A photodetector with wide spectral response characteristics and a preparation method and application thereof

Abstract

The application provides a photoelectric detector with wide spectrum response characteristics and a preparation method and application thereof, and the device adopts a two-dimensional device structure of Au / WSe2 / PbI2 / HfO2 / Si. The device preparation process is as follows: firstly, two-dimensional PbI2 nanosheets are prepared on the surface of a HfO2 / Si substrate through a solution method. Then, WSe2 nanosheets are stacked on the surface of the PbI2 nanosheets by adopting a van der Waals integration process to prepare a WSe2 / PbI2 heterostructure, and the process needs to be highly accurately operated to ensure that the hetero-interface is clean and in close contact. Subsequently, a gold (Au) electrode is accurately drawn and deposited on the surface of the WSe2 / PbI2 heterostructure by using electron beam lithography (EBL) and vacuum coating technology. The photoelectric detector exhibits wide spectrum detection characteristics and has good spectrum response capability in the ultraviolet, visible light and near-infrared ranges. The application provides a solid material foundation and technical support for the fields of wide spectrum imaging and optical communication.

Description

Technical Field

[0001] This invention relates to the fields of photoelectric sensing and detection technology and micro / nano fabrication technology, and innovatively proposes a photodetector with broad spectral response characteristics and its fabrication method. The detector operates over a wide spectral range, including ultraviolet, visible, and infrared light, meeting the needs of various applications requiring precise multispectral detection. Furthermore, this invention encompasses a set of micro / nano fabrication processes, which are highly versatile and applicable, and can be widely used in the precision manufacturing of micro / nano optoelectronic devices. Background Technology

[0002] With the rapid development of science and technology, photodetectors, as key devices that convert light signals into electrical signals, play an irreplaceable role in many fields such as optical imaging, environmental monitoring, biomedical detection, and communication technology. Among these, wide-spectrum response characteristics have become one of the important indicators for evaluating the performance of photodetectors.

[0003] Wide-spectral detection technology is of great significance in many application fields: In optical imaging, wide-spectral response photodetectors can simultaneously capture light information in multiple wavelength bands, significantly improving the realism and integrity of imaging; in environmental monitoring, due to the unique spectral characteristics of different pollutants, wide-spectral detectors can achieve simultaneous monitoring of multiple pollutants; in biomedical detection, wide-spectral response helps to obtain characteristic spectral information of biomolecules, providing important evidence for disease diagnosis and treatment evaluation; in the field of communication technology, the application of wide-spectral detectors can effectively expand communication bandwidth and improve data transmission efficiency.

[0004] However, existing technologies still face many technical bottlenecks in achieving broadband detection. Traditional photodetectors are often only sensitive to specific wavelengths; for example, ultraviolet detectors, infrared detectors, and visible light detectors each operate in different spectral regions. To achieve broadband detection, a common solution is to integrate multiple detectors into the same system. However, this approach not only increases system complexity and cost but also easily leads to signal interference and system compatibility issues, severely hindering the widespread application of broadband detection technology.

[0005] Currently available broadband detectors still have significant shortcomings in performance: on the one hand, their spectral response range is narrow, making it difficult to meet the needs of full-band detection; on the other hand, they generally suffer from insufficient detection sensitivity across a wide spectral range, resulting in limited ability to capture weak light signals and affecting detection accuracy. These technical limitations make it difficult for existing broadband detectors to meet the increasingly demanding performance requirements in practical applications.

[0006] Therefore, developing novel broadband photodetectors to overcome existing technological bottlenecks and improve detection performance has significant theoretical and practical value. This invention aims to provide a photodetector with excellent broadband response characteristics and its fabrication method, thereby addressing existing problems and promoting the innovative development of photodetector technology. Summary of the Invention

[0007] This invention aims to address the limitations of existing photodetectors in terms of spectral response range. Traditional photodetectors are typically sensitive only to specific wavelengths; for example, ultraviolet detectors, infrared detectors, and visible light detectors each operate within different spectral regions, failing to meet the requirements for full-spectrum detection. Existing broadband detectors on the market still have relatively narrow spectral response ranges, making it difficult to adapt to the requirements of detecting a wider spectral range in practical applications, thus limiting their further development in fields such as optical imaging, environmental monitoring, biomedical detection, and communication technologies. Therefore, the technical problem this invention aims to solve is how to design a photodetector that can simultaneously cover a wide spectral range of ultraviolet, visible, and infrared light to adapt to various complex environments and application scenarios.

