Photodetectors and detection methods for detecting target light sources using them

Abstract

This invention discloses a photodetector, comprising: an insulating substrate; a channel layer suitable for receiving a target light source; a source and a drain; a gate material layer suitable for receiving the target light source and an auxiliary light source with a wavelength greater than that of the target light source; and a gate; wherein the channel layer is made of a first material sensitive to the target light source, such that the target light source excites the channel layer to generate photogenerated carriers and induces a negative grating effect in the photodetector, thereby increasing the channel current I. ds The gate material layer is made of a second material that is sensitive to both the target light source and the auxiliary light source. This allows the auxiliary light source to increase the conductivity of the gate material layer and induce a positive grating effect in the photodetector, thereby accelerating the turn-off of the channel layer after the target light source disappears and improving the response speed of the photodetector. This invention also provides a method for detecting a target light source. The photodetector provided by this invention improves the detection performance of target light sources in different wavelength bands by selecting channel layer materials with different bandgap widths.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to a photodetector, and more particularly to a photodetector and a detection method for detecting a target light source using the same. Background Technology

[0002] Photodetectors are components that convert optical signals into electrical signals. They play an increasingly important role in many fields, including photoelectric imaging, target tracking, spectral analysis, environmental monitoring, optical communication, and security inspection. Two key performance parameters of photodetectors are responsivity and response speed; however, there is a trade-off between these two indicators, which severely limits the improvement of the overall performance of the device.

[0003] To improve the photoelectric performance of photodetectors, current strategies primarily involve optimizing materials and enhancing device-level control. Optimizing growth parameters to obtain high-quality materials can improve either responsivity or response speed. Unlike material optimization, enhancing device-level control introduces new dimensions (such as heat, stress, atmosphere, and external fields), potentially weakening the constraint between responsivity and response speed. However, these control methods inevitably increase the complexity and cost of the photoelectric detection system. Furthermore, heat and stress control methods require materials to exhibit thermoelectric or piezoelectric effects, lacking universality. Therefore, a simpler and more universal solution is urgently needed to address the constraint between responsivity and response speed. Summary of the Invention

[0004] In view of this, the present invention provides a photodetector and a detection method for detecting a target light source using the photodetector. By introducing an auxiliary light source, the continuous photoconductive effect of the device is suppressed without deteriorating the responsivity of the photodetector, thereby improving the response speed of the device and achieving a photodetector with better overall performance.

[0005] As one aspect of the present invention, a photodetector is provided, comprising: an insulating substrate; a channel layer formed on the insulating substrate, the channel layer being adapted to receive a target light source; a source and a drain located on the channel layer; a gate material layer in contact with the channel layer, adapted to receive a target light source and an auxiliary light source, the wavelength of the auxiliary light source being greater than the wavelength of the target light source; and a gate formed on the gate material layer; wherein the channel layer is made of a first material sensitive to the target light source, such that the target light source excites the channel layer to generate photogenerated carriers (electron-hole pairs) and induces a negative grating effect in the photodetector, thereby causing a channel current I between the source and drain. dsThe rise ensures high responsivity of the device; the gate material layer is made of a second material that is sensitive to both the target light source and the auxiliary light source, so that the auxiliary light source increases the conductivity of the gate material layer and induces the photodetector to generate a positive grating effect, thereby accelerating the turn-off of the channel layer after the target light source disappears, increasing the rate of decrease of the channel current of the device, and thus improving the response speed of the device.

[0006] In another aspect, the present invention provides a detection method for detecting a target light source using the aforementioned photodetector, comprising: illuminating the photodetector with an auxiliary light source and a target light source, and using the auxiliary light source to assist the photodetector in detecting the target light source; wherein, when the photodetector detects the target light source, the target light source induces a negative grating effect in the photodetector, and the channel current I between the source and drain on the channel layer... ds The auxiliary light source increases the conductivity of the gate material layer and induces a positive grating effect in the photodetector after the target light source disappears, thereby accelerating the turn-off of the channel layer after the target light source disappears and increasing the descent speed of the device.

[0007] According to embodiments of the present invention, by selecting different application schemes of the auxiliary light source, the device has two different operating modes, wherein,

[0008] Operating mode a: The auxiliary light source is set to be continuously on, so that the auxiliary light source continuously illuminates the photodetector, which can enhance the device's detection of the target light source without the need for feedback circuit.

