Quantum dot mid-infrared photodetector and preparation method thereof

Abstract

The present invention relates to a quantum dot mid-infrared photodetector and a preparation method thereof. The preparation method comprises: growing an indium gallium zinc oxide conductive channel layer on a silicon / silicon dioxide substrate; preparing a source electrode and a drain electrode on the surface of the indium gallium zinc oxide conductive channel layer; patterning the indium gallium zinc oxide conductive channel layer; preparing single-crystalline tin telluride colloidal quantum dots by hot injection; spin-coating the single-crystalline tin telluride colloidal quantum dots onto the surface of the patterned indium gallium zinc oxide conductive channel layer to obtain an initial device; annealing the initial device to obtain a quantum dot mid-infrared photodetector. The quantum dot mid-infrared photodetector prepared by the above method can solve the problem of non-toxicity of mid-infrared quantum dot materials and the problem of broadening the response band of quantum dot detectors.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial photoelectric detection, and in particular to a quantum dot mid-infrared photoelectric detector and a preparation method thereof. Background Art

[0002] Quantum dots have the advantages of adjustable band gap, unique photosensitivity and quantum effects, and solution processing. They are one of the core competitive materials for photodetectors, especially uncooled infrared detectors. Most quantum dot devices only respond to the visible and near-infrared bands, which are difficult to expand to the mid-infrared band. Only mercury telluride quantum dot detectors have mid-infrared detection performance. However, due to the high toxicity and instability of mercury telluride and its easy degradation, the application range and reliability of mercury telluride quantum dot detectors are restricted. Therefore, the development of non-toxic and stable mid-wave quantum dot detectors is a key issue that needs to be solved urgently.

[0003] The existing methods for preparing non-toxic and stable medium-wavelength quantum dot detectors are mainly for thin-film devices prepared by CVD, MBE and PVD methods, which are expensive to prepare. In addition, there is no relevant research on single-crystal tin telluride colloidal quantum dots, nor is there a device structure for detectors combined with IGZO. Summary of the invention

[0004] In order to solve the problem of non-toxicity of mid-infrared quantum dot materials and broaden the response band of quantum dot detectors, the present invention provides a quantum dot mid-infrared photoelectric detector and a preparation method thereof.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0006] The present invention provides a method for preparing a quantum dot mid-infrared photodetector, comprising:

[0007] Growing an indium gallium zinc oxide (IGZO) conductive channel layer on a silicon / silicon dioxide (Si / SiO2) substrate;

[0008] Prepare a source electrode and a drain electrode on the surface of the indium gallium zinc oxide conductive channel layer;

[0009] Patterning the indium gallium zinc oxide conductive channel layer;

[0010] Single-crystalline tin telluride (SnTe) colloidal quantum dots were prepared by hot implantation;

[0011] Spin coating the single crystal tin telluride colloidal quantum dots onto the surface of the patterned indium gallium zinc oxide conductive channel layer to obtain an initial device;

[0012] The initial device is annealed to obtain a quantum dot mid-infrared photodetector.

[0013] According to one aspect of the present invention, a magnetron sputtering coating process is used to prepare and grow an indium gallium zinc oxide thin film to form the indium gallium zinc oxide conductive channel layer, and an annealing process is used to make the carrier mobility of the indium gallium zinc oxide conductive channel layer 9.23m 2 V -1 s -1 , the on / off ratio is 5×10 7 , with a thickness of 10 to 100 nm. The indium gallium zinc oxide conductive channel layer has an appropriate thickness and conductivity to play the best role in carrier transport, and the controllable conductivity of the IGZO film is achieved through the annealing process.

[0014] According to one aspect of the present invention, the process of preparing the source electrode and the drain electrode includes: patterning the photoresist using ultraviolet lithography technology, and evaporating a titanium / gold (Ti / Au) composite electrode film through a thermal evaporation coating process to prepare the source electrode and the drain electrode.

