A photodetector and a method of fabricating the same, and an electrical device

Abstract

The application provides a photoelectric detector and a preparation method thereof, and an electrical device, and relates to the technical field of photoelectricity. The photoelectric detector comprises a substrate layer; a thin film transistor on the substrate layer; a planar layer covering the thin film transistor; an anode layer and a cathode layer which are arranged on the planar layer in the same layer, and the anode layer is connected with a first electrode of the thin film transistor; and a photosensitive layer which is located between the anode layer and the cathode layer and is connected with the anode layer and the cathode layer. In the application, the anode layer and the cathode layer are arranged in the same layer, and the photosensitive layer is arranged between the anode layer and the cathode layer, so that the cathode layer, the photosensitive layer and the anode layer form a transverse structure in the direction from the cathode to the anode, the facing area between the electrodes is small, the distance between the electrodes can be set to be large, the parasitic capacitance is reduced, and the detection response time is shortened. In addition, the length of the photosensitive layer is increased in the transverse direction, which is simpler and easier than increasing the thickness of the photosensitive layer in the longitudinal direction, the photosensitive area can be increased, and the detection response speed is improved. By shortening the response time and improving the response speed, the response efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and in particular to a photodetector and its fabrication method, as well as an electrical device. Background Technology

[0002] With the development of semiconductor technology, high-performance semiconductor photodetectors that can convert optical signals into electrical signals have gradually matured and have been widely used in environmental protection, medical care, communications and other fields. At present, the response efficiency of photodetectors still needs to be improved. Summary of the Invention

[0003] This invention provides a photodetector and its fabrication method, as well as an electrical device, to solve the problem of low response efficiency in existing photodetectors.

[0004] To address the above problems, this invention discloses a photodetector, comprising:

[0005] basal layer;

[0006] Thin-film transistors are disposed on the substrate layer;

[0007] A planarization layer covers the thin-film transistor;

[0008] A cathode layer and an anode layer are disposed on the same layer on the planarization layer, and the anode layer is connected to the first electrode of the thin-film transistor through a via on the planarization layer.

[0009] A photosensitive layer is located between the cathode layer and the anode layer, and is connected to both the cathode layer and the anode layer.

[0010] Optionally, the photosensitive layer is disposed on the planarization layer between the cathode layer and the anode layer.

[0011] Optionally, the photodetector further includes:

[0012] An electrode layer is disposed on the planar layer between the cathode layer and the anode layer;

[0013] A first gate insulating layer covers the electrode layer;

[0014] The photosensitive layer is disposed on the first gate insulating layer.

[0015] Optionally, in the direction from the cathode layer to the anode layer, the length of the photosensitive layer is greater than or equal to 2 micrometers and less than or equal to 5 micrometers.

[0016] Optionally, in the direction perpendicular to the substrate layer, the thickness of the cathode layer is greater than or equal to 200 nanometers and less than or equal to 500 nanometers, and the thickness of the anode layer is greater than or equal to 200 nanometers and less than or equal to 500 nanometers.

[0017] Optionally, the base layer comprises a transparent material.

[0018] Optionally, the photosensitive layer comprises silicon germanide material.

[0019] Optionally, the photodetector further includes:

[0020] A light-shielding layer is disposed on the planarization layer, and the projection of the light-shielding layer on the substrate layer covers the projection of the active layer of the thin-film transistor on the substrate layer.

[0021] To address the above problems, the present invention also discloses a method for fabricating a photodetector, the method comprising:

[0022] Provide a base layer;

[0023] Thin-film transistors are formed on the substrate layer;

[0024] Forming a planar layer covering the thin-film transistor;

[0025] A via is formed on the planarization layer; the projection of the first electrode of the thin-film transistor on the substrate layer covers the projection of the via on the substrate layer;

[0026] A cathode layer and an anode layer are formed on the planarization layer in the same layer by a stripping process; the anode layer is connected to the first electrode of the thin-film transistor through a via on the planarization layer.

