Photoelectric detector with wide spectral response characteristic and preparation method and application thereof

Abstract

The invention provides a photoelectric detector with a wide spectral response characteristic and a preparation method and application thereof. The photoelectric detector adopts a two-dimensional device structure of Au / WSe2 / PbI2 / HfO2 / Si. The preparation process of the device comprises the following steps: firstly, preparing a two-dimensional PbI2 nanosheet on the surface of an HfO2 / Si substrate through a solution method; next, a Van der Waals integration process is adopted, WSe2 nanosheets are stacked on the surfaces of the PbI2 nanosheets, a WSe2 / PbI2 heterostructure is prepared, and the process needs to be operated highly accurately so as to ensure that a heterogeneous interface is clean and is in tight contact; and then accurately drawing and depositing a gold (Au) electrode on the surface of the WSe2 / PbI2 heterostructure by using electron beam exposure (EBL) and vacuum coating technologies. The photoelectric detector shows a wide-spectrum detection characteristic, and has good spectral response capability in ultraviolet, visible light and near-infrared ranges. And a solid material basis and technical support are provided for the fields of wide-spectrum imaging, optical communication and the like.

Description

Technical Field

[0001] The present invention relates to the fields of photoelectric sensing and detection technology and micro-nano processing technology, and innovatively proposes a photoelectric detector with wide spectral response characteristics and a preparation method thereof. The working range of the detector covers a wide spectral range such as ultraviolet, visible light, infrared, etc., meeting the needs of various application scenarios that require accurate detection of multiple spectra. At the same time, the present invention also covers a set of micro-nano processing technology, which has a high degree of versatility and applicability and can be widely used in the precision processing and manufacturing of micro-nano optoelectronic devices. Background Art

[0002] With the rapid development of science and technology, photodetectors, as key devices for converting optical signals into electrical signals, play an irreplaceable role in many fields such as optical imaging, environmental monitoring, biomedical testing and communication technology. Among them, the wide spectrum response characteristic has become one of the important indicators for measuring the performance of photodetectors.

[0003] Wide-spectrum detection technology is of great significance in multiple application fields: in the field of optical imaging, photoelectric detectors with wide-spectrum response can capture light information in multiple bands at the same time, significantly improving the authenticity and integrity of imaging; in environmental monitoring, since different pollutants have unique spectral characteristics, wide-spectrum detectors can achieve simultaneous monitoring of multiple pollutants; in biomedical testing, wide-spectrum response helps to obtain the characteristic spectral information of biological molecules, providing an important basis for disease diagnosis and treatment evaluation; in the field of communication technology, the application of wide-spectrum detectors can effectively expand the communication bandwidth and improve data transmission efficiency.

[0004] However, existing technologies still face many technical bottlenecks in achieving wide-spectrum detection. Traditional photodetectors are often only sensitive to specific bands, such as ultraviolet detectors, infrared detectors, and visible light detectors, each working in a different spectral region. In order to achieve wide-spectrum detection, a common solution is to integrate multiple detectors into the same system, but this approach not only increases the complexity and cost of the system, but also easily causes problems such as signal interference and system compatibility, which seriously restricts the promotion and application of wide-spectrum detection technology.

[0005] The existing wide-spectrum detectors on the market still have significant deficiencies in performance indicators: on the one hand, their spectral response range is narrow, making it difficult to meet the full-band detection requirements; on the other hand, there is a general problem of insufficient detection sensitivity within the wide spectral range, resulting in limited ability to capture weak light signals, affecting detection accuracy. These technical limitations make it difficult for existing wide-spectrum detectors to meet the increasingly high performance requirements in practical applications.

[0006] Therefore, developing a new type of wide-spectrum photodetector, breaking through the bottleneck of existing technology and improving detection performance has important theoretical value and practical significance. The present invention aims to provide a photodetector with excellent wide-spectrum response characteristics and a preparation method thereof, so as to solve the problems existing in the prior art and promote the innovative development of photodetection technology. Summary of the invention

[0007] The present invention aims to solve the limitations of existing photodetectors in terms of spectral response range. Traditional photodetectors are usually only sensitive to specific bands. For example, ultraviolet detectors, infrared detectors, and visible light detectors are each limited to working in different spectral regions and cannot meet the needs of full-band detection. The spectral response range of existing wide-spectrum detectors on the market is still relatively narrow, and it is difficult to adapt to the requirements of detecting a wider spectral region in practical applications, which limits its further development in multiple fields such as optical imaging, environmental monitoring, biomedical testing, and communication technology. Therefore, the technical problem to be solved by the present invention is how to design a photodetector that can simultaneously cover a wide spectral range of ultraviolet light, visible light, and infrared light to adapt to a variety of complex environments and application scenarios.

