A kind of detecting substrate, flat panel detector

Abstract

The application provides a detection substrate and a flat panel detector, and relates to the technical field of photoelectric detection. The detection substrate can improve radiation resistance and prolong service life without increasing the thickness of a scintillator layer. The detection substrate comprises a plurality of detection pixel units arranged in an array. The detection pixel unit comprises a transistor, a photoelectric conversion part and a scintillator layer. The photoelectric conversion part is located between the transistor and the scintillator layer. The photoelectric conversion part comprises a radiation-sensitive layer and a photosensitive unit arranged in a stack. The radiation-sensitive layer is configured to absorb rays and convert the rays into carriers. The photosensitive unit is configured to absorb at least visible light and convert the visible light into carriers. The application is suitable for manufacturing the detection substrate.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to a detection substrate and a flat panel detector. Background Technology

[0002] With the continuous development of X-ray digital imaging technology, the use of flat panel X-ray detectors (FPXD) can directly convert X-ray images into digital images, which has broad application prospects in fields such as medical care, security, and industrial inspection.

[0003] Currently, X-ray flat panel detectors typically employ scintillators and photodiodes. Because high-energy photons in X-rays have high penetrability, scintillators are made from materials with low absorption coefficients. During the emission of light from the scintillator, visible light is scattered between the scintillator grains, resulting in signal dispersion. This leads to a decrease in the spatial modulation transfer function (MTF), which in turn affects the image display quality.

[0004] Therefore, to ensure that signal dispersion is controlled within a certain range, it is necessary not only to control the morphology and optical properties of the scintillator material itself, but more importantly, to control the thickness of the scintillator. However, if the scintillator is too thin, it will not be able to completely absorb X-rays, and about 20% to 60% of the X-rays will pass through the scintillator and reach the location of photodiodes and transistors, causing radiation damage to these devices, thereby significantly reducing their radiation resistance and service life. Summary of the Invention

[0005] Embodiments of the present invention provide a detection substrate and a flat panel detector, which can improve radiation resistance and extend service life without increasing the thickness of the scintillator layer.

[0006] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0007] On the one hand, a detection substrate is provided, including multiple detection pixel units arranged in an array;

[0008] The detection pixel unit includes: a transistor, a photoelectric conversion unit, and a scintillator layer; the photoelectric conversion unit is located between the transistor and the scintillator layer;

[0009] The photoelectric conversion unit includes a radiation-sensitive layer and a photosensitive unit stacked together. The radiation-sensitive layer is configured to absorb radiation and convert it into charge carriers. The photosensitive unit is configured to absorb at least visible light and convert it into charge carriers.

[0010] Optionally, the photosensitive unit is disposed on the side of the radiation-sensitive layer away from the transistor.

[0011] Optionally, the radiation-sensitive layer of each of the detection pixel units is an integral structure, and the photosensitive unit of each of the detection pixel units is an integral structure.

[0012] Optionally, the detection substrate further includes a substrate, and the detection pixel unit is disposed on the substrate;

[0013] In each of the aforementioned detection pixel units, the orthogonal projection of the transistor onto the substrate lies within the orthogonal projection of the radiation-sensitive layer onto the substrate.

[0014] Optionally, the detection substrate further includes a substrate, and the detection pixel unit is disposed on the substrate;

[0015] In each of the aforementioned detection pixel units, the orthographic projection of the photosensitive unit on the substrate is located within the orthographic projection of the radiation-sensitive layer on the substrate.

[0016] Optionally, the material of the radiation-sensitive layer includes heavy elements and has a band gap greater than 2.0 eV.

[0017] Optionally, the photosensitive unit may include a photoconductive device or a photodiode.

[0018] Optionally, the photoelectric conversion unit further includes a connecting electrode located between the radiation-sensitive layer and the photosensitive unit.

[0019] Optionally, the photosensitive unit is also configured to absorb rays and convert them into charge carriers.

[0020] Optionally, the photosensitive unit includes a perovskite layer.

[0021] Optionally, the material of the perovskite layer includes: having A a B b X x Perovskite materials with molecular structure; wherein, A a Includes: any one or more of the following: organic amine groups, formamidinium, cesium ions, rubidium ions, silver ions, and cuprous ions; B b Including: lead ions or bismuth ions; X x Including any one or more of iodine, chlorine, and bromine.

[0022] Optionally, the detection pixel unit further includes a readout electrode and a bias electrode; the readout electrode is located on the side of the photoelectric conversion unit closer to the transistor, and the bias electrode is located on the side of the photoelectric conversion unit away from the transistor.

[0023] Optionally, the readout electrodes of each of the detection pixel units are independent of each other, and the bias electrodes of each of the detection pixel units are an integral structure.

[0024] Optionally, the transistor may include a thin-film transistor or a complementary metal-oxide-semiconductor transistor.

[0025] On the other hand, a flat panel detector is provided, comprising: the aforementioned detector substrate.