[0027] A photosensitive layer is formed between the cathode layer and the anode layer using a chemical vapor deposition process; the photosensitive layer is connected to both the cathode layer and the anode layer.

[0028] Optionally, forming a photosensitive layer between the cathode layer and the anode layer includes:

[0029] A photosensitive layer is formed on the planar layer between the cathode layer and the anode layer.

[0030] Optionally, the step of forming a cathode layer and an anode layer co-layered on the planar layer through a stripping process includes:

[0031] A cathode layer, an anode layer, and an electrode layer are formed on the planar layer using a stripping process; the electrode layer is disposed between the cathode layer and the anode layer.

[0032] The formation of a photosensitive layer between the cathode layer and the anode layer includes:

[0033] A first gate insulating layer is formed covering the electrode layer;

[0034] A photosensitive layer is formed on the first gate insulating layer between the cathode layer and the anode layer.

[0035] Optionally, the step of forming a cathode layer and an anode layer co-layered on the planar layer through a stripping process includes:

[0036] A cathode layer, an anode layer, and a light-shielding layer are formed on the planar layer in the same layer by a stripping process; the projection of the light-shielding layer on the substrate layer covers the projection of the active layer of the thin-film transistor on the substrate layer.

[0037] To address the aforementioned problems, the present invention also discloses an electrical device comprising the aforementioned photodetector.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] In this embodiment of the invention, the cathode layer and anode layer of the photodetector are disposed on the same layer, and the photosensitive layer can be disposed between the cathode layer and the anode layer. Thus, the cathode layer, photosensitive layer, and anode layer can form a transverse structure in the direction from the cathode layer to the anode layer. This results in a smaller facing area between the cathode layer and the anode layer, allowing for a larger electrode distance between them, thereby reducing the parasitic capacitance of the device and shortening the response time of the photodetector. Furthermore, increasing the length of the photosensitive layer laterally is simpler and easier than increasing its thickness vertically, thereby increasing the photosensitive area of ​​the photodetector and improving its response speed. By shortening the response time and increasing the response speed of the photodetector, the response efficiency of the photodetector is improved. Attached Figure Description

[0040] Figure 1 A cross-sectional schematic diagram of a photodetector according to Embodiment 1 of the present invention is shown;

[0041] Figure 2 A cross-sectional schematic diagram of another photodetector according to Embodiment 1 of the present invention is shown;

[0042] Figure 3 The absorbance curve of a SiGe thin film with a 5% Ge content according to Embodiment 1 of the present invention is shown.

[0043] Figure 4 A top view of an array of photodetectors according to Embodiment 1 of the present invention is shown;

[0044] Figure 5 A top view of another array arrangement of photodetectors according to Embodiment 1 of the present invention is shown;

[0045] Figure 6 A flowchart illustrating the steps of a photodetector fabrication method according to Embodiment 2 of the present invention is shown. Detailed Implementation

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] Figure 1 A cross-sectional schematic diagram of a photodetector according to Embodiment 1 of the present invention is shown. (Refer to...) Figure 1 The photodetector includes:

[0049] 10 basal layers;

[0050] Thin-film transistor 20 is disposed on substrate layer 10;

[0051] Planarization layer 30 covers thin-film transistor 20;

[0052] The cathode layer 40 and the anode layer 50 are disposed on the same layer of the planarization layer 30. The anode layer 50 is connected to the first electrode 201 of the thin film transistor 20 through a via on the planarization layer 30.

[0053] The photosensitive layer 60 is located between the cathode layer 40 and the anode layer 50, and is connected to both the cathode layer 40 and the anode layer 50.

