Current-capacitance dual operating mode direct x-ray detector and method of manufacture

Abstract

The application belongs to the technical field of X-ray detectors and the technical field of semiconductor coating, and provides a current-capacitance dual-working-mode direct X-ray detector and a preparation method. The preparation method of the current-capacitance dual-working-mode direct X-ray detector comprises a preparation step of a ferroelectric nanodipole coupling radiation conversion semiconductor thin film active layer: S1: coupling a metal halide perovskite slurry with a ferroelectric nanodipole powder synthesized by a precursor powder chemical synthesis; S2: preparing the ferroelectric nanodipole coupling radiation conversion semiconductor thin film active layer on a conductive substrate by a doctor blade method. The current-capacitance dual-working-mode direct X-ray detector prepared by the application works in a capacitance detection mode under a low alternating voltage, avoiding directional migration of intrinsic ions of a metal halide perovskite under a direct current electric field, which leads to phase separation, decomposition and failure of the device.

Description

Technical Field

[0001] This invention belongs to the fields of X-ray detector technology and semiconductor coating technology, specifically relating to a current-capacitance dual-mode direct X-ray detector and its fabrication method. Background Technology

[0002] X-ray detectors are widely used in daily life, industrial production, remote sensing mapping, and medical diagnosis. Existing X-ray detectors are classified into two categories based on their working mechanism: indirect detection and direct detection. Indirect detectors convert X-rays into visible or near-ultraviolet light using a scintillation crystal, and then convert the optical signal into an electrical signal using an integrated photodetector. These detectors have a slow response speed due to the afterglow of the scintillation crystal, and the conversion from X-rays to low-energy photons loses the energy and momentum information of the X-rays, resulting in poor imaging detail. Direct detectors directly convert X-rays into electrical signals through a semiconductor optical active layer, preserving the energy information of the incident X-ray photons, and offering a faster response speed and better imaging detail. Both types of X-ray detectors belong to the power-detection type, converting photons into electron-hole pairs through the photovoltaic effect, separating the electron-hole pairs under an applied bias voltage, and measuring the electrical signal of the electron-hole pairs passing through the circuit to obtain the radiation signal. In practical applications, to ensure the detector's sensitivity and signal-to-noise ratio, a high bias voltage needs to be applied through an external circuit during operation. This external circuit's electrical injection increases the difference between photocurrent and dark current, but places high demands on the high-voltage resistance of materials and devices. Common X-ray detector materials include silicon, germanium, amorphous selenium, and cadmium telluride. Their fabrication processes are complex, and all require a boost circuit to provide the high voltage needed for detector operation. Metal halide perovskites are ideal X-ray optically active materials, possessing a high X-ray linear attenuation coefficient similar to cadmium telluride, and can be deposited at low temperatures with a simple fabrication process. However, metal halide perovskites are soft-lattice materials, and intrinsic ion migration occurs in a DC electric field of 0.1 volts per micrometer, leading to chemical segregation of the perovskite layer, ultimately resulting in phase separation and decomposition, causing device failure. Therefore, the high operating bias voltage of X-ray detectors also limits the commercial application of metal halide perovskite materials as the active layer of X-ray detectors. Summary of the Invention

[0003] To address the problem of X-ray detectors in the prior art being prone to failure under high operating bias voltage, this invention provides a method for fabricating a direct X-ray detector with current-capacitance dual operating mode.

[0004] The fabrication method of this current-capacitance dual-mode direct X-ray detector includes the following steps: fabrication of a ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer.

[0005] S1: Chemical synthesis of ferroelectric nanopole powder coupled with metal halide perovskite slurry using precursor powder;

[0006] S2: The active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film is prepared on a conductive substrate by a blade coating method.

[0007] Furthermore, the precursor powder includes ferroelectric nanopole powder and calcium precursor powder. The ferroelectric nanopole powder is one or both of barium titanate and bismuth ferrite. The calcium precursor powder is selected from at least two of methylamine iodine, formamidinium iodine, cesium iodide, lead iodide, lead bromide and lead chloride powder.

[0008] Furthermore, the ferroelectric nanopole powder has a particle size between 100 nanometers and 70 micrometers, and the stoichiometric ratio of cations to anions in the calcium precursor powder is 2:3.

