High-sensitivity easy-to-start transistor type photoelectric detector

Abstract

The invention provides a high-sensitivity easy-to-start transistor type photoelectric detector which comprises a substrate, a grid electrode is arranged on the substrate, an insulating layer wraps the grid electrode, an active layer is arranged on the insulating layer, and the active layer comprises an indium gallium zinc oxide thin film, a two-dimensional tungsten diselenide layer and a lead selenide thin film. The left end of the lead selenide film is provided with a source electrode, and the right end is provided with a drain electrode. According to the invention, the lattice defect problem of the indium gallium zinc oxide film and the lead selenide film can be overcome, the photocurrent of the optoelectronic device is improved, the sensitivity is also improved, the excellent conductivity is ensured, the good stability is also provided, and the overall performance of the optoelectronic device is improved. The photoelectric transistor has the remarkable characteristics of high sensitivity and easiness in starting, and is wide in application range.

Description

Technical Field

[0001] This invention belongs to the field of phototransistor technology, and particularly relates to a high-sensitivity, easily startable transistor-type photodetector. Background Technology

[0002] In recent years, the introduction of two-dimensional materials and heterojunction structures has provided new directions for improving the performance of optoelectronic devices. Researchers have conducted extensive research on convenient and efficient fabrication methods for materials used in phototransistors, such as mechanical exfoliation and liquid-phase exfoliation. Similarly, improving the performance of optoelectronic devices has attracted researchers' attention, with sensitivity and threshold voltage, as important indicators of phototransistor performance, drawing particular focus. High sensitivity means that phototransistors can respond more strongly to external signals, while a low threshold voltage means that phototransistors start up faster and enter the working state more easily. However, the semiconductor materials used in traditional phototransistors, although capable of photoelectric conversion, are limited by lattice matching issues and bandgap limitations in improving sensitivity. Considering that two-dimensional materials have nanometer-scale thickness, they can suppress short-channel effects, and the shorter transport path of charge carriers within the material also means that higher carrier mobility can be achieved. How to utilize two-dimensional materials to overcome lattice matching problems and obtain highly sensitive and fast photodiodes has become an urgent problem to be solved. Summary of the Invention

[0003] Objective of the Invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a high-sensitivity, easily startable transistor-type photodetector, comprising a substrate, a gate disposed on the substrate, an insulating layer wrapped around the gate, and an active layer disposed on the insulating layer. The active layer comprises an indium gallium zinc oxide thin film, a two-dimensional tungsten diselenide layer, and a lead selenide thin film; the lead selenide thin film has an active electrode at its left end and a drain electrode at its right end.

[0004] The substrate is made of an insulating material, and the insulating layer is made of SU-8 photoresist.

[0005] The gate, source, and drain are printed using an inkjet printer, which has a high resolution.

[0006] The gate, source, and drain are made of metallic silver.

[0007] The photodetector is prepared using the following method:

[0008] Step 1: Clean the substrate sequentially with acetone, isopropanol, and deionized water, then blow dry;

[0009] Step 2: The gate is fabricated on the substrate surface using conductive silver ink via current inkjet printing technology;

[0010] Step 3: Spin coat SU-8 photoresist onto the gate surface twice using a spin coater. The first spin coat is at 1000 rpm for 15 seconds, and the second spin coat is at 2000 rpm for 45 seconds to obtain an insulating layer.

[0011] Step 4: Open the inflation valve to bring the internal pressure of the magnetron sputtering chamber to atmospheric pressure; after cleaning the sputtering chamber, install the indium gallium zinc oxide target on the target position of the sputtering system, ensuring an appropriate distance between the target and the substrate (approximately 200 mm); after closing the sputtering chamber, evacuate the chamber to a certain vacuum level (approximately 1 × 10⁻⁶). −5 (Pa), turn on the air pump and adjust the ionization unit to 5×10. −5 Pa, introduce argon gas with a purity of 99.999% or higher into the sputtering chamber as the working gas, turn on the activation control, start the ignition, and after the ignition is completed, open the target baffle, set the radio frequency time (500s) and output power (60W), and turn on the rotation start / stop, radio frequency start / stop and DC current control start / stop in sequence to start the coating. After the coating is completed, increase the gas pressure to atmospheric pressure, open and take out the wafer to obtain an indium gallium zinc oxide thin film;

[0012] Step 5: A tungsten diselenide suspension is obtained by liquid phase exfoliation (LPE). Subsequently, the tungsten diselenide suspension is spin-coated at rates of 1500 r / min and 2000 r / min for 15 s and 45 s, respectively, to form a two-dimensional tungsten diselenide layer on an indium gallium zinc oxide (IGaZN) thin film. The tungsten diselenide suspension is prepared by liquid phase exfoliation (LPE), which overcomes the safety challenges in the preparation process (the preparation process is mild, does not produce toxic gases, and does not require high-temperature preparation) and does not damage the crystal structure of tungsten diselenide.