[0015] According to one aspect of the present invention, the patterning process of the indium gallium zinc oxide conductive channel layer includes: patterning the photoresist by ultraviolet exposure process, and patterning the indium gallium zinc oxide conductive channel layer by wet etching process;

[0016] The patterned indium gallium zinc oxide conductive channel layer is an independent unit that is not connected to each other, and the length / width size of the independent unit is any one of 100 / 100 μm, 100 / 80 μm, 100 / 60 μm, 100 / 40 μm, 100 / 20 μm, and 100 / 10 μm.

[0017] According to one aspect of the present invention, the process of preparing single crystal tin telluride colloidal quantum dots by the hot injection method comprises:

[0018] The tellurium source is dissolved in tri-n-octylphosphine, and heated under reflux and stirring in an inert atmosphere to fully dissolve the tellurium source to form a transparent light green solution with a concentration of 90 to 96 mg / mL, which serves as the tellurium source for the reaction; preferably, the concentration of the tellurium source is 92 to 95 mg / mL.

[0019] Add bis[bis(trimethylsilyl)amino]tin(II) to octadecene, heat and stir under an inert atmosphere at 40-120° C. to fully dissolve the bis[bis(trimethylsilyl)amino]tin(II) to form a solution with a concentration of 20-28 mg / mL as a tin source for the reaction; preferably, the concentration of the tin source is 20-25 mg / mL.

[0020] The tin source is injected into an oleylamine solution containing a tellurium source at 120-180° C. by hot injection, and reacted for 1-10 minutes to synthesize tin telluride quantum dots; preferably, the reaction temperature is 150° C. and the reaction time is 8-10 minutes.

[0021] The synthesized tin telluride quantum dots are cooled to room temperature in an ice-water bath, a surfactant is added to obtain a tin telluride quantum dot colloid, acetone / chloroform is first added to the tin telluride quantum dot colloid for centrifugation, the supernatant is removed and dispersed in a quantum dot solvent, the process is repeated 2 to 3 times, and then the acetone / anhydrous ethanol / chloroform is used for centrifugation purification, the supernatant is removed and dispersed in a quantum dot solvent, the process is repeated 2 to 3 times to obtain single crystal tin telluride colloidal quantum dots with a concentration of 20 mg / mL.

[0022] Optionally, the surfactant is oleic acid or n-dodecyl mercaptan. Preferably, the surfactant is n-dodecyl mercaptan.

[0023] According to one aspect of the present invention, the quantum dot solvent is chloroform, n-hexane, n-octane or toluene; preferably, the quantum dot solvent is chloroform.

[0024] The particle size distribution of the single crystal tin telluride colloidal quantum dots is 50-100 nm, and the crystal orientation is mainly (111).

[0025] According to one aspect of the present invention, the process of spin coating the single crystal tin telluride colloidal quantum dots onto the surface of the patterned indium gallium zinc oxide conductive channel layer to obtain an initial device includes:

[0026] The short-chain ligand 2-nitrothiophene was used for ligand replacement to replace the long-chain ligand to increase the conductivity of the quantum dots;

[0027] Through multiple spin coating and ligand replacement, the thickness of the quantum dot film layer is made to be 500-1000nm.

[0028] Preferably, the thickness of the quantum dot thin film layer is 500-700 nm.

[0029] According to one aspect of the present invention, the initial device is annealed by gradient heating and then cooled to room temperature to obtain the quantum dot mid-infrared photodetector, the annealing temperature is 100-350°C, the time is 1-4h, and the atmosphere is an inert gas.

[0030] The present invention also provides a quantum dot mid-infrared photodetector prepared by the above preparation method, which includes a silicon / silicon dioxide substrate, an indium gallium zinc oxide conductive channel layer and a tin telluride quantum dot photosensitive layer from bottom to top, wherein the two ends of the indium gallium zinc oxide conductive channel layer are respectively connected to a source electrode and a drain electrode, and silicon serves as a bottom gate.

[0031] According to another aspect of the present invention, the thickness of silicon dioxide (SiO2) in the silicon / silicon dioxide substrate is 50-200 nm, and the thickness of silicon (Si) is 300-500 μm.

