Internal gain type radiation detector integrated with thin film field effect transistor

Abstract

The invention belongs to the technical field of radiation detection, and discloses an internal gain type radiation detector integrated with a thin film field effect transistor, which comprises a radiation sensitive device part and a gain device part, the radiation sensitive device comprises a radiation sensitive semiconductor substrate layer; a gain function unit contained in the gain device part comprises a thin film field effect transistor and a reference resistor; the radiation sensitive device and the reference resistor form a series voltage division structure; gate voltage of the thin-film field effect transistor is equal to partial voltage at two ends of the reference resistor, and source-drain current of the thin-film field effect transistor is modulated by the gate voltage; in a radiation environment, the resistance of the radiation sensitive semiconductor substrate layer is reduced, so that the partial voltage on the reference resistor is increased, correspondingly, the gate voltage acting on the thin film field effect transistor is increased, the source-drain current of the thin film field effect transistor is increased, and finally internal gain type radiation detection is realized. By improving the composition and the structure of the device, internal gain type radiation detection can be effectively realized, and high response and low noise are both considered.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of radiation detection, and more particularly relates to an internal gain type radiation detector integrated with a thin film field effect transistor. BACKGROUND

[0002] With the progress and development of science and technology, radiation detection has been widely applied in high-energy nuclear physics, national security detection, nuclear medical imaging, environmental radioactivity detection, nuclear power plants, nuclear explosion detection, etc. Its core task is to extract weak radiation signals from background noise while maintaining high sensitivity and wide dynamic range. However, radiation detectors often need to detect extremely low intensity signals, such as signals from cosmic rays, dark matter particles, or low-dose medical imaging. Under the current technical level, there are still multiple challenges to achieve weak signal detection. On the one hand, it is related to the responsivity of the detector to the radiation signal, and on the other hand, it is closely related to noise. Therefore, to achieve high-sensitivity detection of weak signals, it is necessary to provide responsivity while minimizing noise.

[0003] To improve the responsivity of the detector to the radiation signal, in addition to enhancing the conversion efficiency between radiation energy and electrical signal, thereby improving the utilization rate of radiation energy, another approach is to design a radiation detector with signal gain characteristics. Common resistance type and junction type (including PN junction and Schottky junction) radiation detectors have no internal gain, so they cannot achieve high responsivity. At the same time, radiation detectors represented by avalanche diodes have internal gain effect and can achieve high responsivity. However, in avalanche diodes, the large shot noise introduced by collision ionization limits its ability to detect weak signals. Therefore, current radiation detectors are difficult to balance high response and low noise. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide an internal gain type radiation detector integrated with a thin film field effect transistor, wherein by improving the composition and structure of the device, on the basis of a radiation sensitive device with a vertical sandwich structure, a thin film field effect transistor and a reference resistor (especially a variable reference resistor) are introduced to form a gain functional unit, which can effectively realize internal gain type radiation detection and balance high response and low noise.

[0005] To achieve the above purpose, according to one aspect of the present application, an internal gain type radiation detector integrated with a thin film field effect transistor is provided, characterized in that the detector comprises a radiation sensitive device part and a gain device part; the radiation sensitive device is a vertical sandwich structure composed of a front electrode (301), a radiation sensitive semiconductor substrate layer (201), and a bottom electrode (101); the gain device part comprises at least one gain functional unit, and each gain functional unit includes a thin film field effect transistor and a reference resistor. The part of the radiation-sensitive semiconductor substrate layer (201) not covered by the front electrode (301) is further provided with an insulating medium layer (401), and the gain device is integrated on the insulating medium layer (401); the radiation-sensitive device and the reference resistor form a series voltage division structure; the gate voltage of the thin film field effect transistor is equal to the voltage division across the reference resistor, and the source-drain current of the thin film field effect transistor is modulated by the gate voltage based on the MOS capacitor effect; the radiation-sensitive semiconductor substrate layer (201) can generate additional carriers by interacting with rays in a radiation environment, so that the resistance of the radiation-sensitive semiconductor substrate layer (201) decreases, the voltage division across the reference resistor increases, and the gate voltage acting on the thin film field effect transistor increases, thereby causing the source-drain current of the thin film field effect transistor to increase through the gate control effect, and finally realizing the internal gain type radiation detection.