[0009] Furthermore, the preparation method of the ferroelectric nanopole powder coupled with metal halide perovskite slurry includes:

[0010] The precursor powder is uniformly dispersed in a solvent and / or a co-solvent, wherein the solvent is selected from one or more of water, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone, and the co-solvent is selected from one or more of methanol, ethanol, n-propanol and isopropanol.

[0011] One object of the present invention is to provide a current-capacitance dual-mode direct X-ray detector. This current-capacitance dual-mode direct X-ray detector includes a ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer, which exhibits a capacitance change effect when irradiated by X-rays.

[0012] Furthermore, the thickness of the active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film is between 500 nanometers and 1 millimeter, and the particle size of the ferroelectric nanodipole powder and calcium precursor powder dispersed in the active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film is between 100 nanometers and 70 micrometers.

[0013] Furthermore, the current-capacitance dual-mode direct X-ray detector also includes a conductive substrate disposed on one side of the active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film and an electrode on the other side.

[0014] Furthermore, buffer layers are provided between the conductive substrate and the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film, between the active layers of the ferroelectric nanopole coupled radiation conversion semiconductor thin film, and between the electrodes.

[0015] Furthermore, a 500-nanometer-thick indium-doped tin oxide layer is deposited on the conductive substrate.

[0016] One objective of this invention is to provide a non-power X-ray detection method based on the radiation-induced capacitance change effect. The current-capacitance dual-mode direct X-ray detector obtains X-ray signals by measuring capacitance changes, the differential capacitance change with respect to time, or the inductance-capacitance oscillation frequency change in conjunction with a capacitance measurement module, a time differential capacitance measurement module, or a component consisting of a variable inductance module, a frequency discrimination module, and a current signal measurement module.

[0017] This invention provides a current-capacitance dual-mode direct X-ray detector. This detector obtains the radiation signal by measuring the current or capacitance change of the active layer of a ferroelectric nanopole-coupled radiation conversion semiconductor thin film. The capacitance signal can be measured under low AC bias, avoiding the need for high bias voltages required in existing X-ray detectors that characterize radiation signals using current signals based on the photovoltaic effect, thus improving device safety and reliability. Furthermore, this invention uses a ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer, deposited at low temperature using a blade coating process. Compared to the semiconductor device processes required for the fabrication of existing silicon-based, germanium-based, selenium-based, and cadmium telluride-based X-ray detectors, this significantly reduces production costs. The current-capacitance dual-mode direct X-ray detector proposed in this invention operates in capacitance detection mode under low AC bias. This avoids the directional migration of intrinsic metal halide perovskite ions under a DC electric field, which could lead to device phase separation, decomposition, and failure. It also reduces heat generation during device operation through non-power detection, lowering the proportion of thermally excited carriers, thereby improving the signal-to-noise ratio and accuracy of the device's detection signal. Attached Figure Description

[0018] Figure 1 This invention provides a flowchart for the preparation of the active layer of a ferroelectric nanopole coupled radiation conversion semiconductor thin film.

[0019] Figure 2 A schematic diagram of the current-capacitance dual-operating-mode direct X-ray detector provided by the present invention;

[0020] Figure 3 This invention provides a non-power X-ray detection method based on the radiation-induced capacitance change effect;

[0021] Figure 4 This is a circuit diagram of the detection device for measuring X-ray signals using a characteristic oscillation frequency, as described in this invention.

[0022] Figure 5 This invention employs a fixed 30-volt DC bias voltage to respond to the current signal of an X-ray signal in the current detection operating mode.

[0023] Figure 6 The present invention employs a capacitance signal response of ±1 volt and 100 kHz to X-ray signals in the capacitance detection working mode.

[0024] Figure 7 This invention describes the response of X-ray signals to a characteristic oscillation frequency detection method in the capacitance detection working mode.

[0025] Label Explanation:

[0026] A direct X-ray detector with current-capacitance dual operating mode includes: 1. Conductive substrate; 11. First buffer layer; 12. Ferroelectric nanopole coupled radiation conversion semiconductor thin film active layer; 13. Ferroelectric nanopole; 131. Second buffer layer; 14. Metal electrode; 15. Capacitance measurement module; 2. Variable inductance module; 3. Time differential capacitance measurement module; 4. Frequency discrimination module; 5. Current signal measurement module; 6. Signal amplification module; 7. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention.

