A highly sensitive and easily activated transistor-type photodetector

Abstract

The present invention provides a transistor-type photodetector with high sensitivity and easy startup, which includes a substrate. A gate is disposed on the substrate, and an insulating layer is wrapped on the gate. An active layer is disposed on the insulating layer, and the active layer includes an indium gallium zinc oxide thin film, a two-dimensional tungsten diselenide layer, and a lead selenide thin film. A source electrode is disposed at the left end of the lead selenide thin film, and a drain electrode is disposed at the right end. The present invention can overcome the lattice defect problems of the indium gallium zinc oxide thin film and the lead selenide thin film, improve the photocurrent of the optoelectronic device while also improving the sensitivity, ensure excellent electrical conductivity while also providing good stability, and improve the overall performance of the optoelectronic device. This phototransistor has the remarkable characteristics of high sensitivity and easy startup, and has a wide range of applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic transistors, and particularly relates to a transistor-type photodetector with high sensitivity and easy startup. Background Art

[0002] In recent years, the introduction of two-dimensional materials and heterojunction structures has provided a new direction for improving the performance of optoelectronic devices. Researchers have conducted extensive research on convenient and efficient preparation methods for the materials used in optoelectronic transistors, such as mechanical exfoliation and liquid-phase exfoliation. Similarly, improving the performance of optoelectronic devices has also attracted the attention of researchers. Among them, sensitivity and threshold voltage, as important indicators for measuring the performance of optoelectronic transistors, have also caught the attention of researchers. High sensitivity means that the optoelectronic transistor can have a stronger response ability to external signals, and a low threshold voltage means that the optoelectronic transistor starts faster and is easier to enter the working state. However, for the semiconductor materials used in traditional optoelectronic transistors, although optoelectronic conversion can also be achieved, their lattice matching problems and energy band widths limit the improvement of sensitivity. Considering that two-dimensional materials have a nanoscale thickness, which can suppress the short-channel effect while the shorter carrier transport path within the material also means that higher carrier mobility can be achieved. How to use two-dimensional materials to overcome the lattice matching problem and obtain a high-sensitivity and fast photodiode has become an urgent problem to be solved. Summary of the Invention

[0003] Object of the Invention: The technical problem to be solved by the present invention is to provide a transistor-type photodetector with high sensitivity and easy startup in view of the deficiencies of the prior art, including a substrate, on which a gate electrode is provided, the gate electrode is wrapped with an insulating layer, and an active layer is provided on the insulating layer. The active layer includes an indium gallium zinc oxide thin film, a two-dimensional tungsten diselenide layer, and a lead selenide thin film; an anode is provided at the left end of the lead selenide thin film, and a drain is provided at the right end.

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

[0005] The gate electrode, anode, and drain are printed by a current inkjet printer and have high resolution.

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

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

[0008] Step 1, clean the substrate with acetone, isopropyl alcohol, and deionized water in sequence, and then dry it.

[0009] Step 2, prepare the gate electrode on the surface of the substrate by using conductive silver ink through current inkjet printing technology.

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

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

[0012] Step 5: Obtain a tungsten diselenide suspension using the liquid-phase exfoliation method (LPE). Subsequently, spin-coat the tungsten diselenide suspension on the indium gallium zinc oxide thin film 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. The tungsten diselenide suspension is prepared using the liquid-phase exfoliation method (LPE), which overcomes the safety challenges during 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: Magnetron sputter on the surface of the two-dimensional tungsten diselenide layer (set the radio frequency time to 25 s and the output power to 30 W) to obtain a lead selenide thin film.

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

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

[0016] In Step 2, the current inkjet printing technology uses 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 required electrode.

[0017] In Step 5, obtaining the tungsten diselenide suspension using the liquid-phase exfoliation method (LPE) specifically includes the following steps:

[0018] Step 5-1: Disperse 50 mg of tungsten diselenide in a mixed solvent of 100 ml of ethanol and water by high-speed shear at 6000 r / min for X1 For 60 minutes, a tungsten diselenide suspension after dispersion is obtained;

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

[0020] In step 5-1, 1 X takes the value of 60.