[0008] To address the aforementioned technical problems, the present invention proposes a photodetector with a wide spectral response, employing a three-terminal transistor structure, primarily composed of a two-dimensional PbI2 / WSe2 heterostructure, a gate dielectric, and an upper Au electrode. The two-dimensional PbI2 / WSe2 heterostructure serves as the core component, responsible for achieving the wide spectral response function. This structural design fully leverages the advantages of both PbI2 and WSe2 materials, laying the foundation for achieving full-spectrum detection.

[0009] A photodetector with a wide spectral response is characterized by having a five-layer structure, consisting of an Au source / drain electrode, a WSe2 channel layer, a PbI2 functional layer, an HfO2 dielectric layer, and a Si gate electrode, from top to bottom. This device exhibits wide spectral performance.

[0010] The aforementioned photodetector with a wide spectral response comprises two photoactivation layers: WSe2 and PbI2. WSe2 primarily provides electrons for device operation, while PbI2 primarily provides photons and ions. These three types of information carriers work together to function the device. The two-dimensional PbI2 layer exhibits extremely strong photoactivation ionization properties and is thus named the photoactivation ionization layer.

[0011] To solve the above-mentioned technical problems, another technical solution proposed by the present invention is: a method for fabricating a photodetector with broad spectral response characteristics, comprising the following steps:

[0012] (1) Cleaning HfO2 / Si substrate: Clean the HfO2 / Si substrate by ultrasonication for 10 minutes each in an ultrasonic machine using acetone, isopropanol and anhydrous ethanol in sequence, and then dry it with high-purity nitrogen gas for later use.

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

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

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

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

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

[0018] (1) Dissolve 10 mg of yellow granular PbI2 raw material 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) PbI2 solution was drop-coated onto the substrate surface and heated at 40 °C on a hot plate until the moisture evaporated completely. Regularly shaped two-dimensional PbI2 nanosheets were formed on the substrate.

[0020] Preferably, the WSe2 layer can be prepared by either mechanical exfoliation 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 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 them in contact for 2 to 3 minutes at 80 to 90°C;

[0024] (3) Obtaining WSe2 / PbI2 heterojunction: Lifting the heat release tape causes WSe2 to fall onto the PbI2 film, thus completing the preparation of the heterojunction.

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

[0026] (1) Photoresist PMMA-A4 and PMMA-A5 were spin-coated sequentially on the surface of a substrate with WSe2 / PbI2 heterojunction, and then baked on a hot plate at 180°C for 90 s respectively.

[0027] (2) Locate the area around the sample in the scanning electron microscope and delineate alignment marks. Develop the exposed alignment marks and take pictures with a microscope to record them. Position the sample and delineate the pattern.

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

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

[0030] To address the aforementioned technical problems, another technical solution proposed by this invention is: the application of the photodetector with wide spectral response characteristics, which has wide spectral detection performance and can be applied in the fields of optical imaging, environmental monitoring, biomedical detection, and communication technology.

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

[0032] Beneficial effects:

[0033] (1) Wide spectral response range

[0034] This invention, based on a two-dimensional PbI2 / WSe2 heterostructure design, achieves a broad spectral response spanning ultraviolet-visible-infrared light. Compared to existing photodetectors limited to visible light or single-band detection, this invention significantly expands the spectral range, covering a wide spectral region from ultraviolet to infrared light, thus meeting diverse application requirements.

[0035] (2) Synergistic effect of heterojunctions

[0036] This invention employs a heterostructure constructed from PbI2 and WSe2, which reduces the recombination rate of photogenerated carriers through material synergy, significantly improving the uniformity and stability of the spectral response. Compared to the shortcomings of single-material systems in existing photodetectors, the heterojunction structure of this invention can effectively optimize the interfacial photoelectric properties, thereby improving the spectral response range and efficiency.

