Preparation method and application of high-sensitivity photoelectric detector based on Cr2Ge2Te6

Abstract

The invention discloses a preparation method and an application of a high-sensitivity photoelectric detector based on Cr2Ge2Te6. The design method comprises the following steps of: obtaining single-layer or few-layer Cr2Ge2Te6 by using a silver-assisted stripping method, and transferring the single-layer or few-layer Cr2Ge2Te6 to a clean SiO2 / Si substrate by using a PDMS / PVA (Polydimethylsiloxane / Polyvinyl Alcohol) film; and finally, plating titanium at two ends of the Cr2Ge2Te6 to serve as metal electrodes. The structure of the prepared photoelectric detector is a titanium electrode / Cr2Ge2Te6 / titanium electrode. According to the test of a photoelectric test probe station, under the condition that the voltage of the electrodes at the two ends ranges from-1 V to 1 V, lasers with different wavelengths and different powers are additionally arranged on the Cr2Ge2Te6 photoelectric detector, the Cr2Ge2Te6 photoelectric detector can detect visible light (405 nm, 532 nm and 635 nm) and near-infrared light (808 nm) with the optical power density of 30-50 [mu] W / cm < 2 >, and light current is improved by one order of magnitude compared with dark current under weak laser irradiation.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detectors, and more specifically, relates to a preparation method and application of a high-sensitivity photoelectric detector based on Cr2Ge2Te6. Technical Background

[0002] Due to their unique physicochemical properties, two-dimensional materials are considered ideal candidates for building next-generation optoelectronic devices, demonstrating enormous potential for applications in photodetectors, light-emitting diodes, and optical modulators. The discovery of the two-dimensional ferromagnetic material Cr2Ge2Te6 offers a new direction for conventional two-dimensional devices. Cr2Ge2Te6 possesses a band gap of 0.7 eV, enabling it to absorb photons from the visible to the near-infrared wavelength range, suggesting significant potential for broadband photodetection. The preparation of high-quality two-dimensional materials is a cornerstone of device research. While traditional mechanical exfoliation methods can yield high-quality samples, they suffer from extremely low yields and uncontrollable size. To efficiently and reliably obtain large-scale, high-quality single or few-layer Cr2Ge2Te6, we employed a silver-assisted exfoliation method. This technique leverages the strong interlayer interaction between silver and Cr2Ge2Te6, as well as the inherent stress of the silver film, to effectively overcome interlayer van der Waals forces, enabling large-scale, high-quality exfoliation of few or even single layers of Cr2Ge2Te6. Compared with traditional methods, the silver-assisted stripping method has significantly improved the yield and sample size, laying a solid material foundation for the subsequent batch preparation and performance research of devices.

[0003] Therefore, we tried to use the silver-assisted exfoliation method to exfoliate single-layer or few-layer Cr2Ge2Te6 and prepare it as a photodetector, and studied its photoelectric properties at visible light wavelengths and near-infrared light wavelengths. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing the above-mentioned Cr2Ge2Te6 photodetector. The method is tested by a photoelectric test probe station. When a voltage of -1V to 1V is applied to the two electrodes, the Cr2Ge2Te6 photodetector can detect 30-50μW / cm 2 The optical power density of visible light (405nm, 532nm, 635nm) and near-infrared light (808nm) is high, and the photocurrent is an order of magnitude higher than the dark current under weak laser irradiation, which will help promote the further development of two-dimensional ferromagnetic materials in the field of high-sensitivity photodetectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 This is an optical microscope image of the photodetector of Example 1.

[0006] Figure 2This is an AFM atomic force microscope image of the photodetector in Example 1.

[0007] Figure 3 This is a Raman spectrum detection diagram of the photodetector in Example 1.

[0008] Figure 4 When a voltage of -1V to 1V is applied to the two electrodes of the photodetector of Example 1, the Cr2Ge2Te6 photodetector can detect 30-50μW / cm 2 Optical power density of visible light (405nm, 532nm, 635nm) and near infrared light (808nm).

[0009] Figure 5 A voltage of 1 V is applied to the two electrodes of the photodetector of Example 1, and the wavelength is 45.9 μW / cm 2 Photoresponse output curve under laser irradiation with different optical power densities. DETAILED DESCRIPTION

[0010] The present invention will be further described below in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0011] Example 1.

[0012] Step 1. Ultrasonic clean the SiO2 / Si substrate using acetone, anhydrous ethanol, and deionized water for 5 minutes respectively, and then blow dry using a nitrogen gun.