[0013] Step 6: A lead selenide thin film is obtained by magnetron sputtering (setting the radio frequency time to 25s and the output power to 30W) on the surface of the two-dimensional tungsten diselenide layer.

[0014] Step 7: Using current inkjet printing technology, a source electrode is prepared at the left end of the lead selenide film, and a drain electrode is prepared at the right end of the lead selenide film to obtain a sample.

[0015] Step 8: Anneal the sample by heating at 150°C for 30 minutes.

[0016] In step 2, the current inkjet printing technology adopts a square wave mode with a frequency of 200 Hz, an amplitude of 1000, and a duty cycle of 15. After printing, the electrode is obtained by annealing.

[0017] In step 5, tungsten diselenide suspension is obtained using the liquid phase exfoliation (LPE) method, specifically including the following steps:

[0018] Step 5-1: Disperse 50 mg of tungsten diselenide in a mixed solvent of 100 ml ethanol and water at a high speed of 6000 r / min for 1 minute to obtain a dispersed tungsten diselenide suspension.

[0019] Step 5-2: Centrifuge the dispersed tungsten diselenide suspension at 5000 r / min for 2 hours, and then take the supernatant to obtain the tungsten diselenide suspension.

[0020] In step 5-1, X1 is set to 60.

[0021] In step 5-2, X2 takes the value 1.

[0022] Step 7 includes: pre-changing the needle and adding silver ink, continuously adjusting the needle position so that the needle can be clearly observed by the camera and is a certain distance (about 2 mm) from the substrate, setting the following parameters: using square wave mode, frequency of 200 Hz, amplitude of 1000, duty cycle of 15, calibrating the camera and starting printing, and after printing, annealing to obtain the required electrode.

[0023] The present invention has the following beneficial effects: 1. The present invention uses magnetron sputtering to prepare IGZO (indium gallium zinc oxide) thin films on insulating layers, which has both good deposition effect and high deposition efficiency.

[0024] 2. This invention uses a convenient and efficient liquid phase stripping method to obtain tungsten diselenide suspension. This method avoids complex conditions (such as high reaction temperature), and the preparation process is simpler and safer than other methods (such as metal-organic chemical vapor deposition, which produces toxic chemical gases during the process). It protects the crystal structure of tungsten diselenide. At the same time, by controlling different rotation speeds and spin coating times, it also reduces bubbles and controls the thickness.

[0025] 3. This invention prepares composite thin films of indium gallium zinc oxide / tungsten diselenide / lead selenide with high carrier mobility by methods such as magnetron sputtering. The two-dimensional tungsten diselenide layer can be prepared simply and safely, while also overcoming the lattice defect problem of indium gallium zinc oxide thin films and lead selenide thin films. This improves the photocurrent of optoelectronic devices and also improves sensitivity, so that the prepared phototransistor has high sensitivity and easy start-up capability.

[0026] 4. The phototransistor proposed in this invention enables precise detection of medical drug concentrations in the near-infrared spectroscopy field. Excellent polarization data means it can identify and analyze drug components and sample concentrations with higher precision and accuracy, which is of great significance for drug development and quality control. Attached Figure Description

[0027] Figure 1This is a flowchart of the composite thin-film phototransistor fabrication method of the present invention.

[0028] Figure 2 This is a schematic diagram of the three-dimensional structure of the composite thin-film phototransistor of the present invention.

[0029] Figure 3 This is a schematic diagram of the side structure of the composite thin-film phototransistor of the present invention.

[0030] Figure 4 This is a microscope image of the composite thin-film phototransistor of the present invention.

[0031] Figure 5 This is a transmission electron microscope image of the composite thin-film phototransistor of the present invention.

[0032] Figure 6 This is a polar coordinate diagram of the polarization angle of the composite thin-film phototransistor of the present invention.