[0006] As a further preferred embodiment of the present application, the resistivity of the radiation-sensitive semiconductor substrate layer (201) is greater than 10 3 Ω·cm, and is one of an amorphous selenium (a-Se) layer, a cadmium zinc telluride (CdZnTe) layer, a single crystal silicon (Si) layer, an amorphous silicon (a-Si) layer, a gallium selenide (GaSe) layer, a diamond layer, a gallium arsenide (GaAs) layer, a silicon carbide (SiC) layer, a mercury iodide (HgI2) layer, a lead iodide (PbI2) layer, or a bismuth iodide (BiI3) layer; The thickness of the radiation-sensitive semiconductor substrate layer (201) is 50-1000 μm.

[0007] As a further preferred embodiment of the present application, the radiation-sensitive semiconductor substrate layer (201) is a semiconductor material composite structure with a PN junction or a semiconductor material composite structure with a PIN junction, comprising a semiconductor substrate (801-1) and a PN junction or a PIN junction located thereon; wherein, The resistivity of the semiconductor substrate (801-1) is greater than 10 3 Ω·cm, and is one of amorphous selenium (a-Se), cadmium zinc telluride (CdZnTe), single crystal silicon (Si), amorphous silicon (a-Si), gallium selenide (GaSe), diamond, gallium arsenide (GaAs), silicon carbide (SiC), mercury iodide (HgI2), lead iodide (PbI2), or bismuth iodide (BiI3); The PN junction is obtained by preparing a thin layer semiconductor with opposite carrier polarity on the semiconductor substrate (801-1) by ion implantation, thermal diffusion, epitaxial growth, or vapor deposition; The PIN junction is obtained by first preparing an intrinsic thin layer semiconductor on the semiconductor substrate (801-1) and then preparing a thin layer semiconductor with opposite carrier polarity on the semiconductor substrate (801-1) by ion implantation, thermal diffusion, epitaxial growth, or vapor deposition; The PN junction or the PIN junction is a homojunction or a heterojunction. The thickness of the radiation-sensitive semiconductor substrate layer (201) is 50-1000 μm.

[0008] As a further preferred embodiment of the present application, the thin film field effect transistor is an N-type enhancement mode thin film field effect transistor or a P-type enhancement mode thin film field effect transistor, which is in an off state at zero gate voltage. The thin film field effect transistor channel layer (501-1) in the thin film field effect transistor is made of any one of intrinsic semiconductor material, compound semiconductor material, and two-dimensional layered semiconductor material or a composite structure composed of them, the thickness of the thin film field effect transistor channel layer (501-1) is 1 nm-500 nm, and the doping concentration is not higher than 10 18 cm -3 ; Preferably, the intrinsic semiconductor material is one or more of Si, Ge, diamond; the compound semiconductor material is one or more of GaAs, GaN, InP, AlN, CdTe, ZnS, SiC, ZnO, Ga2O3, In2O3, SnO2; and the two-dimensional layered semiconductor material is one or more of graphene, MoS2, WSe2, WS2, MoTe2.

[0009] As a further preferred embodiment of the present application, the reference resistance is a variable reference resistance, which adopts a field effect transistor structure and can independently control its resistance value through gate voltage. Preferably, in the working state of the detector, the field effect transistor as the variable reference resistance is in a linear region. The variable reference resistance channel layer (601-1) in the variable reference resistance is made of any one of intrinsic semiconductor material, compound semiconductor material, and two-dimensional layered semiconductor material or a composite structure composed of them, and the thickness of the variable reference resistance channel layer (601-1) is 1 nm-500 nm. Preferably, the intrinsic semiconductor material is one or more of Si, Ge, diamond; the compound semiconductor material is one or more of GaAs, GaN, InP, AlN, CdTe, ZnS, SiC, ZnO, Ga2O3, In2O3, SnO2; and the two-dimensional layered semiconductor material is one or more of graphene, MoS2, WSe2, WS2, MoTe2.

