Infrared detector based on TeOx thin film heterojunction and preparation method thereof

Abstract

The invention discloses an infrared detector based on a TeOx thin film heterojunction and a preparation method thereof, and belongs to the technical field of infrared photoelectric detectors. The invention discloses an infrared detector based on a TeOx thin film heterojunction. The infrared detector comprises an ITO glass substrate, an N-type buffer layer thin film, a P-type TeOx thin film and an Au electrode which are sequentially stacked from bottom to top, wherein the N-type buffer layer thin film and the P-type TeOx thin film form a PN heterojunction; the N-type buffer layer thin film is any one of a CdS thin film, a ZnO thin film, a TiO2 thin film and a SnO2 thin film. Benefited from the wide spectrum absorption and efficient carrier separation efficiency of the N-type transmission layer / P-type TeOx heterojunction, the detector has relatively high light responsivity in a near-infrared band (such as 800-1200 nm); the detector shows excellent rectification characteristics (rectification ratio gt; 103) and a very low dark current (lt; 10 <-7 > A), which is suitable for low-noise infrared sensing application.

Description

Technical Field

[0001] This invention belongs to the field of infrared photodetector technology, specifically relating to a TeO2-based... x Infrared detectors with thin-film heterojunctions and their fabrication methods. Background Technology

[0002] Te thin films are p-type semiconductors, and current research on Te thin films mainly focuses on the analysis of Te's crystal structure and film preparation. In 2008, the Department of Technical Physics and Prototype Engineering at the Bhabha Atomic Research Centre in Mumbai, India, successfully prepared Te thin films through thermal evaporation in a tube furnace. In 2016, the theoretical group of the School of Physics and Engineering at Zhengzhou University successfully predicted the multivalent driving force of Te using first-principles calculations. Recently, the State Key Laboratory of Surface Physics at the Institute of Physics, Chinese Academy of Sciences / Beijing National Research Center for Condensed Matter Physics successfully prepared Te thin films on the surface of graphene epitaxially grown on SiC(0001) substrates using molecular beam epitaxy. The College of Industrial Engineering at Purdue University in the United States prepared ultrathin Te thin films using a chemical solution synthesis method, which exhibited higher carrier mobility compared to other materials. When applied to field-effect transistors, these films maintained stability in air for up to two months. There are many methods for preparing Te thin films, and different methods produce films with different structures, properties, and applications. The main methods for preparing Te thin films include vacuum evaporation, molecular beam epitaxy, pulsed laser deposition, chemical vapor deposition, and chemical synthesis. However, Te films prepared by existing methods suffer from problems such as large dark current and weak photoelectric response. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a TeO-based... x The infrared detector based on a thin-film heterojunction and its fabrication method solves the problems in the existing technology.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A TeO-based x The infrared detector of the thin-film heterojunction comprises, from bottom to top, the following layers stacked in sequence: ITO glass substrate, N-type buffer film, and P-type TeO. x The thin film and Au electrode, the N-type buffer layer thin film and the P-type TeO x The thin film forms a PN heterojunction.

[0006] Furthermore, the N-type buffer layer film is any one of CdS film, ZnO film, TiO2 film, and SnO2 film.

[0007] Based on TeO xThe method for fabricating a thin-film heterojunction infrared detector includes the following steps:

[0008] S1, ultrasonic cleaning of the ITO glass substrate;

[0009] S2, deposit an N-type buffer layer thin film on an ITO glass substrate;

[0010] S3, P-type TeO is deposited on an N-type buffer layer film using magnetron sputtering technology. x film;

[0011] S4, in P-type TeO x Gold electrodes are deposited on the thin film to obtain an infrared detector.

[0012] Furthermore, the ITO glass substrate was ultrasonically cleaned using detergent, isopropanol, anhydrous ethanol, and deionized water, respectively.

[0013] Furthermore, when the N-type buffer layer film is a CdS film, the step of depositing the N-type buffer layer film on the ITO glass substrate is as follows:

[0014] Deionized water, cadmium sulfate solution, and ammonia were mixed and heated in a water bath with stirring. Then, thiourea solution was added, and an ITO glass substrate was immersed in the mixture. CdS was deposited on the ITO glass substrate. The ITO glass substrate was then ultrasonically cleaned and dried. Finally, the CdS film on the ITO glass substrate was treated with UVO.

[0015] Furthermore, the water bath heating temperature is 70-75℃.

