the alloy between aluminum and indium in the nanowire can be accurately controlled by the above method, so as to achieve the AlGaN nanowire or InGaN nanowire with the corresponding light wavelength. The composition ratio of aluminum or indium is estimated by comparing the BEP of aluminum or indium and gallium beams, and the BEP ratio is adjusted by controlling the temperature to achieve the purpose of adjusting the composition. For example, during the preparation of AlGaN nanowires corresponding to ultraviolet light, Adjust the Al equivalent pressure (BEP) between 6×10 ^-8 Torr and 1×10 ^-8 Torr to achieve the purpose of adjusting the Al composition; or, the preparation process of InGaN nanowires corresponding to visible light and infrared light In this, the purpose of regulating the In composition is achieved by adjusting the BEP of indium between 4×10 ^-8 Torr and 1×10 ^{-8 Torr.}

As an optional embodiment, during the preparation process of molecular beam epitaxy, the aluminum (Al) source furnace or the indium (In) source furnace is controlled to be turned on or off, and the temperature rise program of the source furnace is controlled according to the corresponding AlGaN or InGaN group. In addition, forming the AlGaN nanowires or InGaN nanowires of the corresponding composition on the substrate also includes: controlling the opening or closing of the aluminum (Al) source furnace or the indium (In) source furnace, setting the temperature of the magnesium source furnace to the first Control the magnesium source furnace or the silicon source furnace to open or close at five temperatures or when the silicon source furnace is the sixth temperature, so that the AlGaN nanowires or InGaN nanowires of the corresponding composition formed on the substrate become p-type doped or n Type doping. The photoelectrode is divided into photoanode or photocathode. Correspondingly, p-type doped AlGaN nanowires or InGaN nanowires can better complete the water reduction reaction, especially when the surface is modified with co-catalyst nanoparticles, it can be used as photoelectrochemistry The photocathode of the system. Generally, a certain proportion of magnesium can be doped to make the doped AlGaN nanowires or InGaN nanowires become p-type doped materials. This doping method can achieve better material stability and will not treat doped materials. For any impact, the water reduction reaction will respond better in the later stage. On the contrary, n-type doped AlGaN nanowires or InGaN nanowires can better complete the water oxidation reaction, especially when the surface is modified with co-catalyst nanoparticles, it can be used as a photoanode in a photoelectrochemical system. Generally, a certain proportion of silicon can be doped to make the doped AlGaN nanowires or InGaN nanowires become n-type doped materials. This doping method can achieve better water oxidation reaction response. Specifically, in this embodiment, taking the preparation of p-type AlGaN nanowires as an example, when the aluminum (Al) source furnace is controlled to be turned on while ensuring that the indium (In) source furnace is closed, the magnesium source furnace is turned on, and the temperature of the magnesium source furnace is The fifth temperature is 360°C, so that the AlGaN nanowires of the corresponding composition formed on the substrate become p-type doped. On the contrary, if the preparation of n-type InGaN nanowires is taken as an example, the silicon source furnace needs to be turned on, and the sixth reaction temperature of the silicon source furnace is 1180°C.

As an optional embodiment, modifying the promoter nanoparticles on the AlGaN nanowires or InGaN nanowires includes: disposing the AlGaN nanowires or InGaN nanowires in a precursor aqueous solution of a first concentration, and simultaneously applying the nanowires and the nanowires. It can be irradiated with light of corresponding wavelength to modify the promoter nanoparticles on the surface of AlGaN nanowires or InGaN nanowires. Specifically, in this embodiment, taking the preparation of p-type AlGaN nanowire modified promoter Pt nanoparticles as an example, a certain concentration of chloroplatinic acid solution can be selected as the precursor aqueous solution, and the grown p-type Al _x Ga _{1 -x} N nanowires are placed in 50mL deionized water, in a sealed container, the reaction temperature is maintained at 10℃ by circulating water cooling method, and a certain vacuum degree is maintained. At the same time, inert gas such as argon is introduced into the container as a protective gas, and 1ml A chloroplatinic acid solution with a concentration of 10 mg/ml is injected into the container, and light with a wavelength corresponding to the band gap of the _{Al x} Ga _{1-x N nanowire is applied, and the light is maintained for more than 30 minutes.} Due to the semiconductor photoelectric effect, Al _x Ga _1-x N nanowires absorb photons and generate photo-generated electron-hole pairs. Then the photogenerated electrons diffuse to the surface of the nanowires. Because the energy of the photogenerated electrons is greater than _{the reduction potential of the platinum acid radical ([PtCl 6} ] ^2- ) group in the solution, the photogenerated electrons diffused to the surface of the nanowire will be reduced and adsorbed on the surface of the nanowire. PtCl ₆ ] ^2- , forming platinum particles on the surface of the nanowires, that is, the photodeposition process. After the photodeposition reaction is completed, the sample is taken out and cleaned to obtain the p-type AlGaN nanowires modified with the promoter platinum nanoparticles, in which the particle size of the platinum particles can reach 0.1nm-1000nm. For n-type nanowires, it is only necessary to replace the precursor aqueous solution of chloroplatinic acid solution with a ruthenium chloride solution of equal concentration. By distributing the modified cocatalyst nanoparticles on the surface of the nanowires, the photoelectrode can react more intensely during the water reduction/oxidation reaction, the reaction speed is faster, and the photocurrent is larger.

