CN113192991B - Flexible X-ray detector, preparation method thereof and three-dimensional flexible X-ray detector - Google Patents

Flexible X-ray detector, preparation method thereof and three-dimensional flexible X-ray detector Download PDF

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CN113192991B
CN113192991B CN202110470823.0A CN202110470823A CN113192991B CN 113192991 B CN113192991 B CN 113192991B CN 202110470823 A CN202110470823 A CN 202110470823A CN 113192991 B CN113192991 B CN 113192991B
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flexible
electrode layer
ray detector
photoelectric conversion
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CN113192991A (en
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张琛
陈明
杨春雷
王忠国
王伟
胡明珠
张陈斌
宁德
闻权
王鄂豫
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Shenzhen Zhuo Mao Technology Co ltd
Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Zhuo Mao Technology Co ltd
Shenzhen Institute of Advanced Technology of CAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H01L27/14658—X-ray, gamma-ray or corpuscular radiation imagers
    • H01L27/14663—Indirect radiation imagers, e.g. using luminescent members
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14692—Thin film technologies, e.g. amorphous, poly, micro- or nanocrystalline silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
    • H01L31/0322—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/541—CuInSe2 material PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention provides a flexible X-ray detector and a preparation method thereof, wherein the X-ray detector comprises a photoelectric conversion unit and a scintillator layer; the scintillator layer is arranged on the photoelectric conversion unit and used for converting the received X-rays into fluorescence and emitting the fluorescence to the photoelectric conversion unit; the support substrate of the photoelectric conversion unit is a flexible substrate, the light absorption layer in the photoelectric conversion unit is a copper indium gallium selenide light absorption layer, and the photoelectric conversion unit is used for performing photoelectric conversion on the fluorescence converted by the scintillator layer; the scintillator layer is provided with a light-in surface for receiving X rays and a light-out surface for emitting fluorescence, the light-out surface is connected to the photoelectric conversion unit, and the light-in surface is a side surface intersected with the light-out surface. The flexible X-ray detector has the excellent characteristics of high sensitivity and high energy spectrum resolution, and the ultrathin photodiode array is manufactured by adopting the stainless steel substrate, so that the flexible X-ray detector has the characteristics of flexibility and easiness in folding.

Description

Flexible X-ray detector, preparation method thereof and three-dimensional flexible X-ray detector
Technical Field
The invention belongs to the technical field of X-ray detectors, and particularly relates to a flexible X-ray detector and a preparation method thereof, and further relates to a three-dimensional flexible X-ray detector.
Background
In the field of medical equipment, X-ray medical imaging equipment is wide in audience and large in use amount, can be applied to various medical detections in orthopedics, mammary gland, dentistry, gastrointestinal tract, oncology and the like, and the imaging result is a key basis for diagnosis and treatment of serious diseases.
According to the detection principle, medical X-ray detectors are mainly classified into indirect type and direct type detectors. The indirect detector can realize the conversion of X-ray, fluorescence signal and electric signal by combining the scintillator material, the photodiode, the thin film transistor layer or the CCD layer or the CMOS layer. Taking an indirect X-ray detector based on a CsI scintillator as an example, csI has a large X-ray absorption coefficient, high quantum detection efficiency and high imaging speed, and the grain boundary surface of the acicular crystal can effectively inhibit the diffuse reflection of a fluorescence signal, but the application of CsI is always limited by the stability of a CsI material. The direct X-ray flat panel detector enables the photoelectric conversion layer to generate electron-hole pairs under the action of X-rays, and the electron-hole pairs are rapidly separated under the action of an external electric field and read by a pixel electrode, but is limited by the material selection of the photoelectric layer. For example, a direct detector based on a CdZnTe single crystal material has attracted great attention in recent years, can obtain high detection efficiency, is suitable for application under low radiation dose, and is more hopeful to realize energy-resolved imaging, but has no advantages in large area and rapid imaging, only an amorphous selenium material can realize large-area deposition applied to a direct flat panel detector at present, but because the absorption performance of an Se element on X-rays is poor, the quantum detection efficiency and sensitivity of a device are low, performance attenuation is caused by thermal crystallization, the amorphous selenium detector is only suitable for some application scenes with high requirements on imaging resolution, and the structural advantages of the direct detector cannot be exerted.