[0032] Preferably, the thickness of the silicon dioxide is 50-80 nm.

[0033] Beneficial effects:

[0034] According to the solution of the present invention, the quantum dots in the SnTe quantum dot mid-infrared detector have single crystal characteristics, are mainly (111) crystalline, have non-toxic and stable properties, and have photoelectric response to the mid-infrared 3-5μm band. The preparation of colloidal quantum dots has cheap raw materials, simple process, and good photoelectric properties, such as high absorption coefficient, adjustable bandgap width, etc., which provide a basis for the rapid application and development of colloidal quantum dot materials in the field of optoelectronics.

[0035] The quantum dot mid-infrared photodetector prepared by the preparation method of the quantum dot mid-infrared photodetector is a phototransistor device composed of a tin telluride (SnTe) quantum dot photosensitive layer, an indium gallium zinc oxide (IGZO) conductive channel layer, a Si / SiO2 substrate, a source-drain electrode and a bottom gate. The SnTe quantum dots are excited by light to generate photogenerated carriers, which form a photocurrent through the source-drain voltage at both ends of the conductive channel layer to achieve infrared photodetection. The IGZO carrier concentration is then regulated by the bottom gate to improve the overall photoelectric response and detection rate of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart schematically showing a method for preparing a quantum dot mid-infrared photodetector according to an embodiment of the present invention;

[0037] Figure 2 A schematic diagram schematically shows the structure of a quantum dot mid-infrared photodetector prepared according to an embodiment of the present invention;

[0038] Figure 3 Schematically showing an XRD spectrum of tin telluride quantum dots prepared according to an embodiment of the present invention;

[0039] Figure 4 A Fourier transform infrared spectrum diagram schematically showing a tin telluride quantum dot film prepared according to an embodiment of the present invention;

[0040] Figure 5 Schematically represents the photoelectric data of the present invention under 637nm laser radiation;

[0041] Figure 6 Schematically represents the photoelectric data of the present invention under 1310nm laser radiation;

[0042] Figure 7 Schematically represents the photoelectric data of the present invention under 2000nm laser radiation;

[0043] Figure 8The photoelectric data of the present invention under 4000nm laser radiation are schematically shown. DETAILED DESCRIPTION

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0045] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0046] Figure 1 The following schematically shows a flow chart of a method for preparing a quantum dot mid-infrared photodetector according to each embodiment of the present invention. Figure 1 The preparation method shown is implemented.

[0047] Example 1

[0048] (1) An IGZO film with a thickness of about 10 to 100 nm was grown on a Si / SiO2 substrate by magnetron sputtering in an Ar / O2 mixed atmosphere. The IGZO film served as the conductive channel layer. The background vacuum reached 10 -4 ~10 -5 Pa; the pressure in the chamber during growth is 0.7 Pa. The plated IGZO film is annealed at 200-500°C to make its carrier mobility reach 9.23m 2 V -1 s -1 , the on / off ratio is 5×10 7 .

[0049] (2) Prepare source and drain electrodes on the surface of the IGZO film. Specifically, the photoresist is patterned by UV exposure or UV lithography, and a Ti / Au composite electrode film is further deposited by thermal evaporation to serve as the source and drain electrodes. The thickness of the Ti film is 5 to 10 nm, and the thickness of the Au film is 50 to 200 nm.

[0050] (3) Patterning of the IGZO conductive channel layer. The photoresist is patterned by ultraviolet exposure process, and the IGZO conductive channel layer is patterned with hydrochloric acid as an etchant. The patterned IGZO is an independent unit that is not connected to each other. The IGZO channel size (length / width) is any one of 100 / 100μm, 100 / 80μm, 100 / 60μm, 100 / 40μm, 100 / 20μm or 100 / 10μm.