[0028] To overcome the shortcomings of existing high-power direct X-ray detectors that rely on high operating bias voltages to generate sufficiently strong current signals, this invention provides a current-capacitance dual-mode direct X-ray detector based on the radiation-induced capacitance change effect. The detector includes a ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer. The X-ray active layer thin film comprises a semiconductor material and nanopole powder coupled to the semiconductor material. The semiconductor material converts electromagnetic radiation into electron-hole pairs, and the ferroelectric nanopole powder is polarized by a built-in or applied electric field. The working principle of this detector is as follows: under X-ray irradiation, electron-hole pairs are generated in the semiconductor material. Due to the polarization of the ferroelectric dipoles in the electric field, the surface-bound charges of the dipoles attract electrons or holes of opposite sign, partially shielding the polarization intensity of the dipoles themselves. This changes the relative permittivity of the ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer, i.e., changes the capacitance of the coupling layer. By measuring the capacitance change of the ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer under irradiation, the intensity of the radiation signal can be obtained. The advantages of the detector provided by this invention include: 1. High sensitivity. The detector's equivalent capacitance signal sensitivity is higher than 1000 microcoulombs per gri / cm². Simultaneously, the detector can also extract X-ray-excited photogenerated carriers and read current signals under a bias voltage, with a current signal sensitivity exceeding 1000 microcoulombs per gri / cm². 2. It features dual operating modes. The detector can separately read radiation-induced capacitance changes and radiation-induced photogenerated carrier current signals. In current operating mode, a DC bias voltage is applied to the detector device, and the device current signal is read. When X-rays enter the device, the rays excite photogenerated carriers in the semiconductor material. These excited photogenerated carriers are separated by the DC bias voltage and collected by electrodes, generating an electrical signal in the detection circuit. In capacitance operating mode, a fixed AC voltage between ±1 volt and 1 MHz is applied to the detector device, with a voltage frequency between 100 Hz and 10 MHz, and the device capacitance signal is read. In the dark, semiconductor materials are in their intrinsic state, and ferroelectric dipoles are in a polarized state. When X-rays enter the device, the rays excite photogenerated carriers in the semiconductor material. Under AC bias, these photogenerated carriers cannot continue to migrate directionally and are captured and stored by the opposite-signal surface charge of the ferroelectric dipoles. The polarization of the ferroelectric dipoles is partially shielded by the captured photogenerated carriers, causing a change in the device capacitance. Traditional X-ray detectors operate only in current mode, where the brightness of the imaging pixels is proportional to the current signal intensity, while the pixel contrast is limited by the device's dark current intensity and sensitivity. Improving the imaging pixel contrast requires increasing the incident X-ray dose rate, while medical X-ray imaging requires the X-ray dose rate to be as low as possible. The current-capacitance dual-mode direct X-ray detector of this invention can adjust the device capacitance by applying different AC bias values ​​and AC bias frequencies in capacitive operating mode, thereby changing the pixel contrast of X-ray imaging without changing the X-ray dose rate.

[0029] This invention utilizes calcium metal halide as the semiconductor material to achieve the function of detecting X-ray dose through capacitance signal when the detector operates under high-frequency AC bias. Simultaneously, this invention overcomes the defect of intrinsic ion migration in metal halide perovskites under DC bias, which prevents long-term detector operation. Specifically, because the signal applied to the measuring capacitor is a low AC bias, the ionic components of the metal halide perovskite cannot be driven by an AC electric field with a frequency higher than the threshold, i.e., no field-driven chemical component segregation occurs. This solves the problem of device failure caused by phase separation and decomposition of metal halide perovskites due to high operating DC bias in X-ray detector applications. Since the capacitance detection mode is a non-power detection mode, it does not require a continuous DC bias to generate directional current in the circuit. Compared with existing X-ray detectors, the capacitance detection mode of this invention consumes less power and reduces the dark current introduced by electrical injection, resulting in a lower dark current background signal compared to existing X-ray detectors.

[0030] Refer to the instruction manual Figure 1 The fabrication method of a current-capacitance dual-mode direct X-ray detector includes the following steps:

[0031] S1: Chemically synthesize ferroelectric nanopole powder coupled with metal halide perovskite slurry using precursor powder.

[0032] The precursor powder includes ferroelectric nanopole powder and calcium precursor powder. The molar ratio of ferroelectric nanopole powder to calcium precursor powder is 1:2-99. Preferably, the molar ratio of ferroelectric nanopole powder to calcium precursor powder is less than 1:3. More preferably, the molar ratio of ferroelectric nanopole powder to calcium precursor powder is 1:9.

