A photodetecting thin film transistor and a method for manufacturing the same

Abstract

The application discloses a photoelectric detection thin film transistor, which comprises a substrate, a gate electrode, a gate dielectric layer, a source electrode, a drain electrode and a channel layer; wherein the gate electrode is located on the substrate, the gate dielectric layer is located on the gate electrode, the source electrode and the drain electrode are arranged on the gate dielectric layer in a spaced manner, and the channel layer is located above the source electrode and the drain electrode; the channel layer is a zinc tin nitrogen oxygen thin film, the chemical formula of the zinc tin nitrogen oxygen thin film is Zn a Sn b N y O z , and a+b>y+z in the thin film. The photoelectric detection thin film transistor has high responsivity and response speed, and the application further discloses a preparation method of the photoelectric detection thin film transistor.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device technology, and in particular relates to a photodetector thin-film transistor and its fabrication method. Background Technology

[0002] With the rapid development of the Internet of Things (IoT), the demand for high-performance visible light photoelectric sensors in interconnection is gradually increasing. Currently, photodetectors are mainly divided into two structures: two-terminal devices, which are simple in structure and mature in technology, and three-terminal devices, such as thin-film transistors (TFTs), which can simultaneously perform signal detection and amplification, thus simplifying circuits and reducing power consumption. Furthermore, TFT photodetectors can not only drive switching elements but also serve as core light-sensing components, facilitating further backplane integration with elements such as pixel sites. They are widely used in backlight adjustment and under-display fingerprint detection in smart devices.

[0003] Metal-oxide-semiconductor (MOS) thin-film transistors (TFTs) possess significant advantages due to their high mobility and low dark current. They can also be fabricated on a large scale and uniformly, and are compatible with silicon-based processes, leading to their application in displays, drivers, and many other fields. However, the extensive use of rare elements such as indium and gallium in MOS transistors, such as indium gallium zinc oxide (IGZO), is not only environmentally unfriendly but also increases manufacturing costs.

[0004] Furthermore, the development of metal oxide thin-film transistors in the field of photodetection remains limited. Due to the wide bandgap (3eV) of oxides, the response wavelength range is generally concentrated in the ultraviolet light band, and the absorption coefficient decreases with increasing wavelength. Therefore, the application of metal oxide photodetectors in the visible light range is limited.

[0005] In addition, the oxide material contains donor level defect oxygen vacancies (V0). O Under illumination, it ionizes to produce a large number of photogenerated electrons, and oxygen vacancies are transformed into charged oxygen vacancies (V). O + V O 2+ This process enhances the conductivity of the channel layer and improves the photoresponse of the device. However, this transformation causes minor distortions in the local lattice, requiring additional energy to restore charged oxygen vacancies to their ground state. This results in severe persistent photoconductivity in metal-oxide thin-film transistors with high photoresponse, which is detrimental to real-time detection by photodetectors.

[0006] Photodetectors with lower oxygen vacancy content in the channel layer have faster response times, but their responsivity still needs improvement. Therefore, it is necessary to develop photodetector thin-film transistor devices that simultaneously possess high responsivity and high response speed.

[0007] In existing technologies, a positive gate voltage pulse is typically applied to the device to promote current recovery, achieving both high responsivity and fast response time. If a high-responsivity device can also have a fast response without external activation energy, the circuit can be simplified, and low-power devices can be developed. Therefore, there is an urgent need to design a high-responsivity photodetector thin-film transistor that still has a fast response under stimulation conditions without the need for external activation energy. Summary of the Invention

[0008] This invention provides a photodetector thin-film transistor that simultaneously possesses high responsivity and response speed.

[0009] This invention provides a photodetector thin-film transistor, which includes a substrate, a gate electrode, a gate dielectric layer, a source electrode, a drain electrode, and a channel layer;

[0010] The gate electrode is located on the substrate, the gate dielectric layer is located on the gate electrode, the source electrode and the drain electrode are disposed alternately on the gate dielectric layer, and the channel layer is located above the source electrode and the drain electrode;

[0011] The channel layer is a zinc-tin-oxygen-oxide thin film, and the chemical formula of the zinc-tin-oxygen-oxide thin film is Zn. a Sn b N y O z , a+b>y+z.