[0008] In order to solve the above technical problems, the technical solution proposed in the present invention is: a photodetector with wide spectral response characteristics, adopting a three-terminal transistor structure, mainly composed of a two-dimensional PbI2 / WSe2 heterostructure, a gate dielectric and an upper Au electrode. The two-dimensional PbI2 / WSe2 heterostructure is the core part responsible for realizing the wide spectral response function. This structural design can give full play to the advantages of both PbI2 and WSe2 materials, laying the foundation for achieving full-spectrum detection.

[0009] A photodetector with wide spectrum response characteristics, characterized in that: the photodetector has a five-layer structure, which is Au source and drain electrodes, WSe2 channel layer, PbI2 functional layer, HfO2 dielectric layer, and Si gate electrode from top to bottom. The device has wide spectrum performance.

[0010] The photodetector with wide spectrum response characteristics comprises two photoactive layers, WSe2 and PbI2. WSe2 mainly provides electrons for the device, and PbI2 mainly provides photons and ions for the device. The three types of information carriers work together to realize the function of the device. The two-dimensional PbI2 has extremely strong photoactive ion characteristics and is named as the photoactive ion layer.

[0011] In order to solve the above technical problem, another technical solution proposed by the present invention is: a method for preparing the photoelectric detector with wide spectral response characteristics, comprising the following steps:

[0012] (1) Cleaning the HfO2 / Si substrate: Use acetone, isopropanol and anhydrous ethanol to clean the HfO2 / Si substrate in an ultrasonic machine for 10 minutes each, and then blow dry with high-purity nitrogen for later use;

[0013] (2) Preparation of photoactivated ion layer: Directly grow two-dimensional PbI2 nanosheets on the surface of a clean HfO2 / Si substrate by solution method;

[0014] (3) Preparation of WSe2 / PbI2 heterojunction: The two-dimensional WSe2 nanosheets are transferred to the surface of the two-dimensional PbI2 nanosheets through the van der Waals integration process. The process is carried out in a nitrogen atmosphere to ensure that the interface between the two layers of materials is clean and in close contact;

[0015] (4) Preparation of source and drain electrodes: Using photolithography or EBL method combined with Auto CVD software, design the structure and electrode pattern with reasonable size on the surface of WSe2 / PbI2 heterojunction, and deposit metal electrode Au on the surface of heterojunction through thermal evaporation coating process.

[0016] Preferably, the specific parameters include: WSe2 is 1-4 layers with a thickness of 0.7-3 nm, PbI2 thickness is 1-5 nm, Au thickness is 60-100 nm, and channel width is 200 nm-5 μm.

[0017] Preferably, the preparation steps of the two-dimensional PbI2 nanosheets are as follows:

[0018] (1) Dissolve 10 mg of yellow granular PbI2 in 10 ml of ultrapure water and stir on a magnetic stirring table at 90 °C for more than 4 h to fully dissolve the PbI2 particles.

[0019] (2) The PbI2 solution was drop-coated on the substrate surface and heated at 40 °C on a hot plate until the water evaporated completely. Regularly shaped two-dimensional PbI2 nanosheets were formed on the substrate.

[0020] Preferably, the WSe2 layer can be prepared by mechanical stripping or chemical vapor deposition.

[0021] Preferably, the preparation steps of the WSe2 / PbI2 heterojunction are as follows:

[0022] (1) Preparation of WSe2: Mechanically exfoliated WSe2 is directly exfoliated onto PDMS to obtain WSe2 / PDMS; or WSe2 prepared by chemical vapor deposition is transferred by wet transfer technology, and WSe2 on the surface of the aqueous solution is extracted by PDMS during the transfer process to obtain WSe2 / PDMS;

[0023] (2) Transfer WSe2: Under the microscope, align the target WSe2 with the target PbI2 and keep it in contact at 80-90°C for 2-3 minutes;

[0024] (3) Obtaining a WSe2 / PbI2 heterojunction: Lift the thermal release tape to allow WSe2 to fall onto the PbI2 film, completing the preparation of the heterojunction.

[0025] Preferably, the steps of the surface Au electrode are as follows:

[0026] (1) Spin-coat PMMA-A4 and PMMA-A5 photoresists on the surface of the substrate with WSe2 / PbI2 heterojunction in sequence and bake them on a hot plate at 180°C for 90 s respectively;

[0027] (2) Find the area around the sample in the SEM and draw the alignment marks, develop the exposed alignment marks, and take photos with a microscope to record, locate the sample and draw the pattern;

[0028] (3) Align the mark and expose the sample;

[0029] (4) After development, the film is dried with a nitrogen gun and Au electrodes are deposited by thermal evaporation.