[0026] Embodiments of the present invention provide a detection substrate and a flat panel detector. The detection substrate includes multiple detection pixel units arranged in an array. Each detection pixel unit includes a transistor, a photoelectric conversion unit, and a scintillator layer. The photoelectric conversion unit is located between the transistor and the scintillator layer. The photoelectric conversion unit includes a radiation-sensitive layer and a photosensitive unit stacked on top of each other. The radiation-sensitive layer is configured to absorb radiation and convert it into charge carriers. The photosensitive unit is configured to absorb at least visible light and convert it into charge carriers. Thus, when radiation irradiates the detection substrate, the scintillator layer converts the radiation into visible light, which is then absorbed and converted into charge carriers by the photosensitive unit. Simultaneously, radiation passing through the scintillator layer can be absorbed by the radiation-sensitive layer and converted into charge carriers, thereby preventing unabsorbed radiation from radiating the transistor. This improves radiation resistance and extends service life without increasing the thickness of the scintillator layer. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a probe substrate provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of a detection pixel unit provided in an embodiment of the present invention;

[0030] Figure 3 For along Figure 2 A schematic diagram of a cross-section in the CC' direction;

[0031] Figure 4 For along Figure 2 Another cross-sectional diagram in the CC' direction;

[0032] Figure 5 For along Figure 2 Another schematic diagram of a cross-section in the CC' direction;

[0033] Figure 6 This is a schematic diagram of another detection pixel unit provided in an embodiment of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In embodiments of the present invention, "multiple" means two or more, unless otherwise explicitly defined.

[0036] In the embodiments of the present invention, the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0037] This invention provides a detection substrate, with reference to... Figure 1 As shown, it includes multiple detector pixel units 100 arranged in an array.

[0038] refer to Figure 3 As shown, the detection pixel unit includes: transistors ( Figure 3 The diagram shows a thin-film transistor 11, a photoelectric conversion unit 2, and a scintillator layer 3; the photoelectric conversion unit 2 is located between the transistor and the scintillator layer 3.

[0039] Among them, reference Figure 3 As shown, the photoelectric conversion unit 2 includes a radiation-sensitive layer 21 and a photosensitive unit 22 stacked together. The radiation-sensitive layer is configured to absorb rays and convert rays into charge carriers, and the photosensitive unit is configured to absorb at least visible light and convert visible light into charge carriers.

[0040] In the aforementioned photoelectric conversion unit, the relative positions of the radiation-sensitive layer and the photosensitive unit are not limited. For example, the photosensitive unit can be disposed on the side of the radiation-sensitive layer away from the transistor; alternatively, the photosensitive unit can also be disposed on the side of the radiation-sensitive layer closer to the transistor. The accompanying drawings of the embodiments of the present invention illustrate the former approach. The specific structure of the radiation-sensitive layer and the photosensitive unit is not limited here, as long as it meets the corresponding requirements.

[0041] In the aforementioned multiple detection pixel units, the radiation-sensitive layer of each photoelectric conversion unit can be an integral structure or independent of each other; the photosensitive unit of each photoelectric conversion unit can be an integral structure or independent of each other; no limitation is made here.

[0042] The type of transistor mentioned above is not limited; it can be, for example, Figure 3-5 The thin-film transistor 11 shown; or, it could be as shown in the figure. Figure 6 The complementary metal-oxide-semiconductor transistor (CMOS transistor) shown; or, it could be other types of field-effect transistors.

[0043] The material of the scintillator layer is not limited. For example, the material of the scintillator layer may include CsI (cesium iodide), GOS (gadolinium oxysulfide), tungstates, alkali metal halides, lutetium fine silicates (LFS), yttrium lutetium silicate (LYSO), thallium-doped sodium iodide (NaI:Tl), cesium iodide (CsI), and bismuth germanate (Bi4Ge3O4). 12 The materials used are any one of the following: BGO (gadolinium aluminum gallium garnet), GAGG (gadolinium aluminum gallium garnet), etc.; among which, tungstates can include: cadmium tungstate (CdWO4) or lead tungstate (PWO), etc. The scintillator layer formed by these materials can convert X-rays into visible light.

[0044] refer to Figure 3 As shown, when X-rays ( Figure 3 When scintillator layer 3 is irradiated (represented by a single arrow), some of the X-rays are absorbed by scintillator layer 3 and converted into visible light (…). Figure 3 (Represented by double arrows in the image), the remaining X-rays pass through the scintillator layer 3 and are directed to the photoelectric conversion unit 2. The photosensitive unit 22 absorbs visible light and converts it into charge carriers. The X-rays passing through the scintillator layer 3 are absorbed by the radiation-sensitive layer 21 and converted into charge carriers, thereby preventing unabsorbed X-rays from radiating the transistor. This improves radiation resistance and extends service life without increasing the thickness of the scintillator layer. It should be noted that... Figure 3 The illustration is given with the photosensitive unit positioned on the side of the radiation-sensitive layer furthest from the transistor. If the photosensitive unit is positioned on the side of the radiation-sensitive layer closer to the transistor, then the radiation-sensitive layer is closer to the scintillator layer than the photosensitive unit. In this case, after X-rays irradiate the scintillator layer, the X-rays that pass through the scintillator layer are absorbed by the radiation-sensitive layer and converted into charge carriers. Visible light passes through the radiation-sensitive layer and is directed to the photosensitive unit. The photosensitive unit absorbs the visible light and converts it into charge carriers. In this structure, it is also possible to further prevent X-rays that are not absorbed by the scintillator layer from radiating to the photosensitive unit, thereby reducing radiation damage to the photosensitive unit.