[0012] This invention uses a zinc-tin-nitrogen-oxygen thin film rich in metals as the channel layer, which reduces the content of oxygen vacancies and nitrogen vacancies and other oxygen vacancy defects in the channel layer, thereby improving the response speed.

[0013] Furthermore, the chemical formula of the zinc-tin-oxygen thin film is Zn. a Sn b N y O z The atomic percentages of each element are 25at%≤a≤62at%, 2at%≤b≤6at%, 6at%≤y≤20at%, 21at%≤z≤53at%, and a+b+y+z=100.

[0014] This invention improves the photosensitive response speed by fabricating a channel layer film rich in internal metals, and ensures high responsivity in the visible light range by introducing nitrogen. Photodetector thin-film transistors with channel layers conforming to stoichiometry and lacking metal enrichment exhibit significant continuous photoconductivity. Introducing nitrogen can reduce oxygen vacancy defect content; however, excessive nitrogen can generate defects such as nitrogen vacancies, also causing continuous photoconductivity. The presence of elemental metal within the film, which is easily oxidized, can to some extent protect nitrides from oxidation, improving device stability. Furthermore, the metal enrichment within the film is the main reason for reducing defects such as oxygen and nitrogen vacancies.

[0015] Furthermore, divalent Zn ions, divalent Sn ions, and tetravalent Sn ions are present both inside and on the surface of the channel layer.

[0016] Furthermore, on the surface of the channel layer, the atomic percentage of divalent Sn ions in the Sn element is 47at%-67at, and the atomic percentage of tetravalent Sn ions is 33at%-53at.

[0017] The metal on the channel surface is mainly in an ionic state with a high oxygen content. This is due to the oxidation of the metal on the thin film surface. This oxide layer is denser and plays a protective role against the metastable metals and nitrides inside the thin film, thereby improving the stability of the device.

[0018] Furthermore, within the channel layer, the atomic percentage of divalent Zn ions in Zn is 92 at%-96 at%, and the atomic percentage of elemental Zn is 4 at%-8 at%.

[0019] Inside the channel layer, the atomic percentage of divalent Sn ions in Sn is 21at%-29at, the atomic percentage of tetravalent Sn ions is 21at%-24at, and the atomic percentage of elemental Sn is 48at%-58at. The sum of the atomic percentages of divalent Sn ions, tetravalent Sn ions, and elemental Sn is 100at.

[0020] The channel layer exhibits a significant metal-rich phenomenon, with the presence of elemental metals, particularly Sn, which exists primarily in its elemental Sn state. This reduces the content of defects such as oxygen and nitrogen vacancies in the channel layer, thereby improving the response speed. However, excessive Zn content will decrease the Sn content, affecting device stability because Zn-N bonds readily react with H₂O to produce ZnO and NH₃ on the surface, causing nitrogen to diffuse outward from the thin film. Excessive Sn content will also reduce device mobility and impair carrier transport.

[0021] Furthermore, the bandgap of the photodetector thin-film transistor is 1.36-1.53 ​​eV.

[0022] Furthermore, the photodetector thin-film transistor has a responsivity of 253-1097 A / W under 350-650 nm illumination;

[0023] The response time of the photodetector thin-film transistor is divided into rise time and fall time. The rise time is 0.38-4.58 s, and the fall time is 0.53-1.12 s. The rise time is the time it takes for the photocurrent to rise from 10% to 90% of its peak value, and the fall time is the time it takes for the photocurrent to fall from 90% to 10% of its peak value. Therefore, it can be seen that the photodetector thin-film transistor provided by this invention has both high light responsivity and a short light response time.

