Black phosphorus photovoltaic detector based on graphene intercalation and preparation method thereof

Abstract

The invention discloses a graphene intercalation-based black phosphorus photovoltaic detector and a preparation method thereof. The graphene intercalation-based black phosphorus photovoltaic detector comprises a low-resistance silicon / silicon dioxide substrate, a left contact electrode, a right contact electrode and a sandwich structure layer from bottom to top, the left contact electrode and the right contact electrode are deposited on the low-resistance silicon / silicon dioxide substrate, and a conducting channel structure is formed between the left contact electrode and the right contact electrode; the sandwich structure layer is a sandwich structure constructed by an upper black phosphorus film layer, a middle graphene intercalation layer and a lower black phosphorus film layer, and is located in the conductive channel as a photosensitive region; and the left contact electrode and the right contact electrode are respectively in Schottky contact connection with the upper black phosphorus film layer and the lower black phosphorus film layer. According to the graphene intercalation-based black phosphorus photovoltaic detector and the preparation method thereof, visible light and infrared light can be efficiently detected at the same time, and the graphene intercalation-based black phosphorus photovoltaic detector has the excellent characteristics of low dark current, quick response, high-sensitivity low-power-consumption detection and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and in particular relates to a black phosphorus photovoltaic detector based on graphene intercalation and a preparation method thereof. Background Art

[0002] Photodetectors, devices that convert light signals into electrical signals, are widely used in various fields across the military and the national economy. In the military, photodetectors are used for high-precision detection tasks such as infrared night vision, missile guidance, and lidar. In the civilian sector, their applications include industrial automation, medical imaging, environmental monitoring, security surveillance, and consumer electronics. For example, in the visible and near-infrared bands, photodetectors are used for precision measurement tasks such as radiation measurement, photometry, and spectral analysis. In industrial production, they are used for automated inspection and quality control. In consumer electronics, they are used in scenarios such as smartphone cameras and facial recognition. However, photodetectors based on traditional semiconductor materials such as silicon (Si), gallium arsenide (GaAs), and indium gallium arsenide (InGaAs) generally suffer from narrow response bands and insufficient sensitivity. Silicon-based detectors are primarily suitable for visible light, with their response efficiency significantly declining in the near-infrared band. While GaAs and InGaAs detectors can cover parts of the infrared band, their response range is still limited and their manufacturing costs are high. In addition, commercial infrared detectors such as mercury cadmium telluride detectors usually need to work in ultra-low temperature environments, cooled to 77K by liquid nitrogen. This not only significantly increases equipment costs and energy consumption, but also limits their promotion in portable devices and integrated applications.

[0003] As an emerging two-dimensional material, black phosphorus has significant advantages in the field of photodetectors, mainly due to its unique structure and physical and chemical properties. First, it has the characteristic of adjustable band gap. The band gap of single-layer black phosphorus is about 2eV, while the band gap of multilayer or bulk black phosphorus is about 0.3eV. Its narrow band gap, excellent light absorption ability and high carrier mobility can reach 1000cm at room temperature. 2 / V·s provides a theoretical possibility for ultra-wide spectrum and high sensitivity photoelectric detection. Graphene is also an emerging two-dimensional material with its ultra-high carrier mobility of 200,000cm 2 / (V·s) and zero bandgap properties are widely used in various optoelectronic devices. In recent years, high-efficiency photodetectors based on two-dimensional semiconductor materials such as graphene and black phosphorus have made significant progress in scientific research and industrial production. For example, photodetectors based on black phosphorus / graphene van der Waals heterojunctions can achieve wide-spectrum detection from visible light to mid-infrared light, and have a fast response speed - microseconds; black phosphorus / black phosphorus homojunction devices have also been reported to show excellent optoelectronic performance. However, such devices still face two key problems: excessive dark current leads to a decrease in signal-to-noise ratio, which limits their application in low-light intensity environments. High bias voltage requirements require a large bias voltage to be applied to the source and drain, usually 1-5V, which significantly increases power consumption and limits its application in low-power scenarios.

