Solar-blind ultraviolet photocathode, preparation method thereof, solar-blind ultraviolet detector and detection method

Abstract

The invention discloses a solar-blind ultraviolet photocathode, a preparation method thereof, a solar-blind ultraviolet detector and a detection method. The solar blind ultraviolet photocathode comprises a cesium oxide layer, the thickness of the cesium oxide layer can be 2 nm to 10 nm. The solar blind ultraviolet photocathode has the advantages of being stable in performance, sensitive in detection, small in dark current, good in signal to noise ratio, excellent in solar blind detection characteristic and the like.

Description

Technical Field

[0001] The present application relates to the fields of semiconductor device technology and optoelectronic device detection technology, and specifically to a solar-blind ultraviolet photocathode and a preparation method thereof, a solar-blind ultraviolet light detector and a detection method, and further to a gallium oxide solar-blind ultraviolet photocathode and a preparation method thereof, a solar-blind ultraviolet light detector and a solar-blind ultraviolet light detection method. Background Art

[0002] With the development and application of technologies such as power detection and fire monitoring, miniature solar-blind ultraviolet cameras used for miniature airborne platforms have been widely used in the field of rapid detection due to their compact structure and low cost.

[0003] Ultraviolet light with a wavelength of 220 to 280 nm (called day-blind ultraviolet light) is almost completely absorbed when passing through the atmospheric ozone layer, which can effectively avoid the influence of space solar background radiation. It has the characteristics of high sensitivity, strong confidentiality, low background interference, and low false alarm rate. This makes day-blind ultraviolet light have many advantages in missile tail flame detection, flame detection, and high-voltage transmission line corona detection.

[0004] At present, most of the commercialized solar-blind ultraviolet detection devices are vacuum detection devices based on solar-blind ultraviolet cathode combined with microchannel plate technology, which are inseparable from the modulation effect of solar-blind filters. However, solar-blind filters are expensive and complex in process, which limits the promotion and popularization of solar-blind ultraviolet detection devices. With the development of technology, traditional detectors can no longer meet the needs of the market, especially the weak processing ability of weak signals, which leads to limited applications. Even wide-bandgap semiconductor ultraviolet detectors based on SiC, GaN and ZnO cannot achieve solar-blind detection and are easily disturbed by sunlight. The band gap of gallium oxide material is 4.5-5.3eV (different crystal structures, optical anisotropy shows different band gaps). It is a natural solar-blind material and a direct bandgap III-VI wide-bandgap semiconductor. It has attracted the attention of scientific researchers in recent years. Recent studies have found that gallium oxide materials have shown very excellent performance in solar-blind ultraviolet photoelectric detection. Gallium oxide materials can be uniformly formed on a large area on a substrate without the need for a single crystal substrate. The process is simple and the cost is low, which is well received by the market.

[0005] However, the current gallium oxide solar-blind ultraviolet detectors are mainly concentrated in semiconductor devices, which limits the improvement of their sensitivity and application promotion; in addition, there are certain limitations in the structure, such as internal defects and dislocations caused by the mismatch of lattice components, which lead to structural mismatch between conduction bands, which will seriously affect the continuous working performance of the device. In summary, the main difficulty in the research of gallium oxide detectors lies in the design and preparation methods of the structure, which has become a bottleneck technology restricting the development of high-performance solar-blind ultraviolet detectors, and seriously restricting the further optimization and improvement of the performance of solar-blind ultraviolet detectors. Summary of the invention

[0006] Based on this, the embodiments of the present application at least provide a day-blind ultraviolet photocathode and its preparation method and application, further provide a day-blind ultraviolet photocathode and its preparation method, a day-blind ultraviolet light detector and a detection method, and further provide a gallium oxide day-blind ultraviolet photocathode and its preparation method, a day-blind ultraviolet light detector and a day-blind ultraviolet light detection method.

[0007] In a first aspect of the present application, a solar-blind ultraviolet photocathode is provided, which includes a cesium oxide layer. The thickness of the cesium oxide layer can be 2nm to 10nm. The solar-blind ultraviolet photocathode has the advantages of stable performance, sensitive detection, small dark current, good signal-to-noise ratio, and excellent solar-blind detection characteristics.

[0008] In some embodiments, a solar-blind ultraviolet photocathode is provided, comprising a substrate layer, a gallium oxide layer, and a cesium oxide layer stacked in sequence;

[0009] Wherein, the thickness of the cesium oxide layer is 2nm~10nm.

[0010] In some embodiments, the cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to alternately grow the cesium layer and the oxygen layer; optionally, the vacuum degree is less than or equal to 1.0×10 -5 The current ranges of Pa, cesium source and oxygen source are each independently 2.5A~4.5A.

[0011] In some embodiments, the cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow; optionally, the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A.

[0012] In some embodiments, the gallium oxide layer has a thickness of 20 nm to 40 nm.

[0013] In some embodiments, the material of the gallium oxide layer is selected from at least one of amorphous gallium oxide, polycrystalline gallium oxide, or single crystal gallium oxide.

[0014] In some embodiments, the oxygen vacancy concentration and density of the gallium oxide layer are controlled by a deposition scheme such as magnetron sputtering under an oxygen flow rate of 3 sccm to 5 sccm.

[0015] In some embodiments, the day-blind ultraviolet photocathode also includes a passivation layer, which is located between the gallium oxide layer and the cesium oxide layer; optionally, the passivation layer satisfies one or more of the following characteristics: the thickness of the passivation layer is 5nm~10nm; and the material of the passivation layer is selected from one or more of Si3N4, SiO2 and Al2O3.

[0016] In some embodiments, the base layer is a rigid base or a flexible base; optionally, the material of the rigid base is selected from at least one of sapphire Al2O3, quartz glass, gallium nitride, aluminum nitride and single crystal silicon; alternatively, the material of the flexible base is selected from at least one of polyethylene naphthalate, polyethylene terephthalate, polyimide, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride, polycarbonate, polystyrene and organic glass.

[0017] In some embodiments, the base layer is a rigid base. Optionally, the material of the rigid base is selected from at least one of sapphire Al2O3, quartz glass, gallium nitride, aluminum nitride and single crystal silicon.

[0018] In some embodiments, the base layer is a flexible base. Optionally, the material of the flexible base is selected from at least one of polyethylene naphthalate, polyethylene terephthalate, polyimide, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride, polycarbonate, polystyrene and plexiglass.

[0019] In some embodiments, the day-blind ultraviolet photocathode also includes an electrode, which is located on the side of the cesium oxide layer and forms a conductive structure with the cesium oxide layer for introducing an external electrical signal into the photocathode; optionally, the material of the electrode is selected from one or more of Ti, Al, Ni, Au, Mo, and Pt.

[0020] In a second aspect of the present application, a method for preparing a solar-blind ultraviolet photocathode is provided, which can be used to prepare the solar-blind ultraviolet photocathode described in the first aspect of the present application.

