A preparation method of a PdSe2 / Bi2O2Se van der waals heterojunction self-driven photodetector
By preparing PdSe2 and Bi2O2Se nanosheets using CVD and constructing dry-transferred van der Waals heterojunctions, the band mismatch and interface contamination problems of existing two-dimensional heterojunction optoelectronic devices are solved, realizing a self-driven photodetector with a wide spectral response, suitable for flexible electronics and biomedical imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUIZHOU NORMAL UNIVERSITY
- Filing Date
- 2025-07-16
- Publication Date
- 2026-06-19
AI Technical Summary
Existing two-dimensional heterojunction optoelectronic devices suffer from problems such as band mismatch, interface contamination, narrow response band, and complex fabrication processes. In particular, the construction of van der Waals heterojunctions between PdSe2 and Bi2O2Se is a challenge, and high-quality, low-energy-consumption self-driven photoelectric detection has not yet been achieved.
PdSe2 and Bi2O2Se nanosheets were prepared by chemical vapor deposition (CVD), and a clean van der Waals heterojunction was constructed by dry transfer technology. Electrodes were formed by ultraviolet lithography and electron beam evaporation technology, and a self-driven photoelectric response was achieved without external bias voltage.
The high-quality PdSe2/Bi2O2Se heterointerface was successfully constructed, which expanded the response band of the device, improved its self-driving performance, and provided it with wide spectral response, low power consumption and high sensitivity, making it suitable for flexible electronics and biomedical imaging.
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Figure CN120786977B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optoelectronic device technology, specifically relating to a method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector. Background Technology
[0002] With the rapid development of information technology, wearable devices, environmental monitoring, and biomedicine, the demand for high-performance, low-power, and wide-spectrum response photodetectors is becoming increasingly urgent. In recent years, two-dimensional materials with atomic-level thickness have become an important material system for constructing novel optoelectronic devices due to their excellent optoelectronic properties, flexible heterogeneous integration capabilities, and potential for compatibility with flexible electronic devices.
[0003] Currently, photodetectors based on two-dimensional material heterostructures (such as black phosphorus / MoS2, WSe2 / MoTe2, SnS2 / MoS2, etc.) have exhibited advantages such as high responsivity, low dark current, and self-driving (References: Xia, F. et al., Nat. Photonics, 2014, 8, 899–907; Roy, T. et al., Nat. Nanotechnol., 2013, 8, 826–830). Among them, two-dimensional Bi2O2Se has attracted widespread attention in recent years due to its high electron mobility, wide-band photoresponse capability, and environmental stability, becoming a promising n-type two-dimensional semiconductor material. Existing research has utilized Bi2O2Se with materials such as WSe2 and SnS2 to construct heterojunction optoelectronic devices, relying on the built-in electric field generated at the heterojunction interface to achieve self-driven photoresponse (see: Adv. Funct. Mater. 2021, 31, 2008351).
[0004] However, existing two-dimensional heterojunction optoelectronic devices generally suffer from the following problems: 1) imperfect bandgap matching at the heterojunction interface limits effective carrier separation and photoresponse efficiency; 2) wet transfer is often used in the fabrication process, which easily introduces interface contamination and organic residues, affecting device performance and stability; 3) limited response capability in the near-infrared band makes it difficult to meet the practical application requirements of weak light imaging and infrared detection. Furthermore, although there have been preliminary studies in recent years on constructing heterostructures using PdSe2 combined with materials such as MoS2 and WS2 for photoelectric detection, there are no systematic reports on constructing van der Waals heterojunctions of PdSe2 and Bi2O2Se and achieving self-driven detection functionality. The main technical bottlenecks include the challenge of large-area controllable growth of PdSe2, the controllable exfoliation of Bi2O2Se nanosheets, and the complexity of bandgap modulation at the heterojunction interface. Therefore, a high-quality, low-energy-consumption, and simple fabrication method for PdSe2 / Bi2O2Se van der Waals heterojunction photodetectors is urgently needed. Summary of the Invention
[0005] (a) Technical problems to be solved
[0006] This invention aims to overcome the technical challenges of existing two-dimensional material heterojunction photodetectors, such as band mismatch, interface contamination, narrow response band, and complex fabrication process. It proposes a self-driven photodetector fabrication method based on PdSe2 / Bi2O2Se van der Waals heterostructure, which has the characteristics of wide spectrum response, high sensitivity and low power consumption.