[0009] Operating mode b: The auxiliary light source is initially set to the off state, and the channel current I of the channel layer is detected by a feedback circuit set between the source and drain. ds The change in channel current I when the feedback circuit captures the change. ds The feedback circuit will reduce the channel current I when the signal drops. ds The decreasing signal is fed back to the control terminal of the auxiliary light source, triggering the auxiliary light source to turn on. The auxiliary light source induces a positive grating effect in the photodetector, thereby accelerating the turn-off of the channel layer. When the feedback circuit detects the channel current I... ds The rising signal, the feedback circuit will reduce the channel current I ds The rising signal is fed back to the control terminal of the auxiliary light source, triggering the auxiliary light source to turn off.

[0010] According to the photodetector provided in the above embodiments of the present invention, by introducing an auxiliary light source, the auxiliary light source can generate photogenerated carriers (photogenerated electron-hole pairs) in the gate material layer, improve the conductivity of the gate material layer, increase the effective gate voltage applied to the space charge region formed by the gate material layer and the channel layer after the target light source disappears, accelerate the separation of electron-hole pairs, increase the rate of decrease of the photogenerated current in the channel layer, suppress the continuous photoconductivity effect of the device, and improve the response speed of the photodetector while ensuring the responsivity of the photodetector, thereby improving the overall performance of the device. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of a photodetector according to an embodiment of the present invention;

[0012] Figure 2 This is a cross-sectional schematic diagram of a photodetector according to another embodiment of the present invention;

[0013] Figure 3 This is a circuit diagram of a photodetector according to an embodiment of the present invention;

[0014] Figure 4 This is a flowchart of a detection method for photodetector operating mode b according to an embodiment of the present invention;

[0015] Figure 5 A circuit diagram of the feedback circuit in operating mode b according to an embodiment of the present invention;

[0016] Figure 6 This is a response curve of the photodetector according to an embodiment of the present invention without an auxiliary light source;

[0017] Figure 7 This is a response curve of the photodetector according to an embodiment of the present invention in operating mode a;

[0018] Figure 8 This is a response curve of the photodetector according to an embodiment of the present invention in operating mode b;

[0019] Figure 9 This is a response curve of a photodetector according to an embodiment of the present invention to solar blind light in operating mode a;

[0020] Figure 10 This is a flowchart of a method for fabricating a photodetector according to an embodiment of the present invention.

[0021] [Explanation of Labels in the Attached Image]

[0022] 1-Insulating substrate; 2-Channel layer; 3-Source; 4-Drain; 5-Gate material layer; 6-Gate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. However, this invention can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the invention thorough and complete, and to fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated, and the same reference numerals denote the same elements throughout.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0025] From a device structure design perspective, compared to two-terminal photoconductive and photovoltaic devices, three-terminal field-effect transistors (FETs) can utilize the gate to control the carrier concentration in the channel and have an internal gain mechanism, making them promising for achieving photodetectors with high responsivity and fast response speed. Among three-terminal FETs, junction field-effect transistors (JFETs) avoid interface traps and reliability issues originating from hot electron injection and trapping found in metal-oxide-semiconductor field-effect transistors (MOSFETs). Unlike metal-semiconductor field-effect transistors (MESFETs), which rely on good Schottky contact formation, JFETs can reduce gate leakage current through a higher built-in potential.

[0026] In view of this, the present invention provides a junction field-effect transistor photodetector based on a heterojunction and a detection method for detecting a target light source using the photodetector.

[0027] Figure 1 This is a cross-sectional schematic diagram of a photodetector according to an embodiment of the present invention.

[0028] According to an exemplary embodiment of the present invention, the present invention provides a photodetector, with reference to... Figure 1As shown, it includes: an insulating substrate 1; a channel layer 2 formed on the insulating substrate 1, the channel layer 2 being suitable for receiving a target light source; a source electrode 3 and a drain electrode 4 located on the channel layer 2; a gate material layer 5 in contact with the channel layer 2, located above or below the channel layer 2, suitable for receiving a target light source and an auxiliary light source, the wavelength of the auxiliary light source being greater than the wavelength of the target light source; and a gate electrode 6 formed above or below the gate material layer 5. The channel layer 2 is made of a first material sensitive to the target light source, causing the target light source to excite the channel layer 2 to generate photogenerated carriers (electron-hole pairs) and induce a negative grating effect in the photodetector, thereby increasing the channel current I between the source electrode 3 and the drain electrode 4. ds The rise ensures the high responsivity of the device; the gate material layer 5 is made of a second material that is sensitive to both the target light source and the auxiliary light source, so that the auxiliary light source increases the conductivity of the gate material layer 5 and induces the photodetector to generate a positive grating effect, thereby accelerating the turn-off of the channel layer 2 after the target light source disappears and improving the descent speed of the device.