[0045] This invention provides a detection substrate in which a scintillator layer converts the radiation into visible light when it is irradiated. The visible light is then absorbed by the photosensitive unit and converted into charge carriers. Simultaneously, radiation passing through the scintillator layer can be absorbed by the radiation-sensitive layer and converted into charge carriers, thus preventing unabsorbed radiation from radiating the transistor. This improves radiation resistance and extends lifespan without increasing the thickness of the scintillator layer, i.e., without reducing the spatial modulation transfer function. Furthermore, the radiation-sensitive layer's ability to absorb radiation passing through the scintillator layer and convert it into charge carriers increases the photocurrent and reduces the dark current of the photosensitive unit without reducing the photocurrent, thereby improving the signal-to-noise ratio.

[0046] Optionally, to maximize the conversion of visible light into electrical signals and further improve photoelectric conversion efficiency, the photosensitive unit is positioned on the side of the radiation-sensitive layer away from the transistor. In this case, the photosensitive unit is closer to the scintillator layer than the radiation-sensitive layer, allowing the visible light converted by the scintillator layer to enter the photosensitive unit through a shorter path, where it is absorbed and converted into charge carriers.

[0047] Optionally, to reduce the number of patterning steps and minimize the impact of the patterning process on transistor characteristics, the radiation-sensitive layer of each detector pixel unit is a single integrated structure, and the photosensitive unit of each detector pixel unit is a single integrated structure. That is, the radiation-sensitive layers of each detector pixel unit are interconnected, and the photosensitive units of each detector pixel unit are interconnected.

[0048] Of course, the radiation-sensitive layer of each detection pixel unit can be set independently, and the photosensitive unit of each detection pixel unit can also be set independently to reduce the mutual influence between detection pixel units.

[0049] Optional, see reference Figure 3 As shown, the detection substrate may also include a substrate 10, and the detection pixel unit 2 is disposed on the substrate 10.

[0050] In each detection pixel unit, the orthogonal projection of the transistor onto the substrate lies within the orthogonal projection of the radiation-sensitive layer onto the substrate. This allows the radiation-sensitive layer to better protect the transistor, further reducing radiation damage and thus improving transistor performance and lifespan.

[0051] The above-mentioned orthogonal projection of the transistor on the substrate refers to the projection of the transistor on the substrate along a direction perpendicular to the substrate; the above-mentioned orthogonal projection of the radiation-sensitive layer on the substrate refers to the projection of the radiation-sensitive layer on the substrate along a direction perpendicular to the substrate.

[0052] Optional, see reference Figure 3 As shown, the detection substrate may also include a substrate 10, and the detection pixel unit 2 is disposed on the substrate 10.

[0053] In each detection pixel unit, the orthographic projection of the photosensitive unit onto the substrate lies within the orthographic projection of the radiation-sensitive layer onto the substrate. This allows the radiation-sensitive layer to better protect the photosensitive unit, further reducing damage from radiation and thus improving its performance and lifespan.

[0054] The above-mentioned orthogonal projection of the photosensitive unit onto the substrate refers to the projection of the photosensitive unit onto the substrate along a direction perpendicular to the substrate.

[0055] Of course, in order to maximize the conversion of visible light into charge carriers and improve photoelectric conversion efficiency, the orthogonal projection of the photosensitive unit on the substrate can also coincide with the orthogonal projection of the radiation-sensitive layer on the substrate. (See the attached diagram of this embodiment.) Figure 3 This will be illustrated using this as an example.

[0056] Optionally, the material of the radiation-sensitive layer may include heavy elements and have a band gap greater than 2.0 eV.

[0057] The aforementioned heavy elements refer to elements with high atomic numbers and relatively large atomic masses, such as lead and bismuth. The band gap is the energy difference between the lowest point of the conduction band and the highest point of the valence band, also known as the energy gap. The larger the band gap, the more difficult it is for electrons to be excited from the valence band to the conduction band, resulting in a lower intrinsic carrier concentration and lower conductivity. The band gap of the aforementioned radiation-sensitive layer is greater than 2.0 eV, which is considered a wide band gap. It can absorb radiation and convert it into carriers while allowing some visible light to pass through. For example, this band gap could be 2.1 eV, 2.2 eV, 2.3 eV, etc., and further, it could be greater than 2.3 eV. No specific limitation is made here; it can be determined according to actual requirements.

[0058] Alternatively, the material of the radiation-sensitive layer may include any one of lead iodide, lead oxide, or bismuth iodide. Lead iodide or lead oxide is preferred.

[0059] Optionally, the photosensitive unit may include a photoconductor or a photodiode.

[0060] For example, the photoconductive device may include an MSM (metal-semiconductor-metal) type photoconductive device. An MSM type photoconductive device includes a first metal layer, a semiconductor layer, and a second metal layer stacked together, with the first metal layer closer to the transistor than the second metal layer. This type of MSM photoconductive device structure belongs to the category of vertical photoconductive devices. The semiconductor layer may include any one of an intrinsic aSi:H monolayer (intrinsic hydrogenated amorphous silicon layer), an aSi:H PIN composite layer (intrinsic hydrogenated amorphous silicon composite layer), or a perovskite monolayer.