[0033] The ferroelectric nanopole powder is one or both of barium titanate and bismuth ferrite, with a particle size between 100 nanometers and 70 micrometers. Preferably, the particle size is between 100 nanometers and 38 micrometers. More preferably, the particle size is between 30 micrometers and 1 micrometer. Preferably, the ferroelectric nanopole powder is a mixture of barium titanate and bismuth ferrite powder. Preferably, the mixture of barium titanate and bismuth ferrite powder can be a solid solution powder of barium titanate and bismuth ferrite, or a mixture of pure barium titanate powder and pure bismuth ferrite powder.

[0034] The calcium precursor powder is selected from at least two of the following: methylamine iodine, formamidinium iodine, cesium iodide, lead iodide, lead bromide, and lead chloride powder. The stoichiometric ratio of cations to anions in the calcium precursor powder is 2:3.

[0035] In one embodiment, the preparation method of ferroelectric nanopole powder coupled with metal halide perovskite slurry includes:

[0036] The precursor powder is uniformly dispersed in a dispersion medium, which includes a solvent and / or a co-solvent. The solvent is selected from one or more of water, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone. The co-solvent is selected from one or more of methanol, ethanol, n-propanol, and isopropanol. Preferably, a mixed solution of ethylene glycol and isopropanol is used as the dispersion medium, wherein the mass ratio of ethylene glycol to isopropanol is 1:18-23.2.

[0037] The dispersion process involves magnetic stirring for 1 hour followed by ultrasonic vibration for 1 hour, repeated three times. Preferably, the magnetic stirring speed is between 800 and 1200 rpm, and the stirring temperature is room temperature. In some embodiments, the magnetic stirring speed can be 1000 rpm.

[0038] S2: The active layer of a ferroelectric nanopole coupled radiation conversion semiconductor thin film is prepared on a conductive substrate by a blade coating method.

[0039] The conductive substrate can be a material that is inherently conductive, such as a metal, or a material that is not inherently conductive but has been plated or coated with a conductive layer, such as glass, polymer films, and crystals. The conductive layer can include silver nanoparticles, silver nanowires, indium-doped tin oxide, tungsten-doped tin oxide, cerium-doped tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, tungsten-doped zinc oxide, or cadmium stannate. Preferably, the conductive substrate is a material plated with 500 nanometers of indium-doped tin oxide. A buffer layer can also be plated or coated on the conductive substrate, and the active layer of the ferroelectric nanopole-coupled radiation conversion semiconductor thin film is prepared on the buffer layer. The buffer layer can be prepared on the conductive substrate by a deposition process. The buffer layer can include tin oxide, nickel oxide, titanium oxide, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), or fullerene or fullerene derivatives.

[0040] The active layer of a ferroelectric nanopole-coupled radiation conversion semiconductor thin film is prepared under an inert atmosphere, preferably a nitrogen atmosphere with water and oxygen content below 1 ppm. During blade coating, the slurry prepared in step S1 is uniformly coated onto the conductive substrate using a blade. The thickness of the active layer is controlled by the blade height, which is between 700 nm and 1 mm. After coating, the dispersion medium is slowly evaporated and cured in a nitrogen atmosphere by gradient heating, with temperatures between 20°C and 200°C and holding times between 20 minutes and 8 hours per step. Preferably, the blade height is between 500 μm and 1 mm, and the coating speed is between 5 mm and 30 mm per second. More preferably, the blade height is 500 μm and the coating speed is 7 mm. Preferably, the drying process involves holding at 35°C for 4 hours, then increasing to 45°C for 4 hours, and finally holding at 110°C for 2 hours.

[0041] This invention uses a low-temperature scraping process to coat an active layer of a ferroelectric nanopole coupled radiation conversion semiconductor thin film onto a substrate. Depending on the range of X-ray energy detected, the thickness of the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film ranges from 500 nanometers to 1 millimeter, wherein the size of the dispersed ferroelectric nanopole ranges from 100 nanometers to 70 micrometers.

[0042] In one embodiment, the fabrication method of a current-capacitance dual-mode direct X-ray detector further includes the following steps:

[0043] S3: A carbon electrode is prepared by depositing a metal electrode on the surface of the active layer of the above-mentioned ferroelectric nanodipole coupled radiation conversion semiconductor thin film using physical vapor deposition or by printing.