[0033] Figure 7 The graphs show the output characteristics of the composite thin-film phototransistor of the present invention at different wavelengths.

[0034] Figure 8 This is a pulse response diagram of the composite thin-film phototransistor of the present invention.

[0035] Figure 9 To analyze the drug potency of 0.9% sodium chloride solutions of ambroxol hydrochloride at different concentrations at an incident wavelength of 960 nm.

[0036] Figure 10 To analyze the drug potency of 0.9% sodium chloride solutions of ambroxol hydrochloride at different concentrations at an incident wavelength of 1340 nm.

[0037] Figure 11 To analyze the drug potency of 5% glucose solutions with different concentrations of amphenicol at an incident wavelength of 960 nm.

[0038] Figure 12 To analyze the drug potency of 5% glucose solutions with different concentrations of amphenicol at an incident wavelength of 1340 nm.

[0039] Explanation of reference numerals in the attached figures: 1-substrate, 2-gate, 3-insulating layer, 4-indium gallium zinc oxide thin film, 5-two-dimensional tungsten diselenide layer, 6-lead selenide thin film, 7-source, 8-drain. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0041] like Figure 2As shown, this embodiment of the invention provides a high-sensitivity, easily startable transistor-type photodetector, including a substrate 1, a gate 2 disposed on the substrate 1, an insulating layer 3 wrapped on the gate 2, an active layer disposed on the insulating layer 3, the active layer including an indium gallium zinc oxide thin film 4, a two-dimensional tungsten diselenide layer 5, and a lead selenide thin film 6; an active electrode 7 is disposed at the left end of the lead selenide thin film 6, and a drain electrode 8 is disposed at the right end.

[0042] The substrate 1 is made of an insulating material, and the insulating layer 3 is made of SU-8 photoresist.

[0043] The gate 2, source 7 and drain 8 are printed using an inkjet printer.

[0044] The gate 2, source 7 and drain 8 are made of metallic silver.

[0045] like Figure 1 As shown in the figure, this invention also provides a method for fabricating a highly sensitive, easily startable transistor-type photodetector, comprising the following steps:

[0046] S1. Clean the substrate 1; first clean it with acetone for 15 minutes, then clean it with isopropanol for 15 minutes, then clean the isopropanol residue on the surface of the substrate 1 with deionized water, and finally dry it in a nitrogen gas environment to obtain a clean transparent insulating substrate 1.

[0047] S2. A gate 2 is fabricated on substrate 1. The gate 2 is fabricated using silver ink and current inkjet printing technology. The current inkjet printer adopts a square wave mode with a frequency of 200 Hz, an amplitude of 1000, and a duty cycle of 15.

[0048] S3. When preparing insulating layer 3 on the gate surface, SU-8 photoresist is selected as the insulating material. Spin coating is performed using a spin coater, with two layers coated in total. In the first stage, the spin coating speed is set to 1000 rpm for 15 seconds; in the second stage, the spin coating speed is increased to 2000 rpm and maintained for 45 seconds.

[0049] S4. An indium gallium zinc oxide thin film 4 is fabricated on the surface of the insulating layer 3 in an argon atmosphere using magnetron sputtering technology. The magnetron sputtering system has a time of 500s and a power of 60W.

[0050] S5. Disperse 50 mg of tungsten diselenide in a mixed solvent of 100 ml ethanol and water at a high speed of 6000 r / min for 60 min. Centrifuge the dispersed suspension for 1 h at a speed of 5000 r / min. Transfer the supernatant to obtain a two-dimensional tungsten diselenide suspension.

[0051] S6. Spin-coating the tungsten diselenide suspension layer by layer at a temperature of 95°C. The spin-coating is carried out at a speed of 1500 r / min for 15 s in the first stage and at a speed of 2000 r / min for 45 s in the second stage. Three layers are spin-coated to form a two-dimensional tungsten diselenide layer 5.

[0052] S7. Repeat step S4 to generate lead selenide thin film 6 on two-dimensional tungsten diselenide layer 5 using magnetron sputtering technology (magnetron sputtering system time is 25s, power is 30W).

[0053] S8. A source electrode 7 is prepared at the left end of the lead selenide film 6 generated in S7, and a drain electrode 8 is prepared at the right end of the lead selenide film 6 generated in S7. The source electrode 7 and the drain electrode 8 are also prepared by conductive silver ink through current inkjet printing technology, using square wave mode, frequency of 200HZ, amplitude of 1000, and duty cycle of 15.