[0030] In order to solve the above technical problems, another technical solution proposed by the present invention is: application of the photoelectric detector with wide spectrum response characteristics, which has wide spectrum detection performance and is applied to the fields of optical imaging, environmental monitoring, biomedical detection and communication technology.

[0031] Preferably, the detector meets the detection requirements of the ultraviolet, visible or infrared bands; the specific spectral detection range is 200-1100 nm.

[0032] Beneficial effects:

[0033] (1) Wide spectral response range

[0034] The present invention is based on a two-dimensional PbI2 / WSe2 heterostructure design and achieves a wide spectrum response from ultraviolet to visible light to infrared. Compared with the photodetectors in the prior art that are limited to visible light or a single band detection, the present invention significantly expands the spectral range and can cover a wide spectrum region from ultraviolet to infrared light, meeting diverse application needs.

[0035] (2) Heterojunction synergy

[0036] The present invention adopts a heterojunction structure constructed by PbI2 and WSe2, which reduces the recombination rate of photogenerated carriers through the synergistic effect of materials, and significantly improves the uniformity and stability of spectral response. Compared with the shortcomings of the single material system in existing photodetectors, the heterojunction structure of the present invention can effectively optimize the interface photoelectric performance, thereby improving the spectral response range and efficiency.

[0037] (3) Wide spectrum detection capability applicable to multiple scenarios

[0038] Compared with the limitations of the single spectrum detector in the prior art, the wide spectrum response characteristics of the present invention make it suitable for a variety of complex scenarios, such as:

[0039] In the ultraviolet spectrum, it can be used for microbial detection and environmental monitoring;

[0040] In the visible spectrum, it can be used for target recognition and intelligent vision;

[0041] In the infrared spectrum, it can be used for thermal radiation detection and night vision imaging.

[0042] This feature significantly broadens the application areas of photodetectors and enhances their practical value.

[0043] (4) High-quality heterojunction interface design

[0044] The PbI2 / WSe2 heterojunction constructed by dry transfer technology ensures the high quality and stability of the interface. Compared with the unstable performance problem that may be caused by material interface defects in the prior art, the preparation process of the present invention effectively reduces the impact of interface defects and impurities, and significantly improves the performance and stability of the device.

[0045] (5) Strong process controllability

[0046] The present invention adopts a solution method to prepare PbI2 nanosheets and a mechanical exfoliation method to prepare WSe2 materials. These methods are simple and easy to implement with low cost. At the same time, the heterojunction is accurately constructed by dry transfer, which ensures the repeatability of the device and the possibility of mass production. Compared with the photodetectors in the prior art that rely on complex processes to prepare, the process of the present invention is more controllable and has higher practicality and promotion value.

[0047] (6) High responsiveness detection

[0048] The detector can detect light of different wavelengths from 405nm to 1064nm with high responsivity, among which the responsivity at 405nm reaches 67000000000A / W, the responsivity at 520nm reaches 20000000000A / W, the responsivity at 658nm reaches 1200000000A / W, the responsivity at 830nm reaches 69000000A / W, and the responsivity at 1064nm reaches 5200A / W. Based on the inverse relationship between the energy of light and its wavelength, the shorter the wavelength, the stronger the photon energy, and the energy of light below 405nm is stronger than that of light below 405nm. Therefore, from a theoretical analysis, this detector can effectively detect 405nm light, so for the light of the band below 405nm with stronger energy, it has the ability to effectively detect it under the same or better conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described below in conjunction with the accompanying drawings.

[0050] Figure 1 It is the WSe2 / PbI2 photoelectric-light-changing wavelength transfer curve of the present invention.

[0051] Figure 2 It is a bar graph of the response rates of two materials (WSe2 / PbI2 and WSe2) at different wavelengths of the present invention.