[0013] Step 2. Cut a piece of PDMS of appropriate size, stick the side with the soft film removed to the mechanically peeled Cr2Ge2Te6 tape and press for 15 seconds, then stick the PDMS to the copper-based substrate with double-sided tape.

[0014] Step 3. Using a thermal evaporation coating apparatus, evaporate metallic silver onto the copper-based substrate with Cr2Ge2Te6 at a constant rate.

[0015] Step 4. Use thermal release tape to transfer Cr2Ge2Te6 from the copper-based substrate to the cleaned SiO2 / Si substrate, and heat to remove the thermal release tape.

[0016] Step 5. The etching solution is prepared by mixing potassium iodide (KI), elemental iodine (I2), and deionized water. It is divided into three equal parts. The SiO2 / Si substrate with Cr2Ge2Te6 is placed in the three parts of etching solution in turn for five minutes each. Then, it is soaked in acetone, isopropanol, and deionized water in turn for five minutes each. Finally, it is dried to obtain a small layer of Cr2Ge2Te6 on the SiO2 / Si substrate.

[0017] Step 6. Cut a piece of PDMS of appropriate size and stick one side of the hard film to a glass slide. Apply the PVA solution with a rubber-tipped dropper and then scrape it with a clean glass slide until it is flat. Place it on a heating plate at 55°C for 10 minutes to dry.

[0018] Step 7. After finding a suitable sample under the five-fold microscope on the two-dimensional material transfer platform, switch to the ten-fold microscope to refocus, place the slide with PVA in the card slot, find a clean PVA area, press until there are no bubbles around it, and heat it.

[0019] Step 8. Use a needle to separate the PVA with the sample from the SiO2 / Si substrate, place it on the PDMS with the sample facing up, check whether the sample is successfully transferred to the PVA, select a suitable area on the clean SiO2 / Si substrate, press the PVA until there are no bubbles around it, and heat it.

[0020] Step 9. Place the Cr2Ge2Te6 device made by the silver-assisted stripping method into the coating machine, use a glue-tipped dropper to evenly apply photoresist on the surface of the silicon wafer, select multi-step spin coating to run the coating machine, and after coating, place the substrate on a heating table at 105°C and dry it for 4 minutes.

[0021] Step 10. Place the dried device into a photolithography machine and photolithographically pattern the two ends of Cr2Ge2Te6 as electrodes.

[0022] After photolithography is completed, the device is quickly placed in the developer. After 18 seconds, the device is transferred to deionized water, and then the deionized water on the surface is blown away with a nitrogen gun.

[0023] Step 11. Use a high vacuum electron beam evaporation coating machine to coat the device with titanium and gold.

[0024] Step 12. After evaporation, immerse the substrate in an acetone solution and use a rubber-tipped dropper to rinse off excess gold on the substrate. Then place it in anhydrous ethanol to remove the acetone solution, then use deionized water to clean the device surface, and finally blow dry with an air gun.

[0025] Step 13: Anneal the prepared device at 200° C. in an inert atmosphere for 30 minutes.

[0026] Figure 1 This is an optical microscope image of the photodetector of Example 1.

[0027] Figure 2 This is an AFM atomic force microscope image of the photodetector in Example 1. Through analysis software, it can be seen that the thickness of Cr2Ge2Te6 in Example 1 is about 15nm.

[0028] Figure 3 This is a Raman spectrum detection diagram of the photodetector in Example 1.

[0029] Figure 4 When a voltage of -1V to 1V is applied to the two electrodes of the photodetector of Example 1, the Cr2Ge2Te6 photodetector can detect 30-50μW / cm 2 Optical power density of visible light (405nm, 532nm, 635nm) and near infrared light (808nm). Figure 3 It can be seen that the Cr2Ge2Te6 photodetector has a good photoresponse under weak light of four wavelengths, and the photocurrent is improved by an order of magnitude compared to the dark current.

[0030] Figure 5 For the photodetector of Example 1, a voltage of 1 V is applied to the source and drain, and the wavelength is 45.9 μW / cm 2 The light response output curve under laser irradiation with different optical power density. Figure 4 It can be seen that the Cr2Ge2Te6 photodetector responds to it with high sensitivity, and has a very obvious light response when the laser starts and stops irradiating.