In the existing indirect flat panel detector: on one hand, the ultra-thin performance requirement of a three-dimensional structure cannot be met by growing substrates such as glass, silicon wafers and the like; on the other hand, the two-dimensional photoelectric array is perpendicular to the incident direction of the X-ray, directly receives and reads the visible light signal excited by the X-ray, and the resolution is limited by the longitudinal scattering of the visible light signal in the scintillator.
Disclosure of Invention
In view of the defects in the prior art, the invention provides a flexible X-ray detector and a preparation method thereof, so as to improve the detection sensitivity and the energy spectrum resolution of the X-ray detector, and have the characteristics of flexibility and easy folding.
In order to achieve the purpose, the invention adopts the following technical scheme:
a flexible X-ray detector includes a photoelectric conversion unit and a scintillator layer;
the scintillator layer is arranged on the photoelectric conversion unit and used for converting the received X-rays into fluorescence and emitting the fluorescence to the photoelectric conversion unit;
the support substrate of the photoelectric conversion unit is a flexible substrate, the light absorption layer in the photoelectric conversion unit is a copper indium gallium selenide light absorption layer, and the photoelectric conversion unit is used for performing photoelectric conversion on the fluorescence converted by the scintillator layer;
the scintillator layer is provided with a light-in surface for receiving X rays and a light-out surface for emitting fluorescence, the light-out surface is connected to the photoelectric conversion unit, and the light-in surface is a side surface intersected with the light-out surface.
Preferably, the photoelectric conversion unit comprises a flexible support substrate, a barrier layer, a metal back electrode layer, a copper indium gallium selenide light absorption layer, a buffer layer, a window layer and a transparent top electrode layer which are sequentially arranged; wherein the scintillator layer is disposed on the transparent top electrode layer.
Preferably, the flexible supporting substrate is stainless steel, the barrier layer is made of silicon dioxide, the metal back electrode layer is made of molybdenum, the buffer layer is made of cadmium sulfide, the window layer is made of intrinsic zinc oxide, the transparent top electrode layer is made of aluminum-doped zinc oxide, and the scintillator layer is made of gadolinium oxysulfide.
Preferably, the thickness of the barrier layer is 100nm to 300nm, the thickness of the metal back electrode layer is 300nm to 1500nm, the thickness of the copper indium gallium selenide light absorption layer is 1 μm to 2 μm, the thickness of the buffer layer is 20nm to 100nm, the thickness of the window layer is 50nm to 100nm, the thickness of the transparent top electrode layer is 50nm to 300nm, and the thickness of the scintillator layer is 0.4mm to 1.2mm.
Preferably, an electrode connection area is disposed in the metal back electrode layer, and a nickel metal layer and an aluminum metal layer are sequentially deposited on the electrode connection area of the metal back electrode layer.
Preferably, the metal back electrode layer is divided into m sub back electrodes extending along a first direction, and the transparent top electrode layer is divided into n sub top electrodes extending along a second direction perpendicular to the first direction; wherein m and n are each an integer of 2 or more.
Preferably, m is 200. Ltoreq. M.ltoreq.300, n is 4. Ltoreq. N.ltoreq.8.
It is a further aspect of the present invention to provide a flexible X-ray detector as described above, comprising:
s10, taking stainless steel as a flexible supporting substrate, and sequentially preparing and forming a silicon dioxide barrier layer and a molybdenum back electrode layer on the flexible supporting substrate through a magnetron sputtering process;
s20, arranging an electrode connection area on the molybdenum back electrode layer, and preparing and forming a copper indium gallium selenide light absorption layer on the molybdenum back electrode layer except the electrode connection area by adopting a co-evaporation process;
s30, preparing and forming a cadmium sulfide buffer layer on the CIGS light absorption layer by adopting a chemical water bath process;
s40, sequentially preparing and forming an intrinsic zinc oxide window layer and an aluminum-doped zinc oxide transparent top electrode layer on the cadmium sulfide buffer layer by adopting a magnetron sputtering process;
s50, sequentially depositing a nickel metal layer and an aluminum metal layer on the electrode connecting area of the molybdenum back electrode layer by adopting a magnetron sputtering process;
and S60, preparing and forming a gadolinium oxysulfide scintillator layer on the aluminum-doped zinc oxide transparent top electrode layer by adopting a coating process, and preparing and obtaining the flexible X-ray detector.