[0054] S9. Anneal the fabricated overall device sample for 30 minutes to obtain an indium gallium zinc oxide / two-dimensional tungsten diselenide / lead selenide thin film phototransistor.

[0055] like Figure 3 As shown in the schematic diagram of the side structure of the fabricated phototransistor, the indium gallium zinc oxide thin film, the two-dimensional tungsten diselenide layer, and the lead selenide thin film together constitute the active layer of the phototransistor. The insulating layer prevents direct contact between the gate and the channel region, while allowing the gate electric field to affect the carrier distribution in the channel region, thereby controlling the conductivity of the channel. When a sufficient voltage is applied to the gate, a conductive channel is formed in the channel region, allowing current to flow from the source to the drain.

[0056] like Figure 4 As shown in the microscope image of the prepared phototransistor, the gate (the two triangles in the middle and their connection), source (the triangle in the lower left corner), and drain (the triangle in the upper right corner) of the phototransistor can be seen.

[0057] like Figure 5 As shown in the transmission electron microscope image, the lattice distances in the three directions of the two-dimensional tungsten diselenide in the manufactured phototransistor are: "010": 0.328 nm; "100": 0.328 nm; "110": 0.284 nm. The short lattice distance helps the carriers to transport within the material and improves the carrier mobility.

[0058] like Figure 6 As shown in the figure, the photocurrent as a function of the polarization angle at a wavelength of 960nm is a polar coordinate graph. The measurement interval is every 20° polarization angle. It was observed that the maximum photocurrent is about 3.5uA when the incident angle is about 100° and 280°.

[0059] like Figure 7As shown, during the turn-on process of the fabricated phototransistor at different wavelengths, the transistor gradually enters the conduction state as the gate voltage increases. When the gate voltage exceeds the threshold voltage, the drain current begins to increase, and it increases rapidly with further increases in the gate voltage. Among the selected wavelengths, the 1060nm wavelength exhibits the best conductivity, and the lower threshold voltage also means that the fabricated transistor has an easy-to-start characteristic.

[0060] like Figure 8 As shown in the figure, the fabricated phototransist operates at an incident wavelength of 960 nm and a wavelength of 0.03 mW / cm². 2 The pulse response diagram under irradiation intensity shows a rise time of 56 µs, indicating that the fabricated phototransistor can quickly capture changes in optical signals and convert them into corresponding electrical signals.

[0061] In another specific embodiment of the present invention, the phototransistor in the first embodiment can be used to achieve precise detection of medical drug concentration in the near-infrared spectral range. Furthermore, excellent polarization data means it can identify and analyze the concentration of the drug solution with higher precision and accuracy. The detection steps include:

[0062] Step 1: The DFB laser control system emits a high-frequency laser, which passes through test solutions of different concentrations.

[0063] Step 2: The laser light passing through the drug solution is used to irradiate the phototransistor, causing it to output current;

[0064] Step 3: The output current is converted into a voltage signal by a current-to-voltage conversion circuit;

[0065] Step 4: The data is sent to the microcontroller for processing via the modulation / demodulation circuit and the AD conversion circuit.

[0066] Step 5: The microcontroller transmits the data of different concentrations of medicine to the computer, compares it with the database, and then the concentration of the medicine can be detected.

[0067] like Figure 9 , Figure 10 As shown, the pharmacodynamic analysis of 0.9% sodium chloride solutions of ambroxol hydrochloride at different concentrations was performed at incident wavelengths of 960 nm and 1340 nm, respectively. It can be seen that the amplitudes of the 0.9% sodium chloride solutions of ambroxol hydrochloride at different concentrations exhibit relatively significant differences within the yellow box. Similarly, as... Figure 11 , Figure 12As shown, the drug potency analysis of 5% glucose solutions of different concentrations of biamphenicol was performed at incident wavelengths of 960 nm and 1340 nm, respectively. It can be seen that the amplitude of 5% glucose solutions of different concentrations of biamphenicol at the yellow box shows a relatively obvious difference. This characteristic allows us to accurately analyze and determine the drug concentration.