[0052] Figure 3 It is a device structure diagram of the present invention. DETAILED DESCRIPTION

[0053] Example 1

[0054] The present embodiment proposes a photodetector with a wide spectral response characteristic, as shown in FIG3 , which includes, from top to bottom, Au source and drain electrodes, WSe2 channel layer, PbI2 functional layer, HfO2 dielectric layer, and Si gate electrode. The specific parameters include: WSe2 is 1-4 layers (0.7-3 nm), PbI2 thickness is 1-5 nm, Au thickness is 60-100 nm, and channel width is 200 nm-5 μm. The specific steps are as follows:

[0055] Step 1) Use acetone, isopropanol and anhydrous ethanol to clean the HfO2 / Si substrate (Suzhou Jingsi Electronic Technology) in sequence in an ultrasonic machine for 10 minutes each, and then blow dry with high-purity nitrogen for later use;

[0056] Step 2) Take 10 mg of PbI2 raw material (yellow granules) and dissolve it in 10 ml of ultrapure water. Stir it on a magnetic stirring table at 90°C for more than 4 hours to fully dissolve the PbI2 particles.

[0057] Step 3) drop-coating the PbI2 solution on the surface of the HfO2 / Si substrate that has been cleaned in step 1, and heating it on a hot plate at 40°C until the water evaporates completely, and a two-dimensional PbI2 nanosheet with a regular shape is formed on the substrate;

[0058] Step 4) preparing a WSe2 layer, and directly peeling the mechanically peeled WSe2 onto the PDMS to obtain WSe2 / PDMS;

[0059] Step 5) Through the van der Waals integration process, under the microscope field of view, align the target WSe2 obtained in step 4 with the target PbI2 prepared in step 3, keep the fit at 80-90°C for 2-3 minutes, lift the thermal release tape to make WSe2 fall on the PbI2 film, and complete the preparation of the heterojunction. The process is kept in a nitrogen atmosphere to ensure that the interface of the two layers of materials is clean and in close contact.

[0060] Step 6) Spin-coating photoresists PMMA-A4 and PMMA-A5 on the surface of the substrate with the WSe2 / PbI2 heterojunction in sequence, and baking them on a hot plate at 180°C for 90s respectively;

[0061] Step 7) Find the area around the sample in the SEM and draw alignment marks. Develop the exposed alignment marks and take photos with a microscope to record the positioning of the sample and the pattern.

[0062] Step 8) performing mark alignment and sample exposure;

[0063] Step 9) After development, the film is dried with a nitrogen gun, and an electrode pattern with a reasonable structure and size is designed on the surface of the WSe2 / PbI2 heterojunction by the EBL method combined with the Auto CVD software, and a metal electrode (Au) is deposited on the surface of the heterojunction by a thermal evaporation coating process;

[0064] Step 10) The equipment used for the test is Keithley's 2612B series source meter and Blue Ocean Scientific low-temperature probe station, which are used in conjunction with Kickstart program control to achieve comprehensive measurement of the device. During the test, the gate voltage is fixed at ±6V and the bias voltage is 1V.

[0065] Figure 1 Shows: Fixed power is 3.75 μw / cm 2 At the same time, the detector can detect light in different wavelength bands from 405nm to 1064nm, reflecting good wide spectrum characteristics.

[0066] Example 2

[0067] This embodiment is basically the same as Embodiment 1, except that: Step 10): the measurement output result is the response of the photodetector under different wavelengths of light.

[0068] Figure 2 It shows that the detector can achieve high responsivity detection for different wavelength bands of light from 405nm to 1064nm, among which the responsivity at 405nm reaches 67000000000A / W, the responsivity at 520nm reaches 20000000000A / W, the responsivity at 658nm reaches 1200000000A / W, the responsivity at 830nm reaches 69000000A / W, and the responsivity at 1064nm reaches 5200A / W. Based on the inverse relationship between the energy of light and its wavelength, the shorter the wavelength, the stronger the photon energy, and the energy of light below 405nm is stronger than that of light below 405nm. Therefore, from a theoretical analysis, this detector can effectively detect 405nm light, so for the light below 405nm with stronger energy, it has the ability to achieve effective detection under the same or better conditions.

[0069] Comparative Example 1

[0070] This comparative example is basically the same as Example 2, except that: Step 2): a WSe2 layer is directly prepared on a cleaned HfO2 / Si substrate, omitting the preparation of PbI2 nanosheets.

[0071] Figure 2 It shows that the detector can only detect light in different wavelength bands from 405nm to 658nm, among which the responsivity at 405nm reaches 2511254A / W, the responsivity at 520nm reaches 1463769A / W, and the responsivity at 658nm reaches 51347A / W, which is much lower than the responsivity of Example 2.

[0072] The present invention adopts a heterojunction structure constructed by PbI2 and WSe2, which reduces the recombination rate of photogenerated carriers through the synergistic effect of materials, and significantly improves the uniformity and stability of spectral response. Compared with the shortcomings of the single material system in existing photodetectors, the heterojunction structure of the present invention can effectively optimize the interface photoelectric performance, thereby improving the spectral response range and efficiency.