[0061] This photodiode can be a PIN photodiode or an organic diode. For example, see [reference needed]. Figure 4As shown, the photosensitive unit 22 may include a first doped layer 221, an intrinsic layer 220, and a second doped layer 222 stacked together, with the first doped layer 221 closer to the transistor than the second doped layer 222. The first doped layer may be a P-type doped layer, and the second doped layer may be an N-type doped layer; in this case, the photodiode can be called a NIP photodiode. Alternatively, the first doped layer may be an N-type doped layer, and the second doped layer may be a P-type doped layer; in this case, the photodiode can be called a PIN photodiode. The intrinsic layer 220 may include an organic or inorganic perovskite layer.

[0062] To precisely define the operating voltages of the radiation-sensitive layer and the photosensitive unit, and to make the substrate flatter for easier fabrication of the photosensitive unit, reference is provided. Figure 4 As shown, the photoelectric conversion unit may further include a connecting electrode 25, which is located between the radiation-sensitive layer 21 and the photosensitive unit 22. The material of the connecting electrode may include conductive materials such as metals.

[0063] It should be noted that the connecting electrodes of each detector pixel unit can be an integral structure or they can be independent of each other. To reduce the number of patterning steps and the impact of the patterning process on the transistor characteristics, the former can be chosen; to reduce the mutual interference between detector pixel units, the latter can be chosen. There is no limitation here.

[0064] Optionally, the photosensitive unit is also configured to absorb rays and convert them into charge carriers.

[0065] Further optional, see reference Figure 5 As shown, the photosensitive unit includes a perovskite layer 223. A perovskite heterojunction can be formed between the perovskite layer 223 and the radiation-sensitive layer 21. The charge carriers generated by the perovskite layer can be effectively injected into the radiation-sensitive layer. The perovskite layer can absorb visible light and convert it into charge carriers, and it can also absorb some of the rays passing through the scintillator layer and convert them into charge carriers.

[0066] Optionally, the material of the perovskite layer includes: having A a B b X x Perovskite materials with molecular structure; wherein, A a Includes: any one or more of the following: organic amine groups, formamidinium, cesium ions, rubidium ions, silver ions, and cuprous ions; B b Including: lead ions or bismuth ions; X xThis includes any one or more of iodine, chlorine, and bromine. For example, the material of the perovskite layer may include perovskite materials with an ABX3 (e.g., MAPbI3) molecular structure; or it may include perovskite materials with molecular structures such as A3B2X9 (e.g., Cs3Bi2I9), AB2X7 (e.g., AgBi2I7), ABX4 (e.g., AgBiI4), A2BX5 (e.g., Ag2BiI5), and A3BX6 (e.g., Ag3BiI6).

[0067] For example, the material of the perovskite layer includes MAPbI3 (methylamine iodide). In this case, if the radiation-sensitive layer includes lead iodide, a PbI2 and MAPbI3 perovskite heterojunction can be formed. The charge carriers generated by the MAPbI3 perovskite layer can be effectively injected into the PbI2 radiation-sensitive layer.

[0068] Optional, see reference Figure 3 As shown, the detection pixel unit also includes a readout electrode 23 and a bias electrode 24; the readout electrode 23 is located on the side of the photoelectric conversion unit 2 closer to the transistor, and the bias electrode 24 is located on the side of the photoelectric conversion unit 2 away from the transistor.

[0069] The read electrode can be made of conductive materials such as metals or metal alloys. For example, the read electrode can include a metal layer made of molybdenum (Mo), with a thickness of [missing information]. Alternatively, the read electrode may also include two stacked layers, wherein the layer closer to the transistor may include molybdenum with a thickness ranging from 100 to 400 nm; and the layer farther from the transistor may include ITO (Indium Tin Oxide) with a thickness of 70 nm.

[0070] The bias electrode material can include transparent conductive materials such as ITO, FTO (fluorine-doped tin oxide transparent conductive glass), AZO (aluminum-doped zinc oxide transparent conductive glass), and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate).

[0071] If no connecting electrode is provided between the photosensitive unit and the radiation-sensitive layer, refer to Figure 3As shown, when the detection substrate is in operation, a certain bias voltage can be applied to the bias electrode 24. This bias voltage value can be the sum of the operating voltages of the photosensitive unit 22 and the radiation-sensitive layer 21. For example, if the photosensitive unit is an aSi:H PIN diode and the radiation-sensitive layer is a 50µm thick PbI2 layer, with a PbI2 operating electric field of 0.5V / µm and an aSi:H PIN operating reverse bias voltage of 7V, then the sum of their operating voltages is 0.5V / µm * 50µm + 7V = 32V. That is, relative to the same potential, a -32V voltage can be applied to the bias electrode and a 0V voltage can be applied to the read electrode.

[0072] If a connecting electrode is provided between the photosensitive unit and the radiation-sensitive layer, refer to Figure 4 As shown, when the detection substrate is in operation, a certain bias voltage can be applied to the bias electrode 24 and the connection electrode 25 respectively. For example, if the photosensitive unit uses an aSi:H PIN diode and the radiation-sensitive layer uses a 50µm thick PbI2 layer, and the working electric field of PbI2 is 0.5V / µm, and the working reverse bias voltage of aSi:H PIN is 7V, then the sum of the working voltages of the two is 0.5V / µm * 50µm + 7V = 32V. That is, relative to the same potential, a voltage of -32V can be applied to the bias electrode, a voltage of -7V can be applied to the connection electrode, and a voltage of 0V can be applied to the readout electrode.

