A silicon-based metal micro-bath array graphene photoelectric detector and a preparation method thereof

Abstract

The application discloses a silicon-based metal micro-pot array graphene photodetector and a preparation method thereof, and comprises a metal micro-pot array, which is composed of a plurality of concave metal micro-pot units; a graphene layer, which is covered above the metal micro-pot array and a surrounding area thereof and forms a Schottky junction with a semiconductor substrate; a top electrode, which is arranged on a surface of the graphene layer or an edge area thereof and is electrically connected with the graphene layer, and is used for collecting and outputting photo-generated carriers; the semiconductor substrate, which is provided with an insulating medium layer on a surface thereof, and a window structure exposing the substrate is formed in a photosensitive working area, and the window structure is used for defining a Schottky junction area and a distribution area of the metal micro-pot array; and a bottom contact electrode, which is arranged on a back surface of the semiconductor substrate and is used for realizing electrical connection between the semiconductor substrate and an external test circuit. The application solves the technical problems of the existing silicon-based graphene photodetector, such as limited light absorption efficiency and weak response in a near-infrared wave band.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection technology, and particularly relates to a silicon-based metal micro-basin array graphene photodetector and its preparation method. Background Technology

[0002] With the development of information technology, intelligent sensing, and optoelectronic imaging technology, broadband photodetectors capable of responding to ultraviolet, visible, and near-infrared light bands have wide-ranging application demands in machine vision, medical detection, environmental monitoring, and space remote sensing. Silicon-based photodetectors have played a crucial role in image sensing and photoelectric detection due to their mature technology, low cost, ease of large-area integration, and compatibility with existing semiconductor processes. However, traditional silicon-based photodetectors are limited by the intrinsic band gap and absorption characteristics of silicon materials, resulting in weak responses to near-infrared light, especially long-wavelength near-infrared light, making it difficult to meet the future development needs of broadband, high-sensitivity silicon-based intelligent sensing devices. In recent years, graphene, with its broadband absorption, high carrier mobility, and ability to form Schottky junctions with silicon, has been considered an important material for expanding the response range of silicon-based photodetectors. However, ordinary planar graphene / silicon photodetectors still suffer from limited light absorption efficiency, insufficient interface light field enhancement, and low photogenerated carrier collection efficiency. Therefore, combining graphene, micro / nano structures, and silicon-based devices is an important direction for achieving broadband, high-performance detection.

[0003] Chinese patent application CN112133777A discloses a core-shell quantum dot broadband photodetector and its fabrication method. This patent uses a single-crystal silicon substrate, a silicon oxide insulating layer, a graphene channel layer, and a core-shell quantum dot photosensitive dielectric layer to construct the broadband detector. It utilizes the broadband absorption characteristics of quantum dots and the high carrier mobility of graphene to improve the device's response performance. In this patent, the core-shell quantum dot photosensitive layer is formed by spin coating, and the quantum dot spectral absorption range is 250-1600 nm. However, quantum dot materials are easily affected by dispersion uniformity, film continuity, and interface stability during large-area fabrication, which may limit the batch consistency and long-term stability of the devices. Furthermore, the quantum dot solution processing also increases the complexity of device fabrication and post-processing.

[0004] Chinese patent CN112909118B discloses a differential conversion type broadband photodetector and its fabrication method. This patent uses a silicon substrate to form a heterojunction with semiconductor thin films such as titanium oxide, copper oxide, zinc oxide, or tin oxide, achieving a broadband response in the 280-1150 nm range and outputting the differential form of the light intensity signal as a current signal. However, this type of device focuses more on the differential conversion and dynamic detection of changing light signals. Its output signal is closely related to the rate of change of incident light intensity, and there are still certain limitations in conventional steady-state light intensity detection, broadband imaging, and signal readout methods in different application scenarios. Furthermore, its response range is mainly concentrated in the ultraviolet, visible, and near-infrared bands, and there is still room for improvement in the effective utilization of longer-band near-infrared light.

[0005] Chinese patent CN120051055B discloses a tunable broadband photodetector based on a Schottky junction and its fabrication method. This patent uses an N-type silicon substrate, a ferroelectric gate dielectric, a gate electrode, a source electrode, and a drain electrode to construct a silicon-based Schottky junction device. It utilizes the change in the polarization state of the ferroelectric dielectric to regulate the channel current, achieving near-infrared detection. However, this approach relies on the polarization regulation of the ferroelectric material, and its device performance may be affected by the quality of the ferroelectric thin film, polarization retention characteristics, fatigue effects, and pulse modulation conditions. Furthermore, this type of device requires applying different voltage pulses to the ferroelectric gate to achieve response adjustment, making the device operating mode and external control methods relatively complex. Further optimization is needed for stable detection in large-area arrays and for long-term repetitive operation.