[0004] Bulk photovoltaic detectors, due to their unique operating principles and technical advantages, have become an important solution to the challenges of low-power, high-sensitivity photoelectric detection. The traditional photovoltaic effect relies on the built-in electric field of the PN junction to drive carrier separation, while the bulk photovoltaic effect (BPVE) directly induces the asymmetric transition of photogenerated carriers through internal material symmetry breaking, such as polar crystal structure, heterojunction polarization, or strain gradient, and can generate photocurrent without the need for an external bias. This self-powered feature not only simplifies the device structure, but also significantly reduces dark current. For example, the dark current of a two-dimensional MoS2 / black phosphorus heterojunction can be as low as pA, thereby significantly improving the signal-to-noise ratio of weak light detection and demonstrating excellent performance in scenarios such as biosensing and deep space exploration. In recent years, research has further broken through the limits of bulk photovoltaics through material design and dynamic regulation: for example, the Hunan University team used the dual polarization synergistic effect of MoS2 / black phosphorus heterojunction to drive the photocurrent through in-plane polarization while accelerating carrier transport through out-of-plane polarization, achieving an intrinsic response time of 26ps and a bulk photovoltaic coefficient of 0.6V-1; Stanford University controlled the piezoelectric polarization of monolayer MoS2 through strain gradient, increasing the response speed to below 50ps; Tsinghua University developed ferroelectric HfO2 thin films integrated with CMOS processes to achieve low dark current at the micro-nano scale, with a dark current of <0.1nA and a high on-off ratio of >10 6 These advances not only deepen our understanding of ultrafast polarized carrier dynamics but also provide transformative solutions for high-speed optical communication sensing and imaging technologies, marking a crucial transition from fundamental research to practical applications of the bulk photovoltaic effect. Therefore, the design of bulk photovoltaic detection devices is an important approach to addressing the challenges of low-power, high-sensitivity photodetection.

[0005] Therefore, how to solve the problem of significantly reducing device power consumption and widening the response band without sacrificing detection performance, and provide a self-powered photovoltaic detection device that can operate under zero bias and has a wide band, high sensitivity, low dark current and fast response is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the Invention

[0006] The first object of the present invention is to provide a graphene-intercalated black phosphorus photovoltaic detector to address the problems in the prior art.

[0007] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A black phosphorus photovoltaic detector based on graphene intercalation, comprising, from bottom to top, a low-resistance silicon / silicon dioxide substrate, a left contact electrode, a right contact electrode, and a sandwich structure layer;

[0009] The left contact electrode and the right contact electrode are deposited on the low-resistance silicon / silicon dioxide substrate to form a conductive channel structure therebetween;

[0010] The sandwich structure layer is a sandwich structure constructed by an upper black phosphorus thin film layer, a middle graphene intercalation layer and a lower black phosphorus thin film layer, and is located in the conductive channel as a photosensitive area;

[0011] The left contact electrode and the right contact electrode form Schottky contact connections with the upper black phosphorus thin film layer and the lower black phosphorus thin film layer respectively.

[0012] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0013] As a preferred technical solution of the present invention: the ratio of the area of ​​the overlapping region of the upper black phosphorus thin film layer and the lower black phosphorus thin film layer in the vertical direction to the area of ​​the graphene intercalation layer is 1:1.5, and the upper black phosphorus thin film layer and the lower black phosphorus thin film layer do not contact each other.

[0014] As a preferred technical solution of the present invention: the thickness of the upper black phosphorus thin film layer and the lower black phosphorus thin film layer are both 10nm-70nm, and the thickness of the middle graphene intercalation layer is 5nm-30nm.

[0015] As a preferred technical solution of the present invention: the thickness of the portion where the upper black phosphorus thin film layer contacts the left contact electrode is increased to 50 nm-70 nm.

[0016] As a preferred technical solution of the present invention: the upper black phosphorus thin film layer and the lower black phosphorus thin film layer are both composed of a single layer or multiple layers of black phosphorus, and the graphene intercalation layer is composed of multiple layers of graphene.

[0017] As a preferred technical solution of the present invention: the material of the left contact electrode and the right contact electrode includes at least one of gold, silver and chromium.

[0018] As a preferred technical solution of the present invention: the left contact electrode and the right contact electrode adopt a laminated structure of a chromium layer and a gold layer, wherein the thickness of the chromium layer is 5nm-10nm, and the thickness of the gold layer is 20nm-50nm;

[0019] The distance between the left and right contact electrodes is 15 μm-20 μm.