[0024] The present invention also provides a method for fabricating a photodetector thin-film transistor, comprising:

[0025] A gate electrode and a gate dielectric layer are sequentially deposited on the substrate surface using a vacuum deposition method. Source and drain electrodes are then deposited on the surface of the gate dielectric layer. The source and drain electrodes are independently separated. A channel layer is then deposited on the surface of the source and drain electrodes to obtain a deposited photodetector thin film transistor. The material of the channel layer is a zinc tin nitrogen oxide thin film.

[0026] Photodetector thin-film transistors are obtained by annealing the deposited state photodetector thin-film transistors.

[0027] This invention improves the orderliness of deposited zinc-tin-oxygen nitrogen thin films through an annealing process, thereby enhancing carrier transport capability and improving the photoresponsivity of photodetector thin-film transistors. Furthermore, moderate oxidation of the film surface improves device stability.

[0028] Furthermore, the deposited photodetector thin film transistor is subjected to annealing treatment. The process parameters for the annealing treatment are: annealing temperature of 350℃-450℃, annealing time of 5-15min, annealing atmosphere of nitrogen, and nitrogen purity of 99.995%.

[0029] If the annealing temperature is too low, the film will have insufficient ordering and mobility, requiring further optimization of the device's electrical performance. If the annealing temperature is too high, it will first increase the crystallinity of the channel material, increasing the grain boundary content within the film and hindering carrier transport; secondly, it will damage the electrode material and the interfaces between the electrode channels and the electrode dielectric layers; moreover, high-temperature annealing increases energy consumption in the manufacturing process, making industrialization more complex. If the annealing time is too short, the film will have insufficient ordering and inadequate annealing effect. If the annealing time is too long, it will first enhance film crystallization, secondly, the oxidation reaction of the film will be more complete, divalent Sn ions and elemental metals will be further oxidized, and the hydrolysis reaction of nitrogen on the film surface with air will be more intense, accelerating nitrogen loss from the film, resulting in an increased band gap, reduced photoresponsivity in the visible light range, and a shift in the response wavelength range towards shorter wavelengths.

[0030] Furthermore, the source electrode is made of Au, W, Cu, Al, ITO, Pt, Ag, Cr, Ta, Mo, or Ti, and the drain electrode is made of Au, W, Cu, Al, ITO, Pt, Ag, Cr, Ta, Mo, or Ti.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The present invention uses a zinc-tin-nitrogen-oxygen thin film with internal metal richness as the channel layer, which reduces the content of oxygen vacancy defects and improves the photoresponse speed, resulting in a photodetector thin film transistor with high photoresponse speed and high photoresponsivity in the ultraviolet-visible wide response band.

[0033] (2) The present invention uses a zinc-tin-oxygen-nitride thin film rich in metals as the channel layer. The elemental metals present inside the film are more easily oxidized than nitrides, which can protect nitrides and improve device stability.

[0034] (3) The photoelectric detection thin film transistor of the present invention does not require the application of additional activation energy, has a fast response speed, and has the advantages of low power consumption, simple fabrication process, and real-time detection.

[0035] (4) The thin-film transistor of the present invention uses Zn a Sn b N y O z Zinc-tin-nitrogen-oxygen thin films are used as the channel layer. Their constituent elements are common elements, which significantly reduces the production cost of thin-film transistors (TFTs). Furthermore, TFT fabrication does not require high-temperature processes and can be achieved under low-temperature conditions. Therefore, it effectively reduces the requirements for TFT fabrication conditions and does not pollute the environment. Attached Figure Description

[0036] Figure 1 A schematic cross-sectional view of a photodetector thin-film transistor provided in a specific embodiment of the present invention;

[0037] Figure 2 The fine XPS core energy level spectrum of oxygen in the zinc-tin-oxygen-nitrogen thin film provided in Example 1;

[0038] Figure 3 The fine XPS core energy level spectrum of tin in the zinc-tin-oxygen-nitrogen thin film provided in Example 1;

[0039] Figure 4 The fine XPS core energy level spectrum of zinc in the zinc-tin-oxygen-nitrogen thin film provided in Example 1;

[0040] Figure 5The zinc-tin-oxygen-nitrogen thin film (αhν) provided in Example 1 2 Relationship diagram with hν;

[0041] Figure 6 The graph shows the transfer curves of the photodetector thin-film transistor prepared in Example 1 under dark environment and different wavelength light environments.