[0051] (4) Preparation of single-crystalline SnTe colloidal quantum dots. Single-crystalline SnTe colloidal quantum dots were prepared by hot injection, with a particle size distribution of 50 to 100 nm and a crystal orientation of (111). Figure 3 The specific preparation steps are as follows:

[0052] a) Preparation of tellurium source

[0053] Dissolve tellurium powder in tri-n-octylphosphine, heat under reflux and stir in an inert atmosphere to fully dissolve the tellurium powder, which is transparent light green after dissolution. The tellurium source for the reaction has a concentration of 90 to 96 mg / mL, preferably 92 to 95 mg / mL.

[0054] b) Preparation of tin source

[0055] Add bis(bis(trimethylsilyl)amino)tin(II) to octadecene, heat and stir under an inert atmosphere to fully dissolve. The tin source used in the reaction has a concentration of 20 to 28 mg / mL, a preferred dissolution temperature of 40 to 120°C, and a tin source concentration of 20 to 25 mg / mL.

[0056] c) Synthesis of SnTe quantum dots

[0057] The tin source is injected into an oleylamine solution containing a tellurium source at a temperature of 120 to 180°C by hot injection, and the reaction is carried out for 1 to 10 minutes to obtain tin telluride quantum dots. The preferred reaction temperature is 150°C and the reaction time is 8 to 10 minutes. After the quantum dot synthesis is completed, the solution is cooled to room temperature by an ice water bath, and a surfactant is added. The surfactant can be oleic acid or n-dodecyl mercaptan, preferably n-dodecyl mercaptan.

[0058] d) Centrifugal purification of tin telluride quantum dots

[0059] Add acetone / chloroform to the prepared tin telluride quantum dot colloid and centrifuge, remove the supernatant and disperse in chloroform (quantum dot solvent), repeat 2 to 3 times; then use acetone / anhydrous ethanol / chloroform for centrifugal purification, remove the supernatant and disperse in chloroform (quantum dot solvent), repeat 2 to 3 times. The quantum dot solvent can be chloroform, n-hexane, n-octane or toluene, preferably chloroform. Control the concentration of tin telluride quantum dots to about 20 mg / mL for thin film preparation.

[0060] (5) Spin-coat the SnTe colloidal quantum dots obtained in step 4 onto the patterned IGZO surface in step 3. Use the short-chain ligand 2-nitrothiophene for ligand replacement to replace the long-chain ligand to increase the conductivity of the quantum dots. If necessary, multiple spin coatings and ligand replacements are required to achieve the desired thickness of the quantum dot film. The thickness of the quantum dot film layer is 500 to 1000 nm, preferably 500 to 700 nm.

[0061] (6) Annealing the initial device obtained in step 5 in an inert gas atmosphere, using a gradient temperature increase, and then cooling to room temperature and maintaining a constant temperature to obtain a final mid-infrared detection device. The annealing temperature is 100 to 350° C., and the annealing time is 1 to 4 hours.

[0062] Figure 4 This is the infrared absorption spectrum of the thin film device. It can be seen that the infrared absorption peak of the quantum dot film is exactly located in the mid-infrared 3-5μm, which also lays the foundation for the mid-infrared photoelectric response of the later device.

[0063] Example 2

[0064] (1) An IGZO film with a thickness of 40 nm was grown on a Si / SiO2 substrate by magnetron sputtering in an Ar / O2 mixed atmosphere. The IGZO film served as the conductive channel layer. The background vacuum reached 5×10 -4 Pa; the pressure in the chamber during growth is 0.7 Pa. The atomic ratio of the target InGaZn is In:Ga:Zn=2:2:1, and the purity is 99.99%. The plated IGZO film is annealed at 350°C.

[0065] (2) Prepare source and drain electrodes on the IGZO surface. Pattern the photoresist by UV exposure or UV lithography, and then deposit Ti / Au composite electrode thin film by thermal evaporation to serve as source and drain electrodes. The thickness of the Ti film is 5 to 10 nm, and the thickness of the Au film is 50 to 200 nm.