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

[0038] Compared to the limitations of single-spectral detectors in existing technologies, the wide spectral response characteristics of this invention make it suitable for a variety of complex scenarios, such as:

[0039] Within the ultraviolet spectral range, it can be used for microbial detection and environmental monitoring;

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

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

[0042] This characteristic 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 using dry transfer technology ensures high-quality and stable interfaces. Compared to the performance instability issues that may arise from material interface defects in existing technologies, the fabrication process of this invention effectively reduces the impact of interface defects and impurities, significantly improving device performance and stability.

[0045] (5) Strong process controllability

[0046] This invention employs a solution-based method to prepare PbI2 nanosheets and a mechanical exfoliation method to prepare WSe2 materials. These methods are simple, easy to implement, and low-cost. Furthermore, the precise construction of heterojunctions via dry transfer ensures the reproducibility of the devices and the possibility of mass production. Compared to existing photodetectors that rely on complex fabrication processes, the process of this invention is more controllable and has high practicality and promotional value.

[0047] (6) High-response detection

[0048] This detector achieves high responsivity for light across different wavelengths from 405nm to 1064nm. Specifically, the responsivity reaches 67000000000A / W at 405nm, 200000000000A / W at 520nm, 12000000000A / W at 658nm, 69000000A / W at 830nm, and 5200A / W at 1064nm. Based on the inverse relationship between light energy and wavelength, shorter wavelengths have higher photon energy; light below 405nm has higher energy than light below 405nm. Therefore, theoretically, if this detector can effectively detect 405nm light, it should also be able to effectively detect higher-energy light below 405nm under the same or even better conditions. Attached Figure Description

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

[0050] Figure 1 This is the WSe2 / PbI2 photoelectric-wavelength shift curve of the present invention.

[0051] Figure 2 This is a bar chart showing the responsivity of the two materials (WSe2 / PbI2 and WSe2) at different wavelengths according to the present invention.

[0052] Figure 3 This is a structural diagram of the device of the present invention. Detailed Implementation

[0053] Example 1

[0054] This embodiment proposes a photodetector with a wide spectral response, as shown in Figure 3. From top to bottom, it consists of Au source / drain electrodes, a WSe2 channel layer, a PbI2 functional layer, an HfO2 dielectric layer, and a Si gate electrode. Specific parameters include: 1-4 WSe2 layers (0.7-3 nm), PbI2 thickness of 1-5 nm, Au thickness of 60-100 nm, and channel width of 200 nm-5 μm. The specific steps are as follows:

[0055] Step 1) Clean the HfO2 / Si substrate (Suzhou Crystal Silicon Electronics Technology) by ultrasonication for 10 minutes each in an ultrasonic machine using acetone, isopropanol and anhydrous ethanol in sequence, and then dry it with high-purity nitrogen gas for later use.

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

[0057] Step 3) Drop-coat the PbI2 solution onto the surface of the HfO2 / Si substrate that has been cleaned in Step 1, and heat it at 40°C on a hot plate until the moisture evaporates completely, forming a regular two-dimensional PbI2 nanosheet on the substrate.

[0058] Step 4) Prepare the WSe2 layer by directly peeling the mechanically exfoliated WSe2 onto PDMS to obtain WSe2 / PDMS;

[0059] Step 5) Using van der Waals integration, under a microscope, align the target WSe2 obtained in Step 4 with the target PbI2 prepared in Step 3, keep them bonded at 80-90°C for 2-3 minutes, and lift the heat-release tape to allow WSe2 to fall onto the PbI2 film, thus completing the preparation of the heterojunction. The process is carried out in a nitrogen atmosphere to ensure that the interface between the two materials is clean and in close contact.

[0060] Step 6) Spin-coat photoresist PMMA-A4 and PMMA-A5 sequentially on the substrate surface with WSe2 / PbI2 heterojunction, and bake them on a hot plate at 180°C for 90s respectively.