[0020] As a preferred technical solution of the present invention: the sandwich structure layers are connected by van der Waals forces to form a stable van der Waals heterojunction.

[0021] The second object of the present invention is to provide a method for preparing a graphene-intercalated black phosphorus photovoltaic detector in response to the problems in the prior art.

[0022] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0023] The preparation scheme of the black phosphorus photovoltaic detector based on graphene intercalation includes the following steps: first, the left contact electrode and the right contact electrode are pre-evaporated and deposited on the low-resistance silicon / silicon dioxide substrate, forming a conductive channel structure between the two electrodes; the sandwich structure constructed by the upper and lower layers of black phosphorus films and the middle graphene intercalation acts as a photosensitive area located in the conductive channel, and the left contact electrode and the right contact electrode are respectively in contact with the upper and lower layers of black phosphorus films.

[0024] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0025] As a preferred technical solution of the present invention: the upper and lower layers of black phosphorus film and the graphene intercalation layer are prepared by a mechanical exfoliation method.

[0026] Compared with the prior art, the black phosphorus bulk photovoltaic detector based on graphene intercalation and the preparation method thereof of the present invention have the following beneficial effects: the present invention inserts an intermediate graphene intercalation between the upper and lower black phosphorus films to form a black phosphorus / graphene / black phosphorus heterojunction structure, and the high carrier mobility of graphene constructs a fast transmission channel, which significantly improves the separation and collection efficiency of photogenerated carriers; at the same time, graphene effectively passivates and modifies the surface defects of black phosphorus, reduces non-radiative recombination losses, and improves the efficiency of photogenerated carriers. At the same time, in the sandwich structure, the upper and lower black phosphorus layers form the same built-in electric field with the graphene, and a built-in electric field is formed at the interface between graphene and black phosphorus, realizing efficient photoelectric conversion under zero bias, and inducing a bulk photovoltaic effect through spontaneous interface polarization, realizing efficient self-powered photoelectric detection under zero bias. The present invention combines the transmission advantages of graphene with the optical properties of black phosphorus through a black phosphorus / graphene / black phosphorus (BP / G / BP) sandwich heterojunction structure, achieving efficient self-powered photodetection under zero bias, and providing a new type of high-performance self-powered photodetector with great application prospects in environmental monitoring, infrared imaging, spectral analysis and other fields.

[0027] In addition, by optimizing the black phosphorus thickness in the electrode contact area to 50-70nm and regulating the energy band structure to transform into a low-barrier Schottky contact, the dark current is effectively reduced, enabling the detector to have ultra-low noise characteristics while maintaining high responsiveness.

[0028] The present invention successfully solves the problems of large dark current, high power consumption, insufficient sensitivity and narrow detection band of traditional photodetectors through the innovative design of graphene intercalation sandwich structure, and realizes zero-bias, high-sensitivity, wide-band and low-power photodetection. The detector of the present invention shows excellent performance in the visible light to infrared band: the specific detection rate at room temperature is improved, the response time is as fast as microseconds, and it can work without external bias, which effectively reduces power consumption. The black phosphorus photovoltaic detector based on graphene intercalation of the present invention is based on the black phosphorus / graphene / black phosphorus heterostructure integrated by van der Waals forces, which not only solves the contradiction between wide-spectrum detection and low power consumption, but also realizes the controllable preparation of high-performance devices through simple processes such as mechanical peeling, providing a breakthrough solution for the new generation of environmental monitoring, spectral analysis and photoelectric sensing systems, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a front view of the atomic structure diagram of the device detection structure unit of Example 1 of the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of a black phosphorus photovoltaic detector based on graphene intercalation according to the present invention.

[0031] Figure 3 This is the photocurrent versus time curve of square wave modulated laser.

[0032] Figure 4 Graph showing the relationship between the photocurrent and the applied bias voltage under the conditions of 1550nm, 940nm and 638nm light irradiation in the absence of light.

[0033] Figure 5 The graphs are relationship graphs between the photocurrent and bias voltage at different positions of a black phosphorus photovoltaic detector based on graphene intercalation of the present invention under no light conditions and 1550nm light irradiation conditions.

[0034] Figure 6 The graph is a relationship curve between the photocurrent of a black phosphorus photovoltaic detector based on graphene intercalation and the illumination power of a 1550nm wavelength laser.