[0016] Furthermore, when the N-type buffer layer film is a ZnO film, the N-type buffer layer film is deposited on an ITO glass substrate using magnetron sputtering technology, the steps of which include:

[0017] The background vacuum is 7×10 -4 Under sputtering pressure of 2-5 Pa, a high-purity ZnO target was used as the sputtering target material, and pre-sputtering was performed before deposition; then radio frequency sputtering was performed in a mixed atmosphere of argon and oxygen to obtain a ZnO thin film; the flow ratio of argon to oxygen was 99:1 sccm-99:20 sccm.

[0018] Furthermore, P-type TeO was deposited using magnetron sputtering technology. x The thin film process includes:

[0019] The background vacuum is 7×10 -4 Under conditions of Pa and sputtering pressure of 0.5-1.5 Pa, using a Te target as the sputtering target, pre-sputtering was performed before deposition, followed by DC sputtering in a mixed atmosphere of argon and oxygen to obtain P-type TeO. xThin film; the argon to oxygen flow rate ratio is 10:1 sccm to 10:5 sccm.

[0020] Furthermore, in P-type TeO x The process of depositing gold electrodes on thin films is as follows:

[0021] A thin film with an N-type buffer layer and a P-type TeO x The thin-film ITO glass substrate was transferred to a vacuum chamber for thermal evaporation; gold electrodes were deposited on the p-type TeO using a metal mask. x On the thin film layer.

[0022] An imager based on a TFT chip, wherein the imager is equipped with the aforementioned TeO chip-based imager. x Infrared detectors for thin-film heterojunctions.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention employs magnetron sputtering to deposit P-type TeO on an N-type buffer layer (selected as CdS and ZnO thin films). x There are currently no reports of this production technology in China; and compared with conventional methods, thin films produced by magnetron sputtering technology have a high deposition rate, are dense and uniform, have strong adhesion, and have a wide range of material applicability.

[0025] 2. The present invention significantly improves the performance of the resulting device by using UVO treatment on the surface of the N-type buffer layer (selected as CdS thin film).

[0026] 4. This invention adjusts the argon-oxygen flow ratio to TeO x The performance of heterojunction optoelectronic devices has been greatly improved.

[0027] 5. This invention can produce high-performance TeO in a short time (within 2 hours). x There are currently no reports on heterojunction optoelectronic devices in China.

[0028] 6. The device manufactured by this invention has excellent performance and repeatability under infrared light irradiation. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of the infrared detector of the present invention;

[0031] Figure 2 It is the CdS-TeO prepared in Example 1 x Dark characteristic curves and illumination characteristic curves of thin-film heterojunction infrared detectors;

[0032] Figure 3 It is the CdS-TeO prepared in Example 1 x Current-time test curve of thin-film heterojunction infrared detector;

[0033] Figure 4 It is the ZnO-TeO prepared in Example 2 x Dark characteristic curves and illumination characteristic curves of thin-film heterojunction infrared detectors;

[0034] Figure 5 It is the ZnO-TeO prepared in Example 2 x Current-time test curve of thin-film heterojunction infrared detector. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, a method based on TeO x The infrared detector of the thin-film heterojunction comprises, from bottom to top, the following layers stacked in sequence: ITO glass substrate, N-type buffer film, and P-type TeO. x Thin films and Au electrodes, including N-type buffer layer films and P-type TeO films. x The thin film forms a PN heterojunction;

[0037] The N-type buffer layer film can be any one of CdS film, ZnO film, TiO2 film, or SnO2 film.

[0038] Based on TeO x The method for fabricating a thin-film heterojunction infrared detector includes the following steps:

[0039] S1, ultrasonic cleaning of the ITO glass substrate;

[0040] S2, deposit an N-type buffer layer thin film on an ITO glass substrate;

[0041] S3, P-type TeO is deposited on an N-type buffer layer film using magnetron sputtering technology. x film;

[0042] S4, in P-type TeO x Gold electrodes are deposited on the thin film to obtain an infrared detector.

[0043] in:

[0044] In S1, the ITO glass substrate is 1cm×1cm. Before use, the ITO glass substrate should be cleaned for 10-15 minutes each in an ultrasonic cleaner with detergent, isopropanol with a purity greater than 99.5%, anhydrous ethanol with a purity of 99.99%, and deionized water.