[0021] In some embodiments, a method for preparing a solar-blind ultraviolet photocathode is provided, comprising the following steps:

[0022] providing a substrate including a base layer;

[0023] growing a gallium oxide layer on the substrate layer;

[0024] A cesium oxide layer is grown on a side of the gallium oxide layer away from the base layer, and the thickness of the cesium oxide layer is 2 nm to 10 nm.

[0025] In some embodiments, the growth method of the cesium oxide layer is one of an alternating growth method and a symbiotic method based on a thermal evaporation method.

[0026] In some embodiments, the cesium oxide layer is prepared by controlling a cesium source current and an oxygen source current under vacuum conditions.

[0027] In some embodiments, the step of preparing the cesium oxide layer satisfies one or more of the following characteristics:

[0028] The vacuum degrees for cesium source activation and oxygen source activation are each independently less than or equal to 1.0×10 -5 Pa;

[0029] The current range of the cesium source and the oxygen source is independently 2.5A to 4.5A;

[0030] The material of the cesium source is selected from cesium salts that can decompose elemental cesium. Optionally, the cesium salt is selected from one or more cesium salts such as cesium oxalate and acetate;

[0031] The material of the oxygen source is selected from metal oxides that can decompose elemental oxygen. Optionally, the metal oxide is selected from one or more metal oxides such as barium oxide and silver oxide.

[0032] In some embodiments, the growth mode of the cesium oxide layer is an alternating growth based on a thermal evaporation method, and the cesium oxide layer is composed of alternatingly grown cesium layers and oxygen layers;

[0033] The step of growing a cesium oxide layer on a side of the gallium oxide layer away from the substrate layer satisfies one or more of the following characteristics:

[0034] The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow the cesium layer and the oxygen layer to grow alternately;

[0035] Any cesium layer is formed by activating a cesium source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3.5A;

[0036] The oxygen layer of any layer is formed by activating the oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the oxygen source is 3.5A~4.5A.

[0037] In some embodiments, the cesium oxide layer is grown by a symbiotic method, where cesium and oxygen in the cesium oxide layer are grown by symbiotic growth;

[0038] The step of growing a cesium oxide layer on a side of the gallium oxide layer away from the substrate layer satisfies one or more of the following characteristics:

[0039] The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow;

[0040] The cesium oxide layer is formed by activating a cesium source and an oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A.

[0041] In some embodiments, the gallium oxide layer is grown by at least one method selected from magnetron sputtering deposition, pulsed laser deposition, chemical vapor deposition, atomic layer deposition, and molecular beam epitaxial deposition.

[0042] In some embodiments, the growth mode of the gallium oxide layer is selected from magnetron sputtering deposition; optionally, the step of preparing the gallium oxide layer includes: evacuating the chamber under an argon atmosphere, introducing oxygen, controlling the oxygen flow rate, heating the substrate layer, depositing a gallium oxide film on the substrate layer by magnetron sputtering, and performing in-situ annealing after heating to form the gallium oxide layer;

[0043] Further optionally, the step of preparing the gallium oxide layer satisfies one or more of the following characteristics:

[0044] The target material is a gallium oxide target;

[0045] The distance between the target material and the substrate layer is controlled to be 28 cm to 32 cm;

[0046] In the step of evacuating the cavity under an argon atmosphere, the cavity pressure is increased to less than or equal to 3.0 Pa under the argon atmosphere; the oxygen flow rate is controlled to be 3 sccm to 5 sccm to control the oxygen vacancy concentration and density of the gallium oxide layer;

[0047] In the step of heating the base layer, the base layer is heated to 450° C. to 460° C.;

[0048] In the step of depositing a gallium oxide film on the substrate layer by magnetron sputtering, the sputtering power is 60W-80W and the sputtering time is 0.5h-3h;

[0049] In the step of in-situ annealing after heating, the annealing temperature is 700°C to 750°C, and the annealing time is 10min to 15min.

[0050] In some embodiments, the solar-blind ultraviolet photocathode described in the first aspect of the present application is prepared.

[0051] The third aspect of the present application provides a solar-blind ultraviolet light detector, comprising at least one of the solar-blind ultraviolet photocathode described in the first aspect of the present application and the solar-blind ultraviolet photocathode prepared by the preparation method described in the second aspect of the present application.

[0052] The fourth aspect of the present application provides a day-blind ultraviolet light detection method, which comprises the following steps: using the day-blind ultraviolet photocathode described in the first aspect of the present application, the day-blind ultraviolet photocathode prepared by the preparation method described in the second aspect of the present application, or the day-blind ultraviolet light detector described in the third aspect of the present application to detect day-blind ultraviolet light.

[0053] In some embodiments, the working voltage for performing the detection is 100V~200V.

[0054] The aforementioned solar-blind ultraviolet photocathode includes a gallium oxide layer and a cesium oxide layer. The cesium oxide layer improves the quantum efficiency of the solar-blind ultraviolet photocathode and can combine with oxygen to protect the surface of the photocathode from environmental factors, making its performance more stable. Furthermore, based on the wide bandgap of gallium oxide, it can achieve absorption of solar-blind ultraviolet light and has high sensitivity to solar-blind ultraviolet light. Through the coordination of the gallium oxide layer and the cesium oxide layer, the solar-blind ultraviolet photocathode has both high sensitivity and low dark current, and has the characteristics of stable performance, sensitive detection, small dark current, good signal-to-noise ratio, and excellent solar-blind detection characteristics. During detection, it can obtain a large photocurrent gain and achieve high detection efficiency.

[0055] In the preparation method of the solar-blind ultraviolet photocathode provided in the present application, the gallium oxide layer can be obtained by magnetron sputtering deposition, and the cesium oxide layer can be obtained by alternating growth or symbiosis based on thermal evaporation. The preparation method combines semiconductor technology and vacuum device packaging technology, is simple to operate, and has controllable process. It can be used for large-scale production. The prepared solar-blind ultraviolet photocathode meets the use requirements of high-gain, miniaturized and lightweight solar-blind ultraviolet detection devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the implementation methods and examples of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for use in the description of the implementation methods or examples. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should also be noted that the drawings are all drawn in a simplified form and are only used to conveniently and clearly assist in explaining the present application. The various sizes of each component shown in the drawings are arbitrarily shown, and may be accurate or may not be drawn according to the actual scale. For example, in order to make the illustration clearer, the size of the components is appropriately exaggerated in some places in the drawings. Unless otherwise specified, the components in the figures are not drawn to scale. The drawings of this application do not limit each size of each component.

[0057] In the following description, the same reference numerals denote the same parts.

[0058] Figure 1 Schematic diagram of the structure of a gallium oxide solar-blind ultraviolet photocathode in one embodiment of the present application.