[0073] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. A photodetector having a wide spectral response characteristic, characterized in that: The photodetector has a five-layer structure, which includes, from top to bottom, Au source and drain electrodes, WSe2 channel layer, PbI2 functional layer, HfO2 dielectric layer, and Si gate electrode.

2. The photoelectric detector with wide spectral response characteristics according to claim 1, characterized in that: It contains two photoactive layers, WSe2 and PbI2.

3. The method for preparing a photodetector having a wide spectral response characteristic according to claim 1, characterized in that: The following steps are involved: (1) Cleaning the HfO2 / Si substrate: Use acetone, isopropanol and anhydrous ethanol to ultrasonically clean the HfO2 / Si substrate in an ultrasonic machine, and then blow dry it with high-purity nitrogen for later use; (2) Preparation of photoactivated ion layer: Directly growing two-dimensional PbI2 nanosheets on the surface of a clean HfO2 / Si substrate by solution method; (3) Preparation of WSe2 / PbI2 heterojunction: The two-dimensional WSe2 nanosheets are transferred to the surface of the two-dimensional PbI2 nanosheets through the van der Waals integration process. The process is carried out in a nitrogen atmosphere to ensure that the interface between the two layers of materials is clean and in close contact; (4) Preparation of source and drain electrodes: Using photolithography or EBL method combined with Auto CVD software, design the structure and electrode pattern with reasonable size on the surface of WSe2 / PbI2 heterojunction, and deposit metal electrode Au on the surface of heterojunction through thermal evaporation coating process.

4. The method for preparing a photodetector having a wide spectral response characteristic according to claim 3, characterized in that: Specific parameters include: WSe2 is 1-4 layers with a thickness of 0.7-3 nm, PbI2 thickness is 1-5 nm, Au thickness is 60-100 nm, and channel width is 200 nm-5 μm.

5. The method for preparing a photoelectric detector having a wide spectral response characteristic according to claim 3, characterized in that: The preparation steps of two-dimensional PbI2 nanosheets are as follows: (1) Dissolve 10 mg of yellow granular PbI2 in 10 ml of ultrapure water and stir on a magnetic stirring table at 90 °C for more than 4 h to fully dissolve the PbI2 particles. (2) The PbI2 solution was drop-coated on the substrate surface and heated at 40 °C on a hot plate until the water evaporated completely. Regularly shaped two-dimensional PbI2 nanosheets were formed on the substrate.

6. The method for preparing a photoelectric detector having a wide spectral response characteristic according to claim 3, characterized in that: The WSe2 layer can be prepared by mechanical stripping or chemical vapor deposition.

7. The method for preparing a photoelectric detector having a wide spectral response characteristic according to claim 3, characterized in that: The preparation steps of the WSe2 / PbI2 heterojunction are as follows: (1) Preparation of WSe2: Mechanically exfoliated WSe2 is directly exfoliated onto PDMS to obtain WSe2 / PDMS; or WSe2 prepared by chemical vapor deposition is transferred by wet transfer technology, and WSe2 on the surface of the aqueous solution is extracted by PDMS during the transfer process to obtain WSe2 / PDMS; (2) Transfer WSe2: Under the microscope, align the target WSe2 with the target PbI2 and keep it in contact at 80-90°C for 2-3 minutes; (3) Obtaining a WSe2 / PbI2 heterojunction: Lift the thermal release tape to allow WSe2 to fall onto the PbI2 film, completing the preparation of the heterojunction.

8. The method for preparing a photoelectric detector having a wide spectral response characteristic according to claim 3, characterized in that: The steps for the surface Au electrode are as follows: (1) Spin-coat PMMA-A4 and PMMA-A5 photoresists on the surface of the substrate with WSe2 / PbI2 heterojunction in sequence and bake them on a hot plate at 180°C for 90 s respectively; (2) Find the area around the sample in the SEM and draw the alignment marks, develop the exposed alignment marks, and take photos with a microscope to record, locate the sample and draw the pattern; (3) Align the mark and expose the sample; (4) After development, the film is dried with a nitrogen gun and Au electrodes are deposited by thermal evaporation.

9. The use of the photodetector with wide spectral response characteristics according to claim 1, characterized in that: The detector has wide spectrum detection performance and is used in the fields of optical imaging, environmental monitoring, biomedical testing and communication technology.

10. The use of the photodetector with wide spectral response characteristics according to claim 1, characterized in that: The detector meets the detection requirements of ultraviolet, visible or infrared bands; the specific spectral detection range is 200-1100 nm.

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