[0054] Among them, reference Figure 1 The thin-film transistor 20 specifically includes a first electrode 201, a second electrode 202, a gate 203, and an active layer 204, with the gate 203 disposed on the substrate layer 10. The photodetector also includes a second gate insulating layer (GI) 70, which covers the gate 203. The active layer 204 is disposed on the second gate insulating layer 70, and its projection on the substrate layer 10 at least partially overlaps with the projection of the gate 203 onto the substrate layer 10. The first electrode 201 and the second electrode 202 of the thin-film transistor 20 are separately disposed, and the active layer 204 is connected to both the first electrode 201 and the second electrode 202. A planarization layer 30 covers the active layer 204, the first electrode 201, and the second electrode 202.

[0055] The photosensitive layer 60 can be a PIN structure, wherein the part near the cathode layer 40 can be a P region, the part near the anode layer 50 can be an N region, and the area between the P region and the N region is an I region.

[0056] In this embodiment of the invention, the cathode layer 40 and the anode layer 50 can be disposed in the same layer, and the photosensitive layer 60 can be disposed between the cathode layer 40 and the anode layer 50. Thus, the cathode layer 40, the photosensitive layer 60, and the anode layer 50 can form a transverse structure in the direction from the cathode layer 40 to the anode layer 50. In this transverse structure, the facing area S between the cathode layer 40 and the anode layer 50 is the facing area between the thickness sections of the cathode layer 40 and the anode layer 50 in the direction perpendicular to the substrate layer 10. Since the thickness of the film layer is typically small, the facing area S between the cathode layer 40 and the anode layer 50 is relatively small. Furthermore, in this transverse structure, since the cathode layer 40 and the anode layer 50 are disposed in the same layer, the electrode distance d between the cathode layer 40 and the anode layer 50 can be set to be relatively large.

[0057] In traditional PIN photodetectors, the cathode layer, PIN photosensitive layer, and anode layer are typically stacked vertically. Therefore, in this traditional vertical structure, the facing area S between the cathode layer 40 and the anode layer 50 is usually large. Furthermore, in this traditional vertical structure, the electrode distance d between the cathode layer 40 and the anode layer 50 is equal to the thickness of the PIN photosensitive layer film. Since the film thickness is typically small, the electrode distance d between the cathode layer 40 and the anode layer 50 is relatively small.

[0058] According to the capacitance formula (1) below, compared with the traditional vertical structure, the lateral structure provided by the present invention can reduce the facing area S between the cathode layer and the anode layer, and increase the electrode distance d between the cathode layer and the anode layer. Therefore, the parasitic capacitance of the device can be reduced. The detection circuit time constant τ = RC. As the capacitance decreases, the detection circuit time constant τ also decreases accordingly, thereby shortening the response time of the photodetector.

[0059]

[0060] Where ε represents the dielectric constant and k represents the electrostatic constant.

[0061] Furthermore, in traditional vertical structures, the thickness of the PIN photosensitive layer is typically 1 micrometer. However, in the lateral structure provided in this invention, the length of the photosensitive layer can be increased to more than 1 micrometer. Moreover, increasing the length of the photosensitive layer laterally is simpler and easier than increasing its thickness vertically, thereby increasing the photosensitive area of ​​the photodetector and improving its response speed. For example, in the lateral structure, the length of the photosensitive layer can be 4 micrometers, resulting in approximately a 4-fold increase in response speed compared to the vertical structure.

[0062] In this embodiment of the invention, the response efficiency of the photodetector can be improved by shortening the response time of the photodetector and increasing the response speed of the photodetector.

[0063] In an embodiment of the present invention, optionally, in the direction from the cathode layer 40 to the anode layer 50, the length of the photosensitive layer 60 is greater than or equal to 2 micrometers and less than or equal to 5 micrometers.

[0064] In an embodiment of the present invention, optionally, in the direction perpendicular to the substrate layer 10, the thickness of the cathode layer 40 is greater than or equal to 200 nanometers and less than or equal to 500 nanometers, and the thickness of the anode layer 50 is greater than or equal to 200 nanometers and less than or equal to 500 nanometers.