[0029] According to an embodiment of the present invention, the channel layer 2 is made of a first material that is sensitive to the target light source, that is, the channel layer 2 responds to the target light source and is excited to generate photogenerated carriers; the gate material layer 5 is made of a second material that is sensitive to both the target light source and the auxiliary light source, that is, the gate material layer 5 responds to both the auxiliary light source and the target light source and can be excited to generate photogenerated carriers, that is, both the auxiliary light source and the target light source can improve the conductivity of the gate material layer 5.

[0030] According to an embodiment of the present invention, when the gate material layer 5 is located above the channel layer 2, the gate material layer 5 is formed between the source 3 and the drain 4 on the channel layer 2 and is electrically isolated from the source 3 and the drain 4.

[0031] According to an embodiment of the present invention, when the gate material layer 5 is located above the channel layer 2 and the gate 6 is located below the gate material layer 5, the gate material layer 5 is formed between the source 3 and the drain 4 on the channel layer 2 and is electrically isolated from the source 3 and the drain 4, and the gate 6 is electrically isolated from the channel layer 2.

[0032] It should be noted that when the target light source illuminates the photodetector, the channel layer 2 generates photogenerated carriers (electron-hole pairs) under the excitation of the target light source, causing the photodetector to produce a negative grating effect. The initial voltage V between the source 3 and the drain 4 of the electron-hole pairs... ds Under the action of [something], they are separated and collected at source 3 and drain 4 respectively, forming a photocurrent, which causes the channel current I between source 3 and drain 4 to [something]. ds rise.

[0033] It should be noted that when the auxiliary light source illuminates the photodetector, the gate material layer 5 generates photogenerated carriers under the excitation of the auxiliary light source, which causes the photodetector to produce a positive grating effect. The conductivity of the gate material layer 5 is increased, thereby increasing the effective gate voltage applied to the space charge region formed by the gate material layer 5 and the channel layer 2, thereby accelerating the separation of electron-hole pairs, increasing the rate of decrease of the photogenerated current in the channel layer 2, and thus improving the response speed of the device.

[0034] It should be noted that the negative grating effect refers to the generation of a large number of photogenerated carriers (photogenerated electron-hole pairs) inside the device when a target light source is detected. The photogenerated holes are separated and trapped in the gate material layer 5 under the influence of the built-in electric field formed by the channel layer 2 and the gate material layer 5, and the trapped states of the gate material. The large number of trapped holes increases the carrier concentration in the channel layer 2 under electrostatic induction, thus increasing the channel current I. ds Increasing the threshold voltage of the photodetector shifts it to the negative direction, thus ensuring high responsivity.

[0035] It should be noted that the positive grating effect refers to the generation of photogenerated carriers within the gate material layer 5 under auxiliary light source illumination, leading to an increase in the conductivity of the gate material layer 5. This allows for a more effective application of the gate voltage across the space charge region formed by the gate material layer 5 and the channel layer 2. Due to the initially preset gate voltage V... g This will cause the channel layer 2 to be depleted. Therefore, under the illumination of the auxiliary light source, the carrier concentration of the channel layer 2 will decrease, and the conductive channel between the source 3 and the drain 4 will be turned off more completely. The threshold voltage of the device will shift to the positive direction, thereby achieving a faster response speed.

[0036] Figure 2 This is a cross-sectional schematic diagram of a photodetector according to another embodiment of the present invention.

[0037] This invention provides another photodetector, referenced Figure 2 As shown, the channel layer 2 is formed on the gate material layer 5 and is electrically isolated from the gate 6.