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

[0022] Step 7 includes: Pre-replace the needle and add silver ink. Continuously adjust the position of the needle so that the needle can be clearly observed by the camera and is at a certain distance (about 2 mm) from the substrate. Set the following parameters: Use the square wave mode, with a frequency of 200 HZ, an amplitude of 1000, and a duty cycle of 15. After calibrating the camera, start printing. After printing, perform annealing to obtain the required electrode.

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

[0024] 2. The present invention uses a convenient and efficient liquid-phase exfoliation method to obtain a tungsten diselenide suspension. This method avoids complex condition requirements (such as high reaction temperature, etc.). The preparation process is simpler and safer compared to other methods (such as metal-organic chemical vapor deposition which will generate toxic chemical gases during the process), protects the crystal structure of tungsten diselenide, and at the same time reduces bubbles and controls the thickness by controlling different rotation speeds and spin-coating times.

[0025] 3. The present invention prepares a composite film 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 overcome the lattice defect problems of indium gallium zinc oxide thin film and lead selenide thin film while being simple and safe to prepare, improves the photocurrent of optoelectronic devices and also improves the sensitivity, making the prepared phototransistor have high sensitivity and easy startup ability.

[0026] 4. The phototransistor proposed by the present invention can accurately detect the concentration of medical liquid in the near-infrared spectrum field. Excellent polarization data means that it can identify and analyze the components and sample concentration in the liquid medicine with higher precision and accuracy, which is of great significance for drug research and development and quality control. Description of the Drawings

[0027] Figure 1Flow chart of the manufacturing method of the composite thin-film phototransistor of the present invention.

[0028] Figure 2 Schematic diagram of the three-dimensional structure of the composite thin-film phototransistor of the present invention.

[0029] Figure 3 Schematic diagram of the side structure of the composite thin-film phototransistor of the present invention.

[0030] Figure 4 Microscopic physical diagram of the composite thin-film phototransistor of the present invention.

[0031] Figure 5 Transmission electron microscope image of the composite thin-film phototransistor of the present invention.

[0032] Figure 6 Polar coordinate diagram of the polarization angle of the composite thin-film phototransistor of the present invention.

[0033] Figure 7 Output characteristic curve diagram of the composite thin-film phototransistor of the present invention at different wavelengths.

[0034] Figure 8 Pulse response diagram of the composite thin-film phototransistor of the present invention.

[0035] Figure 9 Drug strength analysis of 0.9% sodium chloride solution with different concentrations of ambroxol hydrochloride at an incident wavelength of 960 nm.

[0036] Figure 10 Drug strength analysis of 0.9% sodium chloride solution with different concentrations of ambroxol hydrochloride at an incident wavelength of 1340 nm.

[0037] Figure 11 Drug strength analysis of 5% glucose solution with different concentrations of imipenem at an incident wavelength of 960 nm.

[0038] Figure 12 Drug strength analysis of 5% glucose solution with different concentrations of imipenem at an incident wavelength of 1340 nm.

[0039] Explanation of reference numerals: 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 electrode, 8 - Drain electrode. Detailed implementation manners

[0040] The following further specifically describes the present invention in conjunction with the accompanying drawings and specific implementation manners, and the above and / or other advantages of the present invention will become clearer.

[0041] As Figure 2As shown in the figure, an embodiment of the present invention provides a highly sensitive and easily activated transistor-type photodetector, including a substrate 1, on which a gate 2 is provided. An insulating layer 3 is wrapped around the gate 2, and an active layer is provided on the insulating layer 3. The active layer includes an indium gallium zinc oxide thin film 4, a two-dimensional tungsten diselenide layer 5, and a lead selenide thin film 6. An anode 7 is provided at the left end of the lead selenide thin film 6, and a drain 8 is provided 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, the anode 7, and the drain 8 are printed using an inkjet printer.