[0059] Figure 2 This is a schematic structural diagram of a gallium oxide solar-blind ultraviolet photocathode in one embodiment of the present application, which includes a passivation layer.

[0060] Figure 3 Schematic diagram of the structure of a gallium oxide solar-blind ultraviolet photocathode in one embodiment of the present application, which includes a cesium oxide layer formed by alternating growth of cesium layers and oxygen layers.

[0061] Figure 4 Schematic diagram of the structure of a gallium oxide solar-blind ultraviolet photocathode in one embodiment of the present application, which includes a cesium oxide layer formed by co-growth of cesium and oxygen.

[0062] The reference numerals in the drawings are: 10 is a base layer, 20 is a gallium oxide layer, 30 is a passivation layer, 40 is a cesium oxide layer, 42 is a cesium oxide layer formed by alternating growth of cesium layers and oxygen layers, and 44 is a cesium oxide layer formed by co-growth of cesium and oxygen. DETAILED DESCRIPTION

[0063] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0065] In this application, "optionally" means optional, that is, it means to select any one of the two parallel solutions of "yes" or "no". If there are multiple "optionally" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optionally" is independent.

[0066] In the present application, “preferred” is only used to describe an implementation method or example with better effects. It should be understood that it does not constitute a limitation on the scope of protection of the present application.

[0067] The terms "having", "containing" and "including" used in this application are synonymous, which are inclusive or open-ended and do not exclude additional, uncited members or features. Members or features include materials or components, structures, elements, instruments, etc.; non-limiting examples of members or features include actions, conditions for the occurrence of actions, timing, states, etc.

[0068] In this application, the technical features or technical solutions described in open language include closed technical features or technical solutions composed of the listed contents, and also include open technical features or technical solutions of the listed contents.

[0069] In this application, if the unit of the data range is followed only by the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3-5 sccm means that the units of the left endpoint "3" and the right endpoint "5" are both sccm, which have the same meaning as 3 sccm-5 sccm. In addition, if there are similar descriptions involving other parameters, the above understanding also applies.

[0070] In this application, if there are multiple steps involved in the method flow, unless there is a clear different description in this document, there is no strict order restriction for the execution of these steps, and they can be executed in other orders than described. Moreover, any step can include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn, alternating or simultaneously with other steps or parts of sub-steps or stages of other steps.

[0071] In the present application, exemplary descriptions such as "in some implementation modes (or examples)" and "in one implementation mode (or example)" may include but are not limited to the following meanings: these solutions may be combined with other solutions in a suitable manner to form a new technical solution.

[0072] In the present application, the terms "first", "second", "third", "fourth", etc. in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0073] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0074] The parameter units involved in this application, unless otherwise specified, are as follows: the size unit nm represents nanometers, the gas flow unit sccm represents standard cubic centimeters per minute, the current unit A represents amperes, the voltage unit V represents volts, the pressure unit Pa represents Pascals, the power unit W represents watts, and the temperature unit ℃ represents degrees Celsius.

[0075] In the present application, unless otherwise specified, “less than or equal to” can be regarded as providing two solutions of “less than” and “equal to”.

[0076] In this application, unless otherwise specified, "solar-blind ultraviolet" refers to ultraviolet light with a wavelength of 220nm~280nm.

[0077] In this application, unless otherwise specified, "photocathode" refers to an electrode that can release electrons based on the photoelectric effect, which is made of light-emitting materials, and the electrons can be released into free space through the external photoelectric effect.

[0078] In the current gallium oxide solar-blind ultraviolet detectors, the focus is mainly on semiconductor devices, which limits the improvement of its sensitivity and application promotion; in addition, there are certain limitations in the structure, such as internal defects and dislocations caused by the mismatch of lattice components, which lead to structural mismatch between conduction bands, which will seriously affect the continuous working performance of the device. The main difficulty in the research of gallium oxide detectors lies in the design and preparation methods of the structure, which has become a bottleneck technology restricting the development of high-performance solar-blind ultraviolet detectors, and seriously restricts the further optimization and improvement of the performance of solar-blind ultraviolet detectors.

[0079] Based on this, the embodiments of the present application at least provide a day-blind ultraviolet photocathode and its preparation method and application, further provide a day-blind ultraviolet photocathode and its preparation method, a day-blind ultraviolet light detector and a detection method, and further provide a gallium oxide day-blind ultraviolet photocathode and its preparation method, a day-blind ultraviolet light detector and a day-blind ultraviolet light detection method.

[0080] In a first aspect of the present application, a solar-blind ultraviolet photocathode is provided, which includes a cesium oxide layer. The thickness of the cesium oxide layer can be 2nm to 10nm. The solar-blind ultraviolet photocathode has the advantages of stable performance, sensitive detection, small dark current, good signal-to-noise ratio, and excellent solar-blind detection characteristics.

[0081] In this application, unless otherwise specified, "cesium oxide layer" refers to a film composed of cesium and oxygen. In the embodiments provided in this application, the distribution of cesium and oxygen in the cesium oxide layer can be a cesium layer and an oxygen layer grown alternately, or a mixed layer formed by co-growth of cesium and oxygen. In a solar-blind ultraviolet photocathode, the cesium oxide layer improves the quantum efficiency of the solar-blind ultraviolet photocathode, and can combine with oxygen to protect the surface of the photocathode from environmental factors, making its performance more stable.

[0082] In some embodiments, the thickness of the cesium oxide layer may be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or a value or range between any two of the above values.

[0083] In some embodiments, a solar-blind ultraviolet photocathode is provided, which includes a gallium oxide layer and a cesium oxide layer stacked in sequence; optionally, the thickness of the cesium oxide layer is 2 nm to 10 nm.

[0084] In the solar-blind ultraviolet photocathode provided in the present application, unless otherwise specified, the "gallium oxide layer" as a photosensitive layer has the ability to highly selectively absorb solar-blind ultraviolet light; in addition, it also has high sensitivity to solar-blind ultraviolet light.

[0085] The gallium oxide material in the gallium oxide layer has a wide band gap. When the solar-blind ultraviolet light is irradiated into the gallium oxide layer, the electrons in the valence band of the gallium oxide material will be excited to the conduction band by absorbing the photon energy, forming electron-hole pairs; under the action of the electric field, the electrons and holes generated by the solar-blind ultraviolet light are transmitted in different directions respectively, forming photocurrent.

[0086] Through the coordination of the gallium oxide layer and the cesium oxide layer, the photocathode has both high sensitivity and low dark current, and has stable performance, sensitive detection, small dark current, good signal-to-noise ratio, and excellent day-blind detection characteristics. During detection, a large photocurrent gain can be obtained to achieve high detection efficiency.

[0087] In some embodiments, a solar-blind ultraviolet photocathode is provided, which includes a substrate layer, a gallium oxide layer, and a cesium oxide layer stacked in sequence; optionally, the thickness of the cesium oxide layer is 2 nm to 10 nm.