[0044] Physical vapor deposition (PVD) methods can include magnetron sputtering, electron beam deposition, thermal evaporation, or reactive plasma deposition. The metal electrode can be a single element, alloy, or stack of copper, silver, gold, aluminum, chromium, nickel, or tungsten, with a thickness between 10 and 100 nanometers. Preferably, the PVD process is thermal evaporation, the metal electrode is copper, the evaporation power is 80 watts, and the electrode thickness is 10 to 100 nanometers. More preferably, a buffer layer is deposited on the active layer of the ferroelectric nanopole-coupled radiation conversion semiconductor thin film, and the metal electrode is then fabricated on the buffer layer.

[0045] The printing method can be screen printing or stencil printing. Carbon paste is printed onto the surface of the active layer of a ferroelectric nanopole-coupled radiation conversion semiconductor thin film using a screen or stencil. After drying at 100°C to 150°C, an electrode is obtained, with an electrode thickness between 500 nanometers and 0.1 millimeters. Preferably, the printing method is screen printing, with the carbon paste drying temperature at 100°C to 120°C and a drying time of 10 to 20 minutes.

[0046] According to the manufacturing process of this invention, a direct X-ray detector with current-capacitance dual operating mode can be prepared. The active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film can be prepared by low-temperature coating process. The subsequent curing process is simple. The device does not require a high DC bias voltage during operation, which avoids the intrinsic ion migration of metal halide perovskite under DC bias voltage driving the device to cause phase separation, decomposition and failure.

[0047] Refer to the instruction manual Figure 2 The present invention also provides a direct X-ray detector with current-capacitance dual operating mode.

[0048] The current-capacitance dual-mode direct X-ray detector 1 includes, from bottom to top, a conductive substrate 11, a first buffer layer 12, a ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer 13, a second buffer layer 14, and a metal electrode 15. Ferroelectric nanopoles 131 are uniformly distributed in the ferroelectric nanopole-coupled radiation conversion semiconductor thin film active layer 13.

[0049] This current-capacitance dual-mode direct X-ray detector utilizes the radiation-induced capacitance change effect to obtain X-ray radiation signals by measuring the capacitance changes of the active layer of a ferroelectric nanopole-coupled radiation conversion semiconductor thin film, operating under low AC bias. This invention simplifies the circuit structure, reduces the detector system integration cost, and improves device safety. Simultaneously, the low AC bias operating condition of this invention avoids the directional migration of intrinsic ions in metal halide perovskite under a DC electric field, which could lead to device phase separation, decomposition, and failure, thus making metal halide perovskite materials practically applicable. It also reduces heat generation during device operation, lowers the proportion of thermally excited charge carriers, and thereby improves the signal-to-noise ratio of the detected signal.

[0050] Refer to the instruction manual Figure 3 The present invention also provides a non-power X-ray detection method based on the radiation-induced capacitance change effect.

[0051] The non-power X-ray detection method based on the radiation-induced capacitance change effect includes three approaches: First, a direct X-ray detector 1 operating in both current and capacitance modes is used in conjunction with a capacitance measurement module 2 to measure capacitance changes and obtain the X-ray radiation signal. Second, a direct X-ray detector 1 operating in both current and capacitance modes is used in conjunction with a time-differential capacitance measurement module 4 to measure the differential change of capacitance over time and obtain the X-ray radiation signal. Third, a direct X-ray detector 1 operating in both current and capacitance modes is used in conjunction with a component consisting of a variable inductance module 3, a frequency discriminator module 5, and a current signal measurement module 6 to measure the inductance-capacitance oscillation frequency and obtain the X-ray radiation signal. Specifically, the direct X-ray detector 1 operating in both current and capacitance modes is connected in parallel with the variable inductance module 3 to generate an oscillating current. The frequency discriminator module 5 converts the inductance-capacitance oscillation frequency signal into a current signal, which is then transmitted to the current signal measurement module 6 to obtain the X-ray radiation signal.

[0052] To further illustrate the feasibility of measuring X-ray signals based on the characteristic oscillation frequency of the current-capacitance dual-mode direct X-ray detector 1, this invention provides a detection device 200 that measures X-ray signals using the characteristic oscillation frequency. See the specification. Figure 4 The detection device 200 includes a current-capacitance dual-mode direct X-ray detector 1, a variable inductance module 3, a frequency discrimination module 5, and a signal amplification module 7.