[0035] Figure 7 The graph is a graph of photocurrent versus time of a black phosphorus photovoltaic detector based on graphene intercalation according to the present invention under different square wave modulation frequencies under a 1550nm wavelength laser;

[0036] In the figure: low-resistance silicon / silicon dioxide substrate 1, left contact electrode 2, right contact electrode 3, upper black phosphorus film 4, graphene intercalation layer 5, lower black phosphorus film 6. DETAILED DESCRIPTION

[0037] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0038] To address the problems of existing photodetectors, such as excessive dark current, high power consumption, low sensitivity, and limited detection bands, this invention proposes a graphene-intercalated black phosphorus bulk photovoltaic detector. By incorporating a graphene-intercalated sandwich structure and utilizing the bulk photovoltaic effect, this detector significantly improves its high-efficiency visible and infrared detection capabilities, significantly expanding its application range.

[0039] Specifically, the photodetector provided by the present invention includes the following components: a silicon and SiO2 substrate, left and right contact electrodes, and a sandwich structure constructed by upper and lower black phosphorus thin films and an intermediate graphene intercalation layer. The left and right contact electrodes are pre-evaporated and deposited on the low-resistance silicon / silicon dioxide substrate, forming a conductive channel structure between the left and right contact electrodes. The sandwich structure constructed by the upper and lower black phosphorus thin films and the intermediate graphene intercalation layer serves as a photosensitive region located within the conductive channel. The left and right contact electrodes are Schottky-connected to the upper and lower black phosphorus thin film layers, respectively.

[0040] The working principle of this photodetector is as follows: by constructing a sandwich structure of graphene intercalation layers, the graphene intercalation layers serve as fast channels for carrier transport, significantly improving the detector's response speed. Graphene intercalation layers can also modify the surface defects of the black phosphorus film, allowing the black phosphorus film to generate photogenerated carriers more efficiently. Furthermore, the presence of graphene intercalation layers causes spontaneous polarization at the two interfaces, giving the photodetector a bulk photovoltaic effect. Furthermore, the synergistic effect of the upper and lower black phosphorus films enables the detector to have excellent photoelectric conversion efficiency in both the visible and infrared bands, achieving wide-band self-powered detection. At the same time, as the thickness of the upper black phosphorus film increases in contact with the metal electrode, the band gap shrinks, the work function adjusts, the quantum effect weakens, and the interface state changes work together, resulting in a significant change in the band alignment at the metal-semiconductor contact. These factors may transform the interface, which was originally close to an ohmic contact in the thin layer, into a contact with a small barrier, effectively reducing dark current and improving specific detectivity.

[0041] In the present invention, by introducing a sandwich structure of graphene intercalation and utilizing the bulk photovoltaic effect, the efficient detection capability of the zero-bias photodetector for visible light and infrared light at room temperature is significantly improved, and the power consumption of the detector is effectively reduced. Compared with the black phosphorus / black phosphorus homojunction photodetector in the prior art, the innovation of the present invention lies in the introduction of a graphene layer into the black phosphorus / black phosphorus homojunction to form a sandwich structure. This design effectively improves the light response of the detector to visible light to infrared light under no bias, and achieves high-performance and low-power detection. In addition, the photogenerated electron-hole pairs generated by the upper and lower layers of black phosphorus can be quickly and efficiently separated under the action of the graphene layer in the electric field, which greatly improves the photoelectric response speed of the detector. Furthermore, the detector achieves a combination of low dark current and high photoelectric response, giving it an ultra-high detectivity.

[0042] In the present invention, the substrate may be a low-resistance silicon / silicon dioxide substrate. In the present invention, the size of the substrate is not limited and may be selected according to actual needs.

[0043] In the present invention, the detection range of the detector is from visible to infrared band.

[0044] Optionally, the left and right contact electrodes are made of at least one of gold, silver, and chromium. In the present invention, the materials of the two electrodes can be the same or different, and there is no limitation on this.

[0045] Furthermore, both the left and right contact electrodes utilize a multilayer structure, including a connecting layer and a metal layer, with the connecting layer in direct contact with the substrate. More specifically, the connecting layer can be made of gold or chromium, while the metal layer can be made of at least one of gold, silver, and chromium. In the present invention, the connecting layer not only serves as a conductor but also enhances adhesion, forming a stronger bond between the metal layer and the substrate, thereby significantly improving the bonding strength between the left and right contact electrodes and the substrate.

