WO2024109770A1 - 一种电流-电容双工作模式直接型x射线探测器和制备方法 - Google Patents

一种电流-电容双工作模式直接型x射线探测器和制备方法 Download PDF

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WO2024109770A1
WO2024109770A1 PCT/CN2023/133067 CN2023133067W WO2024109770A1 WO 2024109770 A1 WO2024109770 A1 WO 2024109770A1 CN 2023133067 W CN2023133067 W CN 2023133067W WO 2024109770 A1 WO2024109770 A1 WO 2024109770A1
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current
ferroelectric
capacitance
working mode
ray detector
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PCT/CN2023/133067
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English (en)
French (fr)
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李云龙
朱子尧
陈慧雯
喻学锋
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中国科学院深圳先进技术研究院
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/10—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising heterojunctions between organic semiconductors and inorganic semiconductors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/60—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation in which radiation controls flow of current through the devices, e.g. photoresistors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/50—Organic perovskites; Hybrid organic-inorganic perovskites [HOIP], e.g. CH3NH3PbI3

Definitions

  • the present invention belongs to the technical field of X-ray detectors and the technical field of semiconductor coating, and specifically relates to a current-capacitance dual working mode direct type X-ray detector and a preparation method thereof.
  • X-ray detectors are widely used in daily life, industrial production, remote sensing mapping and medical diagnosis.
  • Existing X-ray detectors are divided into two categories according to their working mechanism: indirect detection and direct detection.
  • Indirect detectors convert X-rays into visible light or near-ultraviolet light through scintillation crystals, and then convert the light signal into a current signal through an integrated photodetector. Due to the afterglow of the scintillation crystal, this type of detector has a slow response speed, and the conversion process from X-rays to low-energy photons loses the energy and momentum information of the X-rays, resulting in poor imaging details.
  • Direct detectors convert X-rays directly into electrical signals through a semiconductor optically active layer, which can retain the energy information of the incident X-ray photons, and have faster response speeds and better imaging details.
  • Both types of X-ray detectors are power detection X-ray detectors, which convert photons into electron-hole pairs through the photovoltaic effect, separate the electron-hole pairs under an external bias, and measure the electrical signals of the electron-hole pairs through the circuit to obtain radiation signals.
  • a high bias voltage needs to be applied through an external circuit during operation, and the difference between the photocurrent and the dark current is increased by electrical injection from the external circuit, but this places high demands on the high-voltage resistance of materials and devices.
  • Common X-ray detector materials are mainly silicon, germanium, amorphous selenium and cadmium telluride. The preparation process is complicated and all require a boost circuit to provide the high voltage required for the detector to work.
  • Metal halide perovskite is an ideal X-ray optically active material with a high X-ray linear attenuation coefficient similar to that of cadmium telluride, and can be formed at low temperature.
  • metal halide perovskite is a soft lattice material. Intrinsic ion migration will occur in a DC electric field with an intensity of 0.1 volts per micron, resulting in segregation of the chemical components of the perovskite layer, and ultimately phase separation and decomposition, resulting in device failure. Therefore, the high working bias of the X-ray detector also limits the commercial application of metal halide perovskite materials as the active layer of X-ray detectors.
  • the present invention provides a method for preparing a direct X-ray detector in a current-capacitance dual working mode.
  • the method for preparing the current-capacitance dual working mode direct X-ray detector comprises the steps of preparing the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer:
  • the precursor powder includes ferroelectric nanodipole powder and calcium precursor powder
  • the ferroelectric nanodipole powder is one or two of barium titanate and bismuth ferrite
  • the calcium precursor powder is selected from at least two of methylamine iodine, formamidine 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, and the stoichiometric ratio of cations and anions in the calcium precursor powder is 2:3.
  • the preparation method of the ferroelectric nano-dipole powder coupled metal halide perovskite slurry comprises:
  • 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 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.
  • An object of the present invention is to provide a current-capacitance dual working mode direct type X-ray detector.
  • the current-capacitance dual working mode direct type X-ray detector comprises a ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer, wherein the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer generates a capacitance change effect when irradiated by X-rays.
  • 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.
  • the current-capacitance dual working mode direct X-ray detector further includes a conductive substrate arranged on one side of the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer and an electrode on the other side.
  • a buffer layer is provided between the conductive substrate and the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer, between the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layers and between the electrodes.
  • the conductive substrate is plated with a 500 nanometer thick indium-doped tin oxide layer.
  • One object of the present invention is to provide a non-power type X-ray detection method based on the radiation-induced capacitance change effect.
  • the current-capacitance dual working mode direct X-ray detector obtains X-radiation signals by measuring capacitance changes, differential changes of capacitance to time, or changes in inductance-capacitance oscillation frequency 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.
  • the present invention provides a current-capacitance dual working mode direct X-ray detector, which obtains a radiation signal by measuring the current or capacitance change of the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor film, wherein the capacitance signal can be measured under low AC bias, avoiding the requirement of applying a high bias when the existing X-ray detector uses the current signal to characterize the radiation signal based on the photovoltaic effect, thereby improving the safety and reliability of the device.
  • the present invention selects the ferroelectric nano-dipole coupled radiation conversion semiconductor film active layer, and forms a film at low temperature through a scraping process, which greatly reduces the production cost compared to the semiconductor device process required for the preparation of the existing silicon-based, germanium-based, selenium-based and cadmium telluride-based X-ray detectors.
  • the capacitance detection mode of the current-capacitance dual working mode direct X-ray detector proposed by the present invention works under low AC bias, which not only avoids the directional migration of the intrinsic ions of the metal halide perovskite under the DC electric field, resulting in the phase separation, decomposition and failure of the device, but also reduces the heat generation of the device under the working state through the non-power detection method, reduces the proportion of thermal excitation of carriers, thereby improving the signal-to-noise ratio and accuracy of the device detection signal.