[0066] (3) Patterning of the IGZO conductive channel layer. The photoresist is patterned by ultraviolet exposure process, and hydrochloric acid is used as an etchant to pattern the IGZO conductive channel layer. The patterned IGZO is an independent unit that is not connected to each other. The length and width of the IGZO channel are a rectangular structure of 100μm×100μm.

[0067] (4) Preparation of single-crystalline SnTe colloidal quantum dots. Single-crystalline SnTe colloidal quantum dots were prepared by hot injection, with a particle size distribution of 50 to 100 nm and a crystal orientation of (111). Figure 3 The specific preparation steps are as follows:

[0068] a) Preparation of tellurium source

[0069] Weigh 285 mg of tellurium powder (Te) using an analytical balance, add it to a three-necked flask, and use a syringe to add 3.1 mL of tri-n-octylphosphine (TOP), plug the flask mouth with a rubber stopper, and ultrasonically disperse for 30 minutes, then heat it in an oil bath to dissolve it. During the dissolution process, stir magnetically under the protection of inert gas, heat to 200 ° C and react for 4 hours. After the tellurium powder is dissolved, it turns light green, forming a tellurium source (Te / TOP) with a mass concentration of 92 mg / mL of tellurium element.

[0070] b) Preparation of tin source

[0071] 10 mL of octadecene was added to a round-bottom flask, and heated and degassed by magnetic stirring under inert gas protection. Then, 200 uL of bis[bis(trimethylsilyl)amino]tin(II) with a concentration of 1.136 g / mL was added using a syringe to fully dissolve the organotin in octadecene. The above degassing process and the process of adding the organotin were carried out under an inert gas atmosphere to ensure that the tin source was not oxidized.

[0072] c) Synthesis of SnTe quantum dots

[0073] After preparing the tellurium source and tin source according to the method in steps a and b, the oleylamine was degassed in the same way during the preparation of quantum dots, and the temperature was kept constant at 150°C. After degassing, the tin source was injected into the Te / TOP oleylamine solution by syringe to react and generate tin telluride quantum dots. The injection temperature of the tin source was 40°C, the reaction time was 8 to 10 minutes, and after the reaction was completed, it was quickly cooled to room temperature in an ice water bath, and then 2 mL of n-dodecyl mercaptan was added.

[0074] d) Centrifugal purification of tin telluride quantum dots

[0075] The above-mentioned tin telluride quantum dots are added to chloroform and acetone for centrifugal purification 4 to 6 times. For the first time, a centrifugal operation with a speed of 4000 to 6000 r / min and a time of 8 to 15 minutes is used, and the supernatant is removed, chloroform is added, and ultrasonic dispersion treatment is performed; for the second time, acetone is added, and a centrifugal operation with a speed of 4000 to 6000 r / min and a time of 5 to 10 minutes is used, and the supernatant is removed, chloroform is added, and ultrasonic dispersion treatment is performed; for the third time, acetone and anhydrous ethanol are added, and a centrifugal operation with a speed of 6000 to 9000 r / min and a time of 8 to 15 minutes is used, and the supernatant is removed, chloroform is added, and ultrasonic dispersion treatment is performed; the subsequent fourth, fifth, and sixth centrifugal processes are the same as the third. Finally, the centrifuged tin telluride quantum dots are added to chloroform for dispersion and purification to obtain a tin telluride quantum dot colloidal solution with a concentration of about 20 mg / mL.

[0076] (5) The tin telluride quantum dot colloidal solution with a concentration of about 20 mg / mL obtained in step 4 was deposited on the IGZO surface patterned in step 3 using a spin coater. The rotation speed was 1500 r / min, the time was 30 s, and the spin coating was replaced three times for 3 minutes. The concentration of the ligand 2-nitrothiophene was 0.05 mol / L, the solvent was anhydrous ethanol, and the spin coating replacement process was repeated three times. The thickness of the final quantum dot film layer obtained was 500 nm.

[0077] (6) Annealing the initial device obtained in step 5 by gradient heating, then cooling to room temperature and maintaining a constant temperature to obtain a final mid-infrared detection device, wherein the annealing temperature is 200° C. and the annealing time is 2 h.