[0045] In S2, when the N-type buffer layer film is a CdS film, the steps for depositing the N-type buffer layer film on the ITO glass substrate are as follows:

[0046] Pour 219.6 mL of deionized water into a 500 mL graduated cylinder containing water. Pour 15 mL of thiourea solution into a plastic graduated cylinder containing thiourea solution. Pour 30 mL of cadmium sulfate solution into a plastic graduated cylinder containing cadmium sulfate solution. Pour 39.12 mL of ammonia solution (analytical grade) into a graduated cylinder containing ammonia solution. After the temperature of the circulating water bath system stabilizes, pour the deionized water, ammonia solution, and cadmium sulfate solution into a clean 500 mL beaker (with a magnetic stir bar). Place the beaker in a jacketed beaker for preheating (water bath heating) while turning on the magnetic stirrer. After 3 minutes, pour in the thiourea solution, and then immerse the prepared ITO glass substrate in it (be careful not to touch the magnetic stir bar). Set the stopwatch to 17 minutes and start timing. Due to the decomposition and evaporation of ammonia during the experiment, some small bubbles will form on the substrate surface. Therefore, after about 4 minutes of timing, the ITO glass substrate needs to be pulled out of the liquid and then put back in to expel the bubbles. During the CdS deposition process, 300 mL of deionized water was pre-filled into a cleaning beaker. After the timing was completed, the ITO glass substrate was removed from the solution and ultrasonically cleaned in the cleaning beaker to remove large particles from the surface of the ITO glass substrate (ultrasonic power 40 W, time 30 s). Finally, it was dried with nitrogen gas. Subsequently, the CdS film was subjected to UVO treatment (or not); the water bath heating temperature was 70-75℃, and the UVO treatment time was 1 min-10 min.

[0047] In S2, when the N-type buffer layer film is a ZnO film, the N-type buffer layer film is deposited on the ITO glass substrate using magnetron sputtering technology. The specific process is as follows: the base vacuum level is 7×10⁻⁶. -4The sputtering pressure was 2-5 Pa, using a high-purity ZnO target (99.99%). A 2-minute pre-sputtering was performed before deposition to remove surface contaminants from the target. This was followed by 20 minutes of RF sputtering (100-200 W power) in an argon-oxygen mixed atmosphere (argon:oxygen flow rate ratio 99:1 sccm-99:20 sccm). Throughout the deposition process, the ITO glass substrate temperature was maintained at 0-200℃ to obtain N-type ZnO films with good crystallinity.

[0048] In S3, p-type TeO is deposited using magnetron sputtering technology. x The specific parameters for thin film preparation are as follows: the base vacuum is 7 × 10⁻⁶. -4 The sputtering pressure was 0.5-1.5 Pa, using a high-purity Te target (99.99%). A 2-minute pre-sputtering was performed before deposition to remove surface contaminants from the target, followed by 30 minutes of DC sputtering (20-50 W power) in an argon-oxygen mixed atmosphere (argon to oxygen flow rate ratio of 10:1 sccm-10:5 sccm). The substrate temperature was maintained at 100-300℃ throughout the deposition process to obtain P-type TeO with good crystallinity. x film.

[0049] In S4, P-type TeO x The process of depositing gold electrodes on thin films is as follows: a thin film with an N-type buffer layer and a P-type TeO film are deposited. x The thin-film ITO glass substrate was transferred to a vacuum chamber for thermal evaporation; a gold electrode (60 nm) was deposited on the p-type TeO using a metal mask. x Once the device is fabricated on the thin film layer, its performance is measured.

[0050] The technical solution of the present invention will be described below through the following embodiments;

[0051] Example 1

[0052] In this embodiment, CdS-TeO is introduced. x The fabrication process of a thin-film heterojunction infrared detector includes the following steps:

[0053] (1) Cleaning of ITO glass substrate: Ultrasonic cleaning with detergent, isopropanol, anhydrous ethanol and deionized water for 10-15 minutes respectively.

[0054] (2) Fabrication of N-type CdS thin film: Adjust the water bath to 72.5 degrees Celsius. In a beaker, add 220 ml of deionized water, 30 ml of cadmium sulfate, and 39.12 ml of ammonia in sequence. After preheating for 3 minutes, add 15 ml of thiourea to prepare a cadmium sulfide deposition solution. The cleaned substrate is clamped in a rack and vertically immersed in the deposition solution for 17 minutes. Then, remove the ITO glass, sonicate it, and blow it dry to obtain an N-type cadmium sulfide thin film. The prepared N-type cadmium sulfide thin film is treated with UVO for 4 minutes to prepare for the next step.