[0010] As a further preferred embodiment of the present application, the insulating dielectric layer (401) is made of any one of oxide dielectric material and nitride dielectric material or a composite structure composed of them, and the thickness of the insulating dielectric layer (401) is 2-2000 nm. Preferably, the oxide medium material is one or more selected from SiO2, Al2O3, HfO2, TiO2, ZrO2, Y2O3, La2O3, and Ta2O5; and the nitride medium material is one or more selected from boron nitride and silicon nitride.

[0011] As a further preferred embodiment of the present invention, when a voltage is applied to the radiation-sensitive device, the radiation-sensitive device and the reference resistor form a series voltage divider structure, and the voltage division ratio obtained by the radiation-sensitive device is not less than 80%. Under irradiation, the radiation-sensitive semiconductor substrate generates additional charge carriers through interaction with the radiation, thereby increasing its charge carrier concentration and decreasing its resistance, resulting in the reorganization of the series voltage division, wherein the absolute value of the voltage division of the radiation-sensitive device decreases and the absolute value of the voltage division of the reference resistor increases.

[0012] As a further preferred embodiment of the present invention, by utilizing the signal amplification capability of the thin-film field-effect transistor, the internal gain radiation detector integrating the thin-film field-effect transistor can achieve internal gain radiation detection. Preferably, under the irradiation environment to be tested, the thin-film field-effect transistor can be operated in the subthreshold region by adjusting the resistance value of the variable reference resistor.

[0013] As a further preferred embodiment of the present invention, the internal gain radiation detector with integrated thin-film field-effect transistor includes multiple gain functional units, each gain functional unit corresponding to one pixel, forming an array structure; Preferably, the radiation-sensitive semiconductor substrate (201) is a semiconductor material composite structure with a PN junction or a semiconductor material composite structure with a PIN junction. The PN junction or PIN junction between any two adjacent gain functional units and between the thin film field-effect transistor and the reference resistor in each gain functional unit is removed by etching to reduce crosstalk between pixels. More preferably, the etched portion is filled by a passivation layer (901).

[0014] Compared with the prior art, the integrated thin-film field-effect transistor (TFT) internal gain radiation detector designed by this invention comprises a radiation-sensitive device portion and a gain device portion. The gain device portion includes at least one gain functional unit, each of which includes a TFT and a reference resistor (the reference resistor can be a variable reference resistor, employing a TFT structure, and its resistance value can be independently adjusted by the gate voltage). The radiation-sensitive device is a vertical sandwich structure consisting of a front electrode, a radiation-sensitive semiconductor substrate layer, and a bottom electrode. By depositing an insulating dielectric layer on the radiation-sensitive semiconductor substrate, the gain device portion can be integrated on the front side of the radiation-sensitive semiconductor substrate, and the reference resistor is connected to the front electrode of the radiation-sensitive device. When a voltage is applied to the bottom electrode of the radiation-sensitive device, the radiation-sensitive device and the reference resistor form a series voltage divider structure. The high-level end of the reference resistor is connected to the gate of the TFT, and the voltage divider across the reference resistor is used as the gate voltage of the TFT. Based on the MOS capacitance effect, the source and drain currents of the TFT are controlled by the gate voltage. When a radiation-sensitive semiconductor substrate interacts with radiation, it generates additional charge carriers, reducing its resistance and increasing the voltage drop across the reference resistor. Consequently, the gate voltage of the thin-film field-effect transistor (TFT) increases, leading to an increase in the source and drain currents of the TFT through the gate control effect, ultimately achieving internal gain radiation detection. In the irradiated environment under test, the TFT can be operated near the subthreshold region by adjusting the variable reference resistor value, utilizing the high transconductance efficiency of the subthreshold region to obtain high detection gain.

[0015] Furthermore, when there are multiple gain functional units, a two-dimensional (or one-dimensional) periodic array structure can be used. In this case, a semiconductor material composite structure containing PN (PIN) junctions can be used as the radiation-sensitive semiconductor substrate layer, and crosstalk between pixels can be reduced by etching away the PN (PIN) junctions between detector pixels.