  • FIG1 is a flow chart of the preparation of the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film provided by the present invention.
  • FIG2 is a schematic diagram of the structure of a current-capacitance dual working mode direct X-ray detector provided by the present invention.
  • FIG3 is a non-power type X-ray detection method based on the radiation-induced capacitance change effect provided by the present invention
  • FIG4 is a circuit diagram of a detection device for measuring X-ray signals using a characteristic oscillation frequency according to the present invention.
  • FIG5 is a current signal response of the present invention to an X-ray signal using a fixed DC bias voltage of 30 volts in a current detection working mode
  • FIG6 is a capacitance signal response to an X-ray signal using positive and negative 1 volt and a frequency of 100 kHz in the capacitance detection working mode of the present invention
  • FIG7 is a diagram showing the response of the present invention to an X-ray signal using a characteristic oscillation frequency detection method in a capacitive detection working mode
  • a current-capacitance dual working mode direct X-ray detector 1 a conductive substrate 11, a first buffer layer 12, a ferroelectric nanodipole coupled radiation conversion semiconductor thin film active layer 13, a ferroelectric nanodipole 131, a second buffer layer 14, a metal electrode 15, a capacitance measurement module 2, a variable inductance module 3, a time differential capacitance measurement module 4, a frequency discrimination module 5, a current signal measurement module 6, and a signal amplification module 7.
  • the present invention provides a current-capacitance dual working mode direct X-ray detector based on the radiation-induced capacitance change effect.
  • the detector includes a ferroelectric nano-dipole coupled radiation conversion semiconductor film active layer, the X-ray active layer film includes a semiconductor material and a nano-dipole powder coupled with the semiconductor material, the semiconductor material can convert electromagnetic radiation into electron holes, and the ferroelectric nano-dipole powder is polarized by a built-in electric field or an external electric field.
  • the working principle of the detector is: electron-hole pairs are generated in the semiconductor material under X-ray irradiation, and since the ferroelectric dipole is polarized in the electric field, the surface bound charge of the dipole will attract electrons or holes of opposite signs respectively, partially shielding the polarization intensity of the dipole itself, thereby changing the relative dielectric constant of the ferroelectric nano-dipole coupled radiation conversion semiconductor film active layer, that is, changing the capacitance of the coupling layer, and by measuring the capacitance change of the ferroelectric nano-dipole coupled radiation conversion semiconductor film active layer under irradiation, the intensity of the radiation signal can be obtained.
  • the advantages of the detector provided by the present invention include: 1. High sensitivity.
  • the detector equivalent capacitance signal sensitivity is higher than 1000 microcoulombs per gray per square centimeter.
  • the detector can also derive the photogenerated carriers excited by X-rays and read the current signal under the action of bias voltage.
  • the detector current signal sensitivity is higher than 1000 microcoulombs per gray per square centimeter. 2. It has dual working modes. The detector can read the radiation-induced capacitance change signal and the radiation-induced photogenerated carrier current signal respectively. In the current working mode, a DC bias is applied to the detector device to read the device current signal. When X-rays enter the device, the rays excite photogenerated carriers in the semiconductor material. The excited photogenerated carriers are separated by the DC bias and collected by the electrodes, generating electrical signals in the detection circuit.
  • the capacitance working mode In the capacitance working mode, a fixed AC voltage between positive and negative 1 volt is applied to the detector device, and the voltage frequency is between 100 Hz and 10 MHz to read the device capacitance signal.
  • the semiconductor material In the dark state, the semiconductor material is in an intrinsic state, and the ferroelectric dipole is in a polarized state.
  • the photogenerated carriers Under AC bias, the photogenerated carriers cannot continue to migrate in a directional manner, and are captured and stored by the opposite surface charges of the ferroelectric dipole. The polarization of the ferroelectric dipole is partially shielded by the captured photogenerated carriers, causing the device capacitance to change.
  • the current-capacitance dual working mode direct X-ray detector of the present invention can adjust the device capacitance by applying different AC bias values and AC bias frequencies in the capacitance working mode, and can change the pixel contrast of X-ray imaging without changing the X-ray dose rate.
  • the present invention uses metal halide calcium as a semiconductor material to realize the function of detecting X-ray dose through capacitance signal when the detector works under high-frequency AC bias. At the same time, the present invention overcomes the defect that the detector cannot work for a long time due to intrinsic ion migration of metal halide perovskite under DC bias.
  • the signal applied by the measuring capacitor is a low AC bias
  • the ion components of the metal halide perovskite cannot be driven by an AC electric field with a frequency higher than the threshold, that is, no chemical component segregation driven by the electric field will occur, thereby solving the problem of device failure caused by phase separation and decomposition of metal halide perovskite due to high working DC bias in the application of metal halide perovskite in X-ray detectors.
  • the capacitance detection working mode is non-power detection, it is not necessary to continuously apply DC bias in the circuit to generate directional current.
  • the capacitance detection working mode of the present invention has lower power consumption, and at the same time reduces the dark current introduced by electrical injection, so that the present invention has a lower dark current background signal than the existing X-ray detector.
  • the method for preparing a direct X-ray detector in a current-capacitance dual working mode includes the following steps:
  • the precursor powder includes ferroelectric nanodipole powder and calcium precursor powder.
  • the molar ratio of ferroelectric nanodipole powder to calcium precursor powder is 1:2-99.
  • the molar ratio of ferroelectric nanodipole powder to calcium precursor powder is lower than 1:3. More preferably, the molar ratio of ferroelectric nanodipole powder to calcium precursor powder is 1:9.
  • the ferroelectric nanodipole powder is one or both of barium titanate and bismuth ferrite, and the powder particle size is between 100 nanometers and 70 micrometers, preferably, the powder particle size is between 100 nanometers and 38 micrometers. More preferably, the powder particle size is between 30 micrometers and 1 micrometer.