[0053] The current-capacitor dual-operating-mode direct X-ray detector 1 and the variable inductor module 3 are connected in parallel to generate an oscillating current. The frequency discrimination module 5 obtains the frequency of the oscillating current and converts it into a current signal. After the frequency is amplified by the signal amplification module 7, the signal is output to obtain the X-ray radiation signal.

[0054] The current signal of the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film is read through a complementary metal-oxide-semiconductor circuit or a thin film field-effect transistor circuit, and the capacitance signal is read through three methods: direct measurement circuit, capacitance-time differential circuit, and inductor-capacitor oscillation circuit frequency.

[0055] The non-power X-ray detection method based on the radiation-induced capacitance change effect, using a fixed 30-volt DC bias in current detection mode, provides the following current signal response results for the X-ray signal as shown in the instruction manual. Figure 5 As shown; the capacitance signal response results of X-ray signals using ±1 volt and 100 kHz frequencies in capacitance detection mode are as follows. Figure 6 As shown.

[0056] Example 1

[0057] 1.1 Preparation of Ferroelectric Nanopole Powder Coupled with Metal Halide Perovskite Slurry

[0058] Weigh 1.86 g of barium titanate and perovskite precursor powder, wherein barium titanate accounts for 10% of the total molar amount of the powder, and add 1 g of a mixed solution of ethylene glycol and isopropanol, wherein ethylene glycol accounts for 5% of the mass of the mixed solution. Place a magnetic stir bar in the mixture and stir on a magnetic stirring table at 800 rpm for one hour. Then sonicate at room temperature for one hour. Repeat this process three times to obtain a ferroelectric nanopole powder coupled with metal halide perovskite slurry.

[0059] 1.2 Preparation of active layer of ferroelectric nanopole coupled radiation conversion semiconductor thin film

[0060] Sodium-calcium glass with dimensions of 1.5 cm and width, a thickness of 7 mm, and an indium-doped tin oxide conductive layer on one side was used as the conductive substrate. The substrate was vacuum-adsorbed onto a squeegee platform with a squeegee height of 500 micrometers and a squeegee speed of 10 mm per second. The slurry was poured onto the conductive layer surface and squeegeed at a uniform speed with a squeegee. The substrate was dried at 35 degrees Celsius for 4 hours, then heated to 45 degrees Celsius for 4 hours, and finally heated to 110 degrees Celsius for 2 hours.

[0061] 1.3 Metal Electrode Preparation

[0062] The sample coated with the active layer of the dried ferroelectric nanopole coupled radiation conversion semiconductor thin film was taken out and placed in the sample holder of the thermal evaporation equipment. Copper was selected as the evaporation source, the evaporation power was 80 watts, and an 80 nanometer thick copper electrode was deposited.

[0063] 1.4 Integration of Capacitive Signal Reading Module with X-ray Dose and Energy Reading

[0064] After electrode fabrication, the copper electrode and indium-doped tin oxide electrode of the detector were connected in parallel to the two ends of an inductor, respectively. The parallel terminals were then connected to both sides of the frequency discrimination module. The X-ray dose and energy were obtained by reading the changes in the inductor-capacitor oscillation frequency signal of the circuit. The test results are as follows: Figure 7 As shown.

[0065] Example 2

[0066] 2.1 Preparation of Ferroelectric Nanopole Powder Coupled with Metal Halide Perovskite Slurry

[0067] Weigh 1.86 g of barium titanate and perovskite precursor powder, wherein barium titanate accounts for 5% of the total molar amount of the powder, add 1.2 g of ethylene glycol solution, place a magnetic stir bar in the mixture, stir on a magnetic stirring table at 800 rpm for one hour, and then sonicate at room temperature for one hour to obtain ferroelectric nanopole powder coupled with metal halide perovskite slurry.

[0068] 2.2 Preparation of Active Layer of Ferroelectric Nanopole Coupled Radiation Conversion Semiconductor Thin Film

[0069] Sodium-calcium glass with dimensions of 2.5 cm and width, a thickness of 1.1 mm, and a fluorine-doped tin oxide conductive layer on one side was used as the conductive substrate. The substrate was vacuum-adsorbed onto a squeegee platform with a squeegee height of 700 micrometers and a squeegee speed of 7 mm per second. The slurry was poured onto the conductive layer surface and squeegeed at a uniform speed. The substrate was dried at 35 degrees Celsius for 4 hours, then heated to 45 degrees Celsius for 8 hours, and finally heated to 110 degrees Celsius for 3 hours.