[0038] According to an embodiment of the present invention, the insulating substrate 1 is formed of an insulating material, including sapphire or silicon dioxide; the channel layer 2 is made of a first material that is sensitive to the target light source, including gallium oxide; the source electrode 3 and drain electrode 4 are made of Ti / Al / Ni / Au; the gate material layer 5 is made of a second material that is sensitive to both the target light source and the auxiliary light source, including tungsten diselenide; and the gate electrode 6 is made of Cr / Pt / Au.

[0039] According to embodiments of the present invention, the wavelength range of the target light source and the auxiliary light source is between far-infrared and X-ray. It should be noted that by selecting channel layer materials with different bandgap widths, the detection performance of target light sources in different wavelength bands can be improved.

[0040] It should be noted that there are no limitations on the formation methods of the insulating substrate 1, the channel layer 2, the source 3, the drain 4, the gate material layer 5, and the gate 6.

[0041] According to the photodetector provided in the above embodiments of the present invention, by introducing an auxiliary light source, the auxiliary light source can generate photogenerated carriers (photogenerated electron-hole pairs) in the gate material layer 5, thereby increasing the conductivity of the gate material layer 5. After the target light source disappears, it can increase the effective gate voltage applied to the space charge region formed by the gate material layer 5 and the channel layer 2, thereby accelerating the separation of electron-hole pairs, increasing the rate of decrease of the photogenerated current in the channel layer 2, suppressing the continuous photoconductivity effect of the device, and improving the response speed of the photodetector while ensuring the responsivity of the photodetector, thus improving the overall performance of the device.

[0042] According to an exemplary embodiment of the present invention, the present invention provides a detection method for detecting a target light source using the above-described photodetector, comprising: illuminating the photodetector with an auxiliary light source and a target light source, and using the auxiliary light source to assist the photodetector in detecting the target light source; wherein, when the photodetector detects the target light source, the target light source induces a negative grating effect in the photodetector, and the channel current I of the channel layer 2... ds The auxiliary light source increases the conductivity of the gate material layer 5 and induces a positive grating effect in the photodetector, thereby accelerating the turn-off of the channel layer 2 after the target light source disappears, increasing the rate of decrease of the photocurrent of the device, and thus improving the response speed of the device.

[0043] It should be noted that the channel layer 2 and the gate material layer 5 form a pn junction, wherein the channel layer 2 is an n-type semiconductor material and the gate material layer 5 is a p-type semiconductor material; or, the channel layer 2 is a p-type semiconductor material and the gate material layer 5 is an n-type semiconductor material.

[0044] According to an embodiment of the present invention, the detection method for detecting a target light source using a photodetector provided by the present invention has two operating modes, a and b, respectively, by selecting different application schemes of the auxiliary light source.

[0045] According to an embodiment of the present invention, in operating mode a, the auxiliary light source remains continuously on, and the photodetector detects the target light source; in operating mode b, the initial state of the auxiliary light source is set to off, and the channel current I of the channel layer 2 is detected using a feedback circuit disposed between the source 3 and the drain 4. ds The change in channel current I when the feedback circuit captures the change.ds A decreasing signal triggers the auxiliary light source to turn on; when the feedback circuit detects the channel current I... ds The rising signal triggers the auxiliary light source to turn off.

[0046] According to an embodiment of the present invention, in operating mode a, the auxiliary light source is set to a continuously on state, so that the auxiliary light source continuously illuminates the photodetector. In operating mode a, since the auxiliary light source only needs to remain continuously on, there is no need to introduce a feedback circuit to determine and trigger whether the auxiliary light source is on, which simplifies the complexity of the photodetector and saves costs.

[0047] Figure 3 This is a circuit diagram of a photodetector according to an embodiment of the present invention.

[0048] refer to Figure 3 As shown, before detecting the target light source, an initial voltage V is applied between the source 3 and the drain 4. ds An initial gate voltage V is applied to gate 6. g This puts the photodetector in its initial depletion state.

[0049] Figure 4 This is a flowchart of a detection method for photodetector operating mode b according to an embodiment of the present invention.

[0050] According to an exemplary embodiment of the present invention, the present invention provides a working mode b of the detection method for detecting a target light source using the above-described photodetector, referring to... Figure 4 As shown, it includes steps S01 to S03.

[0051] Step S01: Apply an initial voltage V between source 3 and drain 4. ds An initial gate voltage V is applied to gate 6. g This puts the photodetector in its initial depletion state.