  • the ferroelectric nanodipole powder is a mixture powder of barium titanate and bismuth ferrite.
  • the mixture powder of barium titanate and bismuth ferrite 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.
  • the calcium precursor powder is selected from at least two of methylamine iodide, formamidine iodine, cesium iodide, lead iodide, lead bromide and lead chloride powders.
  • the stoichiometric ratio of cations to anions in the calcium precursor powder is 2:3.
  • a method for preparing a ferroelectric nano-dipole powder coupled metal halide perovskite slurry comprises:
  • the precursor powder is uniformly dispersed in a dispersion medium, wherein the dispersion medium includes a solvent and/or a cosolvent.
  • the solvent is selected from one or more of water, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.
  • the cosolvent is selected from one or more of methanol, ethanol, n-propanol and isopropanol.
  • 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.
  • magnetic stirring is first performed for 1 hour, and then ultrasonic vibration is performed for 1 hour, and the cycle is repeated three times.
  • the magnetic stirring speed is between 800 and 1200 rpm, and the stirring temperature is room temperature. In some embodiments, the magnetic stirring speed may be 1000 rpm.
  • the conductive substrate may be a material having conductive properties, such as a metal, or may be a material that is plated or coated with a conductive layer but does not have conductive properties, such as glass, polymer film, and crystal.
  • the conductive layer may include nanosilver particles, nanosilver wires, 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.
  • the conductive substrate is a material plated with 500 nanometers of indium-doped tin oxide.
  • a buffer layer may also be plated or coated on the conductive substrate, and the ferroelectric nano-dipole coupled radiation conversion semiconductor film active layer is prepared on the buffer layer.
  • the buffer layer may be prepared on the conductive substrate by a deposition process.
  • the buffer layer may include tin oxide, nickel oxide, titanium oxide, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or fullerene or fullerene derivatives.
  • the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor film is prepared in an inert atmosphere, and the preferred environmental condition is a nitrogen atmosphere, and the water and oxygen content in the environment is less than 1ppm.
  • the slurry prepared in step S1 is uniformly coated on the conductive substrate by the scraper movement, and the thickness of the active layer is controlled by the scraper height, wherein the scraper height is between 700 nanometers and 1 mm; after scraping, the dispersion medium is slowly evaporated by gradient heating drying and curing in a nitrogen environment, wherein the temperature is between 20 degrees Celsius and 200 degrees Celsius, and the insulation time for each step is between 20 minutes and 8 hours.
  • the scraper height is 500 microns to 1 mm, and the scraping speed is 5 mm to 30 mm per second. More preferably, the scraper height is 500 microns and the scraping speed is 7 mm.
  • the drying process is 35 degrees Celsius for 4 hours, then raised to 45 degrees Celsius for 4 hours, and finally kept at 110 degrees Celsius for 2 hours.
  • the present invention coats a ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer on a substrate through a low-temperature scraping process.
  • the thickness of the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer ranges from 500 nanometers to 1 millimeter, wherein the size of the dispersed ferroelectric nano-dipoles ranges from 100 nanometers to 70 micrometers.
  • the method for preparing a current-capacitance dual working mode direct X-ray detector further includes the following steps:
  • the physical vapor deposition method can be magnetron sputtering, electron beam deposition, thermal evaporation or reactive plasma deposition
  • the metal electrode can be a single substance, alloy or laminate of copper, silver, gold, aluminum, chromium, nickel, tungsten, and the thickness of the metal electrode is between 10 nanometers and 100 nanometers.
  • the physical vapor deposition process is a thermal evaporation process
  • the metal electrode is copper
  • the evaporation power is 80 watts
  • the electrode thickness is 10 to 100 nanometers.
  • a buffer layer is prepared on the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor film by a deposition process, and a metal electrode is prepared on the buffer layer.
  • the printing method can be screen printing or steel screen printing, and the carbon paste is printed on the surface of the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film through the screen or steel screen, and the electrode is obtained after drying at 100 degrees Celsius to 150 degrees Celsius, and the electrode thickness is between 500 nanometers and 0.1 mm.
  • the printing method is screen printing, the carbon paste drying temperature is 100 degrees Celsius to 120 degrees Celsius, and the drying time is 10 minutes to 20 minutes.
  • a current-capacitance dual working mode direct X-ray detector is prepared.
  • the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer can be prepared by a low-temperature scraping process.
  • the subsequent curing process is simple, and no high DC bias does not need to be applied when the device is working, thereby avoiding the intrinsic ion migration of the metal halide perovskite driven by the DC bias, which leads to phase separation, decomposition and failure of the device.
  • the present invention also provides a current-capacitance dual working mode direct type X-ray detector.
  • the current-capacitance dual working mode direct type X-ray detector 1 comprises a conductive substrate 11, a first buffer layer 12, a ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer 13, a second buffer layer 14 and a metal electrode 15 arranged in sequence from bottom to top.
  • the ferroelectric nano-dipole coupled radiation conversion semiconductor thin film active layer 13 is uniformly distributed with ferroelectric nano-dipoles 131.
  • the current-capacitance dual working mode direct X-ray detector utilizes the radiation-induced capacitance change effect, obtains the X-ray radiation signal by measuring the capacitance signal change of the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor film, and works under low AC bias.
  • the present invention simplifies the circuit structure, reduces the detector system integration cost, and improves the device safety.
  • the low AC bias working condition of the present invention not only avoids the directional migration of the intrinsic ions of the metal halide perovskite under the DC electric field, which leads to the phase separation, decomposition, and failure of the device, making the metal halide perovskite material have practical application value, but also reduces the heat generation of the device under the working state, reduces the proportion of thermal excitation of carriers, and thus improves the signal-to-noise ratio of the device detection signal.
  • the present invention also provides a non-power type X-ray detection method based on the radiation-induced capacitance change effect.
  • the non-power type X-ray detection method based on the radiation-induced capacitance change effect includes three approaches.