As an optional embodiment, before the AlGaN nanowires or InGaN nanowires are modified with the promoter nanoparticles, the method further includes: when the AlGaN nanowires or InGaN nanowires are n-type doped, adding the catalyst nanoparticles to the AlGaN nanowires or InGaN nanowires A protective layer is prepared on the surface of the wire. Since n-type doping is easier to achieve in the preparation process of molecular beam epitaxy, the grown nanowires are easy to be corroded by self-generated photo-generated holes during the photodeposition or photodetection process, thus causing certain impact on the photoanode Therefore, it is necessary to prepare a nanowire protective layer on the surface of the nanowire on the basis of the nanowire of the photoanode that has a tunnel conduction effect and at the same time has good conductivity and does not affect the light detection performance. Specifically, in this embodiment, taking the preparation of n-type InGaN nanowires as an example, before photo-depositing them to modify the promoter nanoparticles, an atomic layer deposition method is used to directly deposit a layer of n-type InGaN nanowires on the surface of the n-type InGaN nanowires. A shaped protective layer. The material of the protective layer can be TiO ₂ or a material with similar properties to prevent the n-type InGaN nanowire material from photo-corrosion under the condition of hole enrichment. Taking the amorphous TiO ₂ protective layer as an example, tetrakis(dimethylamino)titanium(IV) TEMAT and water can be used as precursors in the preparation process, and the precursor containers are kept at 65°C and 25°C, respectively, for 60 cycles of co-deposition. Each cycle includes the process of introducing titanium precursor for 0.1 seconds, plasma nitrogen for 10 seconds, water vapor for 0.1 seconds, and N ₂ for 10 seconds. Finally, amorphous TiO can be formed on the surface of n-type InGaN nanowire materials. ₂ protective layer.

As an optional embodiment, encapsulating AlGaN nanowires or InGaN nanowires with modified promoter nanoparticles to obtain a photoelectrode includes: fixing and attaching wires to AlGaN nanowires or InGaN nanowires with modified promoter nanoparticles On the conductive area of the wire substrate, the wire and the substrate are covered and fixed while exposing the AlGaN nanowire or the InGaN nanowire to form a packaged photoelectrode. To encapsulate the photoelectrode, attention needs to be paid to lead out the wires, and also attention to expose the nanowires of the photoelectrode. When pulling out the wire, it should be noted that one end of the wire needs to be opposite to the predetermined conductive area of the silicon wafer. The conductive area can be the back or the front of the silicon wafer and use a diamond pen to scrape off a certain area other than the nanowires. The exposed photocathode nanowires facilitate the light of the corresponding light wavelength to directly irradiate the nanowires.

As an optional embodiment, fixing and attaching the wire to the conductive area of the substrate of AlGaN nanowires or InGaN nanowires with modified promoter nanoparticles includes: scraping off the oxide layer on the conductive area of the substrate, and The conductive area where the oxide layer is removed is coated with liquid alloy, and the conductive glue is coated on the surface of the wire between the wire and the conductive area and opposite to the position of the liquid alloy. In order to prevent the direct contact between the substrate used and the metal wire, which would form a Schottky barrier that is not conducive to current conduction, a photoelectrode with ohmic contact characteristics should be prepared. Specifically, in the embodiments of the present disclosure, a silicon wafer is used as an example. First, a diamond knife is used to scrape off the silicon dioxide (SiO ₂ ) layer naturally grown on the back of the silicon wafer. The conductive area on the back of the sheet is coated with a liquid alloy (such as a gallium indium (GaIn) alloy) to form an ohmic contact. Then apply conductive paste silver (Ag) glue on the copper (Cu) strip of the wire, and compact it with the back of the silicon wafer coated with gallium indium alloy, and finally wrap the entire photoelectrode with epoxy resin, leaving only nanometers The line growth surface is exposed, thereby completing the preliminary packaging of the photoelectrode, avoiding the formation of the Schottky barrier, and facilitating the conduction of the photocurrent.

As an optional embodiment, using a photoelectrode to prepare a photoelectrochemical photodetector includes: arranging the photoelectrode, a reference electrode, and a counter electrode in a second concentration of electrolyte solution at a certain interval to prepare a three-electrode system to form a photoelectrochemistry Light detector. Specifically, in the embodiments of the present disclosure, taking the photocathode three-electrode system for preparing p-type AlGaN nanowires as an example, an electrolyte solution solution (with a second concentration of 0.5 mol/L sulfuric acid (H ₂ SO ₄ ) Aqueous solution as an example), then the Al _x Ga _1-x N nanowire electrode (photocathode), reference electrode (taking silver/silver chloride (Ag/AgCl) as an example), and counter electrode (taking The platinum Pt mesh electrode as an example) is placed in the electrolyte solution solution, the preparation of the three-electrode system is completed, and the photoelectrochemical photodetector of the present disclosure is basically formed. Connect the electrochemical workstation to the conductive end of each electrode, and set the test parameters of the electrochemical workstation through the computer, that is, the light detection performance test or application can be performed. Correspondingly, taking the photoanode of n-type InGaN nanowires as an example, the electrolyte solution can be replaced with a 1 mol/L hydrobromic acid solution. The preparation process of the three-electrode system is simple and easy to implement, which greatly simplifies the preparation process of the photodetector and makes it suitable for mass production.

Another aspect of the present disclosure provides a photoelectrochemical photodetector, which is prepared by applying the above-mentioned photoelectrochemical photodetector preparation method. The photodetector includes a photoelectrode with gallium nitride-based nanowires.