[0078] like Figure 2 As shown, the quantum dot mid-infrared photodetector prepared by the preparation method of the quantum dot mid-infrared photodetector in the above two embodiments is a phototransistor device composed of a tin telluride (SnTe) quantum dot photosensitive layer, an indium gallium zinc oxide (IGZO) conductive channel layer, a Si / SiO2 substrate, a source-drain electrode and a bottom gate. The SnTe quantum dots are excited by light to generate photogenerated carriers, which form a photocurrent through the source-drain voltage at both ends of the conductive channel layer to achieve infrared photoelectric detection. The IGZO carrier concentration is then regulated by the bottom gate to improve the overall photoelectric responsivity and detection rate of the device.

[0079] The photoelectric response test of the above devices was carried out. Figure 5-Figure 8 The photoelectric switching diagrams of the device at wavelengths of 637nm, 1310nm, 2μm, and 4μm are shown when the source-drain voltage is 10V and no gate voltage (Vg) is applied. When the light source switches on and off, the device shows a significant switching ratio from visible light to mid-infrared, with obvious mid-infrared response characteristics.

[0080] The quantum dot mid-infrared photodetector includes, from bottom to top: a silicon / silicon dioxide (Si / SiO2) substrate, an indium gallium zinc oxide (IGZO) conductive channel layer, and a tin telluride (SnTe) quantum dot photosensitive layer. The two ends of the indium gallium zinc oxide (IGZO) conductive channel layer are respectively connected to the source electrode and the drain electrode, and silicon is used as the bottom gate. The thickness of silicon dioxide (SiO2) in the silicon / silicon dioxide substrate is 50 to 200 nm, and the thickness of silicon (Si) is 300 to 500 μm. Preferably, the thickness of silicon dioxide is 50 to 80 nm.

[0081] The embodiments of the present invention use chemical methods to prepare tin telluride colloidal quantum dot materials. Tin telluride exists in the form of colloid. Through the spin coating process, a large area of ​​uniform conductive film can be formed on the surface of any substrate without lattice matching. The material preparation cost and device preparation process cost are much lower than the thin film devices prepared by CVD, MBE and PVD methods. The tin telluride quantum dot materials prepared by the above embodiments of the present invention are mainly (111) crystal orientation (such as Figure 3 The tin telluride colloidal quantum dot material has mid-infrared absorption characteristics. In the device structure, IGZO is used as the transmission layer and quantum dots are used as the upper light absorption layer.

[0082] The size of quantum dots can be controlled through the preparation process, and then its optical band gap can be controlled to achieve the wavelength selectivity of quantum dot optoelectronic devices. This is incomparable to the tin telluride thin film devices prepared by physical methods. At the same time, the mid-infrared detection device based on tin telluride quantum dots of the present invention is expected to replace mercury telluride and become the next generation of mid-infrared quantum dot detectors working at room temperature. It is also the first device in China to realize the mid-infrared photoelectric response of quantum dots.

[0083] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a quantum dot mid-infrared photodetector, comprising: An indium gallium zinc oxide conductive channel layer is grown on a silicon / silicon dioxide substrate; the carrier mobility of the indium gallium zinc oxide conductive channel layer is 9.23 m 2 V -1 s -1 , the on / off ratio is 5×10 7 , thickness is 10~100nm; Prepare a source electrode and a drain electrode on the surface of the indium gallium zinc oxide conductive channel layer; Patterning the indium gallium zinc oxide conductive channel layer; Single crystal tin telluride colloidal quantum dots are prepared by hot injection method; wherein the reaction temperature is 150° C. and the reaction time is 8 to 10 minutes; the particle size distribution of the single crystal tin telluride colloidal quantum dots is 50 to 100 nm, and the crystal orientation is mainly (111); Spin coating the single crystal tin telluride colloidal quantum dots onto the surface of the patterned indium gallium zinc oxide conductive channel layer to obtain an initial device; Annealing the initial device to obtain a quantum dot mid-infrared photodetector; The initial device is annealed by a gradient heating method and then cooled to room temperature to obtain the quantum dot mid-infrared photodetector. The annealing temperature is 100 to 350° C., the time is 1 to 4 hours, and the atmosphere is an inert gas.