[0052] Step S02: A feedback circuit is set between the source 3 and the drain 4. The feedback circuit is used to detect the channel current I. ds The changes.

[0053] Step S03: Set the initial state of the auxiliary light source to the off state, and use the feedback circuit set between the source 3 and the drain 4 to detect the channel current I of the channel layer 2 when probing the target light source. ds The changes are monitored and fed back to the control terminal of the auxiliary light source to control whether the auxiliary light source is turned on or off.

[0054] Figure 5 This is a circuit diagram of the feedback circuit in operating mode b according to an embodiment of the present invention.

[0055] According to an embodiment of the present invention, the feedback circuit further includes an amplifier for amplifying the channel current I. ds The feedback circuit is used to determine the changing trend of current I. ds The changing trend, and based on the channel current I ds The change in the signal triggers the auxiliary light source (light-emitting diode) to turn on or off accordingly. It should be noted that the feedback circuit can be implemented using existing feedback circuit structures.

[0056] According to an embodiment of the present invention, the initial state of the auxiliary light source is set to the off state. When the photodetector detects the target light source, the target light source induces a negative grating effect in the photodetector, increasing the concentration of photogenerated carriers in the channel layer 2, turning the channel layer 2 on, and increasing the channel current I. ds The voltage rises; at this point, the device only exhibits a negative grating effect to regulate the threshold voltage, and there is no positive grating effect to restrict the photocurrent, therefore it will not affect the device's responsivity. The channel current I of channel layer 2 is detected using a feedback circuit located between source 3 and drain 4. ds The change in channel current I caused by the disappearance of the target light source is detected by the feedback circuit. ds When the signal drops, the feedback circuit will reduce the channel current I. ds The decreasing signal is fed back to the control terminal of the auxiliary light source, controlling the auxiliary light source to turn on. The auxiliary light source induces a positive grating effect in the photodetector, accelerating the turn-off of channel layer 2 and causing the channel current I... ds It quickly recovers to the dark current level, improving the response speed of the photodetector; when the feedback circuit captures the channel current I... ds Rising signal, channel current I ds The rising signal indicates that the target light source has reappeared, and the feedback circuit will reduce the channel current I... ds The rising signal is fed back to the control terminal of the auxiliary light source, controlling the auxiliary light source to turn off, without affecting the channel current I under the illumination of the target light source. ds And the responsivity of photodetectors.

[0057] According to an embodiment of the present invention, in working mode b, the auxiliary light source is activated only after the target light source disappears. Therefore, while improving the response speed of the photodetector, working mode b does not affect the responsivity of the photodetector at all, alleviating the contradiction between the responsivity and response speed of the photodetector. This is conducive to realizing a photodetector with better overall performance to meet the application needs of different scenarios.

[0058] Figure 6 This is a response curve of the photodetector according to an embodiment of the present invention without an auxiliary light source.

[0059] refer to Figure 6 As shown, in V ds =1V, V gAt -1.75V, a photodetector without an auxiliary light source can detect light with a wavelength of 254nm and an intensity of 484μW / cm². 2 When the target light source is detected, it exhibits a severe and persistent photoconductive effect. After the target light source disappears, the channel current I... ds The time required for the peak current to drop from 90% to 10% is approximately τ. d =43.18s.

[0060] Figure 7 This is a response curve of the photodetector according to an embodiment of the present invention in operating mode a.

[0061] refer to Figure 7 As shown, the photodetector is sensitive to light with a wavelength of 254 nm and an intensity of 484 μW / cm². 2 The target light source is detected. In V ds =1V, V g When the voltage is -1.75V, add a continuously on light source with a wavelength of 520nm and an intensity of 20μW / cm². 2 The auxiliary light source enables the photodetector to operate in mode a, so that after the target light source disappears, the channel current I... ds The time required for the peak current to drop from 90% to 10% is approximately τ. d =0.576s, the response speed of the photodetector to a target light source of 254nm is greatly improved.

[0062] Figure 8 This is a response curve of the photodetector according to an embodiment of the present invention in operating mode b.