[0065] The settings for the photosensitive layer 60 can include the following two implementation methods:

[0066] In one alternative implementation, refer to Figure 1 The photosensitive layer 60 is disposed on the planar layer 30 between the cathode layer 40 and the anode layer 50.

[0067] In the above implementation, the photosensitive layer 60 can be disposed on the planarization layer 30 in the same layer as the cathode layer 40 and the anode layer 50.

[0068] In another alternative implementation, refer to Figure 2 The photodetector also includes:

[0069] An electrode layer 70 is disposed on a planar layer 30 between a cathode layer 40 and an anode layer 50;

[0070] The first gate insulating layer 80 covers the electrode layer 70;

[0071] The photosensitive layer 60 is disposed on the first gate insulating layer 80.

[0072] In the above implementation, during the photodetection process, a bias voltage can be applied to the electrode layer 70, thereby causing the I region of the photosensitive layer 60 to be in a fully depleted state. This reduces the recombination probability of photogenerated carriers, so that almost all photogenerated carriers are used to generate photocurrent. According to the quantum efficiency formula (2) below, the photocurrent I... L This increases the quantum efficiency of the photodetector.

[0073]

[0074] Where η represents quantum efficiency, q represents unit charge, Pin represents incident light power, and hν is single photon energy.

[0075] Alternatively, the substrate 10 may include a transparent material, such as glass, thus providing the advantage of light transmission in the fabrication of an active photodetector integrated with a display.

[0076] Alternatively, the photosensitive layer 60 may include silicon germanide (SiGe) material. Silicon germanide material can respond to near-infrared light and has great application prospects in near-infrared fingerprint recognition, which has higher accuracy than visible light fingerprint recognition.

[0077] Reference Figure 3 The absorbance curve of a SiGe thin film with a 5% Ge content is shown. Based on this absorbance curve, the band gap width of the SiGe thin film can be fitted, which is about 1.58 eV. Therefore, the photodetector can operate in the near-infrared band.

[0078] Furthermore, the bandgap width of SiGe thin films decreases with increasing germanium content. It's important to note that increasing Ge content also increases device leakage current. Therefore, a balance needs to be struck between the response band and leakage current magnitude during device design. In practical applications, the Ge content can be controlled within the range of 3%–35%.

[0079] Alternatively, the photodetector may also include:

[0080] A light-shielding layer 90 is disposed on the planarization layer 30, and the projection of the light-shielding layer 90 on the substrate layer 10 covers the projection of the active layer 204 of the thin film transistor 20 on the substrate layer 10.

[0081] The light-shielding layer 90 can block the active layer 204 when the photodetector is working.

[0082] Figure 4 and Figure 5 Top views of two different array arrangements of photodetectors are shown below, which will be combined with... Figure 4 and Figure 5 This explains the working principle of the photodetector. It should also be noted that the following explanation will use an N-type thin-film transistor (TFT) as an example, with its first electrode 201 as the drain and its second electrode 202 as the source. It is understood that the source and drain of the TFT can be interchanged under certain conditions.

[0083] Reference Figure 4 and Figure 5During photoelectric detection, a forward bias voltage is applied to the gate 203 of the thin-film transistor 20, turning the TFT 20 on. A forward bias voltage is also applied to the source of the TFT 20, connecting the anode layer 50 and the source of the TFT 20. Together with the cathode layer 40, the anode layer 50 forms a reverse bias on the SiGe photosensitive layer 60. At this time, the detected cathode current is in the pA range. When the SiGe photosensitive layer 60 absorbs incident light, photogenerated carriers are formed. Under the influence of the electric field formed by the cathode layer 40 and the anode layer 50, electrons and holes separate. Electrons move towards the anode layer 50, and holes move towards the cathode layer 40. At this point, the detected cathode current increases to the nA range.