[0046] As a preferred embodiment, the left and right contact electrodes can utilize a laminated structure of a chromium layer and a gold layer, with the chromium layer in contact with the substrate and the gold layer positioned above the chromium layer. Specifically, the thickness of the chromium layer can be controlled between 5nm and 10nm, while the thickness of the gold layer is preferably between 20nm and 50nm. This structural design not only ensures the electrode's electrical conductivity but also further optimizes the interface characteristics between the electrode and the substrate, providing a strong guarantee for the detector's stability and reliability.

[0047] Optionally, the thickness of the left and right contact electrodes is both 50 nm.

[0048] Optionally, a distance between the conductive channels between the left contact electrode and the right contact electrode is 15 μm-20 μm.

[0049] In the present invention, the upper and lower black phosphorus thin film layers are each composed of a single or multiple layers of black phosphorus, and the graphene intercalation layer is composed of multiple layers of graphene. Specifically, but not limited to, single-layer black phosphorus (band gap of approximately 2 eV) to multiple layers of black phosphorus (band gap of approximately 0.3 eV) are all direct band gaps, and graphene is a zero-band gap material.

[0050] Optionally, the thickness of the upper black phosphorus film layer is 10nm-70nm, and near the metal electrode, the upper black phosphorus film layer should be slightly thicker, with a thickness of 50nm-70nm. The thickness of the lower black phosphorus film layer is 10nm-70nm, and the thickness of the graphene intercalation layer is 5nm-30nm.

[0051] Furthermore, part of the upper black phosphorus thin film layer contacts the left electrode, and part of the lower black phosphorus thin film layer contacts the right electrode.

[0052] Optionally, the ratio of the vertical overlap area of ​​the upper and lower black phosphorus films to the graphene intercalation area is 1:1.5. This ratio design can prevent the upper and lower black phosphorus films from contacting each other, ensuring a stable bulk photovoltaic effect of the device.

[0053] In the present invention, the sandwich structure layers are connected by van der Waals forces to form a stable van der Waals heterojunction. This connection method not only ensures the stability of the overall structure of the photodetector, but also optimizes the interface characteristics of the heterojunction, thereby improving the overall performance of the detector.

[0054] The present invention provides a black phosphorus photovoltaic detector based on graphene intercalation, which can simultaneously and efficiently detect visible light and infrared light, and has excellent characteristics such as low dark current, fast response and high-sensitivity low-power detection.

[0055] In a second aspect, the present invention also provides a method for preparing a black phosphorus photovoltaic detector based on graphene intercalation, and the specific steps are as follows: First, the left contact electrode and the right contact electrode are pre-evaporated and deposited on the low-resistance silicon / silicon dioxide substrate, and a conductive channel structure is formed between the two electrodes. The sandwich structure constructed by the upper and lower layers of black phosphorus film and the middle graphene intercalation acts as a photosensitive area located in the conductive channel, and the left contact electrode and the right contact electrode are respectively in contact with the upper and lower layers of black phosphorus film. In the present invention, the upper and lower layers of black phosphorus film and the graphene intercalation can be prepared by mechanical exfoliation.

[0056] The beneficial effects of this invention lie in: by incorporating a graphene intercalation sandwich device structure, a bulk photovoltaic effect is achieved, effectively addressing the excessive power consumption of existing photodetectors, achieving low dark current, fast response, and high sensitivity for low-power detection. Furthermore, the preparation method provided by this invention is simple and easy to implement, providing reliable technical support for the large-scale production of high-performance, low-power photodetectors.