  • the current-capacitance dual working mode direct type X-ray detector 1 is used in conjunction with the capacitance measurement module 2 to measure the capacitance change to obtain the X-radiation signal;
  • the current-capacitance dual working mode direct type X-ray detector 1 is used in conjunction with the time differential capacitance measurement module 4 to measure the differential change of capacitance with respect to time to obtain the X-radiation signal;
  • the current-capacitance dual working mode direct type X-ray detector 1 is used in conjunction with a component consisting of a variable inductance module 3, a frequency discrimination module 5, and a current signal measurement module 6 to measure the inductance-capacitance oscillation frequency to obtain the X-radiation signal.
  • the current-capacitance dual working mode direct type X-ray detector 1 is connected in parallel with the variable inductance module 3 to generate an oscillating current, the frequency discrimination module 5 converts the inductance-capacitance oscillation frequency signal into a current signal, and the current signal is transmitted to the current signal measurement module 6 to obtain the X-ray radiation signal.
  • the present invention provides a detection device 200 for measuring X-ray signals using the characteristic oscillation frequency.
  • the detection device 200 includes a current-capacitance dual working mode direct type X-ray detector 1, a variable inductance module 3, a frequency discrimination module 5 and a signal amplification module 7.
  • the current-capacitance dual working mode direct X-ray detector 1 and the variable inductance 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, which is amplified by the signal amplification module 7 and then output to obtain an X-radiation signal.
  • the current signal of the active layer of the ferroelectric nano-dipole coupled radiation conversion semiconductor 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 inductance-capacitance oscillation circuit frequency.
  • the non-power X-ray detection method based on the radiation-induced capacitance change effect uses a fixed DC bias of 30 volts in the current detection working mode to respond to the current signal of the X-ray signal as shown in Figure 5 of the specification; the capacitance signal response results of the X-ray signal using positive and negative 1 volt and 100 kHz frequency in the capacitance detection working mode are shown in Figure 6.
  • Soda-lime glass with a length and width of 1.5 cm, a thickness of 7 mm, and a single-sided indium-doped tin oxide conductive layer is used as a conductive substrate. It is vacuum adsorbed on a coating platform with a scraper height of 500 ⁇ m and a coating speed of 10 mm per second. The slurry is poured on the surface of the conductive layer and coated at a uniform speed with a scraper. It is 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.