Preferably, in the step S10, after the molybdenum back electrode layer is prepared, the molybdenum back electrode layer is scribed along a first direction by applying a laser scribing process, so that the molybdenum back electrode layer is divided into m sub back electrodes extending along the first direction; in step S40, after the intrinsic zinc oxide window layer and the aluminum-doped zinc oxide transparent top electrode layer are prepared, the intrinsic zinc oxide window layer and the aluminum-doped zinc oxide transparent top electrode layer are scribed along a second direction by using a laser scribing process, so that the aluminum-doped zinc oxide transparent top electrode layer is divided into n sub top electrodes extending along the second direction; in the step S50, after the nickel metal layer and the aluminum metal layer are prepared, the nickel metal layer and the aluminum metal layer are scribed by a laser scribing process so as to be in one-to-one correspondence with the m sub back electrodes; wherein the first direction and the second direction are perpendicular to each other, and m and n are each an integer of 2 or more.
The invention also provides a three-dimensional flexible X-ray detector which comprises i flexible X-ray detectors which are sequentially stacked, wherein the jth flexible X-ray detector and the jth +1 flexible X-ray detector are electrically connected with each other through a conductive connecting wire, so that the i flexible X-ray detectors which are sequentially stacked are sequentially connected in series; wherein i is an integer of 2 or more, j =1, 2, \ 8230;, i-1.
The embodiment of the invention provides a flexible X-ray detector which comprises the following components: on one hand, the manufacturing of the ultrathin photodiode array is realized by adopting a stainless steel substrate, and the ultrathin photodiode array has the characteristics of flexibility and easiness in folding; on the other hand, a novel high-quantum-efficiency thin-film photoelectric material Copper Indium Gallium Selenide (CIGS) is used as a light absorption layer, a scintillator and a photoelectric conversion layer of an indirect X-ray detector are structurally and innovatively designed, the X-ray propagation direction and the visible light fluorescent signal propagation direction are vertically configured, the thickness of the absorption layer can be greatly increased under the condition of not sacrificing resolution, and high-sensitivity detection is realized. The X-ray is incident from the side surface of the scintillator layer, the energy resolution imaging capability can be obtained by combining the penetration depth direction space resolution detection technology, and the finally integrated detection device realizes the excellent characteristics of ultrahigh sensitivity, energy spectrum resolution and the like.
The fluorescent signals collected in the flexible X-ray detector structure are perpendicular to the X-rays and are incident to the CIGS thin film, namely the CIGS thin film collects the fluorescent signals along the propagation direction parallel to the X-rays, the absorption direction of the X-rays and the visible fluorescent signals are decoupled in the propagation direction, and the purposes of inhibiting fluorescent scattering and improving resolution are achieved. Meanwhile, different energy spectrum resolution areas are arranged in the X-ray propagation direction, and the energy spectrum resolution function is realized by utilizing the absorption difference of the GOS scintillator material on the X-rays with different energies, so that more abundant information is provided for medical diagnosis based on X-ray imaging.
Drawings
FIG. 1 is a schematic structural diagram of a flexible X-ray detector in an embodiment of the invention;
FIG. 2 is an exemplary illustration of an X-ray incidence direction and a fluorescence emission direction in an embodiment of the present invention;
FIG. 3 is an exemplary illustration of scribing the back electrode layer and the top electrode layer in an embodiment of the invention;
FIG. 4 is a process flow diagram of a method of making a flexible X-ray detector in an embodiment of the invention;
FIG. 5 is a graph of dark current for a flexible X-ray detector in an embodiment of the invention;
FIG. 6 is a graph of the external quantum efficiency of a flexible X-ray detector in an embodiment of the invention;
FIG. 7 is an SEM image of an CIGS light absorbing layer in an embodiment of the present invention;
FIG. 8 is an SEM image of the upper surface of a GOS scintillator layer in an embodiment of the present invention;
FIG. 9 is an SEM image of a cross-section of a GOS scintillator layer in an embodiment of the present invention;
fig. 10 is a schematic structural diagram of a three-dimensional flexible X-ray detector in an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described in accordance with the drawings are merely exemplary and the invention is not limited to these embodiments.
It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not so relevant to the present invention are omitted.
Embodiments of the present invention first provide a flexible X-ray detector, as shown in fig. 1 and 2, which includes a photoelectric conversion unit 10 and a scintillator layer 20.
Wherein the scintillator layer 20 is disposed on the photoelectric conversion unit 10, and is configured to convert the received X-rays into fluorescence and emit the fluorescence to the photoelectric conversion unit 10; the photoelectric conversion unit 10 is configured to photoelectrically convert the fluorescence converted by the scintillator layer 30.