[0084] When the photodetector includes the electrode layer 70, while inputting a forward bias voltage to the gate 203 of the thin film transistor 20, a forward bias voltage can also be applied to the electrode layer 70 so that the I region of the SiGe photosensitive layer 60 is in a fully depleted state. At this time, the probability of recombination of the generated photogenerated carriers will be reduced, and the detected cathode current can be on the sub-µA level.

[0085] For an array of photodetectors, the gate 203 of the thin-film transistor 20 can be row-driven, and the source of the thin-film transistor 20 can be column-driven. By scanning the gate 203 of different rows and the source of different columns, the addressing switch of the thin-film transistor can be controlled, thereby enabling active detection of light.

[0086] In addition, Figure 4 In this process, the leads of the cathode layer 40 can be parallel to the leads of the gate 203. Figure 5 In this embodiment, the leads of the cathode layer 40 can be parallel to the leads of the source electrode, but this is not specifically limited in this respect.

[0087] In this embodiment of the invention, the cathode layer and anode layer of the photodetector are disposed on the same layer, and the photosensitive layer can be disposed between the cathode layer and the anode layer. Thus, the cathode layer, photosensitive layer, and anode layer can form a transverse structure in the direction from the cathode layer to the anode layer. This results in a smaller facing area between the cathode layer and the anode layer, allowing for a larger electrode distance between them, thereby reducing the parasitic capacitance of the device and shortening the response time of the photodetector. Furthermore, increasing the length of the photosensitive layer laterally is simpler and easier than increasing its thickness vertically, thereby increasing the photosensitive area of ​​the photodetector and improving its response speed. By shortening the response time and increasing the response speed of the photodetector, the response efficiency of the photodetector is improved.

[0088] Example 2

[0089] Figure 6 A flowchart illustrating the steps of a photodetector fabrication method according to Embodiment 2 of the present invention is shown. (Refer to...) Figure 6 The method includes the following steps:

[0090] Step 601: Provide the base layer.

[0091] In this embodiment of the invention, the substrate layer 10 may optionally be made of a transparent material, such as glass. Compared with SOI (Silicon-On-Insulator) photodetectors fabricated using common CMOS (Complementary Metal-Oxide-Semiconductor) processes, this invention eliminates the need for a Si substrate, saving the Si thinning process, the fabrication of buried SiO2, and the strain layer, and is fully compatible with existing glass-based thin-film transistor fabrication processes.

[0092] Step 602: Form a thin-film transistor on the substrate.

[0093] In this step, the gate of the thin-film transistor is deposited and patterned on the substrate using magnetron sputtering. The gate material can be a metal such as Mo or Ti / Al / Ti, and the thickness can be 100 nm. Subsequently, a second gate insulating layer composed of SiN or SiO is deposited on top of the gate using full-surface chemical vapor deposition, with a thickness of 50 nm. Next, the active layer of the thin-film transistor is fabricated using chemical vapor deposition, and the active layer material can be a-Si or IGZO, with a thickness of 50 nm. The first and second electrodes of the thin-film transistor are fabricated using magnetron sputtering, and the materials of the first and second electrodes can be Mo or Ti / Al / Ti, with a thickness of 200 nm.

[0094] Step 603: Form a planarization layer covering the thin-film transistor.

[0095] In this step, a planarization layer covering the active layer, the first electrode, and the second electrode can be formed by spin coating. The planarization layer material can be SU8 adhesive, and the planarization layer thickness can be 2µm.

[0096] Step 604: Form a via on the planarization layer; the projection of the first electrode of the thin-film transistor on the substrate layer covers the projection of the via on the substrate layer.

[0097] In this step, vias leading to the first electrode of the thin-film transistor can be formed on the planarization layer using photolithography.

[0098] Step 605: A cathode layer and an anode layer are formed on the same layer of the planarization layer by a stripping process; the anode layer is connected to the first electrode of the thin-film transistor through a via on the planarization layer.