[0073] Alternatively, the readout electrodes of each detector pixel unit are independent of each other, and the bias electrodes of each detector pixel unit are integrated into a single structure, thereby enabling the output of photocurrent from the photoelectric conversion section of different detector pixel units, while reducing the number of patterning steps and minimizing the impact of the patterning process on the characteristics of the transistor.

[0074] Of course, the bias electrodes of each detector pixel unit can also be independent of each other to reduce the mutual influence between detector pixel units.

[0075] Optionally, the transistor may include a thin-film transistor or a complementary metal-oxide-semiconductor transistor.

[0076] Specifically, a thin-film transistor (TFT) includes a gate, an active layer, a first electrode, and a second electrode. The first and second electrodes can be the drain and source, respectively. Their functions can be interchanged depending on the type of TFT and the input signal; a specific distinction will not be made here. For example, see [reference]. Figure 3-5As shown, the thin-film transistor 11 includes an active layer 111, a gate 110, a source 113, and a drain 112. The material of the active layer is not limited, and it may include any one of aSi (amorphous silicon), IGZO (Indium Gallium Zinc Oxide), and LTPS (Low Temperature Poly-Silicon).

[0077] The thin-film transistor can be as follows: Figure 3-5 The diagram shows a bottom-gate thin-film transistor (with the source and drain located above the gate); alternatively, it could be a top-gate thin-film transistor (with the source and drain located below the gate), without limitation. Furthermore, for a bottom-gate thin-film transistor, an etch stop layer (ESL) can be disposed above the active layer to form a back-channel protected (BCS) TFT; alternatively, no etch stop layer can be disposed above the active layer to form a back-channel etched (BCE) TFT, without limitation.

[0078] refer to Figure 6 As shown, a complementary metal-oxide-semiconductor (CMOS) transistor includes a gate 311, a gate oxide layer 315, a drain 312, a source 313, a lightly doped portion 310, and a silicon epitaxial layer 318. The gate 311 comprises a polysilicon layer, the gate oxide layer 315 comprises a silicon dioxide layer, and the drain 312 and source 313 are heavily doped. To improve conductivity, a metal layer is disposed on each electrode. The material of the metal layer includes tungsten. Specifically, a first metal layer 314 is disposed on the gate 311, a second metal layer 316 is disposed on the drain 312, and a third metal layer 317 is disposed on the source 313. For ease of subsequent electrical connection, refer to... Figure 6 As shown, the detection pixel unit also includes a first electrode 34 and a second electrode 35, wherein the first electrode 34 is electrically connected to the second metal layer 316 and the second electrode 35 is electrically connected to the third metal layer 317.

[0079] Figure 6 In the complementary metal-oxide-semiconductor (CMOS) transistor shown, the core structure consists of a Si layer and a SiO2 layer. Single-crystal silicon is susceptible to radiation, resulting in numerous defects and traps. This leads to the formation of interface states between the lightly doped portion 310 and the gate oxide layer 315, while holes accumulate in the gate oxide layer 315. This alters the transistor's electrical characteristics, such as threshold drift and increased leakage current. If an APS (Active Pixel Sensor) is used as the detection substrate, the transistor's performance requirements will be further increased, thus further reducing its radiation resistance. In this application, a radiation-sensitive layer is introduced to better block radiated photons from reaching the silicon active layer, thereby improving device quality.

[0080] The aforementioned detection substrate can employ either PPS or APS methods; no specific limitation is made here. Specifically, in the PPS method, one detection pixel unit can output photocurrent through a single transistor structure. In the APS method, one detection pixel unit can output photocurrent through structures such as a three-transistor structure (3T1C), a four-transistor structure (4T1C), a five-transistor structure with Vth offset compensation (5T1C), a six-transistor structure with Vth offset compensation (6T1C), or more complex structures; in the 3T1C structure, one transistor serves as an amplifier, acting as an amplifier tube (AMP tube).

[0081] It should be noted that the reference Figure 3-6 As shown, the aforementioned detection substrate may further include a first passivation layer 16, which is located between the scintillator layer 3 and the bias electrode 24. The material of the passivation layer 16 may include any one or a combination of silicon nitride and silicon oxide. Of course, a capping layer may also be provided between the first passivation layer and the scintillator layer to provide further protection; this capping layer may include an organic resin layer and an inorganic silicon nitride layer.

[0082] If the transistor on the probe substrate is a thin-film transistor, refer to Figure 3-5 As shown, the probe substrate may further include a first storage electrode 17 and a second storage electrode 18. The first storage electrode 17 and the second storage electrode 18 are disposed opposite to each other to form a storage capacitor Cst. The first storage electrode 17 may be disposed on the same layer as the gate electrode 110, and the second storage electrode 18 may be disposed on the same layer as the source electrode 113 and the drain electrode 112. (Reference) Figure 2 As shown, the first storage electrode ( Figure 2 (Not shown) or the second storage electrode 18 is electrically connected to the ground wire 6.

[0083] refer to Figure 3-5 As shown, the probe substrate may further include a substrate 10, a gate insulating layer 12, a buffer layer 13, a planarization layer 14, and a second passivation layer 15. The read electrode 23 passes through a first via ( Figure 3-5 (Unmarked) is electrically connected to the source 113, and the first via penetrates the second passivation layer 15, the planarization layer 14 and the buffer layer 13.