[0007] (II) Technical Solution
[0008] To achieve the above objectives, the present invention provides the following preparation method, comprising the following steps:
[0009] (I) Preparation of nanosheets via chemical vapor deposition (CVD):
[0010] PdSe2 nanosheets and Bi2O2Se nanosheets were prepared by CVD process, respectively;
[0011] (II) Preparation of heterostructures:
[0012] PdSe2 nanosheets were transferred to the surface of Bi2O2Se nanosheets using a dry transfer technique to form a van der Waals heterostructure with a clean interface and tight interlayer coupling.
[0013] (III) Device Fabrication:
[0014] Cr / Au (5nm / 60nm) electrodes were deposited at both ends of the heterostructure using ultraviolet lithography and electron beam evaporation to form source and drain electrodes; then the device was subjected to thermal annealing at 150-200℃ for 1 hour in an argon atmosphere.
[0015] (iv) Photoelectric detection:
[0016] Without an external bias voltage, the resulting device achieves a self-driven photoelectric response in the 450–940 nm wavelength range.
[0017] Preferably, the method for preparing the PdSe2 nanosheets includes the following steps:
[0018] S1. High-purity PdCl2 powder and Se powder were selected as precursors;
[0019] S2. Place PdCl2 powder in the high-temperature zone of the CVD apparatus in a quartz boat, and place Se powder in the low-temperature zone at the inlet.
[0020] S3. Under an argon atmosphere, the temperature is raised to 650-750℃, and the temperature of the PdCl2 evaporation zone is controlled at 500-600℃, while the temperature of the Se source zone is controlled at 280-320℃.
[0021] S4. After maintaining the constant temperature reaction for 30-60 minutes, allow it to cool naturally to room temperature to obtain multilayer PdSe2 nanosheets.
[0022] Preferably, the method for preparing the Bi2O2Se nanosheets includes the following steps:
[0023] S1. Bi2O3 powder and Se powder were selected as precursors;
[0024] S2. Place Bi2O3 and Se powder separately in quartz boats at different temperature zones in a low-pressure CVD system;
[0025] S3. React in a mixed gas Ar / O2 atmosphere, controlling the Bi source region temperature at 520–620℃ and the Se source region temperature at 300–350℃;
[0026] S4. After reacting for 20-30 minutes, allow to cool naturally to obtain Bi2O2Se nanosheets.
[0027] Preferably, the thickness of the PdSe2 nanosheets is controlled in the range of 4–15 nm.
[0028] Preferably, the thickness of the Bi2O2Se nanosheets is controlled in the range of 10–20 nm.
[0029] Preferably, the dry transfer process uses polyvinyl alcohol (PVA) or polydimethylsiloxane (PDMS) as an auxiliary transfer medium. PVA is used to assist in peeling and transfer, so that PdSe2 nanosheets are precisely stacked on the surface of Bi2O2Se nanosheets, keeping the interface clean and achieving high-quality van der Waals heterostructure construction.
[0030] Preferably, under 520nm laser irradiation, the device exhibits a short-circuit current of not less than 100nA, an open-circuit voltage of not less than 0.35V, a response time of not more than 10ms, and a photocurrent switching ratio of not less than 10. 3 .
[0031] (III) Beneficial Effects
[0032] This invention provides a method for fabricating a self-driven photodetector using a PdSe2 / Bi2O2Se van der Waals heterojunction. It possesses the following advantages:
[0033] 1. Construction of high-quality PdSe2 / Bi2O2Se heterointerface: By using dry transfer methods, the integrity of the two-dimensional material lattice is maintained while avoiding interference from contaminants and residual solvents on the interface band, thereby improving the separation efficiency of photogenerated carriers.
[0034] 2. Expanding the device response band and improving self-driving performance: By utilizing the narrow bandgap characteristics of PdSe2 and the broadband response characteristics of Bi2O2Se, a stable built-in electric field is formed by constructing a p–n type van der Waals heterojunction, thereby realizing wide-spectrum, low-power photodetection without external voltage.
[0035] 3. Balancing process controllability and flexible integration capability: A fabrication process route with low thermal budget and high versatility is proposed, applicable to various substrates such as silicon, glass, and flexible polyimide, providing process support for the application of photodetectors in flexible electronics, biomedical imaging, and the Internet of Things. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of the PdSe2 / Bi2O2Se van der Waals heterojunction structure, which is a method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector proposed in this invention.