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

[0045] As Figure 1 shown in the figure, an embodiment of the present invention also provides a preparation method for a highly sensitive and easily activated transistor-type photodetector, including 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 residual isopropanol 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. Prepare the gate 2 on the substrate 1. The gate 2 is made by using an inkjet printing technique with silver ink. The inkjet printer uses a square wave mode, with a frequency of 200HZ, an amplitude of 1000, and a duty cycle of 15.

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

[0049] S4. Use magnetron sputtering technology to fabricate the indium gallium zinc oxide thin film 4 on the surface of the insulating layer 3 in an argon environment. The time of the magnetron sputtering system is 500 s, and the power is 60 W.

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

[0051] S6. Spin-coat the tungsten diselenide suspension layer by layer at a temperature of 95 °C. For the spin-coating, the speed in the first stage is 1500 r / min and the time is 15 s, and the speed in the second stage is 2000 r / min and the time is 45 s. Spin-coat 3 layers to form the two-dimensional tungsten diselenide layer 5;

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

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

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

[0055] As Figure 3 shown, in the schematic side view structure diagram of the prepared 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 the gate from directly contacting the channel region, and at the same time allows 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 will be formed in the channel region, allowing current to flow from the source electrode to the drain electrode.

[0056] As Figure 4 shown, in the micrograph of the prepared phototransistor, the gate (the middle two triangles and their connecting parts), the source electrode (the lower left triangle part), and the drain electrode (the upper right triangle part) of the phototransistor can be seen.

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

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

[0059] As Figure 7As shown, during the turn-on process of the fabricated phototransistor at different wavelengths, as the gate voltage rises, the transistor gradually enters the conducting state. When the gate voltage exceeds the threshold voltage, the drain current begins to increase and increases rapidly as the gate voltage further increases. Among the selected wavelengths, the phototransistor exhibits the best conductive properties at a wavelength of 1060 nm. The lower threshold voltage also means that the fabricated transistor has the characteristic of being easily started.

[0060] As Figure 8 shown, the figure is the pulse response diagram of the fabricated phototransistor at an incident wavelength of 960 nm and an irradiation intensity of 0.03 mW / cm 2 . The rise time is 56 us, indicating that the fabricated phototransistor can quickly capture the change of the optical signal and convert it into the corresponding electrical signal.

[0061] In another specific embodiment of the present invention, the phototransistor in the first embodiment can be used to accurately detect the concentration of medical drugs in the near-infrared spectral range. At the same time, the excellent polarization data means that it can identify and analyze the concentration of the liquid medicine in the liquid medicine with higher precision and accuracy. The detection steps include:

[0062] Step 1, the DFB laser control system emits high-frequency laser, and the laser passes through the liquid medicine to be measured with different concentrations;

[0063] Step 2, make the laser passing through the liquid medicine irradiate on the phototransistor to output current;

[0064] Step 3, the output current passes through the current-voltage conversion circuit to convert it into a voltage signal;

[0065] Step 4, the data is sent to the single-chip microcomputer for processing through the modulation and demodulation circuit and the AD conversion circuit;

[0066] Step 5, the single-chip microcomputer transmits the data of detecting the liquid medicine with different concentrations to the computer, and compares it with the database to detect the concentration of the liquid medicine.

[0067] As Figure 9 , Figure 10 shown, at an incident wavelength of 960 nm and 1340 nm respectively, for the drug strength analysis of 0.9% sodium chloride solution with different concentrations of ambroxol hydrochloride, it can be seen that the amplitudes of 0.9% sodium chloride solution with different concentrations of ambroxol hydrochloride in the marked yellow box show relatively obvious differences; Similarly, as Figure 11 , Figure 12As shown, for the drug strength analysis of 5% glucose solutions with different concentrations of imipenem at incident wavelengths of 960 nm and 1340 nm respectively, it can be seen that the amplitudes of 5% glucose solutions with different concentrations of imipenem in the marked yellow boxes show relatively obvious differences. This characteristic enables us to accurately analyze and determine the concentration of the drug.

[0068] The present invention provides a highly sensitive and easily activated transistor-type photodetector. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

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

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, the time is 15 s, and the second time at a speed of 2000 rpm, the time is 45 s, 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 s and 45 s, 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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