Example 3:

One aspect of the present disclosure proposes a solar-blind ultraviolet photoelectrochemical photodetector. FIG. 8A is a schematic diagram of a solar-blind ultraviolet photoelectrochemical photodetector GaN-based nanohole array in an embodiment of the present disclosure, and FIG. 8B is the present disclosure As shown in a schematic diagram of a solar-blind ultraviolet photoelectrochemical photodetector modified with a GaN-based nanohole array of cocatalyst nanoparticles in an embodiment, the photodetector includes a photoelectrode, the photoelectrode includes a substrate 810, and also includes a substrate 810 The GaN-based nanohole 840 array 830 formed on the surface of the 810 constitutes the basic structure 800 of the photocathode of the novel photoelectrochemical photodetector proposed in the present disclosure.

Among them, those skilled in the art should understand that the nanopore structure can be a regular arrangement, such as a nanopore structure prepared by directional growth, or it can also include an irregular, disordered nanopore structure. The so-called "regular" can be understood as a nanopore structure. Whether the arrangement is periodic. l In addition, the gallium nitride-based material can be selected as AlGaN in the present disclosure. AlGaN is only a symbol expression for this material, and does not represent the standard chemical formula of this material. Specifically, the GaN-based chemical formula can be one of B _x Al _y Ga _1-xy N or In _x Al _y Ga _1-xy N, 0≤x<1, 0≤y≤1. That is, the gallium nitride-based material may be AlGaN or InGaN, or a gallium nitride-based material such as AlInGaN, which is not limited in the present disclosure.

The photoelectrode mentioned in the claims in the present disclosure can be a photocathode or a photoanode, and can be specifically distinguished by its doping component (such as magnesium doping or silicon doping), which corresponds to the reduction in the present disclosure. Reaction or oxidation reaction. In order to clearly express the function of the photoelectrode in the present disclosure, the present disclosure mainly uses the AlGaN photocathode as an example for description. Those skilled in the art should understand that it is not a limitation on the photoanode, nor is it a limitation on the non-AlGaN photoelectrode.

As an embodiment of the present disclosure, the AlGaN nanohole array grown on the substrate can be conventionally performed by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD). Chemical vapor deposition, halide vapor phase epitaxy, pulsed laser deposition and other methods are used for preparation, which are not specifically limited in this disclosure. At the same time, in order to express the AlGaN nanohole array of the present disclosure more clearly, the following mainly uses metal organic chemical vapor deposition (MOCVD) as a basic preparation method for introduction.

Oriented formation of high crystal quality n-type doped AlGaN nanohole arrays on the surface of the substrate. Compared with ordinary oxide and nitride nanomaterials (such as gallium oxide nanostructures), it has high stability and high crystal quality. The advantages of matching and adjustable gap height can ensure excellent water oxidation performance under solar blind light irradiation, that is, light detection performance. In addition, for AlGaN materials, the band gap can be changed with the doping of the composition, specifically:

Eg=3.42eV+x*2.86eV-x(1-x)*1.0eV…………………………(1)

Eg is the semiconductor forbidden band width, corresponding to different absorption wavelengths.

Therefore, according to formula (1), by controlling the proportions of Al and Ga in the preparation process, the band gap of the prepared photoanode can be precisely adjusted to achieve light absorption in the solar-blind ultraviolet band.

In addition, the AlGaN nanopores with high crystal quality prepared in the present disclosure can be p-type doped materials, specifically, silicon Si atoms can be doped, and they move to the electrolyte solution/semiconductor interface as electrons during the subsequent photoelectrochemical reaction process. It will have any impact on AlGaN nanomaterials or structures. Compared with oxide nanomaterials (such as gallium oxide nanostructures) that have not yet been realized, the stability is very high. Correspondingly, the prepared AlGaN nanopores of the present disclosure may be p-type doped materials, specifically, magnesium Mg atoms may be doped in order to prepare them for use as a photocathode. It should be noted that in the structure of the photoanode, a protective layer of a certain thickness needs to be deposited on the surface of the photoanode to prevent it from being corroded by photo-generated holes during the photodetection process.

As shown in FIG. 8A, as an embodiment of the present disclosure, the AlGaN nanohole 840 may be a cylindrical hole, a prismatic or other regular hole, or a curved shape or other irregular hole, and the nanohole 840 may be a cylindrical hole. The diameter of the nanopore 840 is 0.1 μm-5 μm, and the optional diameter is 2 μm; its depth is 50 nm-600 nm, and the optional depth is 200 nm. This makes the specific surface area of the nanopore 840 array larger, and at the same time increases the specific surface area of the photodetection reaction. In addition, the pore size of the nanopore 840 exceeds 500 nm, which is far beyond the design size of conventional nanopores, and is not considered a nanoscale structure in a certain sense. This size design can prevent the bubbles generated in the subsequent photodetection process from adhering to the inner surface of the nanopore 840 to cause difficulty in mass transfer of the solution. The large-diameter nanopore design is likely to cause unstable performance such as short circuits, and is used in the field. There is no such large-diameter nanopore design research in China, which will hinder those skilled in the art from implementing this solution. Therefore, this is a breakthrough design scheme in the field, which is beyond the imagination of those skilled in the art.