[0063] refer to Figure 8 As shown, the photodetector is sensitive to light with a wavelength of 254 nm and an intensity of 484 μW / cm². 2 The target light source is detected. In V ds =1V, V g When the voltage is -1.75V, a feedback circuit is set between the source 3 and drain 4 of the photodetector to detect the channel current I of the channel layer 2. ds The changes were monitored, and the wavelength was controlled at 520 nm with a light intensity of 20 μW / cm². 2 By turning the auxiliary light source on or off, the photodetector operates in mode b (the auxiliary light source is turned on at the falling edge of each target light source and turned off at the rising edge). This significantly suppresses the continuous photoconductive effect of the photodetector's response to the 254nm target light source, reducing the channel current I. ds The time required for the peak current to drop from 90% to 10% is approximately τ. d =1.532s, which shortens the response time and improves the response speed.

[0064] Figure 9 This is a response curve of a photodetector according to an embodiment of the present invention to solar blind light in operating mode a.

[0065] refer to Figure 9 As shown, the photodetector further enhances the light intensity of the auxiliary light source to 380 μW / cm² in operating mode a. 2 And adjust the initial gate voltage to V g When the voltage is -2.5V, the device's response time τ d =0.014s, the photodetector can achieve an ultrafast response to solar blind light.

[0066] according to Figures 6-9 It is known that the operating modes a and b of the photodetector have an extremely weak impact on its responsivity, which can be ignored. Therefore, the photodetector provided by this invention can significantly improve the response speed during the detection of target light sources without sacrificing the detector's responsivity, which is beneficial for achieving a photodetector with better overall performance to meet the application needs of different scenarios.

[0067] Figure 10 This is a flowchart of a method for fabricating a photodetector according to an embodiment of the present invention.

[0068] The present invention also provides a method for fabricating the above-mentioned photodetector, with reference to... Figure 10 As shown, it includes steps S11 to S14.

[0069] In step S11, a channel layer 2 is formed on the insulating substrate 1.

[0070] According to an embodiment of the present invention, the material of the insulating substrate 1 may be, for example, SiO2 (300nm) / Si.

[0071] According to an embodiment of the present invention, gallium oxide nanosheets are peeled off using polydimethylsiloxane film (PDMS) and transferred to an insulating substrate 1 using a dry transfer process to form a channel layer 2.

[0072] In step S12, source electrode 3 and drain electrode 4 are grown at both ends of the channel layer 2.

[0073] According to an embodiment of the present invention, electrode regions are photolithographically patterned on the channel layer 2, and the channel layer 2 of the electrode regions is pretreated using inductively coupled plasma. Metal is deposited in the electrode regions as source 3 and drain 4, and then rapid thermal annealing is performed in nitrogen atmosphere.

[0074] According to an embodiment of the present invention, the deposition method of the source electrode 3 and the drain electrode 4 includes electron beam evaporation deposition. The materials of the source electrode 3 and the drain electrode 4 include Ti / Al / Ni / Au.

[0075] According to an embodiment of the present invention, pretreating the channel layer 2 in the electrode region using inductively coupled plasma can enhance the ohmic contact between the channel layer 2 and the subsequently deposited source / drain electrode 4. The pretreating time of the channel layer 2 in the electrode region using inductively coupled plasma is 10s to 60s, for example, 10s, 20s, 30s, 40s, 50s, or 60s; the source 3 and drain 4 are subjected to rapid thermal treatment in nitrogen at a temperature of 450°C to 490°C, for example, 450°C, 460°C, 470°C, 480°C, or 490°C, for a time of 50s to 70s, for example, 50s, 55s, 60s, 65s, or 70s.

[0076] In step S13, a gate material layer 5 is formed on the channel layer 2. The gate material layer 5 is located between the source 3 and the drain 4, and the gate material layer 5 is electrically isolated from the source 3 and the drain 4.

[0077] According to an embodiment of the present invention, tungsten diselenide material is stripped and transferred to the channel layer 2 at a specific point to serve as the gate material layer 5 and form a heterojunction with the channel layer 2.

[0078] In step S14, a gate 6 is grown on the gate material layer 5.

[0079] According to an embodiment of the present invention, a gate region is photolithographically formed on the gate material layer 5, and a metal material is deposited in the gate region as the gate 6. The deposition method of the gate 6 includes electron beam evaporation deposition, and the material of the gate 6 includes Cr / Pt / Au.

[0080] The present invention also provides another method for preparing the above-mentioned photodetector, including steps S21 to S24.