  • the sample coated with the active layer of the dry ferroelectric nano-dipole 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 with an evaporation power of 80 watts to evaporate an 80-nanometer-thick copper electrode.
  • the copper electrode and the indium-doped tin oxide electrode of the detector are connected in parallel to the two ends of the inductor element, and then the parallel ends are connected to the two sides of the demodulation module respectively.
  • the X-ray dose and energy are obtained by reading the changes in the circuit inductor-capacitor oscillation frequency signal. The test results are shown in Figure 7.
  • Soda-lime glass with a length and width of 2.5 cm, a thickness of 1.1 mm and a single-sided fluorine-doped tin oxide conductive layer is used as the conductive substrate. It is vacuum adsorbed on the coating platform, the scraper height is 700 microns, and the coating speed is 7 mm per second. The slurry is poured on the surface of the conductive layer and coated at a uniform speed with a scraper. It is 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.
  • the carbon electrode and the fluorine-doped tin oxide electrode of the detector are connected in parallel with the time-capacitance differential measurement circuit.
  • the X-ray dose and energy are obtained through the differential signal change of the capacitance to time.
  • the test results are shown in Figure 6.

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Abstract

本发明属于X射线探测器技术领域与半导体镀膜技术领域，提供了一种电流-电容双工作模式直接型X射线探测器和制备方法。该电流-电容双工作模式直接型X射线探测器的制备方法包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层的制备步骤：S1：用前驱体粉末化学合成铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料；S2：刮涂法在导电衬底上制备所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层。本发明制备的电流-电容双工作模式直接型X射线探测器电容探测模式工作在低交流偏压下，避免了金属卤化物钙钛矿本征离子在直流电场下的定向迁移导致器件分相、分解、失效。

Description

一种电流-电容双工作模式直接型X射线探测器和制备方法 技术领域
本发明属于X射线探测器技术领域与半导体镀膜技术领域,具体涉及一种电流-电容双工作模式直接型X射线探测器和制备方法。
 背景技术
X射线探测器广泛应用于日常生活、工业生产、遥感测绘与医学诊断等领域。现有X射线探测器按工作机理分为间接探测与直接探测两类。间接探测器通过闪烁晶体将X射线转变为可见光或近紫外光，再通过集成的光电探测器将光信号转变为电流信号。这类探测器由于闪烁晶体存在余辉，因此响应速度慢，并且由X射线到低能光子的转换过程丢失了X射线的能量与动量信息，成像细节差。直接探测器通过半导体光学活性层将X射线直接转化为电信号，能够保留入射X射线光子的能量信息，具有更快的响应速度与更好的成像细节。这两类X射线探测器都属于功率探测型X射线探测器，通过光生伏特效应将光子转换为电子空穴对，在外加偏压下分离电子空穴对，并测量电子空穴对通过电路的电信号得到辐射信号。在实际应用中，为了保证探测器的灵敏度与信噪比，在工作时需要通过外电路施加高偏压，利用外电路的电注入提高光电流与暗电流的差值，但对材料与器件的耐高压特性具有较高要求。常见的X射线探测器材料主要为硅、锗、非晶硒与碲化镉，制备工艺复杂且都需要依靠升压电路提供探测器工作状态所需的高压。金属卤化物钙钛矿是一种理想的X射线光学活性材料，具有与碲化镉相似的高X射线线性衰减系数，并且能够低温成膜，制备工艺简便，但金属卤化物钙钛矿属于软晶格材料，在强度为0.1伏特每微米的直流电场中就会发生本征离子迁移，导致钙钛矿层的化学组分发生偏析，最终分相、分解，导致器件失效，因此X射线探测器的高工作偏压同样限制了金属卤化物钙钛矿材料作为X射线探测器活性层的商业化应用。
 技术问题
为了解决的现有技术中X射线探测器在高工作偏压容易失效的问题，本发明提供了一种电流-电容双工作模式直接型X射线探测器的制备方法。
 技术解决方案
该电流-电容双工作模式直接型X射线探测器的制备方法包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层的制备步骤：
S1：用前驱体粉末化学合成铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料；
S2：刮涂法在导电衬底上制备所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层。
进一步地，所述前驱体粉末包括铁电纳米偶极子粉体和钙前驱体粉末，所述铁电纳米偶极子粉体为钛酸钡和铁酸铋中的一种或两种，所述钙前驱体粉末选自甲胺碘、甲脒碘、碘化铯、碘化铅、溴化铅和氯化铅粉体中的至少两种。
进一步地，其特征在于，所述铁电纳米偶极子粉体的粒径在100纳米至70微米之间，所述钙前驱体粉末中阳离子和阴离子的化学计量之比为2:3。
进一步地，所述铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料的制备方法包括：