2. The method according to claim 1, characterized in that An indium gallium zinc oxide thin film is grown by a magnetron sputtering coating process to form the indium gallium zinc oxide conductive channel layer, and the indium gallium zinc oxide conductive channel layer is treated by an annealing process.

3. The method according to claim 1, characterized in that The process of preparing the source electrode and the drain electrode includes: patterning the photoresist by using ultraviolet photolithography technology, and evaporating a titanium / gold composite electrode film by thermal evaporation coating process to prepare the source electrode and the drain electrode.

4. The method according to claim 1, characterized in that: The patterning process of the indium gallium zinc oxide conductive channel layer includes: patterning the photoresist by using an ultraviolet exposure process, and patterning the indium gallium zinc oxide conductive channel layer by using a wet etching process; The patterned indium gallium zinc oxide conductive channel layer is an independent unit that is not connected to each other, and the length / width size of the independent unit is any one of 100 / 100 μm, 100 / 80 μm, 100 / 60 μm, 100 / 40 μm, 100 / 20 μm, and 100 / 10 μm.

5. The method according to claim 1, characterized in that The process of preparing single crystal tin telluride colloidal quantum dots by the hot injection method includes: Dissolving a tellurium source in tri-n-octylphosphine, heating under reflux and stirring in an inert atmosphere to fully dissolve the tellurium source to form a transparent light green solution with a concentration of 90 to 96 mg / mL, which serves as the tellurium source for the reaction; Add bis[bis(trimethylsilyl)amino]tin(II) to octadecene, heat and stir under an inert atmosphere at 40 to 120° C. to fully dissolve the bis[bis(trimethylsilyl)amino]tin(II) to form a solution with a concentration of 20 to 28 mg / mL as a tin source for the reaction; The tin source is injected into an oleylamine solution containing a tellurium source at 120 to 180° C. by a hot injection method, and the reaction is carried out for 1 to 10 minutes to synthesize tin telluride quantum dots; The synthesized tin telluride quantum dots are cooled to room temperature in an ice-water bath, a surfactant is added to obtain a tin telluride quantum dot colloid, acetone / chloroform is first added to the tin telluride quantum dot colloid for centrifugation, the supernatant is removed and dispersed in a quantum dot solvent, the process is repeated 2 to 3 times, and then the acetone / anhydrous ethanol / chloroform is used for centrifugation purification, the supernatant is removed and dispersed in a quantum dot solvent, the process is repeated 2 to 3 times to obtain single crystal tin telluride colloidal quantum dots with a concentration of 20 mg / mL.

6. The method according to claim 5, characterized in that The quantum dot solvent is chloroform, n-hexane, n-octane or toluene.

7. The method according to claim 1, characterized in that The process of spin coating the single crystal tin telluride colloidal quantum dots onto the surface of the patterned indium gallium zinc oxide conductive channel layer to obtain an initial device includes: The short-chain ligand 2-nitrothiophene was used for ligand replacement to replace the long-chain ligand to increase the conductivity of the quantum dots; Through multiple spin coating and ligand replacement, the thickness of the quantum dot film layer is made to be 500-1000nm.

8. A quantum dot mid-infrared photodetector prepared by the preparation method according to claims 1 to 7, characterized in that: From bottom to top, it includes a silicon / silicon dioxide substrate, an indium gallium zinc oxide conductive channel layer and a tin telluride quantum dot photosensitive layer. The two ends of the indium gallium zinc oxide conductive channel layer are respectively connected to the source electrode and the drain electrode, and silicon serves as the bottom gate.

9. The quantum dot mid-infrared photodetector according to claim 8, characterized in that: The thickness of silicon dioxide in the silicon / silicon dioxide substrate is 50-200 nm, and the thickness of silicon is 300-500 μm.

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