[0031] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A Cr2Ge2Te6 photodetector with high sensitivity detection, wherein the few-layer Cr2Ge2Te6 is stripped using a silver-assisted stripping method, and the Cr2Ge2Te6 high-sensitivity photodetector has high sensitivity detection of visible light wavelengths (405nm, 532nm, 635nm) and near-infrared wavelengths (808nm).

2. The method for preparing Cr2Ge2Te6 according to claim 1, comprising the following specific steps: Step 1. Ultrasonic clean the SiO2 / Si substrate using acetone, anhydrous ethanol, and deionized water for 5 minutes respectively, and then blow dry using a nitrogen gun. Step 2. Cut a piece of PDMS of appropriate size, stick the side with the soft film removed to the mechanically peeled Cr2Ge2Te6 tape and press for 15 seconds, then stick the PDMS to the copper-based substrate with double-sided tape. Step 3. Using a thermal evaporation coating apparatus, evaporate metallic silver onto the copper-based substrate with Cr2Ge2Te6 at a constant rate. Step 4. Use thermal release tape to transfer Cr2Ge2Te6 from the copper-based substrate to the cleaned SiO2 / Si substrate, and heat to remove the thermal release tape. Step 5. The etching solution is prepared by mixing potassium iodide (KI), elemental iodine (I2), and deionized water. It is divided into three equal parts. The SiO2 / Si substrate with Cr2Ge2Te6 is placed in the three parts of etching solution in turn for five minutes each. Then, it is soaked in acetone, isopropanol, and deionized water in turn for five minutes each. Finally, it is dried to obtain a small layer of Cr2Ge2Te6 on the SiO2 / Si substrate. Step 6. Cut a piece of PDMS of appropriate size and stick one side of the hard film to a glass slide. Apply the PVA solution with a rubber-tipped dropper and then scrape it with a clean glass slide until it is flat. Place it on a heating plate at 55°C for 10 minutes to dry. Step 7. After finding a suitable sample under the five-fold microscope on the two-dimensional material transfer platform, switch to the ten-fold microscope to refocus, place the slide with PVA in the card slot, find a clean PVA area, press until there are no bubbles around it, and heat it. Step 8. Use a needle to separate the PVA with the sample from the SiO2 / Si substrate, place it on the PDMS with the sample facing up, check whether the sample is successfully transferred to the PVA, select a suitable area on the clean SiO2 / Si substrate, press the PVA until there are no bubbles around it, and heat it. Step 9. Place the Cr2Ge2Te6 device made by the silver-assisted stripping method into the coating machine, use a glue-tipped dropper to evenly apply photoresist on the surface of the silicon wafer, select multi-step spin coating to run the coating machine, and after coating, place the substrate on a heating table at 105°C and dry it for 4 minutes. Step 10. Place the dried device into a photolithography machine and photolithographically pattern the two ends of Cr2Ge2Te6 as electrodes. After the photolithography is completed, the device is quickly placed in the developer, and after 18 seconds, the device is transferred to deionized water. Then, a nitrogen gun was used to blow away the deionized water on the surface. Step 11. Use a high vacuum electron beam evaporation coating machine to coat the device with titanium and gold. Step 12. After evaporation, immerse the substrate in an acetone solution and use a rubber-tipped dropper to rinse off excess gold on the substrate. Then place it in anhydrous ethanol to remove the acetone solution, then use deionized water to clean the device surface, and finally blow dry with an air gun. Step 13: Anneal the prepared device at 200° C. in an inert atmosphere for 30 minutes.

3. The method for preparing Cr2Ge2Te6 according to claim 2, characterized in that: The evaporation data described in step 3 is a constant rate of 0.3 and a silver thickness of 160 nm.

4. The method for preparing Cr2Ge2Te6 according to claim 2, characterized in that: The heating data of the thermal release adhesive described in step 4 is a temperature of 130° C. and a heat preservation time of 50 seconds.

5. The method for preparing Cr2Ge2Te6 according to claim 2, characterized in that: The ratio of potassium iodide (KI), elemental iodine (I2), and deionized water described in step 5 is 4g:0.5g:40ml.

6. The method for preparing Cr2Ge2Te6 according to claim 2, characterized in that: The heating temperature in steps 7 and 8 is 90-100° C. and the heating time is 3-4 minutes.

7. The method for preparing Cr2Ge2Te6 according to claim 2, characterized in that: The evaporation data in step 11 are 10nm titanium, 50nm gold, titanium evaporation rate 0.1, gold evaporation rate 0.1 when 0-20nm, and 0.3 when 20-50nm.

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