[0016] Conventional radiation detectors detect radiation by sensing changes in the current or resistance of devices under irradiation conditions. Unlike existing detectors, this invention does not directly use changes in the current or resistance of radiation-sensitive devices as the radiation detection signal. Instead, it utilizes the voltage division effect of a reference resistor (especially a variable reference resistor) combined with a field-effect transistor (FET) to convert these resistance changes into changes in the transistor's gate voltage. This gate voltage change is then efficiently amplified through the MOS capacitance effect into changes in the transistor's source-drain current, achieving in-situ amplification of the radiation signal at the device level. Compared to conventional radiation detectors, this invention, leveraging the signal amplification capability and low dark current noise of the FET, combines high gain, low noise, and low power consumption, enabling highly sensitive detection of weak radiation signals. Furthermore, compared to traditional methods of designing amplification circuits (discrete components or PCB-level circuits) external to the detector, the proposed technique of integrating a thin-film FET onto the surface of a radiation-sensitive semiconductor substrate offers inherent advantages in miniaturization, noise reduction, improved response speed, and optimized power consumption, especially for applications requiring high-density arrays (such as imaging sensors), portable devices, and low power consumption. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the planar structure of the internal gain radiation detector with integrated thin-film field-effect transistor in Embodiment 1 of the present invention.

[0018] Figure 2 This is a schematic cross-sectional view of the internal gain radiation detector with integrated thin-film field-effect transistor in Embodiment 1 of the present invention.

[0019] Figure 3 This is a schematic diagram of a one-dimensional periodic array planar structure of an internal gain radiation detector integrating thin-film field-effect transistors in Embodiment 2 of the present invention.

[0020] Figure 4 This is a schematic diagram of the cross-sectional structure of a one-dimensional periodic array of an internal gain radiation detector integrating thin-film field-effect transistors in Embodiment 2 of the present invention.

[0021] Figure 5 is a schematic diagram of the circuit structure of the internal gain radiation detector with integrated thin-film field-effect transistor in Embodiment 1 of the present invention.

[0022] Figure 6 The circuit simulation results illustrate the working principle of the internal gain radiation detector integrating thin-film field-effect transistors of this invention.

[0023] The meanings of the labels in the figures are as follows: 101 bottom electrode 201 Radiation-Sensitive Semiconductor Substrate 301 front electrode 401 Insulating Dielectric Layer 501-1 Thin Film Field Effect Transistor Channel Layer 501-2 Thin Film Field Effect Transistor Source 501-3 Thin Film Field Effect Transistor Drain 501-4 Thin Film Field Effect Transistor Gate Dielectric Layer 501-5 Thin Film Field Effect Transistor Gate Electrode 601-1 Variable Reference Resistance Channel Layer 601-2 Variable Reference Resistor Source 601-3 Variable Reference Resistor Drain 601-4 Variable Reference Resistance Gate Dielectric Layer 601-5 Variable Reference Resistance Gate Electrode 701 Metal Interconnect Wire 801-1 Semiconductor Substrate 801-2PN (PIN) junction 901 passivation layer Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Taking a variable reference resistor (using a field-effect transistor structure) as an example, the structure of this invention is as follows: an insulating dielectric layer 401 is deposited on the front side of a radiation-sensitive semiconductor substrate 201 containing a bottom electrode 101 and a front electrode 301; then, thin-film field-effect transistors (TFTs) comprising a channel layer (i.e., TFT channel layer 501-1), a source (i.e., TFT source 501-2), a drain (i.e., TFT drain 501-3), a gate dielectric layer (i.e., TFT gate dielectric layer 501-4), and a gate electrode (i.e., TFT gate electrode 501-5) are respectively integrated on the surface of the insulating dielectric layer 401. The system comprises a channel layer (i.e., variable reference resistor channel layer 601-1), a source (i.e., variable reference resistor source 601-2), a drain (i.e., variable reference resistor drain 601-3), a gate dielectric layer (i.e., variable reference resistor gate dielectric layer 601-4), and a gate electrode (i.e., variable reference resistor gate electrode 601-5). A metal interconnect wire 701 connects the front electrode 301 and the drain of the variable reference resistor 601-3, connects the drain of the variable reference resistor 601-3 to the gate electrode 501-5 of the thin-film field-effect transistor (TFT), and finally connects the source of the TFT 501-2 and the source of the variable reference resistor 601-2 to form an equipotential connection. When a voltage is applied to the bottom electrode 101, the radiation-sensitive device and the variable reference resistor form a series voltage divider structure, modulating the source and drain currents of the TFT based on the MOS capacitance effect. In this invention, irradiation on the radiation-sensitive semiconductor substrate 201 generates additional charge carriers, increasing its charge carrier concentration and decreasing its resistance. This leads to an increase in the absolute value of the voltage division of the variable reference resistor, thereby enhancing the effective gate voltage strength acting on the channel layer. By changing the channel charge carrier concentration through the gate control effect, the source and drain current of the thin-film field-effect transistor increases, ultimately achieving internal gain radiation detection.