As an embodiment of the present disclosure, the filling degree of the AlGaN nanohole array can be defined by patterning conditions, the distance between adjacent nanoholes is 0.1 μm-5 μm, and the optional distance is 2 μm. The specific surface area of the nanopore array is made larger, and the specific surface area of the photodetection reaction is increased at the same time.

As shown in FIGS. 8A-8B, as an embodiment of the present disclosure, the substrate 810 includes a sapphire substrate, a gallium nitride substrate, a gallium oxide substrate, a silicon carbide substrate, a silicon substrate, or a thin film of GaN-based material. Substrate, etc. or other substrates with conductive properties. The optional substrate is a sapphire substrate, and in the embodiment of the present disclosure, the substrate material may be aluminum oxide Al ₂ O ₃ or the like.

As an embodiment of the present disclosure, the GaN-based nanohole array is an n-type GaN-based nanohole array, and the surface of the GaN-based nanohole array of the photoelectrode further includes a protective layer covering the surface of the nanohole array. The thickness of the protective layer is less than or equal to 10 nm to protect The layer material includes at least titanium dioxide. The protective layer is used to prevent the photo-corrosion phenomenon of the nanoholes. Correspondingly, for the corresponding p-type gallium nitride-based nanoholes in the present disclosure (for example, AlGaN or InGaN nanoholes, etc., it is not limited here, and is subject to the protection scope defined by the claims), which can be used as the photoelectricity in the present disclosure. The photocathode of the chemical photodetector (corresponding to the gallium nitride-based nanowire photocathode in the foregoing embodiment). Correspondingly, it is optional to directly modify the cocatalyst nanoparticles on the surface of the p-type nanopore, and it is not necessary to modify the cocatalyst The nanoparticles previously formed at least one protective layer on the surface of the nanopore, which will not be repeated here.

Due to the lattice matching, an AlGaN single crystal film with stable and high crystal quality can be epitaxially formed on the substrate 810, which is beneficial to the preparation of the nanohole array in the next step.

As shown in FIGS. 8A-8B, as an embodiment of the present disclosure, a buffer layer 820 is further included between the substrate 810 and the AlGaN nanohole array 830. The buffer layer 820 includes at least three intermediate layers, and the material of the buffer layer includes aluminum nitride. . Since the crystal lattices of the substrate 810 and the AlGaN nanohole array 830 are not matched, adding a buffer layer 820 between the two is beneficial to obtain a stable and high-quality AlGaN single crystal film during the preparation process, which is beneficial to the next step Preparation of nanopore arrays.

As an embodiment of the present disclosure, the buffer layer 820 includes at least three intermediate layers. The first intermediate layer formed on the substrate 810 has a thickness of 3 μm and is used as a nucleation layer; the first intermediate layer formed on the first intermediate layer The second intermediate layer may have a thickness of 100 nm; the third intermediate layer formed on the second intermediate layer may have a thickness of 1 μm, which is used as a template layer. The above-mentioned multiple intermediate layers are not shown in the drawings. The composition of the multi-layer intermediate layer is conducive to the formation of a smoother surface of the third intermediate layer (that is, the surface of the buffer layer 820), so that a stable and high-quality AlGaN single crystal film can be obtained during the preparation process, which is beneficial to the next step of nanopores. Preparation of the array. Correspondingly, for the corresponding p-type gallium nitride-based nanoholes in the present disclosure (for example, AlGaN or InGaN nanoholes, etc., it is not limited here, and is subject to the protection scope defined by the claims), which can be used as the photoelectricity in the present disclosure. The photocathode of the chemical photodetector (corresponding to the gallium nitride-based nanowire photocathode in the foregoing embodiment), correspondingly, the gallium nitride-based nanopore structure can be formed directly on the surface of the substrate without considering the The above-mentioned buffer layer structure is added between the nanopore structure and the substrate.

As shown in FIG. 8B, as an embodiment of the present disclosure, the surface of the AlGaN nanohole array is further covered with a protective layer 870, the thickness of the protective layer 870 is less than or equal to 10 nm, and the optional thickness dimension is 2 nm. In the embodiments of the present disclosure, the protective layer may be an amorphous titanium dioxide TiO ₂ protective layer covering the entire surface of the AlGaN nanohole array, including the inner surface of the nanoholes, to prevent the AlGaN material from being rich in holes during the photodetection process. The photo-corrosion effect occurs under the set conditions, affecting the overall performance of the photodetector.

As shown in FIG. 8B, as an embodiment of the present disclosure, the photoanode further includes co-catalyst nanoparticles 850 distributed on the surface of the protective layer. The co-catalyst nanoparticles 850 are metal particles active in the water redox reaction. The material of the metal particles includes platinum. , Iridium, iron, cobalt, nickel or ruthenium, etc. and their multiple alloys, the alloy is the use of two metals at the same time, such as RuFe, RuCo, etc. In the present disclosure, ruthenium can be selected as the preparation choice of the co-catalyst nanoparticles, and the diameter size of the co-catalyst nanoparticles can be 0.1nm-1000nm, and can be 2nm for better and more modification in the nanopore array. The co-catalyst nanoparticles distributed on the nanohole array can make the AlGaN nanohole array have a stronger water oxidation reaction, so that the photodetector has a stronger photoresponse and a faster photoresponse speed.

As shown in FIG. 8B, as an embodiment of the present disclosure, the surface of the AlGaN nanohole array further includes a first region 860 that is not covered with the protective layer 870, and the first region 860 is disposed outside the nanohole region. The first area is formed on the surface of the nanohole array and does not overlap with the area where the nanoholes are located, so as to prevent the occurrence of short circuits, and also makes the lead electrode more stable and effective.