[0088] In one embodiment of the present application, the solar-blind ultraviolet photocathode comprises a substrate layer 10, a gallium oxide layer 20 and a cesium oxide layer 40 which are stacked in sequence, as shown in FIG. Figure 1 .

[0089] In some embodiments, the cesium oxide layer 40 is a cesium oxide layer 42 formed by alternating growth of cesium layers and oxygen layers.

[0090] In some embodiments, the cesium oxide layer 40 is a cesium oxide layer 44 formed by co-growth of a cesium layer and an oxygen layer.

[0091] In some embodiments, the cesium oxide layer is composed of alternatingly grown cesium layers and oxygen layers.

[0092] In some embodiments, the cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to alternately grow the cesium layer and the oxygen layer, and the cesium oxide layer 42 formed by alternately growing the cesium layer and the oxygen layer can be prepared. Non-limitingly, the vacuum degree can be 1.0×10 -6 Pa, 3.0×10 -6 Pa, 5.0×10 -6 Pa, 7.0×10 -6 Pa, 1.0×10 -5 Pa, or a value or range between any two of the above values. Without limitation, the current of the cesium source may be 2.5A, 3A, 3.5A, 4A, 4.5A, or a value or range between any two of the above values. Without limitation, the current of the oxygen source may be 2.5A, 3A, 3.5A, 4A, 4.5A, or a value or range between any two of the above values. In some embodiments, the vacuum degree is less than or equal to 1.0×10 -5 The current ranges of Pa, cesium source and oxygen source are each independently 2.5A~4.5A.

[0093] In some embodiments, cesium and oxygen in the cesium oxide layer are co-grown.

[0094] In some embodiments, the cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow, and the cesium oxide layer 44 formed by the co-growth of the cesium layer and the oxygen layer can be prepared. Non-limitingly, the vacuum degree can be 1.0×10 -6 Pa, 3.0×10 -6 Pa, 5.0×10 -6 Pa, 7.0×10 -6 Pa, 1.0×10 -5 Pa, etc., or a value or range between any two of the above values. Without limitation, the current of the cesium source can be 2.5A, 2.6A, 2.7A, 2.8A, 2.9A, 3A, or a value or range between any two of the above values. Without limitation, the current of the oxygen source can be 3.5A, 3.6A, 3.7A, 3.8A, 3.9A, 4A, or a value or range between any two of the above values. In some embodiments, the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A.

[0095] In some embodiments, the thickness of the gallium oxide layer may be 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, or a value or range between the above two values.

[0096] In some embodiments, the material of the gallium oxide layer can be selected from at least one of amorphous gallium oxide, polycrystalline gallium oxide, or single crystal gallium oxide. In some embodiments, the material of the gallium oxide layer is amorphous gallium oxide, polycrystalline gallium oxide, or single crystal gallium oxide.

[0097] In some embodiments, the oxygen vacancy concentration and density of the gallium oxide layer are controlled by magnetron sputtering or other deposition schemes under an oxygen flow rate of 3 sccm to 5 sccm. Without limitation, the oxygen flow rate may be 3 sccm, 4 sccm, 5 sccm, or a value or range between any two of the above values. The oxygen vacancy concentration and density of the gallium oxide layer may be controlled by controlling the oxygen flow rate. By controlling the oxygen vacancy concentration and density within the aforementioned oxygen flow rate range, it is advantageous to prepare a stable and high-quality gallium oxide layer, reduce the number of internal defects, and reduce the generation of dark current.

[0098] The gallium oxide layer can be grown by any suitable method in the art, for example, one or more methods including but not limited to magnetron sputtering deposition, pulsed laser deposition, chemical vapor deposition, atomic layer deposition, molecular beam epitaxial deposition, etc. can be used to prepare the gallium oxide layer.

[0099] In some embodiments, the solar-blind ultraviolet photocathode further includes a passivation layer, and further, the passivation layer is located between the gallium oxide layer and the cesium oxide layer.

[0100] In the present application, unless otherwise specified, the "passivation layer" can be used to passivate surface defects to improve photoelectric conversion efficiency and protect the photocathode to improve the performance and stability of the photocathode, but is not limited to the above-mentioned functions.

[0101] The performance and stability of the photocathode can be further improved through the coordination of the gallium oxide layer, the passivation layer and the cesium oxide layer, so that it has high sensitivity during day-blind ultraviolet detection and can obtain higher detection sensitivity.

[0102] Without limitation, the material of the passivation layer may be selected from one or more of silicon nitride Si3N4, silicon dioxide SiO2 and aluminum oxide Al2O3.

[0103] In some embodiments, the material of the passivation layer may be Si3N4, SiO2, Al2O3 or HfO2, etc. These materials have a relatively high bandgap width, which is conducive to ensuring that ultraviolet rays in the solar-blind band can pass through the passivation layer to irradiate the gallium oxide layer.

[0104] In some embodiments, the thickness of the passivation layer is 5 nm to 10 nm. Without limitation, the thickness of the passivation layer can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or a value or range between any two of the above values.

[0105] In some embodiments, a solar-blind ultraviolet photocathode is provided, which includes a substrate layer, a gallium oxide layer, a passivation layer, and a cesium oxide layer stacked in sequence; optionally, the thickness of the cesium oxide layer is 2 nm to 10 nm, and reference may also be made to appropriate examples in the context.

[0106] In one embodiment of the present application, the solar-blind ultraviolet photocathode comprises a base layer 10, a gallium oxide layer 20, a passivation layer 30 and a cesium oxide layer 40 which are stacked in sequence, as shown in FIG. Figure 2 .

[0107] In one embodiment of the present application, the solar-blind ultraviolet photocathode comprises a base layer 10, a gallium oxide layer 20, a passivation layer 30 and a cesium oxide layer 40 which are stacked in sequence, wherein the cesium oxide layer 40 is a cesium oxide layer 42 formed by alternating growth of cesium layers and oxygen layers, which can be referred to Figure 3 .

[0108] In one embodiment of the present application, the solar-blind ultraviolet photocathode comprises a base layer 10, a gallium oxide layer 20, a passivation layer 30 and a cesium oxide layer 40 which are stacked in sequence, wherein the cesium oxide layer 40 is a cesium oxide layer 44 formed by co-growth of cesium and oxygen, which can be referred to Figure 4 .

[0109] Without limitation, the substrate layer may be a rigid substrate or a flexible substrate.

[0110] In some embodiments, the substrate layer is a rigid substrate. Without limitation, the material of the rigid substrate can be selected from at least one of sapphire Al2O3, quartz glass, gallium nitride, aluminum nitride and single crystal silicon.

[0111] In other embodiments, the base layer is a flexible base. In a non-limiting manner, the material of the flexible base is selected from at least one of polyethylene naphthalate, polyethylene terephthalate, polyimide, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride, polycarbonate, polystyrene and organic glass.