[0037] Figure 2 The image shows the IV curves of a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector fabricated according to the present invention under illumination and dark conditions; (a) dark state; (b) under different illumination conditions.
[0038] Figure 3 The images show the light response diagrams under different wavelengths of light for the fabrication method of the PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector proposed in this invention. Detailed Implementation
[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0040] Example 1:
[0041] This invention provides a method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector, comprising the following steps:
[0042] (I) Preparation of nanosheets via chemical vapor deposition (CVD):
[0043] PdSe2 nanosheets and Bi2O2Se nanosheets were prepared by CVD process, respectively;
[0044] (II) Preparation of heterostructures:
[0045] PdSe2 nanosheets were transferred to the surface of Bi2O2Se nanosheets using a dry transfer technique to form a van der Waals heterostructure with a clean interface and tight interlayer coupling.
[0046] (III) Device Fabrication:
[0047] Cr / Au (5nm / 60nm) electrodes were deposited at both ends of the heterostructure using ultraviolet lithography and electron beam evaporation to form source and drain electrodes; the device was then subjected to thermal annealing at 150°C for 1 hour in an argon atmosphere.
[0048] (iv) Photoelectric detection:
[0049] Without an external bias voltage, the resulting device achieves a self-driven photoelectric response in the 450nm wavelength range.
[0050] The dry transfer technology used in step (ii) mainly includes polyvinyl alcohol (PVA) or polydimethylsiloxane (PDMS) assisted transfer, which precisely stacks Bi2O2Se nanosheets onto PdSe2 to construct a clean and pollution-free vertical van der Waals heterostructure; under a microscope, the boundary is aligned and PVA or PDMS is slowly released to ensure close contact between crystals and no bubbles or wrinkles at the interface.
[0051] In step (iii), device construction mainly involves electrode construction and device integration. Electrode patterns are defined using standard ultraviolet lithography. Cr / Au (5nm / 60nm) is deposited as source / drain electrode metals using electron beam evaporation. Finally, thermal annealing or vacuum annealing (150℃, 30min) is used to improve electrode contact quality and interface stability.
[0052] The preparation method of PdSe2 nanosheets includes the following steps:
[0053] S1. High-purity PdCl2 powder and Se powder were selected as precursors;
[0054] S2. Place PdCl2 powder in the high-temperature zone of the CVD apparatus in a quartz boat, and place Se powder in the low-temperature zone at the inlet.
[0055] S3. Under an argon atmosphere, the temperature is raised to 750℃, and the temperature of the PdCl2 evaporation zone is controlled at 500℃, while the temperature of the Se source zone is controlled at 280℃.
[0056] S4. After maintaining the constant temperature reaction for 30 minutes, allow it to cool naturally to room temperature to obtain multilayer PdSe2 nanosheets.
[0057] In the preparation of PdSe2 nanosheets, a fresh sapphire or SiO2 / Si substrate is placed downstream and the system pressure is controlled at 50 Pa. After 30 minutes of reaction, the substrate is cooled to obtain large-sized PdSe2 sheets with a layered structure and good crystal orientation.
[0058] The preparation method of Bi2O2Se nanosheets includes the following steps:
[0059] S1. Bi2O2 powder and Se powder were selected as precursors;
[0060] S2. Place Bi2O3 and Se powder separately in quartz boats at different temperature zones in a low-pressure CVD system;
[0061] S3. React in a mixed gas Ar / O2 atmosphere, controlling the Bi source region temperature at 620℃ and the Se source region temperature at 350℃;
[0062] S4. After reacting for 30 minutes, the mixture was allowed to cool naturally to obtain Bi2O2Se nanosheets.
[0063] In the preparation of Bi2O2Se nanosheets, fresh mica or SiO2 / Si substrates are placed downstream, and after cooling, Bi2O2Se layered crystals with controllable thickness can be obtained.
[0064] The thickness of the PdSe2 nanosheets was controlled within the range of 4 nm.
[0065] The thickness of the Bi2O2Se nanosheets was controlled within the range of 10 nm.
[0066] The dry transfer process uses polyvinyl alcohol (PVA) or polydimethylsiloxane (PDMS) as an auxiliary transfer medium. PVA is used to assist in peeling and transfer, and PdSe2 nanosheets are precisely stacked on the surface of Bi2O2Se nanosheets, keeping the interface clean and achieving high-quality van der Waals heterostructure construction.