[0057] Example 1

[0058] like Figure 1 and Figure 2 As shown, a black phosphorus photovoltaic detector based on graphene intercalation of the present invention includes a low-resistance silicon / silicon dioxide substrate 1, a left contact electrode 2, a right contact electrode 3, an upper black phosphorus film 4, a graphene intercalation layer 5 and a lower black phosphorus film 6. The left contact electrode 2 and the right contact electrode 3 are constructed on the surface of the substrate 1, and a conductive channel structure is formed between the two. The sandwich structure constructed by the upper black phosphorus film 4, the lower black phosphorus film 6 and the intermediate graphene intercalation layer 5 acts as a photosensitive area located in the conductive channel, and the left contact electrode 2 and the right contact electrode 3 are in contact and connected with the upper black phosphorus film 4 and the lower black phosphorus film 6, respectively. The device was then placed on an optical probe platform for characterization, and the lasers of different wavelengths were changed to obtain the following. Figure 3 The photocurrent response of the device at zero bias is shown under square wave modulation of laser at 1550nm, 940nm, 638nm and 520nm wavelengths. Figure 4 Compare the photocurrent responses of the lasers with no light and at constant wavelengths of 1550nm, 940nm and 638nm. Figure 5 Compare the dark current of the device and the photocurrent response of the 1550nm wavelength laser in different positions, including vertical and horizontal structures. Then change the laser power to obtain the following Figure 6 The vertical structure position of the device shows the relationship between the photocurrent response and the laser power. Finally, the square wave modulation frequency of the laser is changed to obtain the following Figure 7 The photocurrent versus time curves at 400Hz, 1000Hz, and 2000Hz frequencies under a 1550nm wavelength laser are shown. In this invention, by introducing a sandwich structure with graphene intercalation, the photodetector not only efficiently detects visible and infrared light at room temperature, but also exhibits low power consumption and significantly improves its photoelectric response sensitivity. This structural design provides a new technical path for the development of high-performance photodetectors and has broad application prospects.

[0059] In the present invention, the specific material of the low-resistance silicon / insulating silicon dioxide substrate 1 can be selected according to actual needs. In one embodiment, the thickness of the low-resistance silicon / insulating silicon dioxide substrate 1 ranges from 100 μm to 1000 μm, more preferably from 300 μm to 800 μm, to meet the needs of different application scenarios.

[0060] In the present invention, the material of the left contact electrode 2 and the right contact electrode 3 can be selected from at least one of gold, silver and chromium. The materials of the left contact electrode 2 and the right contact electrode 3 can be the same or different, and there is no strict limitation on this. Furthermore, the left contact electrode 2 and the right contact electrode 3 adopt a multi-layer structure design, including a connecting layer and a metal layer, wherein the connecting layer is in direct contact with the low-resistance silicon / insulating silicon dioxide substrate 1. More specifically, the material of the connecting layer can be selected from chromium or titanium, and the material of the metal layer includes at least one of gold, silver and chromium. In the present invention, the connecting layer not only performs the conductive function, but also plays the role of enhancing adhesion, so that a stronger bond is formed between the metal layer and the low-resistance silicon / insulating silicon dioxide substrate 1, thereby significantly improving the bonding strength between the left contact electrode 2 and the right contact electrode 3 and the low-resistance silicon / insulating silicon dioxide substrate 1.

[0061] Optionally, the thickness of the connecting layer ranges from 5nm to 10nm, and the thickness of the metal layer ranges from 20nm to 40nm. In a specific embodiment of the present invention, the left contact electrode 2 and the right contact electrode 3 both adopt a laminated structure of a chromium layer and a gold layer, wherein the chromium layer contacts the substrate 1 and the gold layer is located on the chromium layer. The thickness of the chromium layer is controlled between 5nm and 10nm, while the thickness of the gold layer is preferably between 20nm and 40nm. This structural design further optimizes the interface characteristics between the electrode and the low-resistance silicon / insulating silicon dioxide substrate while ensuring the conductive performance of the electrode, providing a strong guarantee for the stability and reliability of the detector.

[0062] In the present invention, the distance between the left contact electrode 2 and the right contact electrode 3 is 15 μm to 20 μm, and the size of the conductive channel structure formed between the left contact electrode 2 and the right contact electrode 3 in the first direction is 15 μm to 20 μm.

[0063] In the present invention, the left contact electrode 2 and the right contact electrode 3 are in contact with the upper black phosphorus film 4 and the lower black phosphorus film 6 respectively. The left contact electrode can serve as a drain electrode, and the right contact electrode can serve as a source electrode.

[0064] In one embodiment of the present invention, the thickness of the upper black phosphorus film 4 is 10nm to 70nm, the thickness of the graphene intercalation layer 5 is 5nm to 30nm, and the thickness of the lower black phosphorus film 6 is 10nm to 70nm. This thickness design not only adjusts the response spectrum range of the photodetector but also helps achieve a low dark current effect.