[0084] If the transistor on the probe substrate is a complementary metal-oxide-semiconductor transistor, refer to Figure 6 As shown, the probe substrate may further include a first interlayer dielectric layer 32 and a second interlayer dielectric layer 33, and the read electrode 23 passes through a second via ( Figure 6 (Unmarked) is electrically connected to the second electrode 35, and the second electrode 35 is connected through the third via ( Figure 6(Unmarked) is electrically connected to the third metal layer 317, thereby realizing the electrical connection between the read electrode 23 and the source electrode 313. The second via penetrates the second interlayer dielectric layer 33, and the third via penetrates the first interlayer dielectric layer 32.

[0085] Optional, see reference Figure 1 As shown, the probe substrate may further include multiple lines along the first direction ( Figure 1 The grid lines 4 arranged in the OB direction and multiple lines along the second direction (as shown) Figure 1 The data lines 5 are arranged in the OA direction shown; the gate lines 4 and data lines 5 intersect to form multiple defined regions; among them, the detection pixel unit 100 is located within the defined region, and the first direction and the second direction intersect. Figure 1 The diagram is illustrated using the example of the first and second directions intersecting perpendicularly. The gate lines are electrically connected to at least one row of transistors in the detector pixel units arranged along the second direction, and the data lines are electrically connected to at least one row of transistors in the detector pixel units arranged along the first direction.

[0086] The aforementioned detection pixel unit can be configured as a strip, and the first direction can be as follows: Figure 1 As shown in the OB direction (i.e., the long side direction of the probe pixel unit), the second direction can be as follows: Figure 1 The OA direction shown (i.e., the direction of the short side of the detected pixel unit). Alternatively, the first direction can also be as follows: Figure 1 As shown in the OA direction (i.e., the direction of the short side of the probe pixel unit), the second direction can be as follows: Figure 1 The OB direction shown is the direction of the long side of the probe pixel unit. This is not limited here. Figure 1 The diagram is illustrated using the first direction as OB and the second direction as OA.

[0087] The aforementioned gate line being electrically connected to the transistors of at least one row of detector pixel units arranged along the second direction means: combining Figure 1 and Figure 2 As shown, gate line 4 is only associated with the second direction ( Figure 1 A row arranged in the OA direction (i.e.) Figure 1 The transistor 1 of the detector pixel unit 100 is electrically connected to the gate line; or the gate line is electrically connected to the transistors of multiple rows of detector pixel units arranged along the second direction, which is not limited here.

[0088] The aforementioned data line being electrically connected to the transistors of at least one row of detector pixel units arranged along the first direction means: combining Figure 1 and Figure 2 As shown, data line 5 is only connected along the first direction ( Figure 1 A row arranged in the OB direction (i.e.) Figure 1The data line is electrically connected to the transistor 1 of the detector pixel unit 100 in one column; or, the data line is electrically connected to the transistors of multiple rows of detector pixel units arranged along the first direction, which is not limited here.

[0089] The aforementioned gate lines can be placed on the same layer as the transistor's gate, and data lines can be placed on the same layer as the transistor's source and drain, thereby reducing the number of patterning processes and lowering costs. Here, "same layer" refers to fabrication using a single patterning process. A single patterning process refers to forming the required layer structure through a single film deposition and photolithography process. A single patterning process includes film deposition, exposure, development, etching, and stripping.

[0090] In the aforementioned detection substrate, the gate line can provide a control signal to the gate of the transistor to control the transistor to turn on or off; the photoelectric conversion unit converts visible light into an electrical signal, which is output through the transistor and transmitted to the processing unit via the data line. The processing unit processes the electrical signal to realize the display of the image.

[0091] Alternatively, the probe substrate may further include multiple bias lines arranged along the second direction, the bias lines being electrically connected to the bias electrodes of at least one row of probe pixel units arranged along the first direction.

[0092] The aforementioned bias line being electrically connected at least to the bias electrodes of a row of detector pixel units arranged along the first direction means: (Referencing) Figure 1 As shown, the bias line 7 can be coupled only along the first direction ( Figure 1 A row arranged in the OB direction (i.e.) Figure 1 The bias electrode of one row of detector pixel units is electrically connected; or, the bias line is electrically connected to the bias electrode of multiple rows of detector pixel units arranged along the first direction. No limitation is made here.

[0093] It should be noted that, Figure 1 In this design, the bias electrodes of each detection pixel unit are independent, requiring multiple bias lines to provide bias signals to different bias electrodes. Alternatively, the bias electrodes of each detection pixel unit can be a single, integrated structure, in which case multiple bias lines are unnecessary.

[0094] The aforementioned bias lines can be placed on the same layer as the data lines, the source and drain of the transistors to reduce the number of patterning processes and lower costs.

[0095] In this probe substrate, a bias signal can be input to the bias electrode through the bias line, thereby providing a bias voltage to the photoelectric conversion unit.

[0096] Further optional, see reference Figure 1As shown, the aforementioned probe substrate may further include a gate driving unit 101, a processing unit 103, and a bias driving unit 102. The gate driving unit 101 is connected to multiple gate lines 4, providing control signals to the gate lines. The processing unit 103 is connected to multiple data lines 5, acquiring and processing the electrical signals output from the data lines. The bias driving unit 102 is connected to multiple bias lines 7, providing bias signals to the bias lines. The specific structures of the gate driving unit, processing unit, and bias driving unit are not limited here. Figure 1 The illustration is based on an example of a detection substrate consisting of three rows and four columns of detection pixel units.