[0042] Figure 7 The image shows the photoresponsivity of the photodetector thin-film transistor prepared in Example 1 under dark conditions and different wavelengths of light.

[0043] Figure 8 The image shows the response time curve of the photodetector thin-film transistor prepared in Example 1, where the incident light wavelength is 450 nm.

[0044] Figure 9 The image shows the response time curve of the photodetector thin-film transistor prepared in Example 2, where the incident light wavelength is 450 nm.

[0045] Figure 10 The image shows the response time curve of the photodetector thin-film transistor prepared in Comparative Example 1, where the incident light wavelength is 450 nm.

[0046] Wherein, 1-substrate and gate electrode layer, 2-gate dielectric layer, 31-source electrode, 32-drain electrode, 4-channel layer. Detailed Implementation

[0047] To further describe the technical solutions of this invention in detail, the following will be explained in conjunction with the accompanying drawings and specific implementation examples.

[0048] like Figure 1 As shown in the figure, a specific embodiment of the present invention provides a photodetector thin film transistor, which includes a substrate and a gate electrode 1, a gate dielectric layer 2, a source electrode 31, a drain electrode 32 and a channel layer 4. The gate dielectric layer 2 is formed on the surface of the substrate and the gate electrode layer 1. The source electrode layer 31 and the drain electrode layer 32 are both formed on the surface of the gate dielectric layer 2, and there is a gap between the source electrode layer 31 and the drain electrode layer 32. The channel layer 4 is formed on the surface of the source electrode layer 31 and the drain electrode layer 32.

[0049] In a specific embodiment of the present invention, the channel layer 4 is a zinc-tin-oxygen-oxide thin film. The chemical formula of this zinc-tin-oxygen-oxide thin film is Zn. a Sn b N y O zInside the thin film, a+b>y+z, where a is the atomic content of zinc (Zn) in the zinc-tin-oxygen thin film, b is the atomic content of tin (Sn) in the zinc-tin-oxygen thin film, y is the atomic content of nitrogen (N) in the zinc-tin-oxygen thin film, and z is the atomic content of oxygen (O) in the zinc-tin-oxygen thin film.

[0050] In a specific embodiment of the present invention, considering that magnetron sputtering technology is mature and has been widely used as an industrial oxide deposition equipment, capable of producing thin films on a large scale and uniformly, magnetron sputtering is selected as the deposition method for the channel layer and the electrode.

[0051] The following explanation will be based on specific implementation cases.

[0052] Example 1

[0053] This embodiment illustrates a method for fabricating a zinc-tin-oxygen-nitrogen photodetector thin-film transistor. Figure 1 The schematic diagram of the device structure is as follows: p+Si 1 serves as the substrate and gate electrode; SiO2 2 is grown by thermal oxidation as the gate insulating layer; source and drain electrodes 31 and 32 are deposited by magnetron sputtering and patterned by photolithography; and zinc-tin-oxygen-nitrogen channel layer 4 is deposited by magnetron sputtering and patterned by photolithography on the same basis.

[0054] The fabrication method of the photodetector thin-film transistor provided in Implementation Case 1 above is as follows:

[0055] Step A: Prepare p + A Si / SiO2 thermally oxidized silicon wafer was used as substrate 1, and clean silicon wafers and quartz glass were used as co-substrates. The wafers were ultrasonically cleaned with acetone, alcohol, and deionized water for 5 min, 5 min, and 5 min respectively, followed by drying with N2. This process aims to provide a contamination-free growth base for the subsequent channel layer. Furthermore, this p... + -Si / SiO2 thermally oxidized silicon wafers have an oxide layer of about 100±30nm on their surface, so they can be used as a substrate, gate electrode and gate dielectric layer at the same time, saving intermediate process time and manufacturing costs.