将所述前驱体粉末均匀分散在溶剂和/或助溶剂中，所述溶剂选自水、乙二醇、N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的一种或多种，所述助溶剂选自甲醇、乙醇、正丙醇和异丙醇中的一种或多种。
本发明的一个目的是提供一种电流-电容双工作模式直接型X射线探测器。该电流-电容双工作模式直接型X射线探测器包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层受到X射线照射产生电容变化效应。
进一步地，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层的厚度在500纳米至1毫米之间，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层中分散的铁电纳米偶极子粉体和钙前驱体粉末的粒径在100纳米至70微米之间。
进一步地，电流-电容双工作模式直接型X射线探测器还包括设置于所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层一侧的导电衬底和另一侧的电极。
进一步地，所述导电衬底和所述所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层之间、所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层之间和电极之间均设有缓冲层。
进一步地，所述导电衬底上镀有500纳米厚铟掺杂氧化锡层。
本发明的一个目的是提供一种基于辐射致电容变化效应的非功率型X射线探测方法，电流-电容双工作模式直接型X射线探测器通过和电容测量模块、时间微分电容测量模块或由可变电感模块、鉴频模块和电流信号测量模块构成的组件联用测量电容变化、电容对时间的微分变化或电感-电容振荡频率变化获取X辐射信号。
 有益效果
本发明提供了的一种电流-电容双工作模式直接型X射线探测器，该探测器通过测量铁电纳米偶极子耦合辐射转换半导体薄膜活性层的电流或电容变化得到辐射信号，其中电容信号可以在低交流偏压下测量，避免了现有X射线探测器基于光生伏特效应利用电流信号表征辐射信号时需要施加高偏压的要求，提高了器件安全性与可靠性。同时本发明选用铁电纳米偶极子耦合辐射转换半导体薄膜活性层，通过刮涂工艺低温成膜，相比于现有的硅基、锗基、硒基与碲化镉基X射线探测器制备时所需的半导体器件工艺，生产成本大幅降低。本发明提出的电流-电容双工作模式直接型X射线探测器电容探测模式工作在低交流偏压下，既避免了金属卤化物钙钛矿本征离子在直流电场下的定向迁移导致器件分相、分解、失效，也通过非功率探测方式降低了器件工作状态下的发热，降低载流子热激发比例，从而提高了器件探测信号的信噪比与准确性。
 附图说明
图1为本发明提供的铁电纳米偶极子耦合辐射转换半导体薄膜活性层制备流程图；
图2为本发明提供的电流-电容双工作模式直接型X射线探测器结构示意图；
图3为本发明提供的基于辐射致电容变化效应的非功率型X射线探测方法；
图4为本发明采用特征振荡频率测量X射线信号的探测装置电路图；
图5为本发明在电流探测工作模式下采用30伏特固定直流偏压对X射线信号的电流信号响应；
图6为本发明在电容探测工作模式下采用正负1伏特与100千赫兹频率对X射线信号的电容信号响应；
图7为本发明在电容探测工作模式下采用特征振荡频率检测方法对X射线信号的响应；
标号说明：
电流-电容双工作模式直接型X射线探测器1、导电衬底11、第一缓冲层12、铁电纳米偶极子耦合辐射转换半导体薄膜活性层13、铁电纳米偶极子131、第二缓冲层14、金属电极15、电容测量模块2、可变电感模块3、时间微分电容测量模块4、鉴频模块5、电流信号测量模块6、信号放大模块7。
 本发明的实施方式
为了使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图对本发明的具体实施方式做详细的说明，但不能理解为对本发明的可实施范围的限定。
为了克服现有功率型直接X射线探测器依赖高工作偏压才能产生足够强度的电流信号缺陷，本发明提供一种基于辐射致电容变化效应的电流-电容双工作模式直接型X射线探测器。该探测器包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层，所述的X射线活性层薄膜包括半导体材料和与半导体材料耦合的纳米偶极子粉体，半导体材料能将电磁辐射转换为电子空穴，铁电纳米偶极子粉体通过内建电场或外加电场发生极化。该探测器的工作原理为：在X射线辐照下半导体材料中产生电子空穴对，由于铁电偶极子在电场中发生极化，偶极子的面束缚电荷会分别吸引异号的电子或空穴，部分屏蔽偶极子自身的极化强度，从而改变铁电纳米偶极子耦合辐射转换半导体薄膜活性层的相对介电常数，即改变了耦合层的电容，通过测量铁电纳米偶极子耦合辐射转换半导体薄膜活性层在辐照下的电容变化，即可得到辐射信号的强度。本发明提供的探测器的优点包括：1、灵敏度高。探测器等效电容信号灵敏度高于1000微库伦每格瑞每平方厘米。同时该探测器也可以在偏置电压作用下导出X射线激发的光生载流子并读取电流信号，探测器电流信号灵敏度高于1000微库伦每格瑞每平方厘米。2、具有双工作模式。该探测器可以分别读取辐射致电容变化信号与辐射致光生载流子电流信号。在电流工作模式下，向探测器器件施加直流偏压，读取器件电流信号。当X射线进入器件时，射线在半导体材料中激发光生载流子，激发的光生载流子被直流偏压分离并被电极收集，在探测回路中产生电信号。在电容工作模式下，向探测器器件施加位于正负1伏特之间的定值交流电压，电压频率在100赫兹至10兆赫兹之间，读取器件电容信号。在暗态下半导体材料处于本征态，铁电偶极子处于极化状态，当X射线进入器件时，射线在半导体材料中激发光生载流子，在交流偏压下光生载流子无法持续定向迁移，被铁电偶极子的异号表面电荷捕获储存，铁电偶极子的极化被捕获的光生载流子部分屏蔽，使器件电容发生变化。传统X射线探测器仅在电流模式下工作，成像像素亮度正比于电流信号强度，而像素对比度则受限于器件暗电流强度与灵敏度。提高成像像素对比度要求提高入射X射线剂量率，而医学X射线成像则要求X射线剂量率尽可能低。本发明的电流-电容双工作模式直接型X射线探测器在电容工作模式下可通过施加不同的交流偏压值与交流偏压频率调节器件电容，在不改变X射线剂量率的条件下能够改变X射线成像的像素对比度。
本发明采用金属卤化物钙作为半导体材料实现了探测器在高频交流偏压下工作时，通过电容信号探测X射线剂量的功能。同时，本发明克服了金属卤化物钙钛矿在直流偏压下存在本征离子迁移导致探测器无法长期工作的缺陷，具体地，由于测量电容施加的信号为低交流偏压，金属卤化物钙钛矿的离子组分无法被频率高于阈值的交流电场驱动，即不会发生电场驱动的化学组分偏析，从而解决了金属卤化物钙钛矿在X射线探测器应用中由于高工作直流偏压引起金属卤化物钙钛矿分相、分解导致的器件失效的问题。由于电容探测工作模式为非功率探测，不需要在电路中持续施加直流偏压产生定向电流，与现有X射线探测器相比，本发明的电容探测工作模式耗更低，同时降低了电注入引入的暗电流，使本发明相对于现有X射线探测器具有更低的暗电流背景信号。