The supporting substrate of the photoelectric conversion unit 10 is a flexible substrate, and the light absorbing layer in the photoelectric conversion unit 10 is a Copper Indium Gallium Selenide (CIGS) light absorbing layer. CIGS thin film materials have the characteristics of good absorbance, good stability and high quantum conversion efficiency, and are widely concerned as absorbing layer materials of thin film photovoltaic devices. The large-grain CIGS photoelectric film can completely absorb visible light only by 1-2 microns in thickness and achieves the quantum conversion efficiency of over 90 percent. The photoelectric conversion layer is applied to a light absorption layer of an X-ray detector, so that the photoelectric conversion efficiency of the X-ray detector can be improved, and the sensitivity of the X-ray detector can be improved.
As shown in fig. 1, the scintillator layer 20 is provided with an incident surface for receiving X-rays and an exit surface for emitting fluorescence, the exit surface is connected to the photoelectric conversion unit 10, and the incident surface is a side surface intersecting with the exit surface, so that, as shown in fig. 2, in the X-ray detector, the propagation direction of the X-rays and the propagation direction of the visible light fluorescence signal FL are perpendicular to each other.
In the embodiment of the present invention, referring to fig. 1, the photoelectric conversion unit 10 includes a flexible supporting substrate 11, a barrier layer 12, a metal back electrode layer 13, a copper indium gallium selenide light absorption layer 14, a buffer layer 15, a window layer 16, and a transparent top electrode layer 17, which are sequentially disposed; wherein the scintillator layer 20 is disposed on the transparent top electrode layer 17.
In a preferred embodiment, the flexible supporting substrate 11 is made of stainless steel, and the material of the barrier layer 12 is silicon dioxide (SiO)2) The metal back electrode layer 13 is made of molybdenum (Mo), the buffer layer 15 is made of cadmium sulfide (CdS), the window layer 16 is made of Intrinsic Zinc Oxide (IZO), the transparent top electrode layer 17 is made of aluminum-doped zinc oxide (AZO), and the scintillator layer is made of gadolinium oxysulfide (GOS, molecular formula Gd)2O2S)。
The manufacturing method of the ultrathin photodiode array is characterized in that a stainless steel substrate is adopted, the ultrathin photodiode array can be manufactured, and the ultrathin photodiode array has the characteristics of flexibility and easiness in folding.
The scintillator layer is made of GOS, absorption coefficients of the GOS scintillator materials in unit volume for X-rays in different energy regions are obviously different, and the absorption coefficient of low-energy X-ray photons is high, so that the penetration depth is lower than that of high-energy X-ray photons. By utilizing the absorption characteristic of the X-ray to image for a plurality of times in the penetration depth, the multi-energy-region energy spectrum type detection can be realized, and further important information of density distribution of different tissues of a human body is provided.
In a preferred scheme, the thickness of the barrier layer is 100nm to 300nm, the thickness of the metal back electrode layer is 300nm to 1500nm, the thickness of the copper indium gallium selenide light absorption layer is 1 μm to 2 μm, the thickness of the buffer layer is 20nm to 100nm, the thickness of the window layer is 50nm to 100nm, the thickness of the transparent top electrode layer is 50nm to 300nm, and the thickness of the scintillator layer is 0.4mm to 1.2mm.
In a preferred embodiment, an electrode connection region 131 is disposed in the metal back electrode layer 13, and a connection metal layer 18 (including a nickel metal layer and an aluminum metal layer) is sequentially deposited on the electrode connection region 131 of the metal back electrode layer 13.
In a more preferable scheme, referring to fig. 3, the metal back electrode layer 13 is divided into m sub back electrodes 13a extending along a first direction (e.g., X direction in fig. 3), and the transparent top electrode layer 17 is divided into n sub top electrodes 17a extending along a second direction (e.g., y direction in the figure) perpendicular to the first direction, whereby the X-ray detector may be formed into m × n pixels. Wherein m and n are integers more than 2, preferably, m is more than or equal to 200 and less than or equal to 300, and n is more than or equal to 4 and less than or equal to 8. Most preferably, m =256,n =4.
In a preferred aspect, the first direction is set to be the same as an incident direction of the X-ray.