[0055] (3) P-type TeO x Thin film fabrication: P-type TeO was deposited on the substrate in (2) using magnetron sputtering technology. x Thin film. Specific preparation parameters are as follows: background vacuum level is 7 × 10⁻⁶. -4 The sputtering pressure was 1 Pa, and a high-purity Te target (99.99%) was used as the sputtering target. A 2-minute pre-sputtering was performed before deposition to remove surface contaminants from the target, followed by 30 minutes of DC sputtering (25 W power) in a mixed atmosphere of argon / oxygen flow rate at a ratio of 10:5 sccm. The substrate temperature was maintained at 200 °C throughout the deposition process to obtain P-type TeO with good crystallinity. x film.

[0056] (4) Device fabrication: In order to fabricate CdS-TeO x Thin-film photodetectors will incorporate CdS-TeO x The thin-film ITO glass substrate was transferred to a vacuum chamber for thermal evaporation. A gold electrode (60 nm) was deposited on the TeO film using a metal mask. x On the thin film layer, the device (CdS-TeO) x The fabrication of a thin-film heterojunction infrared detector has been completed.

[0057] Example 2

[0058] In this embodiment, ZnO-TeO is introduced. x The fabrication process of a thin-film heterojunction infrared detector includes the following steps:

[0059] (1) Cleaning of ITO glass substrate: Ultrasonic cleaning with detergent, isopropanol, anhydrous ethanol and deionized water for 10-15 minutes respectively.

[0060] (2) Preparation steps of N-type ZnO thin film: ZnO thin film was deposited on the substrate using magnetron sputtering technology. Specific preparation parameters are as follows: Base vacuum level: 7 × 10⁻⁶ -4The sputtering pressure was 3 Pa, using a high-purity ZnO target (99.99%). A 2-minute pre-sputtering was performed before deposition to remove surface contaminants from the target, followed by 20 minutes of RF sputtering (150 W power) in a mixed atmosphere of argon / oxygen flow rate at a ratio of 99:6 sccm. The substrate temperature was maintained at room temperature throughout the deposition process to obtain N-type ZnO films with good crystallinity, preparing for the next step.

[0061] (3) p-type TeO x Thin film fabrication: P-type TeO was deposited on the substrate in (2) using magnetron sputtering technology. x Thin film. Specific preparation parameters are as follows: background vacuum level is 7 × 10⁻⁶. -4 The sputtering pressure was 1 Pa, and a high-purity Te target (99.99%) was used as the sputtering target. A 2-minute pre-sputtering was performed before deposition to remove surface contaminants from the target, followed by 30 minutes of DC sputtering (25 W power) in a mixed atmosphere of argon / oxygen flow rate at a ratio of 10:5 sccm. The substrate temperature was maintained at 200 °C throughout the deposition process to obtain P-type TeO with good crystallinity. x film.

[0062] (4) Device fabrication: In order to fabricate ZnO-TeO x Thin-film photodetectors will incorporate ZnO-TeO x The thin-film ITO glass substrate was transferred to a vacuum chamber for thermal evaporation. A gold electrode (60 nm) was deposited on the TeO film using a metal mask. x The device fabrication is now complete on the thin film layer.

[0063] Example 3

[0064] CdS-TeO obtained in Example 1 x Thin-film heterojunction infrared detector and ZnO-TeO obtained in Example 2 x A thin-film heterojunction infrared detector is used for current-voltage and current-time measurements under infrared light (970nm).

[0065] 1) The process of current-voltage testing is as follows:

[0066] IV curves were measured using a KEITHLEY 2636B instrument under ambient conditions of 25°C and 60% relative humidity, using a calibrated light intensity of 111 mW / cm². 2 The IV curve was measured using a 970nm infrared light source;

[0067] Among them, CdS-TeO x The current and voltage test results of the thin-film heterojunction infrared detector are as follows: Figure 2As shown, UVO treatment significantly reduces residual organic impurities on the CdS film surface, leading to interface passivation, reduced surface oxygen vacancies, decreased interfacial recombination centers, and improved band alignment. This, in turn, improves the conductivity of the CdS film. Consequently, the device exhibits enhanced rectification characteristics, as demonstrated in testing.

[0068] ZnO-TeO x The current and voltage test results of the thin-film heterojunction infrared detector are as follows: Figure 4 As shown, it can be seen that ZnO and TeO x PN junctions composed of thin films also have a good rectification effect and very low dark current.