[0081] In step S21, a gate material layer 5 is formed on the insulating substrate 1;

[0082] In step S22, a gate 6 is grown on the gate material layer 5;

[0083] In step S23, a channel layer 2 is formed on the gate material layer 5, wherein the gate 6 and the channel layer 2 are electrically isolated;

[0084] In step S24, source electrode 3 and drain electrode 4 are grown at both ends of the channel layer 2.

[0085] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. (such as changing the gate to below the gate material layer) made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting a target light source, implemented using a photodetector, characterized in that, include: An auxiliary light source and a target light source are irradiated onto a photodetector, and the auxiliary light source is used to assist the photodetector in detecting the target light source. Wherein, the photodetector detects the target light source, and the target light source causes the photodetector to generate a negative grating effect, and the channel current I of the channel layer (2) ds The auxiliary light source increases the conductivity of the gate material layer (5) and induces the photodetector to generate a positive grating effect after the target light source disappears, thereby accelerating the turn-off of the channel layer (2) after the target light source disappears. The photodetector includes: Insulating substrate (1); A channel layer (2) is formed on the insulating substrate (1), and the channel layer (2) is adapted to receive a target light source; The source (3) and drain (4) are located on the channel layer (2); A gate material layer (5) is in contact with the channel layer (2) and is located above or below the channel layer (2). It is suitable for receiving the target light source and the auxiliary light source, wherein the wavelength of the auxiliary light source is greater than the wavelength of the target light source. A gate (6) is formed above or below the gate material layer (5), and the gate (6) is in contact with the gate material layer (5); The channel layer (2) is made of a first material that is sensitive to the target light source, so that the target light source excites the channel layer (2) to generate photogenerated carriers and induces the photodetector to generate a negative grating effect, thereby increasing the channel current I between the source (3) and the drain (4). ds Rise; the gate material layer (5) is made of a second material that is sensitive to both the target light source and the auxiliary light source, such that the auxiliary light source increases the conductivity of the gate material layer (5) and induces the photodetector to generate a positive grating effect, so as to accelerate the turn-off of the channel layer (2) after the target light source disappears; wherein the first material includes gallium oxide and the second material includes tungsten diselenide.

2. The detection method according to claim 1, characterized in that, When the gate material layer (5) is located above the channel layer (2), the gate material layer (5) is formed between the source (3) and the drain (4) on the channel layer (2) and is electrically isolated from the source (3) and the drain (4); When the gate (6) is formed below the gate material layer (5), the gate (6) is electrically isolated from the channel layer (2).

3. The detection method according to claim 1, characterized in that, When the channel layer (2) is located above the gate material layer (5), the channel layer (2) is electrically isolated from the gate (6).

4. The detection method according to claim 1, characterized in that, The auxiliary light source is set to a continuously on state, so that the auxiliary light source continuously illuminates the photodetector.

5. The detection method according to claim 1, characterized in that, A feedback circuit is provided between the source (3) and the drain (4), the feedback circuit being configured to respond to the channel current I of the channel layer (2). ds The change in the auxiliary light source triggers its activation or deactivation.

6. The detection method according to claim 5, characterized in that, The auxiliary light source is initially set to the off state, and the channel current I of the channel layer (2) is detected by the feedback circuit. ds Changes when detecting the target light source When the feedback circuit detects the channel current I caused by the disappearance of the target light source... ds The feedback circuit will reduce the channel current I by a decreasing signal. ds The decreasing signal is fed back to the control terminal of the auxiliary light source, triggering the auxiliary light source to turn on. The auxiliary light source causes the photodetector to generate a positive grating effect, thereby accelerating the turn-off of the channel layer (2). When the feedback circuit detects the channel current I caused by the appearance of the target light source... ds The rising signal, the feedback circuit will turn the channel current I ds The rising signal is fed back to the control terminal of the auxiliary light source, triggering the auxiliary light source to turn off.

7. The detection method according to claim 1, characterized in that, Before detecting the target light source, an initial voltage V is applied between the source (3) and the drain (4). ds An initial voltage V is applied to the gate (6). g This puts the photodetector in an initial depletion state.

8. The detection method according to claim 1, characterized in that, The target light source and the auxiliary light source have a wavelength range between far-infrared and X-ray.

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