[0056] Step B: Using ITO as the target material, an ITO film of approximately 100 nm thickness was deposited by DC sputtering at 65 W for 27 min in a mixed gas of argon (30 SCCM) and oxygen (1.5 SCCM). The film was then patterned into an interdigitated electrode structure using photolithography, wherein the interdigital spacing and width were both 5 μm, and the finger length was 440 nm.

[0057] Step C: Using a ZnSn alloy target (Zn:Sn = 9:1) as the target material, a ZSON thin film of approximately 35 nm was deposited by RF magnetron sputtering at 80 W for 70 min in a nitrogen atmosphere with a flow rate of 50 SCCM. The film was then patterned into a channel layer with dimensions of 800 μm × 400 μm using photolithography. Simultaneously, zinc-tin-oxygen-nitride thin films were prepared as substrates on silicon wafers and quartz glass sheets as co-films.

[0058] Step D: The obtained device is rapidly annealed in a rapid annealing furnace at 400°C for 10 minutes in a high-purity nitrogen atmosphere, and an annealed thin film substrate is obtained at the same time.

[0059] Example 2

[0060] Example 2 uses the same preparation process as Example 1, except that a ZnSn alloy target (Zn:Sn = 5:1) is used as the target material.

[0061] Comparative Example 1

[0062] Unlike Example 1, in step D, the post-annealing process was performed using a muffle furnace at 400°C for 3 hours in an air atmosphere to increase the degree of thin film oxidation and prepare a zinc-tin-nitrogen-oxygen photodetector thin film transistor with a non-metal-rich channel.

[0063] Performance Analysis:

[0064] The photoelectric performance of the zinc-tin-nitrogen-oxygen thin-film transistor in the embodiment was characterized and analyzed using a semiconductor parameter analyzer combined with a monochromator.

[0065] The zinc-tin-oxygen-nitrogen thin film on the silicon substrate was characterized using X-ray photoelectron spectroscopy (XPS) and elliptic polarization spectroscopy.

[0066] The transmittance of the zinc-tin-oxygen-nitrogen thin film on the quartz glass substrate provided in Example 1 was measured using a visible-ultraviolet spectrophotometer.

[0067] By deconvolving the core energy level spectrum of XPS into multiple peaks, the proportion of each element in the zinc-tin-oxygen-nitrogen thin film provided in Example 1 was determined according to the peak area (Table 1). The results showed that the metal element content inside the deposited and annealed films was much greater than the sum of nitrogen and oxygen elements, indicating that the film interior was in a metal-rich state. Meanwhile, from... Figure 2 The values ​​a, b, c, and d in the figure show the bonding of oxygen in the zinc-tin-oxygen-nitrogen thin film: 1) 532.4 ± 0.2 eV (CO / OH) is related to adsorbed oxygen; 2) 531.5 ± 0.1 eV (OM(V)) O)) Related to oxygen vacancy defects; 3) 530.2±0.3 eV (OMO); 4) 529.7±0.1 eV (NMO). From the film surface to the interior, the oxygen vacancy content decreases, the O 1s main peak blue shifts, and the lattice oxygen-related (OM-O+NMO) content increases. From Figure 3 From a, b, c, and d, we can see that tin exists in three forms in zinc-tin-oxygen-nitrogen thin films: 1) Sn 4+ (486.5±0.2eV); 2)Sn 2+ (485.5±0.1eV); 3)Sn 0 (484.1±0.2eV). On the surface of the zinc-tin-oxygen film, it is mainly composed of divalent tin and tetravalent tin, while zero-valent tin is clearly present inside the zinc-tin-oxygen film. The proportions of Sn in each valence state on the surface and inside the zinc-tin-oxygen film are shown in Table 2. Figure 4 From a, b, c, and d in the diagram, we can see that Zn 2p 3 / 2 Zn 2+ Located at 1021.4±0.3 eV, inside the thin film, this peak shows Zn in the high-energy direction. 0 Xiaofeng. The XPS results show that the zinc-tin-oxygen-nitrogen film is in a metal-rich state, containing metallic zinc and metallic tin, as shown in Table 2. After the annealing process, the content of elemental metals inside the film decreased slightly, indicating that the elemental metals acted as sacrificial materials during the oxidation process, protecting the nitrides from oxidation and improving stability.