[0097] This invention also provides a flat panel detector, including the aforementioned detection substrate. This flat panel detector can be an X-ray flat panel detector, applicable in fields such as medical, security, and industrial inspection, and has advantages such as long service life, stable performance, and fast response speed. The relevant structural description of the detection substrate included in this flat panel detector can be found in the above embodiments and will not be repeated here.

[0098] This invention also provides a method for fabricating a probe substrate, the structure of which can be referred to... Figure 3-6 As shown, the method includes:

[0099] S01. Multiple detector pixel units are formed in an array on the substrate.

[0100] The material of the substrate is not limited, and it may include rigid materials, such as glass; or it may include flexible materials, such as polyimide (PI).

[0101] S01, the multiple detector pixel units arranged in an array on the substrate, include:

[0102] S101, forming multiple transistors.

[0103] The transistor can be a thin-film transistor or a complementary metal-oxide-semiconductor transistor. The specific method for forming multiple transistors is not limited here; it depends on the specific structure of the transistor.

[0104] S102. Forming multiple photoelectric conversion units; wherein, each photoelectric conversion unit includes a radiation-sensitive layer and a photosensitive unit stacked together, the radiation-sensitive layer being configured to absorb rays and convert rays into charge carriers, and the photosensitive unit being configured to absorb at least visible light and convert visible light into charge carriers.

[0105] The radiation-sensitive layers of the aforementioned multiple photoelectric conversion units can be an integral structure or independent of each other. The fabrication method of the radiation-sensitive layer and the photosensitive unit depends on the specific structure and is not limited here.

[0106] S103, forming a scintillator layer.

[0107] The scintillator layer may be made of materials such as CsI (cesium iodide), GOS (gadolinium oxysulfide), tungstates, alkali metal halides, lutetium fine silicates (LFS), yttrium lutetium silicate (LYSO), sodium thallium-doped iodide (NaI:Tl), cesium iodide (CsI), or bismuth germanate (Bi4Ge3O4). 12 The materials used are any one of the following: BGO (gadolinium aluminum gallium garnet), GAGG (gadolinium aluminum gallium garnet), etc.; among which, tungstates can include: cadmium tungstate (CdWO4) or lead tungstate (PWO), etc. The scintillator layer formed by these materials can convert X-rays into visible light.

[0108] The following is based on Figure 3 Taking the probe substrate shown as an example, its fabrication method will be explained in detail. The method includes:

[0109] S11, Reference Figure 3 As shown, a gate metal layer, a gate insulating layer 12, an active layer 111, a source / drain metal layer, a buffer layer 13, a planarization layer 14, and a second passivation layer 15 are sequentially formed on a substrate 10; wherein, the gate metal layer includes a plurality of gate electrodes 110 and a first storage electrode 17, and the source / drain metal layer includes a plurality of source electrodes 113 and a plurality of drain electrodes 112.

[0110] S12, Reference Figure 3 As shown, a plurality of independent read electrodes 23 are formed on the second passivation layer 15, wherein the read electrodes 23 are connected through a first via ( Figure 3 (Unmarked) is electrically connected to the source 113, and the first via penetrates the second passivation layer 15, the planarization layer 14 and the buffer layer 13.

[0111] S13, Reference Figure 3 As shown, a radiation-sensitive layer 21 is formed on the reading electrode 23.

[0112] Specifically, radiation-sensitive layers can be fabricated using methods such as PVD (Physical Vapor Deposition), solution methods, CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition). PVD deposition methods include vacuum evaporation and radio frequency magnetron sputtering. Solution methods include spin coating, screen printing, precipitation, and surgical blade coating. The thickness of the radiation-sensitive layer ranges from 1 to 100 μm.

[0113] S14, Reference Figure 3 As shown, a photosensitive unit 22 is formed in the radiation-sensitive layer 21.

[0114] Specifically, the various film layers in the photosensitive unit can be deposited using methods such as PECVD (Plasma Enhanced Chemical Vapor Deposition), solution methods, and thin film transfer bonding. Solution methods include spin coating, screen printing, precipitation, and surgical blade coating.

[0115] It should be noted that if the photosensitive unit includes a perovskite layer, then S14, forming the photosensitive unit on the radiation-sensitive layer, includes:

[0116] S141. Immerse the radiation-sensitive layer in an alcoholic solution of a certain concentration of halide salt, and remove it after a certain reaction time.