[0068] This invention provides a highly sensitive, easily startable transistor-type photodetector. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A highly sensitive and easy-to-start transistor-type photodetector, characterized in that: The invention comprises a substrate (1), a gate electrode (2) being arranged on the substrate (1), an insulating layer (3) being wrapped on the gate electrode (2), an active layer being arranged on the insulating layer (3), the active layer comprising an indium gallium zinc oxide film (4), a two-dimensional tungsten diselenide layer (5) and a lead selenide film (6); a source electrode (7) being arranged at the left end of the lead selenide film (6), and a drain electrode (8) being arranged at the right end.

2. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 1, characterized in that: The substrate (1) is made of insulating material, and the insulating layer (3) is made of SU-8 photoresist.

3. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 2, characterized in that: The gate electrode (2), source electrode (7) and drain electrode (8) are printed using an electric current inkjet printer.

4. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 3, characterized in that: The gate electrode (2), the source electrode (7) and the drain electrode (8) are made of metallic silver.

5. A high-sensitivity, easy-to-start transistor-type photodetector according to any one of claims 1 to 4, characterized in that: The photodetector is prepared by the following method: Step 1, cleaning the substrate (1) with acetone, isopropyl alcohol, and deionized water in sequence, and then drying it; Step 2, using conductive silver ink to prepare a gate electrode (2) on the surface of the substrate (1) by current inkjet printing technology; Step 3, using a coating machine to spin-coat SU-8 photoresist on the surface of the gate (2) twice, the first time at a speed of 1000 rpm for 15 seconds, and the second time at a speed of 2000 rpm for 45 seconds, to obtain an insulating layer (3); Step 4: Open the gas filling valve to make the internal pressure of the magnetron sputtering chamber reach the atmospheric pressure; after cleaning the sputtering chamber, install the InGaZnO target on the target position of the sputtering system and ensure that the distance between the target and the substrate is appropriate; after closing the sputtering chamber, evacuate the sputtering chamber to a certain vacuum degree, turn on the air pump and adjust the ionization unit to 5×10 −5 Pa, introduce inert gas argon with a purity of more than 99.999% as working gas into the sputtering chamber, turn on the activation control, start ignition, open the target baffle after ignition is completed, set the RF time to 500s, the output power to 60W, turn on the rotation start and stop, RF start and stop and DC current control start and stop in sequence, start coating, raise the gas pressure to atmospheric pressure after coating is completed, open and take out the wafer, and obtain InGaZnO thin film (4); Step 5, using liquid phase exfoliation (LPE) to obtain a tungsten diselenide suspension, and then spin coating the tungsten diselenide suspension at a rate of 1500 r / min and 2000 r / min for 15 seconds and 45 seconds, respectively, to form a two-dimensional tungsten diselenide layer (5) on the indium gallium zinc oxide film (4); Step 6, magnetron sputtering is performed on the surface of the two-dimensional tungsten diselenide layer (5) to obtain a lead selenide film (6); Step 7, using current inkjet printing technology, preparing a source electrode (7) at the left end of the lead selenide film (6), and preparing a drain electrode (8) at the right end of the lead selenide film (6), to obtain a sample; Step 8: anneal the sample at 150°C for 30 minutes.

6. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 5, characterized in that: In step 2, the current inkjet printing technology adopts a square wave mode with a frequency of 200 Hz, an amplitude of 1000, and a duty cycle of 15. After printing, annealing is performed to obtain the desired electrode.

7. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 6, characterized in that: In step 5, a tungsten diselenide suspension is obtained by liquid phase exfoliation (LPE), which specifically includes the following steps: Step 5-1, dispersing 50 mg of tungsten diselenide in a mixed solvent of 100 ml of ethanol and water at a high shear speed of 6000 r / min for 1 minute to obtain a dispersed tungsten diselenide suspension; Step 5-2: centrifuge the dispersed tungsten diselenide suspension at a speed of 5000 r / min in a centrifuge for X2 hours, and then take out the supernatant to obtain a tungsten diselenide suspension.

8. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 7, characterized in that: In step 5-1, the value of X1 is 60.

9. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 8, characterized in that: In step 5-2, the value of X2 is 1.

10. A high-sensitivity, easy-to-start transistor-type photodetector according to claim 9, characterized in that: Step 7 includes: replacing the needle in advance and adding silver ink, constantly adjusting the needle position so that the needle can be clearly observed by the camera and is a certain distance away from the substrate, setting the following parameters: using square wave mode, frequency of 200HZ, amplitude of 1000, duty cycle of 15, starting printing after calibrating the camera, and annealing after printing to obtain the required electrode.

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