[0112] In one embodiment of the present application, the material of the base layer can be selected from one or more of single crystal Ga2O3, sapphire Al2O3, GaN, AlN, quartz, single crystal silicon, etc., and a base layer material that is more suitable for the growth of gallium oxide film can be further preferred.

[0113] In some embodiments, the solar-blind ultraviolet photocathode further includes an electrode, and the electrode is used to introduce an external electrical signal into the photocathode.

[0114] Generally, carriers include electrons and holes. It is understood that in some embodiments, the electrode includes a first electrode and a second electrode, one for collecting electrons and the other for collecting holes.

[0115] In some embodiments, the material of the electrode may be selected from, but not limited to, one or more of Ti, Al, Ni, Au, Mo, and Pt.

[0116] The electrodes in the solar-blind ultraviolet photocathode can be prepared by conventional preparation methods in the art.

[0117] The type and position of the electrodes may be any appropriate type and position in the field of solar-blind ultraviolet detectors.

[0118] In some embodiments, the electrode is in contact with the cesium oxide layer. Further, the electrode is located on the side of the cesium oxide layer and forms a conductive structure with the cesium oxide layer for introducing an external electrical signal into the photocathode.

[0119] In some embodiments, the electrode is located in a peripheral region of the photocathode.

[0120] In some embodiments, the electrode is a ring electrode.

[0121] In some embodiments, the electrode is in contact with the gallium oxide layer.

[0122] In other embodiments, the electrode is located on a side of the substrate layer away from the gallium oxide layer, and further, the electrode is an ohmic contact electrode.

[0123] In a second aspect of the present application, a method for preparing a solar-blind ultraviolet photocathode is provided, which can be used to prepare the solar-blind ultraviolet photocathode of the first aspect of the present application.

[0124] In some embodiments, a method for preparing a solar-blind ultraviolet photocathode is provided, comprising the following steps performed in sequence:

[0125] S100: providing a base layer;

[0126] S200: preparing a gallium oxide layer; and

[0127] S400: preparing a cesium oxide layer.

[0128] In some embodiments, a method for preparing a solar-blind ultraviolet photocathode is provided, comprising the following steps:

[0129] S100: providing a substrate including a base layer;

[0130] S200: growing a gallium oxide layer on the substrate layer; and

[0131] S400: growing a cesium oxide layer on a side of the gallium oxide away from the base layer.

[0132] In some embodiments, a method for preparing a solar-blind ultraviolet photocathode is provided, comprising the following steps performed in sequence:

[0133] S100: providing a base layer;

[0134] S200: preparing a gallium oxide layer;

[0135] S300: preparing a passivation layer; and

[0136] S400: preparing a cesium oxide layer.

[0137] In some embodiments, a method for preparing a solar-blind ultraviolet photocathode is provided, comprising the following steps:

[0138] S100: providing a substrate including a base layer;

[0139] S200: growing a gallium oxide layer on the substrate layer;

[0140] S300: growing a passivation layer on a surface of the gallium oxide layer away from the substrate layer; and

[0141] S400: growing a cesium oxide layer on a surface of the passivation layer away from the gallium oxide layer.

[0142] The definition of the cesium oxide layer can refer to the first aspect of the present application. Without limitation, in some embodiments, the thickness of the cesium oxide layer can be 2 nm to 10 nm. Without limitation, the thickness of the cesium oxide layer can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or a value or range between any two of the above values.

[0143] The definition of the substrate layer can refer to the first aspect of the present application. Without limitation, in some embodiments, the substrate layer can be a rigid substrate or a flexible substrate known in the art. Without limitation, the material of the rigid substrate can be selected from but not limited to at least one of sapphire Al2O3, quartz glass, gallium nitride, aluminum nitride and single crystal silicon; the material of the flexible substrate can be selected from but not limited to at least one of polyethylene naphthalate, polyethylene terephthalate, polyimide, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride, polycarbonate, polystyrene and organic glass.

[0144] In some embodiments, in step S200 , the gallium oxide layer may be grown by at least one of magnetron sputtering deposition, pulsed laser deposition, chemical vapor deposition, atomic layer deposition, and molecular beam epitaxy deposition.

[0145] In some embodiments, in step S200, the growth method of the gallium oxide layer is selected from magnetron sputtering deposition; further, the step of preparing the gallium oxide layer may include: evacuating the chamber under an argon atmosphere, introducing oxygen, controlling the oxygen flow rate, heating the base layer, depositing a gallium oxide film on the base layer by magnetron sputtering, and performing in-situ annealing after heating to form the gallium oxide layer.

[0146] In some embodiments, the target material for magnetron sputtering is a gallium oxide target material.

[0147] In some embodiments, in the step of preparing the gallium oxide layer by a magnetron sputtering deposition method, the distance between the target material and the substrate layer can be controlled to be 28 cm to 32 cm. Further, the distance between the target material and the substrate layer can be controlled to be 28 cm, 29 cm, 30 cm, 31 cm, 32 cm or a value or range between any two of the above values.

[0148] In some embodiments, in the step of evacuating the chamber under an argon atmosphere, the chamber pressure under the argon atmosphere is increased to less than or equal to 3.0 Pa. Without limitation, the chamber pressure may be 1.0 Pa, 2.0 Pa, 3.0 Pa, or a value or range between any two of the above values.

[0149] In some embodiments, in the step of preparing the gallium oxide layer by a magnetron sputtering deposition method, the oxygen flow rate can be controlled to be 3 sccm~5 sccm to control the oxygen vacancy concentration and density of the gallium oxide layer. Without limitation, the oxygen flow rate can be 3 sccm, 4 sccm, 5 sccm, or a value or range between any two of the above values.

[0150] In some embodiments, in the step of preparing the gallium oxide layer by a magnetron sputtering deposition method, in the step of heating the base layer, the base layer is heated to 450°C-460°C, and is not limited to 450°C, 455°C, 460°C, or a value or range between any two of the above values.

[0151] In some embodiments, in the step of depositing a gallium oxide film on the substrate layer by magnetron sputtering, the sputtering power is 60W-80W, and the sputtering time is 0.5h-3h. Without limitation, the sputtering power may be 60W, 65W, 70W, 75W, 80W, or a value or range between any two of the above values; the sputtering time may be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, or a time or range between any two of the above time lengths.

[0152] In some embodiments, in the step of preparing the gallium oxide layer by magnetron sputtering deposition method, in the step of performing in-situ annealing after heating, the annealing temperature is 700°C to 750°C, and the annealing time is 10min to 15min. In a non-limiting manner, the annealing temperature is 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, or a value or range between any two of the above values; the annealing time is 10min, 11min, 12min, 13min, 14min, 15min, or a time or range between any two of the above time lengths.