[0067] Under 520nm laser irradiation, the device exhibits a short-circuit current of no less than 100nA, an open-circuit voltage of no less than 0.35V, a response time of no more than 10ms, and a photocurrent on / off ratio of no less than 10. 3 .
[0068] Example 2:
[0069] This invention provides a method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector, comprising the following steps:
[0070] (I) Preparation of nanosheets via chemical vapor deposition (CVD):
[0071] PdSe2 nanosheets and Bi2O2Se nanosheets were prepared by CVD process, respectively;
[0072] (II) Preparation of heterostructures:
[0073] PdSe2 nanosheets were transferred to the surface of Bi2O2Se nanosheets using a dry transfer technique to form a van der Waals heterostructure with a clean interface and tight interlayer coupling.
[0074] (III) Device Fabrication:
[0075] Cr / Au (5nm / 60nm) electrodes were deposited at both ends of the heterostructure using ultraviolet lithography and electron beam evaporation to form source and drain electrodes; the device was then subjected to thermal annealing at 180°C for 3 hours in an argon atmosphere.
[0076] (iv) Photoelectric detection:
[0077] Without an external bias voltage, the resulting device achieves a self-driven photoelectric response in the 940nm wavelength range.
[0078] The preparation method of PdSe2 nanosheets includes the following steps:
[0079] S1. High-purity PdCl2 powder and Se powder were selected as precursors;
[0080] S2. Place PdCl2 powder in the high-temperature zone of the CVD apparatus in a quartz boat, and place Se powder in the low-temperature zone at the inlet.
[0081] S3. Under an argon atmosphere, the temperature is raised to 650℃, and the temperature of the PdCl2 evaporation zone is controlled at 550℃, while the temperature of the Se source zone is controlled at 300℃.
[0082] S4. After maintaining the constant temperature reaction for 60 minutes, allow it to cool naturally to room temperature to obtain multilayer PdSe2 nanosheets.
[0083] The preparation method of Bi2O2Se nanosheets includes the following steps:
[0084] S1. Bi2O2 powder and Se powder were selected as precursors;
[0085] S2. Place Bi2O3 and Se powder separately in quartz boats at different temperature zones in a low-pressure CVD system;
[0086] S3. React in a mixed gas Ar / O2 atmosphere, controlling the Bi source region temperature at 580℃ and the Se source region temperature at 320℃;
[0087] S4. After reacting for 20-30 minutes, allow to cool naturally to obtain Bi2O2Se nanosheets.
[0088] The thickness of the PdSe2 nanosheets was controlled within the range of 15 nm.
[0089] The thickness of the Bi2O2Se nanosheets was controlled within the range of 20 nm.
[0090] The dry transfer process uses polyvinyl alcohol (PVA) or polydimethylsiloxane (PDMS) as an auxiliary transfer medium. PVA is used to assist in peeling and transfer, and PdSe2 nanosheets are precisely stacked on the surface of Bi2O2Se nanosheets, keeping the interface clean and achieving high-quality van der Waals heterostructure construction.
[0091] Under 520nm laser irradiation, the device exhibits a short-circuit current of no less than 100nA, an open-circuit voltage of no less than 0.35V, a response time of no more than 10ms, and a photocurrent on / off ratio of no less than 10. 3 .
[0092] By optimizing material selection, heterogeneous structure design, and device integration methods, we have achieved breakthroughs in multiple aspects and superior device performance, the main achievements of which are as follows:
[0093] 1. Achieving self-driven photoelectric detection with a wide spectral response
[0094] The constructed PdSe2 / Bi2O2Se heterojunction, based on a pn bandgap mechanism, forms a significant built-in electric field. Without the need for an external bias voltage, the built-in electric field enables effective separation of photogenerated carriers, resulting in a stable photocurrent and demonstrating excellent self-driving performance. This structure can respond to laser irradiation in the visible to near-infrared band (450–940 nm), exhibiting a broad spectral response capability, making it suitable for various optoelectronic applications, including environmental monitoring, bioimaging, and smart wearables.
[0095] 2. Low power consumption and energy-saving
[0096] Because the device requires no external bias voltage during operation, its power consumption is extremely low, making it particularly suitable for power-sensitive applications such as edge computing and smart sensor networks. This "zero-power standby" characteristic is an advantage that traditional active photodetectors cannot achieve, and it has significant engineering application value and promising prospects for widespread adoption.