[0025] Example 1: Figure 1 and Figure 2 This is a schematic diagram of an internal gain radiation detector with an integrated thin-film field-effect transistor provided by the present invention, wherein the thin-film field-effect transistor is an N-type enhancement thin-film field-effect transistor.

[0026] This embodiment discloses an internal gain radiation detector integrating a thin-film field-effect transistor, wherein the radiation-sensitive semiconductor substrate 201 is selected from a high-resistivity CdZnTe substrate with a resistivity >10. 6 Ω·cm (In this embodiment, the resistivity of the radiation-sensitive semiconductor substrate 201 is 10 Ω·cm) 7The bottom electrode 101 and the front electrode 301 are made of metal electrodes such as Au, Al, Ni, and Ti (Ti is used in this embodiment). The front electrode 301 is defined by patterning technology, while the bottom electrode 101 is not patterned and covers the entire substrate. A 40 nm Al2O3 layer is prepared on the front side of the radiation-sensitive semiconductor substrate 201 using atomic layer deposition as the insulating gate medium 401. A 100 nm thick single crystal silicon film is integrated on the surface of the Al2O3 insulating gate medium using wafer bonding and thin film transfer technology. The Si film should be in a lightly doped N-type state, and its doping concentration should not exceed 5 × 10⁻⁶. 17 cm -3 (The doping concentration used in this embodiment is 1×10⁻⁶) 17 cm -3 The single-crystal silicon thin film is etched into two independent layers using semiconductor patterning technology. One layer serves as the channel layer 501-1 of the thin-film field-effect transistor (TFT), and a 30 nm Ti and 100 nm Au stack prepared by electron beam evaporation or magnetron sputtering is used as an N-type contact electrode to form the source 501-2 and drain 501-3 connected to the channel layer. Then, an atomic layer deposition is used to prepare a 20 nm Al2O3 layer on the surface of the TFT channel layer 501-1 as the TFT gate dielectric layer 501-4. Finally, a 10 nm Ti and 100 nm Au stack prepared by electron beam evaporation or magnetron sputtering is used on the surface of the gate dielectric layer 501-4 as the TFT gate electrode 501-5. The other layer serves as the variable reference resistor channel layer 601-1, and the source 601-2, drain 601-3, gate dielectric layer 601-4, and gate electrode 601-5 are prepared using the same method. Finally, 100 nm Al was prepared as metal interconnect wire 701 by patterning techniques such as electron beam evaporation or magnetron sputtering.