[0153] In some embodiments, in step S300, the passivation layer can be obtained by chemical vapor deposition, atomic layer deposition, etc., but is not limited thereto. The definition of the passivation layer can also refer to the first aspect of the present application.

[0154] In some embodiments, in step S400, the cesium oxide layer is grown by an alternating growth method or a symbiotic growth method based on a thermal evaporation method.

[0155] In some embodiments, in step S400, the cesium oxide layer is prepared by controlling the cesium source current and the oxygen source current under vacuum conditions. Further, suitable cesium sources and oxygen sources may be selected.

[0156] In some embodiments, in step S400, the vacuum degrees for cesium source activation and oxygen source activation are each independently less than or equal to 1.0×10 -5 Pa.

[0157] In some embodiments, in step S400, the current ranges of the cesium source and the oxygen source are independently 2.5A to 4.5A.

[0158] In some embodiments, in step S400, the material of the cesium source is selected from cesium salts that can decompose into elemental cesium, and non-limitingly, the cesium salts include, but are not limited to, one or more of cesium salts such as cesium oxalate and acetate.

[0159] In some embodiments, in step S400, the material of the oxygen source is selected from metal oxides that can decompose into elemental oxygen, and the metal oxides are, for example but not limited to, one or more of metal oxides such as barium oxide and silver oxide.

[0160] In some embodiments, the cesium oxide layer is grown in an alternating manner based on a thermal evaporation method, and the cesium oxide layer is composed of alternatingly grown cesium layers and oxygen layers. In this case, step S400 may be step S420. The cesium oxide layer prepared is a cesium oxide layer 42 formed by alternatingly growing cesium layers and oxygen layers.

[0161] In some embodiments, in step S420, the cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to alternately grow the cesium layer and the oxygen layer.

[0162] In some embodiments, in step S420, any cesium layer is formed by activating a cesium source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3.5A. Without limitation, the vacuum degree can be 1.0×10 -6 Pa, 3.0×10 -6 Pa, 5.0×10 -6 Pa, 7.0×10 -6 Pa, 1.0×10 -5 Pa, etc., or a value or range between any two of the above values. Without limitation, the current of the cesium source can be 2.5A, 3A, 3.5A, or a value or range between any two of the above values.

[0163] In some embodiments, in step S420, the oxygen layer of any layer is formed by activating the oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the oxygen source is 3.5A~4.5A. Without limitation, the vacuum degree can be 1.0×10 -6 Pa, 3.0×10 -6 Pa, 5.0×10 -6 Pa, 7.0×10 -6Pa, 1.0×10 -5 Pa, etc., or a value or range between any two of the above values. Without limitation, the current of the oxygen source can be 3.5A, 4A, 4.5A, or a value or range between any two of the above values.

[0164] In some embodiments, the cesium oxide layer is grown by a symbiotic method, where cesium and oxygen in the cesium oxide layer are grown by symbiotic growth. In this case, step S400 may be step S440. The cesium oxide layer formed is a cesium oxide layer 44 formed by symbiotic growth of cesium and oxygen.

[0165] In some embodiments, in step S440, the cesium oxide layer is obtained by controlling a cesium source current and an oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow.

[0166] In some embodiments, in step S440, the cesium oxide layer is formed by activating the cesium source and the oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A. Without limitation, the vacuum degree can be 1.0×10 -6 Pa, 3.0×10 - 6 Pa, 5.0×10 -6 Pa, 7.0×10 -6 Pa, 1.0×10 -5 Pa, etc., or a value or range between any two of the above values. Without limitation, the current of the cesium source can be 2.5A, 2.6A, 2.7A, 2.8A, 2.9A, 3A, or a value or range between any two of the above values. Without limitation, the current of the oxygen source can be 3.5A, 3.6A, 3.7A, 3.8A, 3.9A, 4A, or a value or range between any two of the above values.

[0167] In the above-mentioned improved method for preparing solar-blind ultraviolet photocathode, the magnetron sputtering process and the thermal evaporation activation process are combined, the operation is simple, the process is controllable, and it can be used for large-scale production of solar-blind ultraviolet photocathode.

[0168] In some embodiments, the prepared solar-blind ultraviolet photocathode is the solar-blind ultraviolet photocathode described in the first aspect of the present application.

[0169] In the preparation method of the solar-blind ultraviolet photocathode provided above, the gallium oxide layer can be obtained by magnetron sputtering deposition, and the cesium oxide layer can be obtained by alternating growth or symbiosis based on thermal evaporation. The preparation method combines semiconductor technology and vacuum device packaging technology, is simple to operate, and has controllable process. It can be used for large-scale production. The prepared solar-blind ultraviolet photocathode meets the use requirements of high-gain, miniaturized and lightweight solar-blind ultraviolet detection devices.

[0170] In a third aspect of the present application, a solar-blind ultraviolet light detector is provided. The solar-blind ultraviolet light detector is a semiconductor device.

[0171] In some embodiments, a solar-blind ultraviolet light detector is provided, which includes at least one of the solar-blind ultraviolet photocathode of the first aspect of the present application and the solar-blind ultraviolet photocathode prepared by the preparation method of the second aspect of the present application. The solar-blind ultraviolet light detector can be used to detect solar-blind ultraviolet light, and has the advantages of stable performance, sensitive detection, small dark current, good signal-to-noise ratio, and excellent solar-blind detection characteristics.

[0172] In the fourth aspect of the present application, a day-blind ultraviolet light detection method is provided, comprising the following steps: using the day-blind ultraviolet photocathode of the first aspect of the present application, the day-blind ultraviolet photocathode prepared by the preparation method of the second aspect of the present application, or the day-blind ultraviolet light detector of the third aspect of the present application to detect day-blind ultraviolet light.

[0173] In some embodiments, the working voltage for detection is 100 V to 200 V. Without limitation, the working voltage may be 100 V, 110 V, 120 V, 130 V, 140 V, 150 V, 160 V, 170 V, 180 V, 190 V, 200 V, or a value or range between any two of the above values.

[0174] Some examples are provided below.

[0175] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which the conditions are not specified in the following examples are preferably referred to the guidance given in the present application, and can also be based on the experimental manual or normal conditions in the art, or can also be based on the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0176] In the following examples, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument testing accuracy or operating accuracy are allowed.

[0177] In the following embodiments and comparative examples, unless otherwise specified, the thickness of the gallium oxide layer in the photocathode is within the range of 20 nm to 40 nm.

[0178] Example 1

[0179] In this example, the material of the base layer is sapphire Al2O3, and the gallium oxide layer is prepared by a gallium oxide target. The growth method of the cesium oxide layer is an alternating growth based on a thermal evaporation method, the cesium source is cesium acetate, and the oxygen source is barium oxide.

[0180] The difference between Examples 1A, 1B and 1C is only the thickness of the cesium oxide layer.