[0069] 2) The current-time test process is as follows: Under environmental conditions of room temperature 25℃ and relative humidity 60%, a calibrated light intensity of 111mW / cm² is used. 2 TeO under 0V voltage bias irradiation by a 970nm infrared light source x The optical detector was used to obtain the It response curve and calculate the relevant performance parameters.

[0070] CdS-TeO x Thin-film heterojunction infrared detectors and ZnO-TeO x The current-time test results of the thin-film heterojunction infrared detector are as follows: Figure 3 and Figure 5 As shown, it can be seen that the photocurrent of the device changes with time with good repeatability as the incident light is turned on and off, and the dark current can basically recover to the initial state quickly in each cycle. The baseline of the response curve does not shift up or down. This shows that the response curve of the device we fabricated is repeatable, standard and stable, which meets the requirements of high-performance photoconductive detectors.

[0071] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A TeO-based x The infrared detector of the thin-film heterojunction is characterized by, The layers, stacked from bottom to top, include: an ITO glass substrate, an N-type buffer film, and a P-type TeO film. x Thin film and Au electrode, the N-type buffer layer film and the P-type TeO x The thin film forms a PN heterojunction.

2. A method based on TeO as described in claim 1 x The infrared detector of the thin-film heterojunction is characterized by, The N-type buffer layer film is any one of CdS film, ZnO film, TiO2 film, and SnO2 film.

3. The TeO-based method as described in claim 1 or 2 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, Includes the following steps: S1, ultrasonic cleaning of the ITO glass substrate; S2, deposit an N-type buffer layer thin film on an ITO glass substrate; S3, P-type TeO is deposited on an N-type buffer layer film using magnetron sputtering technology. x film; S4, in P-type TeO x Gold electrodes are deposited on the thin film to obtain an infrared detector.

4. The TeO-based method according to claim 3 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, The ITO glass substrates were ultrasonically cleaned using detergent, isopropanol, anhydrous ethanol, and deionized water, respectively.

5. The TeO-based method according to claim 3 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, When the N-type buffer layer film is a CdS film, the steps for depositing the N-type buffer layer film on the ITO glass substrate are as follows: Deionized water, cadmium sulfate solution, and ammonia were mixed and heated in a water bath with stirring. Then, thiourea solution was added, and an ITO glass substrate was immersed in the mixture. CdS was deposited on the ITO glass substrate. The ITO glass substrate was then ultrasonically cleaned and dried. Finally, the CdS film on the ITO glass substrate was treated with UVO.

6. The TeO-based method according to claim 5 x A method for fabricating an infrared detector with a thin-film heterojunction, characterized in that, The water bath heating temperature is 70-75℃.

7. The TeO-based method according to claim 3 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, When the N-type buffer layer film is a ZnO film, the N-type buffer layer film is deposited on an ITO glass substrate using magnetron sputtering technology, and the steps include: The background vacuum is 7×10⁻⁻⁶ 4 Under sputtering pressure of 2-5 Pa, a high-purity ZnO target was used as the sputtering target material, and pre-sputtering was performed before deposition; then radio frequency sputtering was performed in a mixed atmosphere of argon and oxygen to obtain a ZnO thin film; the flow ratio of argon to oxygen was 99:1 sccm-99:20 sccm.

8. The TeO-based method according to claim 3 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, P-type TeO was deposited using magnetron sputtering technology. x The thin film process includes: The background vacuum is 7×10 -4 Under conditions of Pa and sputtering pressure of 0.5-1.5 Pa, using a Te target as the sputtering target, pre-sputtering was performed before deposition, followed by DC sputtering in a mixed atmosphere of argon and oxygen to obtain P-type TeO. x Thin film; the argon to oxygen flow rate ratio is 10:1 sccm to 10:5 sccm.

9. The TeO-based method according to claim 3 x A method for fabricating an infrared detector using a thin-film heterojunction, characterized in that, In P-type TeO x The process of depositing gold electrodes on thin films is as follows: A thin film with an N-type buffer layer and a P-type TeO x The thin-film ITO glass substrate was transferred to a vacuum chamber for thermal evaporation; gold electrodes were deposited on the p-type TeO using a metal mask. x On the thin film layer.

10. An imager based on a TFT chip, characterized in that, It is equipped with a TeO-based material as described in claim 1 or 2. x Infrared detectors for thin-film heterojunctions.

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