[0065] In the present invention, the left contact electrode 2 is in contact with the upper black phosphorus film 4 but not directly with the graphene intercalation layer 5 or the lower black phosphorus film 6. The right contact electrode 3 is in contact with the lower black phosphorus film 6 but not directly with the upper black phosphorus film 4 or the graphene intercalation layer 5. This design not only enables efficient simultaneous detection of visible and infrared light, but also achieves high-performance zero-bias detection while effectively reducing dark current. This structural optimization provides important technical support for the development of high-performance photodetectors.

[0066] Example 2

[0067] The precision low-resistivity silicon / insulating silicon dioxide substrate with the electrode pattern was placed in an electron beam evaporator to deposit a chromium layer and a gold layer, respectively. The chromium layer was 5 nm thick, and the gold layer was 40 nm thick. After completion, the silicon substrate was removed, resulting in a low-resistivity silicon / insulating silicon dioxide substrate with left and right contact electrodes. The total thickness of the left and right contact electrodes was 45 nm, forming a conductive channel structure between them.

[0068] The black phosphorus and graphene were peeled off using Scotch tape and attached to a PDMS film. Subsequently, on a two-dimensional material fixed-point transfer platform, the upper black phosphorus film, the graphene intercalation layer, and the lower black phosphorus film were stacked in a sandwich structure within a conductive channel structure as a photosensitive region. The left contact electrode and the right contact electrode were in contact with the upper black phosphorus film and the lower black phosphorus film, respectively. Through the above steps, a bulk photovoltaic photodetector based on graphene intercalation was produced.

[0069] Effect embodiment

[0070] The present invention characterizes the performance parameters of the photodetector through a comprehensive test scheme system. After Example 1 and the comparative example device are placed in a semiconductor characteristic analyzer probe station, a double probe is used to contact the left and right electrodes of the device respectively. First, the light and dark alternating transient response caused by 1550nm, 940nm, 638nm and 520nm wavelength lasers (power intensity 60mA) is observed in zero bias square wave mode, and the photocurrent-time dynamic curve is recorded. Subsequently, a bias scan of -0.01V to 0.01V is applied to the drain, and the current-voltage characteristic curves under dark state and 1550nm, 940nm, and 638nm laser irradiation are obtained respectively, revealing the evolution law of photocurrent and dark current with bias voltage. Spatial resolution test is carried out for 1550nm laser (60mA), and the irradiation position of the light spot on the device surface is precisely adjusted. The photocurrent-bias voltage response difference of the three characteristic sites (single upper black phosphorus, single lower black phosphorus and vertical junction region) under dark state and illumination conditions is compared, and the spatial sensitivity distribution of device photoelectric conversion is established. The photocurrent was further quantified as a function of incident light intensity by modulating the 1550nm laser drive current (0-60mA). The device's dynamic response was also tested using square wave modulation frequencies of 400Hz, 1000Hz, and 2000Hz, fully capturing both power dependence and frequency response parameters. All tests were performed using NIST-calibrated light sources and certified metrology equipment to ensure data repeatability and accuracy.

[0071] The present invention discloses a black phosphorus photovoltaic detector based on graphene intercalation and a method for preparing the same. The detector comprises, from bottom to top, a low-resistance silicon / silicon dioxide substrate, left and right contact gold electrodes, and a sandwich structure constructed by upper and lower double-layer black phosphorus thin films and a middle graphene intercalation layer. The left and right contact electrodes are pre-evaporated and deposited on the low-resistance silicon / silicon dioxide substrate. A conductive channel structure is formed between the left and right contact electrodes. The sandwich structure constructed by the upper and lower black phosphorus thin films and the middle graphene intercalation layer serves as a photosensitive region located within the conductive channel. The left and right contact electrodes are in contact with the upper and lower black phosphorus thin film layers, respectively.