[0181] This example provides a gallium oxide solar-blind ultraviolet photocathode and a preparation method thereof, which is prepared by the following method:

[0182] (1) Clean the sapphire Al2O3 substrate. The cleaning process is as follows: soak the sapphire substrate in acetone, anhydrous ethanol, and deionized water for 10 minutes each, then rinse it with deionized water for more than 15 minutes, and finally blow it dry with dry N2 gas for standby use.

[0183] (2) Place the gallium oxide target at the target source position of the magnetron sputtering equipment, fix the sapphire Al2O3 substrate prepared in step (1) on the sample holder of the magnetron sputtering table, and place it into the vacuum chamber.

[0184] (3) Evacuate the chamber, introduce argon gas, adjust the pressure in the vacuum chamber, and then introduce oxygen at a flow rate of 4 sccm. Heat the sapphire Al2O3 substrate and use magnetron sputtering to produce a layer of gallium oxide film on the surface of the Al2O3 substrate. Then, continue to increase the temperature and perform rapid in-situ annealing to improve the crystallization properties of the gallium oxide material.

[0185] Specifically, the distance between the gallium oxide target and the Al2O3 substrate was set to 30 cm, and the vacuum degree of the sputtering chamber was less than or equal to 1.0×10 -4 Pa, after argon gas is introduced, the pressure of the vacuum chamber is 3.0 Pa, the temperature of the heated Al2O3 substrate is 450°C, the sputtering power is 80W, and the sputtering time is 1 hour; after heating, the temperature of rapid annealing is 700°C, the annealing time is 10 minutes, and a passivation layer is formed on the surface of the gallium oxide layer.

[0186] (4) Place the material obtained in step (3) into a vacuum chamber, with the material containing the gallium oxide surface facing downward. After sealing, evacuate the chamber until the vacuum degree reaches 1.0×10 -5After Pa, the cesium source current is turned on to 3.0A, and the in-situ current growth is observed at the same time. After the photocurrent rises to the maximum value and then decreases again, the cesium source is turned off, the oxygen source is turned on and the current is adjusted to 4.0A, and cesium and oxygen are alternately activated. After the in-situ photocurrent rises to the maximum value, the in-situ current decreases, and the current is turned off. A cesium oxide layer formed by alternating growth of a cesium layer and an oxygen layer is formed on the surface of the passivation layer, and the thickness of the cesium oxide layer is controlled by controlling the number of alternating growths. The thickness of the cesium oxide layer of control examples 1A, 1B, and 1C is 3nm, 5nm, and 10nm, respectively. The photocathode is made.

[0187] (5) The fabricated photocathode is sealed inside a sealed housing for subsequent solar-blind property testing and characterization.

[0188] Example 2

[0189] In this example, the material of the base layer is quartz, and the gallium oxide layer is prepared by using a gallium oxide target; the growth method of the cesium oxide layer is a symbiotic method, the cesium source is cesium oxalate, and the oxygen source is silver oxide.

[0190] This example provides a gallium oxide solar-blind ultraviolet photocathode and a preparation method thereof, which is prepared by the following method:

[0191] (1) Clean the quartz substrate. The cleaning process is as follows: soak the quartz substrate in acetone, anhydrous ethanol, and deionized water in turn, and ultrasonicate for 10 minutes each. After taking it out, rinse it with deionized water for more than 15 minutes, and finally blow it dry with dry N2 gas for standby use.

[0192] (2) Place the gallium oxide target at the target source position of the magnetron sputtering equipment, fix the sapphire Al2O3 substrate prepared in step (1) on the sample holder of the magnetron sputtering table, and place it into the vacuum chamber.

[0193] (3) Evacuate the chamber, introduce argon gas, adjust the pressure in the vacuum chamber, and then introduce oxygen at a flow rate of 5 sccm. Heat the quartz substrate and use magnetron sputtering to produce a layer of gallium oxide film on the surface of the quartz substrate. Then, continue to increase the temperature and perform rapid in-situ annealing to improve the crystallization properties of the gallium oxide material.

[0194] Specifically, the distance between the gallium oxide target and the quartz substrate was set to 30 cm, and the vacuum degree of the sputtering chamber was less than or equal to 1.0×10 -4 Pa, after argon gas is introduced, the pressure of the vacuum chamber is 3.0 Pa, the temperature of the heated quartz substrate is 450°C, the sputtering power is 60W, and the sputtering time is 1 hour; after heating, the temperature of rapid annealing is 750°C, and the annealing time is 10 minutes, forming a passivation layer on the surface of the gallium oxide layer.

[0195] (4) Place the material obtained in step (3) into a vacuum chamber, with the material containing the gallium oxide surface facing downward. After sealing, evacuate the chamber until the vacuum degree reaches 1.0×10 -5 After Pa, the cesium source and oxygen source are turned on at the same time, and the current is set to 2.8A and 3.8A respectively, to activate the symbiosis of cesium and oxygen, observe the in-situ current growth, and wait until the photocurrent rises to the maximum value and then decreases again, and the cesium source and oxygen source current are turned off to form a cesium oxide layer with a thickness of about 3nm formed by the symbiosis of cesium and oxygen on the surface of the passivation layer. The photocathode is completed.

[0196] (5) The fabricated photocathode is sealed inside a sealed housing for subsequent solar-blind property testing and characterization.

[0197] Testing and characterization of solar blind properties

[0198] The solar-blind characteristic is tested using a universal ultraviolet sensitivity test system to test the photocurrents corresponding to 254nm and 520nm of the devices prepared in Example 1 and Example 2, respectively, and the solar-blind characteristic of the device is evaluated by calculating the ratio of the two.

[0199] The test results show that the ratio of the photocurrents at 254nm and 520nm is much larger than 1.0×10 3 The above indicates that the solar-blind property of the device is qualified, the prepared photocathode has excellent performance, high selectivity for solar-blind ultraviolet light, and high detection sensitivity.

[0200] Comparative Example 1

[0201] The method of Example 1 is basically the same as that of Example 1, except that step (4) is omitted to prepare a photocathode without a cesium oxide layer as Comparative Example 1. The photocathode of Comparative Example 1 is sealed inside a sealed housing, and a universal ultraviolet sensitivity test system is used to test the photocurrents of the device at 254 nm and 520 nm, respectively. The ratio of the two is much less than 1.0×10 3 .

[0202] Comparative Example 2

[0203] The method of Example 2 is basically the same as that of Example 2, except that step (4) is omitted to prepare a photocathode without a cesium oxide layer as Comparative Example 2. The photocathode of Comparative Example 2 is sealed inside a sealed housing, and a universal ultraviolet sensitivity test system is used to test the photocurrents of the device at 254 nm and 520 nm, respectively. The ratio of the two is much less than 1.0×10 3 .