[0099] In this step, the cathode and anode layers can be fabricated using a lift-off process.

[0100] Optionally, if it is desired to further reduce the recombination probability of photogenerated carriers and improve the quantum efficiency of the photodetector, this step may specifically include the following steps: forming a cathode layer, an anode layer, and an electrode layer on the same layer on the planarization layer through a stripping process; the electrode layer is disposed between the cathode layer and the anode layer.

[0101] The cathode layer, anode layer, and electrode layer can be made of the same material, and this embodiment of the invention does not specifically limit this.

[0102] By applying a forward bias voltage to the electrode layer, the I region of the photosensitive layer can be put into a fully depleted state. At this time, the recombination probability of the generated photogenerated carriers will be reduced, thereby improving the quantum efficiency of the photodetector.

[0103] Step 606: A photosensitive layer is formed between the cathode layer and the anode layer by chemical vapor deposition; the photosensitive layer is connected to the cathode layer and the anode layer respectively.

[0104] In this step, a SiGe layer can be formed by introducing silane and germanane through a chemical vapor deposition process, specifically a plasma-enhanced chemical vapor deposition process. Then, P-regions and N-regions are formed by ion implantation and diffusion to obtain a SiGe photosensitive layer.

[0105] In one alternative implementation, the step of forming a photosensitive layer between the cathode layer and the anode layer may specifically include:

[0106] A photosensitive layer is formed on a flat layer between the cathode layer and the anode layer.

[0107] In another alternative implementation, when the photodetector further includes an electrode layer, the step of forming a photosensitive layer between the cathode layer and the anode layer may specifically include:

[0108] A first gate insulating layer is formed to cover the electrode layer;

[0109] A photosensitive layer is formed on the first gate insulating layer between the cathode layer and the anode layer.

[0110] The first gate insulating layer material can be SU8 adhesive. A layer of SU8 adhesive can be spin-coated, followed by photolithography, to form the first gate insulating layer above the electrode layer.

[0111] Further optionally, when the photodetector also includes a light-shielding layer, this step may specifically include:

[0112] Through a stripping process, a cathode layer, an anode layer, and a light-shielding layer are formed on the same layer of the planarization layer; the projection of the light-shielding layer on the substrate layer covers the projection of the active layer of the thin-film transistor on the substrate layer.

[0113] The light-shielding layer may also be made of the same material as the cathode layer, anode layer and electrode layer, and the embodiments of the present invention do not specifically limit this.

[0114] In this embodiment of the invention, a cathode layer and an anode layer can be formed on the same layer of a planarization layer, with a photosensitive layer formed between the cathode and anode layers. This allows the cathode, photosensitive, and anode layers to form a transverse structure in the direction from the cathode to the anode layer, resulting in a smaller facing area between the cathode and anode layers and a larger electrode distance between them. This reduces the parasitic capacitance of the device and shortens the response time of the photodetector. Furthermore, increasing the length of the photosensitive layer laterally is simpler and easier than increasing its thickness vertically, thereby increasing the photosensitive area of ​​the photodetector and improving its response speed. By shortening the response time and increasing the response speed, the response efficiency of the photodetector is improved. Moreover, the fabrication process is simpler compared to traditional photodetectors.

[0115] Example 3

[0116] This invention also discloses an electrical device, including the aforementioned photodetector.

[0117] Alternatively, the electrical device may be a display device, a touch device, an imaging device, etc.

[0118] In this embodiment of the invention, the cathode layer and anode layer of the photodetector are disposed on the same layer, and the photosensitive layer can be disposed between the cathode layer and the anode layer. Thus, the cathode layer, photosensitive layer, and anode layer can form a transverse structure in the direction from the cathode layer to the anode layer. This results in a smaller facing area between the cathode layer and the anode layer, allowing for a larger electrode distance between them, thereby reducing the parasitic capacitance of the device and shortening the response time of the photodetector. Furthermore, increasing the length of the photosensitive layer laterally is simpler and easier than increasing its thickness vertically, thereby increasing the photosensitive area of ​​the photodetector and improving its response speed. By shortening the response time and increasing the response speed of the photodetector, the response efficiency of the photodetector is improved.