As an embodiment of the present disclosure, the first area 860 includes a dot-welded indium ball, which is used to form a conductive area of the photoanode, and is used to draw the photoanode. By spot welding indium balls, a conductive area in ohmic contact with the surface of the nanohole array can be formed on the first area 860. The conductive area can be a square area of 2mm×2mm, which can achieve better conductive characteristics and current stability, and can be fixed at the same time The wire leads to the electrode to form a photoanode.

As an embodiment of the present disclosure, similar to the structure of the photoelectrochemical photodetector formed by the photocathode, the photoelectrochemical photodetector further includes: an electrolyte solution in contact with the photoanode, and a reference electrode and a counter electrode in contact with the electrolyte solution, A certain distance is maintained between the reference electrode, the counter electrode, and the photoanode, where the distance is approximately equal to 0.01 mm; wherein, the reference electrode, the counter electrode, and the photoanode are respectively connected to an electrochemical workstation with current monitoring function. Therefore, a photoelectrochemical photodetector based on a simple water oxidation reaction as a photoelectric reaction mechanism is basically constituted. The preparation conditions are simple, the purity requirements are low, and the working process has almost no influence on the electrode materials.

As an embodiment of the present disclosure, the electrolyte solution includes an acidic or neutral electrolyte solution, the neutral electrolyte solution is sodium sulfate, the acidic electrolyte solution includes phosphoric acid buffer or hydrobromic acid, and the concentration of the electrolyte solution is 0.01 mol/L to 5 mol/L, The present disclosure can choose weak acid electrolyte solutions such as 0.5mol/L hydrobromic acid solution; reference electrodes are silver/silver chloride (Ag/AgCl) electrodes, etc.; counter electrodes include platinum (Pt) electrodes, carbon (C) electrodes, etc. , The specific structure can be made into a mesh electrode and other forms. A complete new solar-blind ultraviolet photoelectrochemical photodetector is formed by the above-mentioned components and the above-mentioned AlGaN nanohole array photoanode together. The new solar-blind ultraviolet photoelectrochemical photodetector can further optimize the photodetection response by modifying the co-catalyst nanoparticles.

Another aspect of the present disclosure provides a solar-blind ultraviolet photoelectrochemical photodetector product, which is similar to the product structure of the photocathode photodetector. The product includes the above-mentioned photodetector and a packaging structure for packaging the photodetector. The packaging structure It includes a housing structure covering the photodetector to encapsulate it; an optical window is opened on one surface of the housing structure, and a light-transmitting surface matched with the optical window for sealing the optical window is provided. The light-transmitting surface is equipped with an AlGaN nanohole array The surface of the photocathode is set at a certain distance, where the distance is approximately equal to 0.01mm. In this embodiment, the distance can be selected to be 0.2cm, which is used for solar-blind ultraviolet light irradiated on the photoanode through the light-transmitting surface. The catalyst nanoparticles are distributed AlGaN nanohole array. The structure is simple, and the preparation materials are easy to obtain.

As an embodiment of the present disclosure, the light-transmitting surface includes a transparent material with limited ability to absorb solar-blind ultraviolet light; the shell structure includes a shell structure formed of a polytetrafluoroethylene material. As an optional embodiment, one surface of the housing structure is provided with a sealable/openable injection hole, an exhaust hole, and at least three electrode holes for setting a photocathode, a reference electrode, and a counter electrode, respectively. The manufacturing process has low requirements and low cost.

The present disclosure proposes a new type of solar-blind ultraviolet photoelectrochemical photodetector product, because the photoelectrochemical photodetector has simple structure, low manufacturing process requirements, low cost, and the product has a very simple packaging structure, which is convenient for practical applications. It is easy to produce on a large scale, and realizes the commercialization of photoelectrochemical photodetectors.

Another aspect of the present disclosure provides a method for preparing a solar-blind ultraviolet photoelectrochemical photodetector, which is applied to prepare the above-mentioned photodetector, as shown in FIG. 9 for a method for preparing a solar-blind ultraviolet photoelectrochemical photodetector in an embodiment of the present disclosure. As shown in the schematic flow chart, the preparation method includes:

S910, forming an AlGaN nanohole array on the surface of the substrate; specifically, as an embodiment of the present disclosure, metal organic chemical vapor deposition (MOCVD) may be selected to prepare it, and triethyl boron may be selected in the preparation process Alkane (TEB), trimethylaluminum (TMAl), trimethylgallium (TMGa), ammonia (NH3) are used as growth precursors to provide B, Al, Ga, and N sources, Si is used as n-type doping source, and H2 As a carrier gas. In gallium nitride-based materials, the corresponding AlGaN materials can be obtained by controlling the composition ratios of different aluminum and gallium. AlGaN materials with different composition ratios can make the energy band of the material itself correspond to different, and the band gap varies with the doping composition. Change to correspond to different light absorption wavelengths. In this embodiment, the composition of aluminum in the gallium nitride-based material can be controlled, and the modification and control of the composition ratio is very simple and precise at the same time. Therefore, it can better adapt to the preparation of nanomaterials corresponding to the broad spectrum light wavelength, and can also accurately control the formation of nanomaterials adapted to the solar-blind ultraviolet light wavelength, simplifying the preparation process. At the same time, silicon is used to dope the formed AlGaN nanohole array to obtain an n-type doped AlGaN nanohole array that is more suitable for photoanodes, which is beneficial to improve the water oxidation reaction of the photodetector and improve the photocurrent response intensity and speed.