参阅说明书图1，电流-电容双工作模式直接型X射线探测器的制备方法包括以下步骤：
S1：用前驱体粉末化学合成铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料。
前驱体粉末包括铁电纳米偶极子粉体和钙前驱体粉末。铁电纳米偶极子粉体与钙前驱体粉末摩尔比为1:2-99。优选的，铁电纳米偶极子粉体与钙前驱体粉末摩尔比低于1比3。更优选地，铁电纳米偶极子粉体与钙前驱体粉末摩尔比为1比9。
铁电纳米偶极子粉体为钛酸钡和铁酸铋中的一种或两种，粉体粒径在100纳米至70微米之间，优选地，粉体粒径在100纳米至38微米之间。更优选地，粉末粒径在30微米至1微米之间。优选地，铁电纳米偶极子粉体为钛酸钡与铁酸铋的混合物粉末。优选地，钛酸钡与铁酸铋的混合物粉末可以为钛酸钡和铁酸铋固溶体粉末，或钛酸钡纯净物粉体和铁酸铋纯净物粉体混合物。
钙前驱体粉末选自甲胺碘、甲脒碘、碘化铯、碘化铅、溴化铅和氯化铅粉体中的至少两种。钙前驱体粉末中阳离子和阴离子的化学计量之比为2:3。
在一个实施例中，铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料的制备方法包括：
将前驱体粉末均匀分散在分散介质中，分散介质包括溶剂和/或助溶剂。溶剂选自水、乙二醇、N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的一种或多种。助溶剂选自甲醇、乙醇、正丙醇和异丙醇中的一种或多种。优选地，采用乙二醇与异丙醇混合溶液作为分散介质，其中乙二醇与异丙醇的质量比为1：18-23.2。
分散过程中先磁力搅拌1小时，再超声振动1小时，循环三次。优选的，磁力搅拌转速在800转每分钟至1200转每分钟，搅拌温度为室温。在一些实施例中磁力搅拌转速可为1000转每分钟。
S2：刮涂法在导电衬底上制备铁电纳米偶极子耦合辐射转换半导体薄膜活性层。
导电衬底可以是本身具有导电性质的材料，例如金属，也可以是镀有或涂有导电层而本身不具有导电性质的材料，如玻璃、高分子薄膜和晶体。导电层可以包括纳米银颗粒、纳米银线、铟掺杂氧化锡、钨掺杂氧化锡、铈掺杂氧化锡、氟掺杂氧化锡、铝掺杂氧化锌、钨掺杂氧化锌或锡酸镉。优选地，导电衬底为镀有500纳米厚铟掺杂氧化锡的材料。在导电衬底上还可以镀有或涂有缓冲层，铁电纳米偶极子耦合辐射转换半导体薄膜活性层制备在缓冲层上。缓冲层可以是通过沉积工艺制备在导电衬底上。缓冲层可以包括氧化锡、氧化镍、氧化钛、2,2',7,7'-四[N,N-二(4-甲氧基苯基)氨基]-9,9'-螺二芴、聚（3,4-乙烯二氧噻吩）-聚（苯乙烯磺酸酯）或富勒烯或富勒烯衍生物。
在惰性气氛下制备铁电纳米偶极子耦合辐射转换半导体薄膜活性层，优选的环境条件为氮气气氛，环境中水与氧气的含量低于1ppm。刮涂时通过刮刀运动将步骤S1制备的浆料匀速涂布在导电衬底上，活性层的厚度通过刮刀高度控制，其中刮刀高度在700纳米至1毫米之间；刮涂后在氮气环境中通过梯度升温干燥固化缓慢蒸发分散介质，其中温度在20摄氏度至200摄氏度之间，每步保温时间在20分钟至8小时之间。优选的，刮刀高度为500微米至1毫米，刮涂速度为5毫米至30毫米每秒。更优选地，刮刀高度为500微米，刮涂速度为7毫米。优选的，干燥工艺为35摄氏度保温4小时，再升至45摄氏度保温4小时，最后在110摄氏度下保温2小时。
本发明通过低温刮涂工艺将铁电纳米偶极子耦合辐射转换半导体薄膜活性层涂覆在衬底上，根据探测X射线能量范围的不同，铁电纳米偶极子耦合辐射转换半导体薄膜活性层的厚度范围在500纳米至1毫米之间，其中分散的铁电纳米偶极子尺寸范围在100纳米至70微米之间。
在一个实施例中，电流-电容双工作模式直接型X射线探测器的制备方法还包括以下步骤：
S3：采用物理气相沉积方法在上述铁电纳米偶极子耦合辐射转换半导体薄膜活性层表面镀金属电极或印刷方法制备碳电极。
物理气相沉积方法可以是磁控溅射、电子束沉积、热蒸发或反应等离子体沉积，金属电极可以是铜、银、金、铝、铬、镍、钨的单质、合金或叠层，金属电极厚度在10纳米至100纳米之间。优选的，物理气相沉积工艺为热蒸发工艺，金属电极为铜，蒸发功率为80瓦特，电极厚度为10至100纳米。优选地，在铁电纳米偶极子耦合辐射转换半导体薄膜活性层上再通过沉积工艺制备一层缓冲层，在缓冲层上制备金属电极。
印刷方法可以是丝网印刷或钢网印刷，将碳浆通过丝网或钢网印制在铁电纳米偶极子耦合辐射转换半导体薄膜活性层表面，在100摄氏度至150摄氏度干燥后得到电极，电极厚度在500纳米至0.1毫米之间。优选的，印刷方法为丝网印刷，碳浆干燥温度为100摄氏度至120摄氏度，干燥时间为10分钟至20分钟。
按照本发明的生产工艺制备电流-电容双工作模式直接型X射线探测器，可以通过低温刮涂工艺制备铁电纳米偶极子耦合辐射转换半导体薄膜活性层，后续固化工艺简便，器件工作时不需要施加高直流偏压，避免了金属卤化物钙钛矿在直流偏压驱动下的本征离子迁移导致器件分相、分解、失效。
参阅说明书图2，本发明还提供了一种电流-电容双工作模式直接型X射线探测器。
电流-电容双工作模式直接型X射线探测器1包括从下往上依次设置的导电衬底11、第一缓冲层12、铁电纳米偶极子耦合辐射转换半导体薄膜活性层13、第二缓冲层14和金属电极15。铁电纳米偶极子耦合辐射转换半导体薄膜活性层13均匀分布有铁电纳米偶极子131。
该电流-电容双工作模式直接型X射线探测器利用辐射致电容变化效应，通过测量铁电纳米偶极子耦合辐射转换半导体薄膜活性层的电容信号变化得到X射线辐射信号，在低交流偏压下工作。本发明简化了电路结构，降低了探测器系统集成成本，提高了器件安全性。同时本发明的低交流偏压工作条件既避免了金属卤化物钙钛矿本征离子在直流电场下的定向迁移导致器件分相、分解、失效，使金属卤化物钙钛矿材料具有实际应用价值，也降低了器件工作状态下的发热，降低载流子热激发比例从而提高了器件探测信号的信噪比。
参阅说明书图3，本发明还提供了一种基于辐射致电容变化效应的非功率型X射线探测方法。
基于辐射致电容变化效应的非功率型X射线探测方法包含三种途径，其一，电流-电容双工作模式直接型X射线探测器1和电容测量模块2联用，测量电容变化得到X辐射信号；其二，电流-电容双工作模式直接型X射线探测器1和时间微分电容测量模块4联用，测量电容对时间的微分变化得到X辐射信号；其三，电流-电容双工作模式直接型X射线探测器1与由可变电感模块3、鉴频模块5、电流信号测量模块6构成的组件联用，测量电感-电容振荡频率得到X辐射信号。具体地，将电流-电容双工作模式直接型X射线探测器1与可变电感模块3并联产生振荡电流，由鉴频模块5将电感-电容振荡频率信号转变为电流信号，并将电流信号传递给电流信号测量模块6，得到X射线辐射信号。
为了进一步说明电流-电容双工作模式直接型X射线探测器1根据特征振荡频率测量X射线信号的可行性，本发明提供了一种采用特征振荡频率测量X射线信号的探测装置200。参阅说明书图4，该探测装置200中包括电流-电容双工作模式直接型X射线探测器1、可变电感模块3、鉴频模块5和信号放大模块7。