[0070] 2.3 Fabrication of carbon electrodes by screen printing

[0071] Remove the active layer coated with the dried ferroelectric nanopole coupled radiation conversion semiconductor thin film, place it under the pattern of the screen template, pour carbon paste onto the screen, and print the carbon paste on the surface of the active layer at a scraping speed of 10 mm / s. Dry at 120 degrees Celsius for 5 minutes.

[0072] 2.4 Integration of Capacitive Signal Reading Module with X-ray Dose and Energy Reading

[0073] After electrode fabrication, the carbon electrode and fluorine-doped tin oxide electrode of the detector were connected in parallel with a time-capacitance differential measurement circuit. The X-ray dose and energy were obtained by measuring the differential signal change of the capacitance with respect to time. The test results are as follows: Figure 6 As shown.

Claims

1. A method for fabricating a direct X-ray detector with current-capacitance dual operating mode, characterized in that, The preparation steps include: ferroelectric nanopole coupled radiation conversion semiconductor thin film active layer: S1: Chemical synthesis of ferroelectric nanopole powder coupled with metal halide perovskite slurry using precursor powder; the preparation method of the ferroelectric nanopole powder coupled with metal halide perovskite slurry includes: The precursor powder is uniformly dispersed in a solvent and / or a co-solvent, wherein the solvent is selected from one or more of water, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone, and the co-solvent is selected from one or more of methanol, ethanol, n-propanol and isopropanol; The precursor powder includes ferroelectric nanopole powder and calcium precursor powder. The ferroelectric nanopole powder is one or both of barium titanate and bismuth ferrite. The calcium precursor powder is selected from at least two of methylamine iodine, formamidinium iodine, cesium iodide, lead iodide, lead bromide and lead chloride powder. The particle size of the ferroelectric nanodipole powder is between 100 nanometers and 70 micrometers. The molar ratio of the ferroelectric nano-dipole powder to the calcium precursor powder is less than 1:3; S2: The active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film is prepared on a conductive substrate by a blade coating method; The active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film generates a capacitance change effect when irradiated by X-rays, and has a current operating mode and a capacitance operating mode. In the current operating mode, a DC bias voltage is applied to the detector device and the device current signal is read. In the capacitance operating mode, a fixed AC voltage between ±1 volt and 1 volt is applied to the detector device and the voltage frequency is between 100 Hz and 10 MHz, and the device capacitance signal is read.

2. The method for fabricating a direct X-ray detector with current-capacitance dual operating mode as described in claim 1, characterized in that, The stoichiometric ratio of cations to anions in the calcium precursor powder is 2:

3.

3. A direct X-ray detector with current-capacitance dual operating mode, characterized in that, It is prepared by the preparation method described in any one of claims 1-2.

4. The current-capacitance dual-mode direct X-ray detector as described in claim 3, characterized in that, The thickness of the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film is between 500 nanometers and 1 millimeter, and the particle size of the ferroelectric nanopole powder and calcium precursor powder dispersed in the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film is between 100 nanometers and 70 micrometers.

5. The current-capacitance dual-mode direct X-ray detector as described in claim 4, characterized in that, It also includes a conductive substrate disposed on one side of the active layer of the ferroelectric nanodipole coupled radiation conversion semiconductor thin film and an electrode on the other side.

6. The current-capacitance dual-mode direct X-ray detector as described in claim 5, characterized in that, Buffer layers are provided between the conductive substrate and the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film, and between the active layer of the ferroelectric nanopole coupled radiation conversion semiconductor thin film and the electrode.

7. The current-capacitance dual-mode direct X-ray detector as described in claim 6, characterized in that, The conductive substrate is coated with a 500-nanometer-thick indium-doped tin oxide layer.

8. A non-power X-ray detection method based on the radiation-induced capacitance change effect, characterized in that a current-capacitance dual-mode direct X-ray detector as described in any one of claims 3-7 is used, wherein the current-capacitance dual-mode direct X-ray detector (1) is used in conjunction with a capacitance measurement module (2), a time differential capacitance measurement module (4) or a component consisting of a variable inductance module (3), a frequency discrimination module (5) and a current signal measurement module (6) to measure capacitance change, differential capacitance change with time, or inductance-capacitance oscillation frequency change to obtain X-ray radiation signal.

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