[0061] Step 7) Locate the area around the sample in the scanning electron microscope and draw alignment marks. Develop the exposed alignment marks and record them by microscopic photography to locate the sample and draw the pattern;

[0062] Step 8) Align the markers and expose the sample;

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

[0064] Step 10) The equipment used for testing is a Keithley 2612B series source meter and a Blue Ocean Scientific low-temperature probe station. Kickstart program control is used 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 This indicates that the fixed power is 3.75 μW / cm. 2 At that time, the detector can detect light in different wavelength bands from 405nm to 1064nm, demonstrating good broadband characteristics.

[0066] Example 2

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

[0068] Figure 2 This indicates that the detector can achieve high responsivity for light in different wavelength ranges from 405nm to 1064nm. Specifically, the responsivity reaches 67000000000A / W at 405nm, 200000000000A / W at 520nm, 12000000000A / W at 658nm, 69000000A / W at 830nm, and 5200A / W at 1064nm. Based on the inverse relationship between light energy and wavelength, the shorter the wavelength, the stronger the photon energy; light below 405nm has stronger energy than light at 405nm. Therefore, theoretically, if this detector can effectively detect 405nm light, it should also be able to effectively detect higher-energy light below 405nm under the same or even better conditions.

[0069] Comparative Example 1

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

[0071] Figure 2 This indicates that the detector can only detect light in different wavelength ranges from 405nm to 658nm, with a responsivity of 2,511,254 A / W at 405nm, 1,463,769 A / W at 520nm, and 51,347 A / W at 658nm, which is far lower than the responsivity of Example 2.

[0072] This invention employs a heterostructure constructed from PbI2 and WSe2, which reduces the recombination rate of photogenerated carriers through material synergy, significantly improving the uniformity and stability of the spectral response. Compared to the shortcomings of single-material systems in existing photodetectors, the heterojunction structure of this invention can effectively optimize the interfacial photoelectric properties, 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. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.

Claims

1. A photodetector with a wide spectral response characteristic, characterized in that: the photodetector comprises, from top to bottom, an Au source-drain electrode, a WSe2 channel layer, a PbI2 functional layer, a HfO2 dielectric layer, and a Si gate electrode, a two-dimensional heterostructure is formed between WSe2 / PbI2 through van der Waals force, WSe2 is 1-4 layers, the thickness is 0.7-3 nm, the thickness of PbI2 is 1-5 nm, the thickness of Au is 60-100 nm, the channel width is 200 nm-5 mm, and the specific steps of the preparation method are as follows: Step (1) clean the HfO2 / Si substrate in an ultrasonic machine with acetone, isopropyl alcohol, and anhydrous ethanol for 10 minutes respectively, then blow dry with high-purity nitrogen for standby; Step (2) dissolve 10 mg of PbI2 raw material in 10 ml of ultrapure water, stir on a magnetic stirrer at 90°C for more than 4 hours to fully dissolve the PbI2 particles; Step (3) drop coat the PbI2 solution on the surface of the HfO2 / Si substrate cleaned in step (1), and heat on a hot plate at 40°C until the water is completely volatilized, forming a regular-shaped two-dimensional PbI2 nanosheet on the substrate; Step (4) prepare a WSe2 layer, directly peel the mechanically peeled WSe2 on the PDMS to obtain WSe2 / PDMS; 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 it at 80-90°C for 2-3 minutes, lift the thermal release tape to make the WSe2 fall on the PbI2 film, complete the preparation of the heterojunction, and the process is carried out in a nitrogen atmosphere to ensure that the interface of the two materials is clean and tightly contacted; Step (6) spin-coat photoresist PMMA-A4 and PMMA-A5 on the substrate surface with WSe2 / PbI2 heterojunction, and bake at 180°C for 90s on a hot plate respectively; Step (7) find the sample surrounding area in the scanning electron microscope and draw the alignment mark, develop the exposed alignment mark, and take a photo record with a microscope, position the sample and draw the pattern; Step (8) align the mark and expose the sample; Step (9) after development, blow dry with a nitrogen gun, design a structure and size reasonable electrode pattern on the surface of the WSe2 / PbI2 heterojunction through the EBL method combined with Auto CVD software, and deposit a metal electrode Au on the surface of the heterojunction through a thermal evaporation film deposition process; The detector meets the detection requirements of ultraviolet, visible, or infrared waveband; The specific spectral detection range is 200-1100 nm. ​

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