[0068] Table 1. Proportion of each element in zinc-tin-oxygen-nitrogen thin films

[0069]

[0070] Table 2. Atomic percentages of Zn and Sn in different valence states on the surface and inside zinc-tin-oxygen thin films.

[0071]

[0072] Due to the wide bandgap of oxides, photodetectors based on oxide thin-film transistors can only respond to the ultraviolet light region, limiting their application in the visible light range. The zinc-tin-oxygen-nitrogen thin film provided in Example 1 reduces the bandgap of the film by introducing nitrogen. Figure 5 Zinc-tin-oxygen-nitrogen thin film (αhν) 2 The relationship between the linear portion and hν, where the intersection of the linear portion with the X-axis reflects the optical bandgap of the thin film. The bandgap of the deposited zinc-tin-oxygen-nitrogen thin film is 1.36 eV, and the bandgap of the annealed film is 1.53 eV, showing a significant decrease in bandgap compared to the oxide.

[0073] In Example 1, the photodetector thin-film transistor using a metal-rich zinc-tin-oxygen-nitrogen thin film as the channel layer also exhibits high responsivity to visible light. For example... Figure 6 As shown, the source and drain currents of the device increase significantly under illumination of 350-650nm. Figure 7 The photoresponsivity of the device under different wavelengths of light is shown. It exhibits high responses of 253, 868, and 1097 A / W at 650 nm (red light), 550 nm (green light), and 450 nm (blue light), corresponding to the narrow bandgap of the zinc-tin-nitrogen-oxygen (ZNI) group. The response time of the photodetector thin-film transistor fabricated in Example 1 includes the rise time and fall time of the device. Specifically, the rise time is defined as the time it takes for the photocurrent to rise from 10% to 90% of its peak value, and the fall time is defined as the time it takes for the photocurrent to fall from 90% to 10% of its peak value. From the device's response time curve (… Figure 8 As can be seen from the data, the device does not exhibit significant sustained photoconductivity, with a rise time of 0.38 s and a fall time of 0.53 s. We believe that the metal-rich phenomenon inside the thin film is the main reason for the decrease in oxygen and nitrogen vacancy content, and that the elemental metal present inside also protects the easily oxidized nitrides from oxidation, as elemental metals are more readily oxidized.

[0074] Example 2 uses the same preparation process as Example 1, except that a ZnSn alloy target (Zn:Sn = 5:1) is used as the target material. The elemental contents of the annealed film are listed in Table 3. The tin content is higher than that in Example 1, and the film still exhibits a metal-rich phenomenon. Figure 9 The results reflect the response time of the fabricated thin-film transistor, with a rise time of 4.58 s and a fall time of 1.12 s. The photoresponsivity of this device under 450 nm illumination is 510 A / W. The slightly slower response time and significantly decreased photoresponsivity are likely due to the increased tin content and decreased mobility.

[0075] Table 3 shows the proportion of each element in the zinc-tin-oxygen-nitrogen film in Example 2.

[0076]

[0077] Comparative Example 1 changed the annealing atmosphere and increased the annealing time to increase the degree of thin film oxidation. The resulting thin film transistor had an atomic percentage of Zn of 22 at, Sn of 8 at, N of 4 at, and O of 66 at in the zinc-tin-oxygen-oxide film. The thin film transistor prepared in Comparative Example 1 exhibited obvious continuous photoconductivity. Figure 10 ).