S920. Modifying the promoter nanoparticles on the nanoholes of the AlGaN nanohole array; specifically, as an embodiment of the present disclosure, optical deposition or atomic layer deposition (Atomic Layer Deposition) is used on the nanoholes of the AlGaN nanohole array. , ALD), electrodeposition method (chemical loading method), impregnation method (chemical loading method) to modify the co-catalyst nanoparticles on the surface/side of the nanoporous structure.

S930. Prepare a photodetector by using the AlGaN nanohole array modified with the promoter nanoparticles as a photoanode.

The photoanode functional layer is prepared on the surface of the substrate to ensure a higher crystal quality AlGaN nanohole array at a lower cost; a buffer layer is formed between the substrate and the AlGaN nanohole array to improve the film-forming effect of the AlGaN film. At the same time, the formation of high crystal quality AlGaN nanohole arrays is ensured; the surface of the AlGaN nanohole arrays is covered with an amorphous protective layer, which can prevent the photoanode from being photo-corrosive during the photodetection process, affecting the overall photodetection performance of the photodetector; In addition, the modification of the promoter nanoparticles on the surface of the protective layer further increases the water oxidation reaction rate, thereby improving the ultraviolet light response.

As shown in FIG. 10A, a schematic diagram of the first stage of the AlGaN nanohole array preparation process in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in an embodiment of the present disclosure, as an embodiment of the present disclosure, an AlGaN nanohole array is formed on the surface of the substrate. Including: pre-annealing the substrate 810; forming a buffer layer 820 on the pre-annealed substrate 810; according to an embodiment of the present disclosure, before growth, the sapphire substrate is pre-treated at 1200°C _{in an H 2} -NH _{3 environment} , 5 minutes of high temperature annealing, making the surface of the sapphire substrate cleaner and smoother, and more suitable as the substrate of the AlGaN nanohole array. The AlGaN nanohole array can be formed on the surface of the buffer layer 820 of the substrate 810 by metal organic chemical vapor deposition, MOCVD, or molecular beam epitaxy (MBE), and the specific method is not limited. Before forming the AlGaN nanohole array, an AlGaN film 831 is pre-formed on the surface of the buffer layer 820. According to an embodiment of the present disclosure, a 200nm AlGaN film is grown on the buffer layer at a temperature of 1150°C. The thin film 831 is operated to form a nanohole array. By forming the thin film 831 first, the high crystal quality for forming the nanohole array can be guaranteed.

As an embodiment of the present disclosure, forming a buffer layer 820 on a pre-annealed substrate 810 includes: including at least two intermediate layers (not shown) on the buffer layer 820; forming a second layer on the substrate 810 under a first condition An intermediate layer, a second intermediate layer is formed on the first intermediate layer under the second condition; and a third intermediate layer is formed on the second intermediate layer under the third condition. Specifically, the buffer layer 820 is formed on the pre-annealed sapphire substrate 810, and MOCVD can be selected as the preparation method, including: AlN is used as the buffer layer preparation material, and the TMAl and NH3 are firstly heated at a temperature of 850°C-950°C. The volume flow rate was controlled under the first conditions of 4sccm and 3000sccm to form a low-temperature AlN nucleation layer with a thickness of 3μm on the sapphire substrate 810 as the first intermediate layer; under the second condition at the temperature of 850-1250℃, An AlN spacer layer with a thickness of up to 100nm is formed on the first intermediate layer as the second intermediate layer; a high-temperature AlN template with a thickness of 1μm is formed on the second intermediate layer under the third condition of 1250℃ and V/III of 180 Layer, as the third intermediate layer. The structure of the multi-layer intermediate layer is beneficial to form a smoother surface of the third intermediate layer (that is, the surface of the buffer layer 820), so that a stable and high-crystalline AlGaN nanohole array can be obtained during the preparation process.

As an embodiment of the present disclosure, forming an AlGaN nanohole array on the surface of the buffer layer of the substrate includes: forming an AlGaN film on the buffer layer under the fourth condition; etching the film to form an AlGaN nanohole array. As shown in the schematic diagram of the first stage of the AlGaN nanohole array preparation process in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in each embodiment of the present disclosure in FIGS. 10A to 10F, a cylindrical nanohole array is prepared by micro-nano processing technology, wherein The AlGaN thin film may be formed on the third intermediate layer. As shown in FIGS. 10A to 10B, the described fourth conditions include any preparation conditions used in the following steps: using photoresist of model S1813 as the etching sacrificial layer 910 in the subsequent etching process, and the coating rate is controlled At 4000 revolutions/min for 30 seconds, a photoresist sacrificial layer 910 with a thickness of about 1.2 μm is formed; as shown in FIG. 10C, a circle with a diameter of 2 μm is drawn on the mask 320, and the distance between adjacent patterns is 2 μm, forming Array structure, post-baking temperature is controlled at 115℃, time is 90 seconds; use Optical Aligner-SUSS MABA6 UV lithography machine for pattern definition, use contact exposure, pitch 60μm, exposure time is 7.5 seconds (step3); then develop in AZ300MIF The pattern is exposed by developing for 50 seconds in the liquid, so that a circular pattern 911 defined by the exposed and developed area corresponding to the position of the nanopore is formed on the sacrificial layer 910, and is washed in clear water. As shown in FIG. 10D, an inductively coupled plasma (ICP) can be optionally used to etch the AlGaN film to first realize the nanopore structure 930 on the sacrificial layer 910. As shown in FIG. 10E, the AlGaN film grown by MOCVD is etched by Oxford ICP 180, and the etched area is a circular pattern 911 defined by ultraviolet lithography. The etching gas is Cl ₂ /BCl ₃ /Ar, the gas flow is controlled at 10/25/25 sccm, the temperature is 50 ℃, the cavity pressure is 6 mTorr, the ICP power is 450 W, and the radio frequency power is 100 W. No sample is placed before the etching starts, and the cavity is operated with the above two process parameters to ensure the gas environment of the cavity. After the etching is started, the etching time is controlled to be 2.5 minutes to form AlGaN nanoholes with a depth of 200 nm. The selection ratio of AlGaN to S1813 photoresist is 1:2, and the remaining thickness of S1813 photoresist after etching is about 800 μm (step 5). Use acetone, isopropanol, and water to wash away the remaining photoresist on the sample to complete the preparation of the nanohole array, as shown in FIG. 10F.