电流-电容双工作模式直接型X射线探测器1和可变电感模块3并联产生振荡电流，鉴频模块5获取振荡电流的频率将其转变为电流信号，经信号放大模块7放大频率后输出，得到X辐射信号。
上述铁电纳米偶极子耦合辐射转换半导体薄膜活性层的电流信号通过互补金属氧化物半导体电路或薄膜场效应晶体管电路读取，电容信号通过直接测量电路、电容-时间微分电路与电感-电容振荡电路频率三种方式读取。
基于辐射致电容变化效应的非功率型X射线探测方法在电流探测工作模式下采用30伏特固定直流偏压对X射线信号的电流信号响应结果如说明书图5所示；在电容探测工作模式下采用正负1伏特与100千赫兹频率对X射线信号的电容信号响应结果如图6所示。
实施例1 
1.1铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料制备
称取1.86克钛酸钡与钙钛矿前驱体粉末，其中钛酸钡占粉体总摩尔量的10%，再加入1克乙二醇与异丙醇混合溶液，其中乙二醇占混合溶液质量的5%，放入磁子，在800转每分钟的磁力搅拌台上搅拌一小时，再室温超声一小时，重复三次，得到铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料。
1.2铁电纳米偶极子耦合辐射转换半导体薄膜活性层制备
采用长宽均为1.5厘米，厚度为7毫米，单面镀有铟掺杂氧化锡导电层的钠钙玻璃作为导电衬底，将其真空吸附在刮涂平台上，刮刀高度为500微米，刮涂速度为10毫米每秒，将浆料倒在导电层表面，用刮刀匀速刮涂，在35摄氏度下干燥4小时，再升温至45摄氏度干燥4小时，最后升温至110摄氏度干燥2小时。
1.3金属电极制备
取出涂有干燥铁电纳米偶极子耦合辐射转换半导体薄膜活性层的样品，置于热蒸发设备样品托中，选用铜作为蒸发源，蒸发功率80瓦特，蒸镀80纳米厚的铜电极。
1.4电容信号读取模块集成与X射线剂量与能量读取
完成电极制备后，将探测器的铜电极与铟掺杂氧化锡电极分别与电感元件的两端并联，再将并联端点分别连接至鉴频模块两侧，通过读取电路电感-电容振荡频率信号变化得到X射线剂量与能量，测试结果如图7所示。
实施例2
2.1铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料制备
称取1.86克钛酸钡与钙钛矿前驱体粉末，其中钛酸钡占粉体总摩尔量的5%，再加入1.2克乙二醇溶液，放入磁子，在800转每分钟的磁力搅拌台上搅拌一小时，再室温超声一小时，得到铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料。
2.2铁电纳米偶极子耦合辐射转换半导体薄膜活性层制备
采用长宽均为2.5厘米，厚度为1.1毫米，单面镀有氟掺杂氧化锡导电层的钠钙玻璃作为导电衬底，将其真空吸附在刮涂平台上，刮刀高度为700微米，刮涂速度为7毫米每秒，将浆料倒在导电层表面，用刮刀匀速刮涂，在35摄氏度下干燥4小时，再升温至45摄氏度干燥8小时，最后升温至110摄氏度干燥3小时。
2.3丝网印刷制备碳电极
取出涂有干燥铁电纳米偶极子耦合辐射转换半导体薄膜活性层，置于丝网模板图形下，将碳浆倒在丝网上，采用10毫米每秒的刮涂速度在活性层表面印刷碳浆，在120摄氏度下干燥5分钟。
2.4电容信号读取模块集成与X射线剂量与能量读取
完成电极制备后，将探测器的碳电极与氟掺杂氧化锡电极与时间电容微分测量电路并联，通过电容对时间的微分信号变化得到X射线剂量与能量，测试结果如图6所示。

Claims (10)

  1. 一种电流-电容双工作模式直接型X射线探测器的制备方法，其特征在于，包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层的制备步骤：
    S1：用前驱体粉末化学合成铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料；
    S2：刮涂法在导电衬底上制备所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层。
  2. 如权利要求1所述的电流-电容双工作模式直接型X射线探测器的制备方法，其特征在于，所述前驱体粉末包括铁电纳米偶极子粉体和钙前驱体粉末，所述铁电纳米偶极子粉体为钛酸钡和铁酸铋中的一种或两种，所述钙前驱体粉末选自甲胺碘、甲脒碘、碘化铯、碘化铅、溴化铅和氯化铅粉体中的至少两种。
  3. 如权利要求1所述的电流-电容双工作模式直接型X射线探测器的制备方法，其特征在于，所述铁电纳米偶极子粉体的粒径在100纳米至70微米之间，所述钙前驱体粉末中阳离子和阴离子的化学计量之比为2:3。
  4. 如权利要求1所述的电流-电容双工作模式直接型X射线探测器的制备方法，其特征在于，所述铁电纳米偶极子粉体耦合金属卤化物钙钛矿浆料的制备方法包括：
    将所述前驱体粉末均匀分散在溶剂和/或助溶剂中，所述溶剂选自水、乙二醇、N，N-二甲基甲酰胺、二甲基亚砜和N-甲基吡咯烷酮中的一种或多种，所述助溶剂选自甲醇、乙醇、正丙醇和异丙醇中的一种或多种。
  5. 一种电流-电容双工作模式直接型X射线探测器，其特征在于，包括铁电纳米偶极子耦合辐射转换半导体薄膜活性层，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层受到X射线照射产生电容变化效应。
  6. 如权利要求5所述的电流-电容双工作模式直接型X射线探测器，其特征在于，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层的厚度在500纳米至1毫米之间，所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层中分散的铁电纳米偶极子粉体和钙前驱体粉末的粒径在100纳米至70微米之间。
  7. 如权利要求5所述的电流-电容双工作模式直接型X射线探测器，其特征在于，还包括设置于所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层一侧的导电衬底和另一侧的电极。
  8. 如权利要求7所述的电流-电容双工作模式直接型X射线探测器，其特征在于，所述导电衬底和所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层之间、所述铁电纳米偶极子耦合辐射转换半导体薄膜活性层之间和电极之间均设有缓冲层。
  9. 如权利要求7所述的电流-电容双工作模式直接型X射线探测器，其特征在于，所述导电衬底上镀有500纳米厚铟掺杂氧化锡层。
  10. 一种基于辐射致电容变化效应的非功率型X射线探测方法，特征在于，电流-电容双工作模式直接型X射线探测器通过和电容测量模块、时间微分电容测量模块或由可变电感模块、鉴频模块和电流信号测量模块构成的组件联用测量电容变化、电容对时间的微分变化或电感-电容振荡频率变化获取X辐射信号。
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