[0204] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0205] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A solar-blind ultraviolet photocathode, characterized in that: It includes a base layer, a gallium oxide layer and a cesium oxide layer which are stacked in sequence; Wherein, the thickness of the cesium oxide layer is 2nm~10nm.

2. The solar-blind ultraviolet photocathode according to claim 1, characterized in that: The solar-blind ultraviolet photocathode satisfies one or more of the following characteristics: The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow the cesium layer and the oxygen layer to grow alternately, and the vacuum degree is less than or equal to 1.0×10 -5 The current ranges of Pa, cesium source and oxygen source are independently 2.5A~4.5A; The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A; The thickness of the gallium oxide layer is 20nm~40nm; The material of the gallium oxide layer is selected from at least one of amorphous gallium oxide, polycrystalline gallium oxide or single crystal gallium oxide; The oxygen vacancy concentration and density of the gallium oxide layer are controlled by magnetron sputtering under the condition of an oxygen flow rate of 3 sccm to 5 sccm.

3. The solar-blind ultraviolet photocathode according to claim 1 or 2, characterized in that: The solar-blind ultraviolet photocathode also satisfies one or more of the following characteristics: The solar-blind ultraviolet photocathode further includes a passivation layer, which is located between the gallium oxide layer and the cesium oxide layer; the passivation layer satisfies one or more of the following characteristics: the thickness of the passivation layer is 5nm to 10nm; the material of the passivation layer is selected from one or more of silicon nitride Si3N4, silicon dioxide SiO2 and aluminum oxide Al2O3; The substrate layer is a rigid substrate or a flexible substrate; the material of the rigid substrate is selected from at least one of sapphire Al2O3, quartz glass, gallium nitride, aluminum nitride and single crystal silicon; the material of the flexible substrate is selected from at least one of polyethylene naphthalate, polyethylene terephthalate, polyimide, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride, polycarbonate, polystyrene and organic glass; The solar-blind ultraviolet photocathode also includes an electrode, the electrode is in contact with the cesium oxide layer, the electrode is located on the side of the cesium oxide layer, and forms a conductive structure with the cesium oxide layer for introducing an external electrical signal into the photocathode; The material of the electrode is selected from one or more of Ti, Al, Ni, Au, Mo, and Pt.

4. A method for preparing a solar-blind ultraviolet photocathode, characterized in that: The following steps are involved: providing a substrate including a base layer; growing a gallium oxide layer on the substrate layer; Growing a cesium oxide layer on a side of the gallium oxide layer away from the base layer, wherein the thickness of the cesium oxide layer is 2 nm to 10 nm; Optionally, the preparation method prepares the solar-blind ultraviolet photocathode as described in any one of claims 1 to 3.

5. The preparation method according to claim 4, characterized in that: The growth method of the cesium oxide layer is one of alternating growth and symbiosis based on thermal evaporation method; The cesium oxide layer is prepared by controlling the cesium source current and the oxygen source current under vacuum conditions; The steps of preparing the cesium oxide layer meet one or more of the following characteristics: The vacuum degrees for cesium source activation and oxygen source activation are each independently less than or equal to 1.0×10 -5 Pa; The current range of the cesium source and the oxygen source is independently 2.5A to 4.5A; The material of the cesium source is selected from cesium salts that can decompose elemental cesium, and the cesium salt is selected from one or more of cesium oxalate and acetate; The material of the oxygen source is selected from metal oxides that can decompose elemental oxygen, and the metal oxide is selected from one or more of barium oxide and silver oxide.

6. The preparation method according to claim 5, characterized in that: The growth mode of the cesium oxide layer is alternating growth based on a thermal evaporation method, and the cesium oxide layer is composed of alternatingly grown cesium layers and oxygen layers; The step of growing a cesium oxide layer on a side of the gallium oxide layer away from the substrate layer satisfies one or more of the following characteristics: The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow the cesium layer and the oxygen layer to grow alternately; Any cesium layer is formed by activating a cesium source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3.5A; The oxygen layer of any layer is formed by activating the oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the oxygen source is 3.5A~4.5A.

7. The preparation method according to claim 5, characterized in that: The growth mode of the cesium oxide layer is a symbiotic method, and the cesium and oxygen in the cesium oxide layer are formed by symbiotic growth; The step of growing a cesium oxide layer on a side of the gallium oxide layer away from the substrate layer satisfies one or more of the following characteristics: The cesium oxide layer is obtained by controlling the cesium source current and the oxygen source current under vacuum conditions to allow cesium and oxygen to co-grow; The cesium oxide layer is formed by activating a cesium source and an oxygen source under vacuum conditions to maximize the in-situ photocurrent, and the vacuum degree is less than or equal to 1.0×10 -5 Pa, the current range of the cesium source is 2.5A~3A, and the current range of the oxygen source is 3.5A~4A.

8. The preparation method according to any one of claims 4 to 7, characterized in that The gallium oxide layer is grown in a manner selected from at least one of magnetron sputtering deposition, pulsed laser deposition, chemical vapor deposition, atomic layer deposition and molecular beam epitaxial deposition; the gallium oxide layer is grown in a manner selected from magnetron sputtering deposition; The steps of preparing the gallium oxide layer include: evacuating the cavity in an argon atmosphere, introducing oxygen, controlling the oxygen flow rate, heating the base layer, depositing a gallium oxide film on the base layer by magnetron sputtering, and performing in-situ annealing after heating to form the gallium oxide layer; The step of preparing the gallium oxide layer satisfies one or more of the following characteristics: The target material is a gallium oxide target; The distance between the target material and the substrate layer is controlled to be 28 cm to 32 cm; In the step of evacuating the cavity under an argon atmosphere, the cavity pressure is increased to less than or equal to 3.0 Pa under the argon atmosphere; the oxygen flow rate is controlled to be 3 sccm to 5 sccm to control the oxygen vacancy concentration and density of the gallium oxide layer; In the step of heating the base layer, the base layer is heated to 450° C. to 460° C.; In the step of depositing a gallium oxide film on the substrate layer by magnetron sputtering, the sputtering power is 60W-80W and the sputtering time is 0.5h-3h; In the step of performing in-situ annealing after heating, the annealing temperature is 700° C. to 750° C., and the annealing time is 10 min to 15 min.

9. A solar-blind ultraviolet detector, characterized in that: It comprises at least one of the solar-blind ultraviolet photocathode as described in any one of claims 1 to 3 and the solar-blind ultraviolet photocathode prepared by the preparation method as described in any one of claims 4 to 8.

10. A solar-blind ultraviolet light detection method, characterized in that: The steps include: The solar-blind ultraviolet light is detected by using the solar-blind ultraviolet photocathode according to any one of claims 1 to 3, the solar-blind ultraviolet photocathode prepared by the preparation method according to any one of claims 4 to 8, or the solar-blind ultraviolet light detector according to claim 9; Optionally, the working voltage for the detection is 100V~200V.

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