Flexible X-ray detector as described above: on one hand, the manufacturing of the ultrathin photodiode array is realized by adopting a stainless steel substrate, and the ultrathin photodiode array has the characteristics of flexibility and easiness in folding; on the other hand, a novel high-quantum-efficiency thin-film photoelectric material Copper Indium Gallium Selenide (CIGS) is used as a light absorption layer, the scintillator and the photoelectric conversion layer of the indirect X-ray detector are structurally and innovatively designed, the X-ray propagation direction and the visible light fluorescent signal propagation direction are vertically configured, the thickness of the absorption layer can be greatly increased under the condition of not sacrificing resolution, and therefore high-sensitivity detection is achieved. The X-ray is incident from the side face of the scintillator layer, and the energy resolution imaging capability can be obtained by combining the penetration depth direction space resolution detection technology, and the finally integrated detection device realizes the excellent characteristics of ultrahigh sensitivity, energy spectrum resolution and the like.
The embodiment of the present invention further provides a method for manufacturing the flexible X-ray detector, which is shown in fig. 4 in combination with the schematic structural diagrams of fig. 1 to 3, and includes the following steps:
step S10, providing a stainless steel support substrate 11, and sequentially preparing and forming a silicon dioxide barrier layer 12 and a molybdenum back electrode layer 13 on the stainless steel support substrate 11 through a magnetron sputtering process.
The growth process of the silicon dioxide barrier layer 12 and the molybdenum back electrode layer 13 may be performed by referring to an existing process, and the silicon dioxide barrier layer 12 and the molybdenum back electrode layer 13 with predetermined thicknesses are formed by adjusting the parameter growth. Preferably, in the present embodiment, the thickness of the silicon dioxide barrier layer 12 is set to 200nm, and the thickness of the molybdenum back electrode layer 13 is set to 1000nm.
In this embodiment, in the step S10, referring to fig. 3, after the molybdenum back electrode layer 13 is prepared, the molybdenum back electrode layer 13 is scribed along a first direction by using a laser scribing process, so that the molybdenum back electrode layer 13 is divided into m sub back electrodes 13a extending along the first direction.
Specifically, firstly, m +1 scribing lines Lx are disposed on the molybdenum back electrode layer 13, then a laser scribing process is applied to scribe along the m +1 scribing lines Lx, the molybdenum back electrode layer 13 is divided into m +2 independent blocks, 2 blocks in two side edge regions are omitted, and m blocks in the middle region are formed into m sub back electrodes 13a. For example, if m is 256, 257 scribe lines Lx are provided to divide the molybdenum back electrode layer 13 into 258 blocks independent from each other, 2 blocks in both side edge regions are omitted, and 256 blocks in the middle region are formed as 256 sub back electrodes 13a. It is understood that in some other embodiments, 255 scribe lines Lx may be directly disposed to divide the molybdenum back electrode layer 13 into 256 independent blocks, and all the blocks are formed into 256 sub back electrodes 13a.
And S20, arranging an electrode connection area 131 on the molybdenum back electrode layer 13, and preparing and forming the copper indium gallium selenide light absorption layer 14 on the molybdenum back electrode layer 13 except the electrode connection area 131 by adopting a co-evaporation process. The copper indium gallium selenide light absorption layer 14 comprises CGI (Cu/(Ga + In), molar ratio) = 0.89-0.95, ggi (Ga/(Ga + In), molar ratio) = 0.4-0.6.
Preferably, in the present embodiment, the thickness of the cigs light absorbing layer 14 is set to 2 μm.
And S30, preparing and forming a cadmium sulfide buffer layer 15 on the CIGS light absorption layer 14 by adopting a chemical water bath process.
In a specific embodiment, the step S30 specifically includes:
weighing 0.184 g of chromium sulfate, placing the chromium sulfate in 60mL of deionized water, and stirring for 15min, wherein the solution is numbered as A; weighing 5.694 g of thiourea, placing the thiourea in 150mL of deionized water, and stirring for 15min, wherein the solution is numbered as B; 425mL of deionized water is weighed and placed in a reaction vessel; weighing 45mL of ammonia water in a beaker; mixing ammonia water and the solution A, pouring the mixture into a reaction vessel, flushing the sample obtained in the step S20 with the solution B, collecting the solution B for flushing the sample into the reaction vessel, placing the sample with the surface facing downwards into the reaction vessel, placing the sample into a water bath (the set temperature of the water bath is 67 ℃, stirring is carried out by using a magnetic stirrer, and the heating power is 500W) for reacting for 9min, taking out the sample, quickly flushing with a large amount of deionized water, and baking for 2 min in an oven at 160 ℃. Preferably, in this embodiment, the thickness of the cadmium sulfide buffer layer 15 is set to 50nm.