[0027] Example 2: Figure 3 and Figure 4 These are schematic diagrams of the planar structure and cross-sectional structure of a one-dimensional periodic array of an internally gain radiation detector integrating thin-film field-effect transistors (TFTs), respectively. The TFTs used are N-type enhancement-mode TFTs. Specifically, the radiation-sensitive semiconductor substrate 201 consists of a semiconductor substrate 801-1 and a PN (PIN) junction 801-2; the semiconductor substrate 801-1 is an N-type GaAs substrate with a doping concentration not exceeding 10⁻⁶. 18 cm -3 (The doping concentration used in this embodiment is 1×10⁻⁶) 17 cm -3 A P-type epitaxial layer is grown on the aforementioned semiconductor substrate 801-1, with a doping concentration of not less than 10⁻⁶. 18 cm-3 (The doping concentration used in this embodiment is 1×10⁻⁶) 19 cm -3 This forms a PN junction 801-2 (of course, a PIN junction can also be used instead of a PN junction); the bottom electrode 101 and the front electrode 301 are made of metal electrodes such as Au, Al, Ni, and Ti (Ti is used in this embodiment), wherein the front electrode 301 is defined by patterning technology while the bottom electrode 101 is not patterned and covers the entire substrate; a 40 nm Al2O3 layer is prepared on the front side of the radiation-sensitive semiconductor substrate 201 using atomic layer deposition technology as the insulating gate medium 401; a 100 nm thick single crystal silicon thin film is integrated on the surface of the Al2O3 insulating gate medium using wafer bonding and thin film transfer technology, wherein the Si thin film should be in a lightly doped N-type state, and its doping concentration is not higher than 5 × 10⁻⁶. 17 cm -3 (The doping concentration used in this embodiment is 1×10⁻⁶) 17 cm -3 The single-crystal silicon thin film is etched into an array structure using semiconductor patterning technology and grouped into pairs. One of the layers in one pair serves as the channel layer 501-1 of the thin-film field-effect transistor (TFT), and a 30 nm Ti and 100 nm Au stack prepared by electron beam evaporation or magnetron sputtering is used as an N-type contact electrode to form the source 501-2 and drain 501-3 connected to the channel layer. Then, an atomic layer deposition is used to prepare a 20 nm Al2O3 layer on the surface of the TFT channel layer 501-1 as the TFT gate dielectric layer 501-4. Finally, a 10 nm Ti and 100 nm Au stack prepared by electron beam evaporation or magnetron sputtering is used on the surface of the gate dielectric layer 501-4 as the TFT gate electrode 501-5. The other layer serves as the variable reference resistor channel layer 601-1, and the source 601-2, drain 601-3, gate dielectric layer 601-4, and gate electrode 601-5 are prepared using the same method. Finally, 100 nm Al metal interconnect wires 701 are fabricated using patterning techniques such as junction electron beam evaporation or magnetron sputtering. This yields a one-dimensional linear array structure of an internally gain radiation detector integrating thin-film field-effect transistors, where each independent pixel unit contains a radiation-sensitive device portion and a gain device portion. Preferably, to reduce crosstalk between pixels, the regions between detector pixels are etched with a GaAs substrate as an etch stop layer, and finally, atomic layer deposition is used to cover the etched regions with Si3N4 as a passivation layer 901.

[0028] Circuit simulation of the detector's working principle: Figure 5 is a schematic diagram of the internal gain radiation detector integrating a thin-film field-effect transistor in this invention. Based on this circuit diagram, we simulated the designed device using Multisim software. A 2N7002 MOSFET Q1 was used to replace the variable reference resistor 601 in the initial design, and an IRLZ44N MOSFET Q2 was used to replace the thin-film field-effect transistor 501 in the initial design. By changing V... dd To change the gate voltage U of the Q1 field-effect transistor GS This changes the resistance R of the variable reference resistor 601. DS Considering the large on-state current and correspondingly low resistance of commercial MOSFETs, we artificially reduced the resistance of the radiation-sensitive component to establish an effective voltage divider relationship with it. In the simulation, the internal resistance of the radiation-sensitive component 201 is set to 165Ω. It should be noted that the above proportional resistor scaling does not change the circuit's operating principle. In the simulation, when V... dd For 3V, V cc 60V, V ee At 12V. Under no radiation conditions, the current (I) flowing through the radiation-sensitive part under the above voltage conditions. Det The current is 348mA; Q2 is in the off state, at which time the detector outputs a signal current (I) of 348mA. DS The current is 5µA. When the radiation-sensitive part is reduced by 30% under irradiation, the current of the radiation-sensitive part is 370mA. Q2 enters the constant current region, and the signal current output by the detector is 620A. Figure 6 As shown. The formula for calculating the signal-to-noise ratio gain is:

[0029] Where, ΔS out For I DS The increment; ΔS in For I Det The increment. The system's signal-to-noise ratio gain is 89dB, and the signal-to-noise ratio is 80.9dB.