As an embodiment of the present disclosure, the AlGaN nanohole array 830 may be formed on the surface of the buffer layer 820 of the substrate, including: forming silicon dioxide islands on the surface of the buffer layer 820, and forming silicon dioxide islands on the surface of the buffer layer 820 where the silicon dioxide islands are formed. The AlGaN nanohole array 830. The islands may be protrusions or regions formed on the surface of the buffer layer 820, which are formed by special processing techniques or special materials. Specifically, it is optional to form small silicon dioxide islands on the surface of the third intermediate layer of the buffer layer 820 by means of micro-nano processing technology, and then through molecular beam epitaxy (MBE) or metal organic chemistry. The vapor deposition method (MOCVD) directly grows the film on the surface of the third intermediate layer where the silicon dioxide islands have been formed. Since the silicon dioxide islands have an obstructive effect on the growth of the film, the location of the silicon dioxide islands does not form a thin film material. Finally, the AlGaN nanohole array 830 is formed on the surface of the buffer layer 820. As an embodiment of the present disclosure, the material of the above-mentioned islands may be silicon dioxide, titanium dioxide, silicon nitride, or metal. The above description of the silicon dioxide islands is not a limitation on the material of the islands.

As an embodiment of the present disclosure, modifying the promoter nanoparticles on the nanopores of the AlGaN nanopore array includes: forming an amorphous protective layer covering the surface of the nanopore array on the surface of the AlGaN nanopore array; modifying the promoter on the surface of the protective layer Nano particles. As shown in Fig. 10G, in the first stage of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in each embodiment of the present disclosure, the 2nm thick amorphous TiO ₂ protection can be deposited by atomic layer deposition (ALD). The layer (a-TiO ₂ ) 870 prevents the AlGaN material from photo-corrosion under the condition of hole enrichment. The deposition process uses tetrakis (dimethylamino) titanium (IV) TEMAT and water as precursors, and the precursor containers are kept at 65°C and 25°C, respectively. Co-deposition for 60 cycles. Each cycle includes the process of introducing titanium precursor for 0.1s, N ₂ purging for 10 seconds, water vapor for 0.1s, and N2 purging for 10 seconds. A layer covering the surface of the AlGaN nanohole array is formed by atomic layer deposition on the surface of the AlGaN nanohole array. The amorphous protective layer 870 is used to protect the nanohole array from corrosion by holes. It has a tunnel conduction effect and has good conductivity and will not affect the detection performance.

As shown in FIG. 10H, in the first-stage schematic diagram of the preparation process of the AlGaN nanohole array in the solar-blind ultraviolet photoelectrochemical photodetector preparation method in each embodiment of the present disclosure, the photodeposition method can be used to modify the promoter nanoparticles 850 on the surface of the protective layer 870, in 20mL of deionized water was added to 100μL 20mg / mL ruthenium chloride (RuCl ₃₎ was added and the produced a-TiO ₂ / n-AlGaN nanohole array disposed therein, while a-TiO ₂ / n-AlGaN nano The hole array applies ultraviolet light corresponding to the band gap. Due to the semiconductor photoelectric effect, the a-TiO ₂ /n-AlGaN nanohole array generates photo-generated electron-hole pairs after absorbing photons. Then the photogenerated electrons diffuse to the surface of the nanopore. Because the energy of the photogenerated electrons is greater than ^{the reduction potential of the ruthenium ion Ru 3+} in the solution, the photogenerated electrons diffused to the surface of the nanopore will be reduced and modified on the surface of the a-TiO ₂ /n-AlGaN nanopore array. Ru ³⁺ , form nano-Ru particles, and the nano-particles can be 2nm.

As an embodiment of the present disclosure, the preparation of a photodetector by using an AlGaN nanohole array modified with cocatalyst nanoparticles as a photoanode includes: forming a first region without a protective layer on the surface of the AlGaN nanohole array, and the first region is provided Outside the nanopore area; spot-welded indium balls are arranged on the first area to form a conductive area of the photoanode, which is used to draw out the photoanode. The first area is formed on the surface of the nanohole array and does not overlap with the area where the nanoholes are located, so as to prevent the occurrence of short circuits, and also makes the lead electrode more stable and effective. By spot welding indium balls, a conductive area in ohmic contact with the surface of the nanohole array can be formed on the first area 860. The conductive area can be a square area of 2mm×2mm, which can achieve better conductive characteristics and current stability, and can be fixed at the same time The wire leads to the electrode to form a photoanode.