[0117] The halide salt may include materials having an AB molecular structure, wherein A includes any one or more of MA, FA, cesium ions, and rubidium ions; and B includes any one or more of iodine, chlorine, and bromine. The halide salt may include organic or inorganic halide salts. For example, the organic halide salt may include organic iodide salts; specifically, the organic iodide salt may include MAI (methylamine iodophor), FAI (methylammonium iodophor), and MAI (methylamine iodophor). 1-x Cl x Any of the following (chloromethylamine). The above alcohol solution may include isopropanol. If the radiation-sensitive layer material is PbI2 and the organic iodide salt is MAI, immersion will promote the reaction between PbI2 and MAI, forming a MAPbI3 perovskite polycrystalline film on the surface of the PbI2 film. The thickness of the perovskite polycrystalline layer can be adjusted to 200–500 nm by controlling the MAI solution concentration and immersion time. This method can form a PbI2 and MAPbI3 perovskite heterojunction, which has a lower defect rate at the interface compared to other types of heterojunctions. During operation, some high-energy rays are absorbed by the scintillator layer and generate visible light, which is then absorbed by the perovskite layer and generates free charge carriers. Meanwhile, rays that are not absorbed by the scintillator layer pass through the scintillator layer and reach the perovskite layer. A small portion is absorbed by the perovskite layer and converted into charge carriers (because this perovskite layer is very thin), while the majority of the remaining rays are absorbed by the PbI2 radiation-sensitive layer and converted into charge carriers. Together with the charge carriers generated by the perovskite layer, they are transported to the readout electrode under the drive of the electric field and converted into signal charges.

[0118] S15, Reference Figure 3 As shown, a bias electrode 24 is formed on the photosensitive unit 22.

[0119] The bias electrode material can include transparent conductive materials such as ITO, FTO (fluorine-doped tin oxide transparent conductive glass), AZO (aluminum-doped zinc oxide transparent conductive glass), and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate).

[0120] S16, Reference Figure 3 As shown, a first passivation layer 16 is formed on the bias electrode 24.

[0121] S17, Reference Figure 3 As shown, a scintillator layer 3 is formed on the first passivation layer 16.

[0122] The scintillator layer may be made of materials such as CsI (cesium iodide), GOS (gadolinium oxysulfide), tungstates, alkali metal halides, lutetium fine silicates (LFS), yttrium lutetium silicate (LYSO), sodium thallium-doped iodide (NaI:Tl), cesium iodide (CsI), or bismuth germanate (Bi4Ge3O4). 12 The materials used are any one of the following: BGO (gadolinium aluminum gallium garnet), GAGG (gadolinium aluminum gallium garnet), etc.; among which, tungstates can include: cadmium tungstate (CdWO4) or lead tungstate (PWO), etc. The scintillator layer formed by these materials can convert X-rays into visible light.

[0123] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A detection substrate, characterized in that, It includes multiple detector pixel units arranged in an array; The detection pixel unit includes: a transistor, a photoelectric conversion unit, and a scintillator layer; the photoelectric conversion unit is located between the transistor and the scintillator layer; The photoelectric conversion unit includes a radiation-sensitive layer and a photosensitive unit stacked together. The radiation-sensitive layer is configured to absorb radiation and convert it into charge carriers. The photosensitive unit is configured to absorb at least visible light and convert it into charge carriers. The photosensitive unit is also configured to absorb radiation and convert it into charge carriers. The photosensitive unit includes a perovskite layer. A perovskite heterojunction is formed between the perovskite layer and the radiation-sensitive layer, so that the charge carriers generated by the perovskite layer can be effectively injected into the radiation-sensitive layer. The photosensitive unit is disposed on the side of the radiation-sensitive layer away from the transistor.

2. The detection substrate according to claim 1, characterized in that, The radiation-sensitive layer of each of the aforementioned detection pixel units is an integral structure, and the photosensitive unit of each of the aforementioned detection pixel units is an integral structure.

3. The detection substrate according to claim 1, characterized in that, The detection substrate further includes a substrate, and the detection pixel unit is disposed on the substrate; In each of the aforementioned detection pixel units, the orthogonal projection of the transistor onto the substrate lies within the orthogonal projection of the radiation-sensitive layer onto the substrate.

4. The detection substrate according to claim 1, characterized in that, The detection substrate further includes a substrate, and the detection pixel unit is disposed on the substrate; In each of the aforementioned detection pixel units, the orthographic projection of the photosensitive unit on the substrate is located within the orthographic projection of the radiation-sensitive layer on the substrate.

5. The detection substrate according to claim 1, characterized in that, The material of the radiation-sensitive layer includes heavy elements and has a band gap greater than 2.0 eV.

6. The detection substrate according to claim 5, characterized in that, The photosensitive unit includes a photoconductor or a photodiode.

7. The detection substrate according to claim 6, characterized in that, The photoelectric conversion unit further includes a connecting electrode, which is located between the radiation-sensitive layer and the photosensitive unit.

8. The detection substrate according to claim 1, characterized in that, The material of the perovskite layer includes: having A a B b X x Perovskite materials with molecular structure; wherein, A a Includes: any one or more of the following: organic amine groups, formamidinium, cesium ions, rubidium ions, silver ions, and cuprous ions; B b Including: lead ions or bismuth ions; X x Including any one or more of iodine, chlorine, and bromine.

9. The detection substrate according to claim 1, characterized in that, The detection pixel unit further includes a readout electrode and a bias electrode; the readout electrode is located on the side of the photoelectric conversion unit closer to the transistor, and the bias electrode is located on the side of the photoelectric conversion unit farther from the transistor.

10. The detection substrate according to claim 9, characterized in that, The readout electrodes of each of the aforementioned detection pixel units are independent of each other, and the bias electrodes of each of the aforementioned detection pixel units are an integral structure.

11. The detection substrate according to any one of claims 1-10, characterized in that, The transistor includes a thin-film transistor or a complementary metal-oxide-semiconductor transistor.

12. A flat panel detector, characterized in that, Includes the probe substrate as described in any one of claims 1-11.

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