[0097] 3. High switching ratio and low dark current
[0098] The band structure of heterojunctions exhibits a significant barrier control effect, suppressing carrier flow in the dark state and thus significantly reducing the device's dark current (in the ~nA range). Under illumination, the built-in electric field rapidly drives carrier separation, generating a large photocurrent, and the device exhibits a high photoelectric on / off ratio (I0). on / I off >10 3This improved the signal-to-noise ratio and ensured the accuracy and stability of the detection signal.
[0099] 4. Good stability and strong environmental adaptability
[0100] Both PdSe2 and Bi2O2Se are stable two-dimensional materials with layered structures, exhibiting good stability in air and resistance to oxidation. Furthermore, their van der Waals interfaces are free of lattice mismatches and do not require chemical bonding, resulting in excellent overall structural stability and anti-interference capabilities, which is beneficial for long-term service and adaptation to complex environments.
[0101] In summary, the PdSe2 / Bi2O2Se heterojunction self-driven photodetector proposed in this invention combines high performance, low power consumption, wide spectral response, and manufacturing compatibility. It overcomes the shortcomings of existing photodetectors, such as the need for external bias voltage, high dark current, and high energy consumption. It has significant technological progress and practical value, and provides an effective solution and theoretical basis for the development of a new generation of low-energy optoelectronic devices.
[0102] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector, characterized in that: Includes the following steps: (a) Preparation of nanosheets via chemical vapor deposition (CVD): PdSe2 nanosheets and Bi2O2Se nanosheets were prepared by CVD process, respectively; (II) Preparation of heterostructures: PdSe2 nanosheets were transferred to the surface of Bi2O2Se nanosheets using a dry transfer technique to form a van der Waals heterostructure with a clean interface and tight interlayer coupling. (III) Device fabrication: Cr / Au electrodes were deposited at both ends of a heterostructure using ultraviolet lithography and electron beam evaporation techniques. The thickness of Cr was 5 nm and the thickness of Au was 60 nm, forming source and drain electrodes. The device was then subjected to heat annealing at 150-200 °C for 1-5 hours under an argon atmosphere. (iv) Photoelectric detection: Without an external bias voltage, the resulting device achieves a self-driven photoelectric response in the 450–940 nm wavelength range.
2. The method for preparing a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 1, characterized in that: The preparation method of the PdSe2 nanosheets includes the following steps: S1. High-purity PdCl2 powder and Se powder were selected as precursors; S2. Place PdCl2 powder in the high-temperature zone of the CVD apparatus in a quartz boat, and place Se powder in the low-temperature zone at the inlet. S3. Under an argon atmosphere, the temperature is raised to 650~750 ℃, and the temperature of the PdCl2 evaporation zone is controlled at 500~600 ℃, and the temperature of the Se source zone is controlled at 280~320 ℃; S4. After maintaining the constant temperature reaction for 30-60 minutes, allow it to cool naturally to room temperature to obtain multilayer PdSe2 nanosheets.
3. The method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 1, characterized in that: The preparation method of the Bi2O2Se nanosheets includes the following steps: S1. Bi2O3 powder and Se powder were selected as precursors; S2. Place Bi2O3 and Se powder separately in quartz boats at different temperature zones in a low-pressure CVD system; S3. React in a mixed gas Ar / O2 atmosphere, controlling the Bi source region temperature at 520–620 ℃ and the Se source region temperature at 300–350 ℃; S4. After reacting for 20-30 minutes, allow to cool naturally to obtain Bi2O2Se nanosheets.
4. The method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 2, characterized in that: The thickness of the PdSe2 nanosheets is controlled within the range of 4–15 nm.
5. The method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 1, characterized in that: The thickness of the Bi2O2Se nanosheets is controlled within the range of 10–20 nm.
6. The method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 1, characterized in that: The dry transfer technique uses polyvinyl alcohol (PVA) or polydimethylsiloxane (PDMS) as an auxiliary transfer medium. PVA is used to assist in peeling and transfer, and PdSe2 nanosheets are precisely stacked on the surface of Bi2O2Se nanosheets, keeping the interface clean and achieving high-quality van der Waals heterostructure construction.
7. The method for fabricating a PdSe2 / Bi2O2Se van der Waals heterojunction self-driven photodetector according to claim 1, characterized in that: Under 520 nm laser irradiation, the device exhibits a short-circuit current of not less than 100 nA, an open-circuit voltage of not less than 0.35 V, a response time of not more than 10 ms, and a photocurrent on / off ratio of not less than 10. 3 .