And S40, sequentially preparing and forming an intrinsic zinc oxide window layer 16 and an aluminum-doped zinc oxide transparent top electrode layer 17 on the cadmium sulfide buffer layer 15 by adopting a magnetron sputtering process.
In a specific embodiment, the step S40 specifically includes:
the IZO window layer 16 is sputtered by performing low-power 120W sputtering and then performing high-power 220W sputtering, the total thickness is about 100nm, and a loose layer is formed by low-power sputtering at first, can be better combined with the CdS buffer layer 15 and is not easy to fall off; the sputtering power of the AZO transparent top electrode layer 17 was 750W and the thickness was about 200nm.
In this embodiment, in step S40, referring to fig. 3, after the IZO window layer 16 and the AZO transparent top electrode layer 17 are prepared, the IZO window layer 16 and the AZO transparent top electrode layer 17 are scribed along the second direction by using a laser scribing process, so that the AZO transparent top electrode layer 17 is divided into n sub top electrodes 17a extending along the second direction.
Specifically, n-1 scribing lines Ly are firstly arranged on the AZO transparent top electrode layer 17, then a laser scribing process is applied to scribe along the n-1 scribing lines Ly to the IZO window layer 16, and the AZO transparent top electrode layer 17 is divided into n independent blocks to form n sub top electrodes 17a. For example, if n is 4, 3 scribe lines Ly are provided to divide the AZO transparent top electrode layer 17 into 4 independent blocks to form 4 sub top electrodes 17a. In other embodiments, referring to the scribing manner of the molybdenum back electrode layer 13 in step S10, n +1 scribing lines Ly may be provided to perform scribing, and then 2 blocks of the two side edge regions are left.
And S50, depositing a connecting metal layer 18 on the electrode connecting area 131 of the molybdenum back electrode layer 13 by adopting a magnetron sputtering process, wherein the connecting metal layer comprises a nickel metal layer and an aluminum metal layer.
Wherein the thickness of the Ni plating layer is 1000 nm-3000 nm; the thickness of the Al coating is 10-30 μm.
In a preferred scheme, after the nickel metal layer and the aluminum metal layer are prepared, a laser scribing process is applied to scribe the nickel metal layer and the aluminum metal layer so as to enable the nickel metal layer and the aluminum metal layer to correspond to the m sub-back electrodes one by one. Specifically, a scribing line is provided to coincide with the scribing line of the molybdenum back electrode layer 13 in step S10, and then the nickel metal layer and the aluminum metal layer are scribed.
And S60, preparing and forming a gadolinium oxysulfide scintillator layer 20 on the aluminum-doped zinc oxide transparent top electrode layer 17 by adopting a coating process, and preparing and obtaining the flexible X-ray detector.
In a specific embodiment, the step S60 specifically includes:
according to the mass ratio of the epoxy resin to the curing agent (0.2-0.8): 1, the mass ratio of the GOS powder to the epoxy resin is (3-4): 1, preparing to form mixed slurry; and (5) blade-coating the mixed solution on the aluminum-doped zinc oxide transparent top electrode layer 17 of the sample obtained in the step (S50), and then drying and curing to obtain the GOS scintillator layer 30. In a most preferred scheme, the mass ratio of the epoxy resin to the curing agent is 0.5:1, the mass ratio of the GOS powder to the epoxy resin is 3.5:1, the thickness of the scintillator layer is 0.5mm.
Fig. 5 is a dark current curve diagram of the flexible X-ray detector obtained in the embodiment of the present invention, fig. 6 is an external quantum efficiency curve diagram of the flexible X-ray detector obtained in the embodiment of the present invention, and fig. 7 is an SEM image of the cigs light absorption layer in the embodiment of the present invention. The detection rate of the detector is inversely proportional to the dark current, and the lower the dark current is, the higher the detection rate of the device is, as can be seen from fig. 5, the X-ray detector based on the CIGS photoelectric thin film material in the invention has the advantage of high detection rate; as shown in fig. 6, the quantum efficiency test results show that the prepared CIGS photoelectric thin film material has a high quantum efficiency of over 90% in the visible light band; as shown in fig. 7, the scanning electron microscope image of the CIGS layer shows that the CIGS layer has good grain growth, large and orderly particles, few grain defects, and excellent photoelectric conversion performance.