[0072] The bulk photovoltaic photodetector provided by the present invention has a small dark current and a high response value at zero bias voltage, thereby realizing high-sensitivity, wide-band, low-power photodetection at zero bias voltage. The present invention also provides a method for preparing a black phosphorus bulk photovoltaic detector based on graphene intercalation. Graphene, as an intermediate intercalation layer, effectively modifies the spontaneous polarization at the black phosphorus interface, thereby improving the mobility of photogenerated carriers. At the same time, the short channel accelerates the effective separation of electron-hole pairs and avoids the coincidence of carriers caused by defects on the black phosphorus surface, which is beneficial for the device to collect more photogenerated carriers. Compared with traditional devices, this design effectively improves the light response of the device at zero bias and realizes low-power detection from visible light to infrared. At the same time, the upper and lower black phosphorus thin film layers of the device can generate Schottky junctions with the contact electrodes, effectively reducing the dark current of the device while improving the specific detection rate. The preparation method of the device is simple and compatible with current semiconductor process technology, making the highly sensitive and low-power photodetection at room temperature valuable for promotion and use.

[0073] The black phosphorus photovoltaic detector based on graphene intercalation provided by the present invention can significantly realize the bulk photovoltaic effect, reduce dark current, improve sensitivity, and achieve self-powered rapid response.

[0074] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. A black phosphorus photovoltaic detector based on graphene intercalation, characterized by: From bottom to top, it includes a low-resistance silicon / silicon dioxide substrate, a left contact electrode, a right contact electrode, and a sandwich structure layer; The left contact electrode and the right contact electrode are deposited on the low-resistance silicon / silicon dioxide substrate to form a conductive channel structure therebetween; The sandwich structure layer is a sandwich structure constructed by an upper black phosphorus thin film layer, a middle graphene intercalation layer and a lower black phosphorus thin film layer, and is located in the conductive channel as a photosensitive area; The left contact electrode and the right contact electrode form Schottky contact connections with the upper black phosphorus thin film layer and the lower black phosphorus thin film layer respectively.

2. The black phosphorus photovoltaic detector according to claim 1, characterized in that: The ratio of the area of ​​the overlapping region of the upper black phosphorus film layer and the lower black phosphorus film layer in the vertical direction to the area of ​​the graphene intercalation layer is 1:1.5, and the upper black phosphorus film layer and the lower black phosphorus film layer do not contact each other.

3. The graphene intercalated black phosphorus photovoltaic detector according to claim 1, characterized in that: The thickness of the upper black phosphorus thin film layer and the lower black phosphorus thin film layer are both 10nm-70nm, and the thickness of the graphene intercalation layer is 5nm-30nm.

4. The graphene intercalated black phosphorus photovoltaic detector according to claim 3, characterized in that: The thickness of the upper black phosphorus film layer in contact with the left contact electrode increases to 50nm-70nm.

5. The graphene intercalation-based black phosphorus photovoltaic detector according to claim 3, characterized in that: The upper black phosphorus film layer and the lower black phosphorus film layer are both composed of a single layer or multiple layers of black phosphorus, and the middle graphene intercalation layer is composed of multiple layers of graphene.

6. The graphene intercalated black phosphorus photovoltaic detector according to claim 1, characterized in that: The left contact electrode and the right contact electrode are made of at least one of gold, silver and chromium.

7. The graphene intercalated black phosphorus photovoltaic detector according to claim 6, characterized in that: The left contact electrode and the right contact electrode adopt a laminated structure of a chromium layer and a gold layer, wherein the thickness of the chromium layer is 5nm-10nm and the thickness of the gold layer is 20nm-50nm; The distance between the left and right contact electrodes is 15 μm-20 μm.

8. The graphene intercalated black phosphorus photovoltaic detector according to claim 1, characterized in that: The sandwich structure layers are connected by van der Waals forces to form a stable van der Waals heterojunction.

9. The method for preparing a black phosphorus photovoltaic detector based on graphene intercalation according to any one of claims 1 to 8, characterized in that: The following steps are involved: First, the left contact electrode and the right contact electrode are pre-evaporated and deposited on the low-resistance silicon / silicon dioxide substrate, forming a conductive channel structure between the two electrodes; the sandwich structure constructed by the upper and lower layers of black phosphorus films and the middle graphene intercalation layer acts as a photosensitive area located in the conductive channel, and the left contact electrode and the right contact electrode are respectively in contact with the upper and lower layers of black phosphorus films.

10. The method for preparing a black phosphorus photovoltaic detector based on graphene intercalation according to claim 9, characterized in that: The upper and lower layers of black phosphorus films and graphene intercalation were prepared by mechanical exfoliation.

Images