[0119] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0120] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0121] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0122] The above provides a detailed description of a photodetector, its fabrication method, and the electrical device provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A photodetector, characterized in that, include: basal layer; Thin-film transistors are disposed on the substrate layer; A planarization layer covers the thin-film transistor; A cathode layer and an anode layer are disposed on the same layer on the planarization layer, and the anode layer is connected to the first electrode of the thin-film transistor through a via on the planarization layer. A photosensitive layer is located between the cathode layer and the anode layer, and is connected to both the cathode layer and the anode layer respectively; The photosensitive layer is disposed on the planar layer between the cathode layer and the anode layer, and the photosensitive layer is disposed in the same layer as the cathode layer and the anode layer; The cathode layer, the photosensitive layer, and the anode layer form a transverse structure in the direction from the cathode layer to the anode layer, and in the transverse structure, the facing area between the cathode layer and the anode layer is the facing area between the thickness sections of the cathode layer and the anode layer in the direction perpendicular to the substrate layer.

2. The photodetector according to claim 1, characterized in that, In the direction from the cathode layer to the anode layer, the length of the photosensitive layer is greater than or equal to 2 micrometers and less than or equal to 5 micrometers.

3. The photodetector according to claim 1, characterized in that, In the direction perpendicular to the substrate layer, the thickness of the cathode layer is greater than or equal to 200 nanometers and less than or equal to 500 nanometers, and the thickness of the anode layer is greater than or equal to 200 nanometers and less than or equal to 500 nanometers.

4. The photodetector according to claim 1, characterized in that, The base layer comprises a transparent material.

5. The photodetector according to claim 1, characterized in that, The photosensitive layer comprises silicon germanide material.

6. The photodetector according to claim 1, characterized in that, The photodetector also includes: A light-shielding layer is disposed on the planarization layer, and the projection of the light-shielding layer on the substrate layer covers the projection of the active layer of the thin-film transistor on the substrate layer.

7. A method for fabricating a photodetector, characterized in that, The method for preparing the photodetector according to any one of claims 1-6 comprises: Provide a base layer; Thin-film transistors are formed on the substrate layer; Forming a planar layer covering the thin-film transistor; A via is formed on the planarization layer; the projection of the first electrode of the thin-film transistor on the substrate layer covers the projection of the via on the substrate layer; A cathode layer and an anode layer are formed on the planarization layer in the same layer by a stripping process; the anode layer is connected to the first electrode of the thin-film transistor through a via on the planarization layer. A photosensitive layer is formed between the cathode layer and the anode layer using a chemical vapor deposition process; the photosensitive layer is connected to both the cathode layer and the anode layer. The formation of a photosensitive layer between the cathode layer and the anode layer includes: A photosensitive layer is formed on the planar layer between the cathode layer and the anode layer; the photosensitive layer is disposed in the same layer as the cathode layer and the anode layer; The cathode layer, the photosensitive layer, and the anode layer form a transverse structure in the direction from the cathode layer to the anode layer, and in the transverse structure, the facing area between the cathode layer and the anode layer is the facing area between the thickness sections of the cathode layer and the anode layer in the direction perpendicular to the substrate layer.

8. The method according to claim 7, characterized in that, The process of forming a cathode layer and an anode layer on the planar layer in the same layer through a stripping process includes: A cathode layer, an anode layer, and a light-shielding layer are formed on the planar layer in the same layer by a stripping process; the projection of the light-shielding layer on the substrate layer covers the projection of the active layer of the thin-film transistor on the substrate layer.

9. An electrical device, characterized in that, Including the photodetector as described in any one of claims 1 to 6.

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