Fig. 8 is an SEM image of the upper surface of the GOS scintillator layer in the example of the present invention, and fig. 9 is an SEM image of a cross-section of the GOS scintillator layer in the example of the present invention, and it can be understood from fig. 8 and 9 that GOS is uniformly distributed in the epoxy resin and the fluorescence conversion efficiency is high.
The embodiment of the invention also provides a three-dimensional flexible X-ray detector, which comprises i flexible X-ray detectors which are sequentially arranged in a laminated manner, and as shown in figure 10, the three-dimensional flexible X-ray detector comprises a 1 st detector T which is sequentially arranged1To the ith detector Ti. Wherein, the i flexible X-ray detectors are respectively the flexible X-ray detectors provided by the foregoing embodiments of the present invention (refer to the detector structure shown in fig. 1). Further, the jth flexible X-ray detector TjAnd the j +1 th flexible X-ray detector Tj+1The flexible X-ray detectors are electrically connected with each other through a conductive connecting line L, so that the i flexible X-ray detectors which are sequentially stacked are sequentially connected in series. Wherein i is an integer of 2 or more, j =1, 2, \ 8230;, i-1. The value of i can be set according to actual needs, for example, i =10, 15, or 20.
In particular, the jth flexible X-ray detector T is connected to the X-ray detector by a conductive connecting line LjAnd the (j + 1) th flexible X-ray detector Tj+1Are electrically connected with each other, thereby connecting the metal back electrode layersThe i flexible X-ray detectors which are sequentially stacked are sequentially connected in series, and the transparent top electrode layers of the flexible X-ray detectors are kept in mutually independent states, so that the three-dimensional flexible X-ray detector is formed, and X-rays can be detected from a three-dimensional space.
The conductive connecting line L is preferably a copper wire, and the diameter of the conductive connecting line L is preferably 0.3mm to 0.5mm, and more preferably a copper wire with a diameter of 0.4 mm.
To sum up, the embodiment of the present invention provides a flexible X-ray detector: on one hand, the manufacturing of the ultrathin photodiode array is realized by adopting a stainless steel substrate, and the ultrathin photodiode array has the characteristics of flexibility and easiness in folding; on the other hand, a novel high-quantum-efficiency thin-film photoelectric material Copper Indium Gallium Selenide (CIGS) is used as a light absorption layer, the scintillator and the photoelectric conversion layer of the indirect X-ray detector are structurally and innovatively designed, the X-ray propagation direction and the visible light fluorescent signal propagation direction are vertically configured, the thickness of the absorption layer can be greatly increased under the condition of not sacrificing resolution, and therefore high-sensitivity detection is achieved. The X-ray is incident from the side surface of the scintillator layer, the energy resolution imaging capability can be obtained by combining the penetration depth direction space resolution detection technology, and the finally integrated detection device realizes the excellent characteristics of ultrahigh sensitivity, energy spectrum resolution and the like.
Furthermore, the fluorescent signal collected in the flexible X-ray detector structure is perpendicular to the X-ray and is incident to the CIGS thin film, namely the CIGS thin film collects the fluorescent signal along the direction parallel to the propagation direction of the X-ray, so that the decoupling of the absorption direction of the X-ray and the visible fluorescent signal in the propagation direction is realized, and the purposes of inhibiting the fluorescent scattering and improving the resolution ratio are achieved. Meanwhile, different energy spectrum resolution areas are arranged in the X-ray propagation direction, and the energy spectrum resolution function is realized by using the absorption difference of the GOS scintillator material on the X-rays with different energies, so that more abundant information is provided for medical diagnosis based on X-ray imaging.
The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims (6)

1. A flexible X-ray detector is characterized by comprising a photoelectric conversion unit and a scintillator layer;
the scintillator layer is arranged on the photoelectric conversion unit and used for converting the received X-rays into fluorescence and emitting the fluorescence to the photoelectric conversion unit;
the support substrate of the photoelectric conversion unit is a flexible substrate, the light absorption layer in the photoelectric conversion unit is a copper indium gallium selenide light absorption layer, and the photoelectric conversion unit is used for performing photoelectric conversion on the fluorescence converted by the scintillator layer;
the scintillator layer is provided with a light-in surface for receiving X rays and a light-out surface for emitting fluorescence, the light-out surface is connected to the photoelectric conversion unit, and the light-in surface is a side surface intersected with the light-out surface;
the photoelectric conversion unit comprises a flexible supporting substrate, a barrier layer, a metal back electrode layer, a copper indium gallium selenide light absorption layer, a buffer layer, a window layer and a transparent top electrode layer which are sequentially arranged; wherein the scintillator layer is disposed on the transparent top electrode layer;
the metal back electrode layer is divided into m sub back electrodes extending along a first direction, and the transparent top electrode layer is divided into n sub top electrodes extending along a second direction perpendicular to the first direction; wherein m and n are integers more than 2, m is more than or equal to 200 and less than or equal to 300, and n is more than or equal to 4 and less than or equal to 8.