[0078] In summary, this invention has prepared a zinc-tin-oxygen-nitrogen thin film with rich metal composition and narrow bandgap. The resulting photodetector thin film transistor exhibits high responsivity in the visible light region and fast response time, providing a new direction for the development of high-performance photodetector devices.

Claims

1. A photoelectric detection thin-film transistor, characterized in that, The photodetector thin-film transistor includes a substrate, a gate electrode, a gate dielectric layer, a source electrode, a drain electrode, and a channel layer; The gate electrode is located on the substrate, the gate dielectric layer is located on the gate electrode, the source electrode and the drain electrode are disposed alternately on the gate dielectric layer, and the channel layer is located above the source electrode and the drain electrode; The channel layer is a zinc-tin-oxygen-oxide thin film, and the chemical formula of the zinc-tin-oxygen-oxide thin film is Zn. a Sn b N y O z Where inside the thin film, a+b>y+z; The chemical formula of the zinc-tin nitrogen-oxygen thin film is Zn. a Sn b N y O z The atomic percentages of each element are 25 at% ≤ a ≤ 62 at%, 2 at% ≤ b ≤ 6 at%, 6 at% ≤ y ≤ 20 at%, 21 at% ≤ z ≤ 53 at%, and a + b + y + z = 100.

2. The photodetector thin-film transistor according to claim 1, characterized in that, Divalent Zn ions, divalent Sn ions, and tetravalent Sn ions are present both inside and on the surface of the channel layer. Elemental Zn and elemental Sn are also present inside the channel layer.

3. The photodetector thin-film transistor according to claim 2, characterized in that, At the surface of the channel layer, the atomic percentage of divalent Sn ions in Sn is 47 at%-67 at, and the atomic percentage of tetravalent Sn ions is 33 at%-53 at.

4. The photoelectric detection thin-film transistor according to claim 2, characterized in that, Inside the channel layer, the atomic percentage of divalent Zn ions in Zn is 92 at%-96 at%, and the atomic percentage of elemental Zn is 4 at%-8 at%. Inside the channel layer, the atomic percentage of divalent Sn ions in Sn is 21 at%-29 at, the atomic percentage of tetravalent Sn ions is 21 at%-24 at, and the atomic percentage of elemental Sn is 48 at%-58 at.

5. The photodetector thin-film transistor according to claim 1, characterized in that, The bandgap of the photodetector thin-film transistor is 1.36-1.53 ​​eV.

6. The photodetector thin-film transistor according to claim 1, characterized in that, The photodetector thin-film transistor has a responsivity of 253-1097 A / W under 350-650 nm illumination. The response time of the photodetector thin-film transistor is divided into rise time and fall time, wherein the rise time is 0.38-4.58 s and the fall time is 0.53-1.12 s.

7. A method for fabricating a photodetector thin-film transistor according to any one of claims 1-6, characterized in that, include: A gate electrode and a gate dielectric layer are sequentially deposited on the substrate surface using a vacuum deposition method. Source and drain electrodes are then deposited on the surface of the gate dielectric layer. The source and drain electrodes are independently separated. A channel layer is then deposited on the surface of the source and drain electrodes to obtain a deposited photodetector thin film transistor. The material of the channel layer is a zinc tin nitrogen oxide thin film. Photodetector thin-film transistors are obtained by annealing the deposited state photodetector thin-film transistors.

8. The method for fabricating a photodetector thin-film transistor according to claim 7, characterized in that, The deposited photoelectric detection thin film transistor is annealed. The annealing process parameters are: annealing temperature of 350℃-450℃, annealing time of 5-15 min, and annealing atmosphere of nitrogen.

9. The method for fabricating a photodetector thin-film transistor according to claim 7, characterized in that, The source electrode is made of Au, W, Cu, Al, ITO, Pt, Ag, Cr, Ta, Mo, or Ti, and the drain electrode is made of Au, W, Cu, Al, ITO, Pt, Ag, Cr, Ta, Mo, or Ti.

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