[0030] The above embodiments are merely examples. In addition to using a field-effect transistor structure to form a variable reference resistor, the reference resistor can also be a reference resistor with a fixed resistance value. In this case, similarly: the radiation-sensitive device and the reference resistor form a series voltage divider structure; the gate voltage of the thin-film field-effect transistor is equal to the voltage division across the reference resistor; based on the MOS capacitance effect, the source and drain current of the thin-film field-effect transistor is modulated by the gate voltage; the radiation-sensitive semiconductor substrate can generate additional charge carriers by interacting with rays in the radiation environment, thereby reducing its resistance and increasing the voltage division across the reference resistor. Correspondingly, the gate voltage acting on the thin-film field-effect transistor increases, and the source and drain current of the thin-film field-effect transistor increases through the gate control effect, ultimately realizing internal gain radiation detection. For example, the thin-film semiconductor channel layer and the variable reference resistor channel layer can also be any one of intrinsic semiconductor materials (such as Si, Ge, diamond), compound semiconductor materials (such as GaAs, GaN, InP, AlN, CdTe, ZnS, SiC, ZnO, Ga2O3, In2O3, SnO2), and two-dimensional layered semiconductor materials (such as graphene, MoS2, WSe2, WS2, MoTe2) or a composite structure thereof; the insulating gate dielectric layer can also be any one of oxide dielectric materials (such as SiO2, Al2O3, HfO2, TiO2, ZrO2, Y2O3, La2O3, Ta2O5) and nitride dielectric materials (such as boron nitride, silicon nitride) or a composite structure thereof.

[0031] It should be noted that the illustrations provided in this example are only schematic representations of the basic concept of the present invention. The figures only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the shape, number and proportion of the components can be changed, and the layout of the components may also be more complex.

[0032] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An internal gain radiation detector integrating a thin-film field-effect transistor, characterized in that, The detector comprises a radiation-sensitive device portion and a gain device portion; the radiation-sensitive device is a vertical sandwich structure consisting of a front electrode (301), a radiation-sensitive semiconductor substrate layer (201), and a bottom electrode (101); the gain device portion comprises at least one gain functional unit, each gain functional unit including a thin-film field-effect transistor and a reference resistor; An insulating dielectric layer (401) is also provided on the portion of the radiation-sensitive semiconductor substrate (201) not covered by the front electrode (301), and the gain device is partially integrated on the insulating dielectric layer (401); the radiation-sensitive device and the reference resistor form a series voltage divider structure; the gate voltage of the thin-film field-effect transistor is equal to the voltage divider across the reference resistor, and the source-drain current of the thin-film field-effect transistor is modulated by the gate voltage based on the MOS capacitance effect; the radiation-sensitive semiconductor substrate (201) can generate additional charge carriers by interacting with rays in a radiation environment, thereby reducing its resistance and increasing the voltage divider across the reference resistor. Correspondingly, the gate voltage acting on the thin-film field-effect transistor increases, and the source-drain current of the thin-film field-effect transistor increases through the gate control effect, ultimately realizing internal gain radiation detection.

2. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The resistivity of the radiation-sensitive semiconductor substrate (201) is > 10. 3 Ω·cm, is one of the following layers: amorphous selenium (a-Se) layer, cadmium zinc telluride (CdZnTe) layer, single crystal silicon (Si) layer, amorphous silicon (a-Si) layer, gallium selenide (GaSe) layer, diamond layer, gallium arsenide (GaAs) layer, silicon carbide (SiC) layer, mercuric iodide (HgI2) layer, lead iodide (PbI2) layer, or bismuth iodide (BiI3) layer; The thickness of the radiation-sensitive semiconductor substrate (201) is 50-1000 μm.

3. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The radiation-sensitive semiconductor substrate (201) is a semiconductor material composite structure with a PN junction or a semiconductor material composite structure with a PIN junction, including a semiconductor substrate (801-1) and a PN junction or PIN junction located thereon; wherein, The resistivity of the semiconductor substrate (801-1) is > 10. 3 Ω·cm is one of amorphous selenium (a-Se), cadmium zinc telluride (CdZnTe), single crystal silicon (Si), amorphous silicon (a-Si), gallium selenide (GaSe), diamond, gallium arsenide (GaAs), silicon carbide (SiC), mercuric iodide (HgI2), lead iodide (PbI2) or bismuth iodide (BiI3); The PN junction is obtained by preparing a thin semiconductor layer with opposite carrier polarities on the semiconductor substrate (801-1) using ion implantation, thermal diffusion, epitaxial growth or vapor deposition. The PIN junction is obtained by first preparing an intrinsic thin-layer semiconductor on the semiconductor substrate (801-1) by ion implantation, thermal diffusion, epitaxial growth or vapor deposition, and then preparing a thin-layer semiconductor with opposite carrier polarity. The PN junction or the PIN junction is a homogeneous junction or a heterogeneous junction; The thickness of the radiation-sensitive semiconductor substrate (201) is 50-1000 μm.

4. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The thin-film field-effect transistor is an N-type enhancement-mode thin-film field-effect transistor or a P-type enhancement-mode thin-film field-effect transistor, and is in the off state at zero gate voltage; The thin-film field-effect transistor (TFT) channel layer (501-1) is a composite structure made of any one of intrinsic semiconductor materials, compound semiconductor materials, and two-dimensional layered semiconductor materials, or a combination thereof. The thickness of the TFT channel layer (501-1) is 1 nm-500 nm, and the doping concentration is not higher than 10. 18 cm -3 ; Preferably, the intrinsic semiconductor material is one or more of Si, Ge, and diamond; the compound semiconductor material is one or more of GaAs, GaN, InP, AlN, CdTe, ZnS, SiC, ZnO, Ga2O3, In2O3, and SnO2; and the two-dimensional layered semiconductor material is one or more of graphene, MoS2, WSe2, WS2, and MoTe2.

5. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The reference resistor is a variable reference resistor, which adopts a field-effect transistor structure and can independently adjust its resistance value through the gate voltage. Preferably, when the detector is in operation, the field-effect transistor, which serves as a variable reference resistor, is in the linear region; The variable reference resistor channel layer (601-1) in the variable reference resistor is a composite structure made of any one of intrinsic semiconductor materials, compound semiconductor materials, and two-dimensional layered semiconductor materials, or a combination thereof, and the thickness of the variable reference resistor channel layer (601-1) is 1 nm-500 nm. Preferably, the intrinsic semiconductor material is one or more of Si, Ge, and diamond; the compound semiconductor material is one or more of GaAs, GaN, InP, AlN, CdTe, ZnS, SiC, ZnO, Ga2O3, In2O3, and SnO2; and the two-dimensional layered semiconductor material is one or more of graphene, MoS2, WSe2, WS2, and MoTe2.

6. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The insulating dielectric layer (401) is a composite structure made of any one of oxide dielectric materials and nitride dielectric materials or a combination thereof, and the thickness of the insulating dielectric layer (401) is 2-2000 nm. Preferably, the oxide medium material is one or more selected from SiO2, Al2O3, HfO2, TiO2, ZrO2, Y2O3, La2O3, and Ta2O5; and the nitride medium material is one or more selected from boron nitride and silicon nitride.

7. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, When a voltage is applied to the radiation-sensitive device, the radiation-sensitive device and the reference resistor form a series voltage divider structure, and the voltage division ratio obtained by the radiation-sensitive device is not less than 80%. Under irradiation, the radiation-sensitive semiconductor substrate generates additional charge carriers through interaction with the radiation, thereby increasing its charge carrier concentration and decreasing its resistance, resulting in the reorganization of the series voltage division. In this process, the absolute value of the voltage division of the radiation-sensitive device decreases, while the absolute value of the voltage division of the reference resistor increases.

8. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 5, characterized in that, By utilizing the signal amplification capability of thin-film field-effect transistors, the internal gain radiation detector with integrated thin-film field-effect transistors can achieve internal gain radiation detection. Preferably, under the irradiation environment to be tested, the thin-film field-effect transistor can be operated in the subthreshold region by adjusting the resistance value of the variable reference resistor.

9. The internal gain radiation detector with integrated thin-film field-effect transistor as described in claim 1, characterized in that, The integrated thin-film field-effect transistor internal gain radiation detector includes multiple gain functional units, each corresponding to one pixel, forming an array structure. Preferably, the radiation-sensitive semiconductor substrate (201) is a semiconductor material composite structure with a PN junction or a semiconductor material composite structure with a PIN junction. The PN junction or PIN junction between any two adjacent gain functional units and between the thin film field-effect transistor and the reference resistor in each gain functional unit is removed by etching to reduce crosstalk between pixels. More preferably, the etched portion is filled by a passivation layer (901).

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