2. The flexible X-ray detector of claim 1, wherein the flexible support substrate is stainless steel, the barrier layer is silicon dioxide, the metal back electrode layer is molybdenum, the buffer layer is cadmium sulfide, the window layer is intrinsic zinc oxide, the transparent top electrode layer is aluminum-doped zinc oxide, and the scintillator layer is gadolinium oxysulfide.
3. The flexible X-ray detector of claim 2, wherein the barrier layer has a thickness of 100nm to 300nm, the metal back electrode layer has a thickness of 300nm to 1500nm, the copper indium gallium selenide light absorption layer has a thickness of 1 μm to 2 μm, the buffer layer has a thickness of 20nm to 100nm, the window layer has a thickness of 50nm to 100nm, the transparent top electrode layer has a thickness of 50nm to 300nm, and the scintillator layer has a thickness of 0.4mm to 1.2mm.
4. The flexible X-ray detector of claim 2, wherein an electrode connection area is disposed in the metal back electrode layer, and a nickel metal layer and an aluminum metal layer are sequentially deposited on the electrode connection area of the metal back electrode layer.
5. A method of manufacturing a flexible X-ray detector according to any one of claims 1 to 4, comprising:
s10, taking stainless steel as a flexible supporting substrate, and sequentially preparing and forming a silicon dioxide barrier layer and a molybdenum back electrode layer on the flexible supporting substrate through a magnetron sputtering process;
s20, arranging an electrode connection area on the molybdenum back electrode layer, and preparing and forming a copper indium gallium selenide light absorption layer on the molybdenum back electrode layer except the electrode connection area by adopting a co-evaporation process;
s30, preparing and forming a cadmium sulfide buffer layer on the CIGS light absorption layer by adopting a chemical water bath process;
s40, sequentially preparing and forming an intrinsic zinc oxide window layer and an aluminum-doped zinc oxide transparent top electrode layer on the cadmium sulfide buffer layer by adopting a magnetron sputtering process;
s50, sequentially depositing a nickel metal layer and an aluminum metal layer on the electrode connecting area of the molybdenum back electrode layer by adopting a magnetron sputtering process;
s60, preparing and forming a gadolinium oxysulfide scintillator layer on the aluminum-doped zinc oxide transparent top electrode layer by adopting a coating process, and preparing and obtaining the flexible X-ray detector;
in step S10, after the molybdenum back electrode layer is prepared, the molybdenum back electrode layer is scribed along a first direction by using a laser scribing process, so that the molybdenum back electrode layer is divided into m sub back electrodes extending along the first direction; in the step S40, after the intrinsic zinc oxide window layer and the aluminum-doped zinc oxide transparent top electrode layer are prepared, the intrinsic zinc oxide window layer and the aluminum-doped zinc oxide transparent top electrode layer are scribed along a second direction by using a laser scribing process, so that the aluminum-doped zinc oxide transparent top electrode layer is divided into n sub top electrodes extending along the second direction; in the step S50, after the nickel metal layer and the aluminum metal layer are prepared, the nickel metal layer and the aluminum metal layer are scribed by a laser scribing process so as to be in one-to-one correspondence with the m sub back electrodes; wherein the first direction and the second direction are perpendicular to each other, and m and n are each an integer of 2 or more.
6. A three-dimensional flexible X-ray detector is characterized by comprising i flexible X-ray detectors as claimed in any one of claims 1 to 4, which are sequentially stacked, wherein the jth flexible X-ray detector and the (j + 1) th flexible X-ray detector are electrically connected with each other through a conductive connecting wire, so that the i flexible X-ray detectors which are sequentially stacked are sequentially connected in series;
wherein i is an integer of 2 or more, j =1, 2, \ 8230;, i-1.
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