As an embodiment of the present disclosure, the preparation of a photodetector using AlGaN nanopore arrays with modified promoter nanoparticles as a photoanode also includes: placing a reference electrode, a counter electrode, and a photoanode in an electrolyte solution at a certain interval to prepare The electrode system constitutes a photodetector. Therefore, a photoelectrochemical photodetector based on a simple water oxidation reaction as a photoelectric reaction mechanism is basically constituted. The preparation conditions are simple, the purity requirements are low, and the working process has almost no influence on the electrode materials.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the present disclosure.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in further detail. It should be understood that the above descriptions are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Within the spirit and principle of the present disclosure, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present disclosure.

Claims

A photoelectrochemical photodetector applied to solar-blind ultraviolet, wherein the photodetector includes a photoelectrode, and the photoelectrode

Including the substrate,

It also includes GaN-based nanowires grown on the surface of the substrate,

GaN-based nanowires include n-type GaN-based nanowires and p-type GaN-based nanowires.
The photodetector according to claim 1, wherein the length of the GaN-based nanowires is 10nm-5000nm, and the diameter is 5nm-5000nm, and the coverage density of the GaN-based nanowires is 1%-99%.
The photodetector according to claim 1, wherein the substrate comprises a conductive substrate.
The photodetector according to claim 1, wherein the photoelectrode includes a photoanode formed by n-type GaN-based nanowires and a photocathode formed by p-type GaN-based nanowires, and further includes a photoelectrode distributed on the surface of the photoelectrode. Of co-catalyst nanoparticles.
The photodetector according to claim 1, wherein the GaN-based nanowires are n-type GaN-based nanowires, and the surface of the photoelectrode further comprises a protective layer formed on the surface of the n-type GaN-based nanowires , The thickness of the protective layer is less than or equal to 10 nm.
The photodetector according to claim 1, wherein the photoelectrode further comprises co-catalyst nanoparticles modified on the surface of the GaN-based nanowires, and the size of the co-catalyst nanoparticles is 0.1 nm-1000 nm.
4. The photodetector according to claim 4, wherein the promoter nanoparticles comprise metal particles with water oxidation reaction or reduction reaction activity.
The photodetector according to claim 1, wherein the photoelectrochemical photodetector further comprises:

Wires arranged in the conductive area of the substrate,

The wire and the photoelectrode are coated and fixed to expose the cured and coated structure of the GaN-based nanowire of the photoelectrode.
8. The photodetector according to claim 8, wherein the wire material includes gold, silver, and copper, and the size of the wire is selected to match the size of the substrate.
8. The photodetector according to claim 8, wherein the material of the solidified coating structure comprises a liquid material that is curable and has insulating properties after curing, and the solidified coating structure comprises epoxy resin.
The photodetector according to claim 8, wherein, between the wire and the substrate, it further comprises a liquid alloy disposed on the conductive area of the substrate and a liquid alloy disposed on the surface of the wire opposite to the liquid alloy. Conductive glue; the liquid alloy includes liquid gallium indium alloy, the purity of the liquid gallium indium alloy is 90%-99.999999%; the conductive glue is silver glue.
The photodetector according to claim 1, wherein the photoelectrochemical photodetector further comprises:

The electrolyte solution in contact with the photoelectrode, and

The reference electrode and the counter electrode in contact with the electrolyte solution,

The distance between the reference electrode and the counter electrode and the photoelectrode is greater than or equal to 0.01 mm;

Wherein, the reference electrode, the counter electrode and the photoelectrode are respectively connected to an electrochemical workstation with current monitoring function.
The photodetector according to claim 12, wherein:

The electrolyte solution is an acidic or neutral electrolyte solution, the acidic electrolyte solution includes sulfuric acid, hydrochloric acid, hydrobromic acid, and perchloric acid, the neutral electrolyte solution includes sodium sulfate and a phosphoric acid buffer solution, and the concentration of the electrolyte solution is 0.01mol/L～5mol/L;

The reference electrode is a silver/silver chloride electrode;

The counter electrode includes a platinum electrode and a carbon electrode.
A solar-blind ultraviolet photoelectrochemical photodetector product, wherein the product comprises the photodetector according to any one of claims 1-13 and a packaging structure for packaging the photodetector,

The packaging structure includes a housing structure that wraps the photodetector to encapsulate it;

An optical window is opened on the surface of the housing structure,

A light-transmitting surface matched with the optical window for sealing the optical window is provided, and the distance between the light-transmitting surface and the surface of the photoelectrode provided with GaN-based nanowires is greater than or equal to 0.01 mm, which is used for solar blind ultraviolet light The GaN-based nanowires modified with promoter nanoparticles are irradiated on the photoelectrode through the light-transmitting surface.
The product according to claim 14, wherein:

The light-transmitting surface includes a material with limited ability to absorb solar-blind ultraviolet light;

The shell structure includes a shell structure formed of polytetrafluoroethylene material.
The product according to claim 14, wherein one surface of the housing structure is provided with a sealable/openable injection hole, a vent hole, and at least three for setting the reference electrode, counter electrode, and photoelectrode. Electrode hole.