[0006] Therefore, this invention proposes a silicon-based metal micro-basin array graphene photodetector and its fabrication method. Summary of the Invention

[0007] The purpose of this invention is to address the technical problems of limited light absorption efficiency and weak near-infrared response in existing silicon-based graphene photodetectors, and to provide a silicon-based metal micro-basin array graphene photodetector and its fabrication method. By controlling the photoresist development time and combining metal sputtering and lift-off processes, a three-dimensional metal micro-basin array is formed on the surface of a silicon substrate or insulating dielectric layer. Then, a macroscopically assembled graphene nanofilm is placed over the metal micro-basin array and the silicon layer to construct a graphene / silicon Schottky junction photosensitive structure, enhancing the effect of incident light in the photosensitive region. Under an applied bias voltage, the graphene / silicon Schottky junction can achieve effective separation and collection of photogenerated carriers, and the metal micro-basin array can enhance the reflection, scattering, and localization of incident light in the photosensitive region, thereby improving the photoelectric response performance in the ultraviolet, visible, and near-infrared bands.

[0008] The objective of this invention is achieved through the following technical solution: a silicon-based metal micro-basin array graphene photodetector, the photodetector comprising:

[0009] The metal micro-basin array is composed of multiple concave metal micro-basin units;

[0010] A graphene layer covers the metal micro-basin array and its surrounding area, and forms a Schottky junction with the semiconductor substrate;

[0011] The top electrode is disposed on the surface of the graphene layer or its edge region and is electrically connected to the graphene layer for collecting and outputting photogenerated carriers;

[0012] A semiconductor substrate having an insulating dielectric layer disposed on its surface and a window structure forming an exposed substrate in a photosensitive working area, the window structure being used to define a Schottky junction region and a distribution area for a metal micro-basin array;

[0013] The bottom contact electrode is located on the back side of the semiconductor substrate and is used to realize the electrical connection between the semiconductor substrate and the external test circuit.

[0014] Furthermore, the metal micro-basin array and the graphene layer are combined to form a three-dimensional heterogeneous photosensitive structure. Through the reflection, scattering, local optical field modulation, and optical path enhancement of incident light by the metal micro-basin array, a wide spectrum of incident light at wavelengths of 375 nm, 532 nm, 1064 nm, and 1550 nm can be detected, improving the generation, separation, and collection efficiency of photogenerated carriers, thereby enhancing the photoelectric response and imaging capabilities of the device in the ultraviolet, visible, and near-infrared bands under room temperature conditions.

[0015] Furthermore, the semiconductor substrate is any one of silicon, germanium, indium gallium arsenide, gallium arsenide, cadmium telluride, indium phosphide, silicon carbide, gallium nitride, gallium oxide, indium selenide, or perovskite semiconductor materials.

[0016] Furthermore, when incident light irradiates the photodetector described in this invention, the graphene layer, the metal micro-basin array, and the silicon layer together constitute a three-dimensional composite Schottky photosensitive structure by utilizing the broad-spectrum absorption characteristics of the graphene layer, the photoelectric conversion characteristics of the silicon layer, and the three-dimensional light field modulation effect of the metal micro-basin array. In this structure, after the graphene layer comes into contact with the silicon layer, a graphene / silicon Schottky junction is formed at the interface, and there are band bending, a barrier region, and a built-in electric field at the Schottky junction interface. When incident light enters the device, some photons are absorbed by the graphene layer, generating photogenerated carriers within it. The remaining photons penetrate the graphene layer and enter the metal micro-basin array and silicon layer region, generating photogenerated electron-hole pairs in the silicon layer. Simultaneously, the metal micro-basin array, with its concave microcavity structure, reflects, scatters, extends the optical path multiple times, and enhances the local optical field of the incident light. This increases the intensity of the interaction between the incident light and the silicon layer at the graphene / silicon Schottky junction interface, thereby improving the light absorption efficiency and the photogenerated carrier generation efficiency. Under an applied bias voltage, the barrier height, depletion region width, and interface electric field distribution of the graphene / silicon Schottky junction are modulated. Photogenerated electrons and holes are effectively separated under the combined action of the built-in electric field and the applied electric field of the Schottky junction, and propagate along the graphene layer, silicon layer, and their interface, ultimately being collected by the top electrode and bottom contact electrode to form a photocurrent.

[0017] Furthermore, since the metal micro-basin array enhances the local optical field distribution and effective absorption path of the incident light near the Schottky junction interface, and the applied bias voltage improves the separation, transport, and collection efficiency of photogenerated carriers, this invention can achieve broadband photoelectric detection of incident light in the ultraviolet, visible, and near-infrared bands at room temperature, especially showing significant optical responses at wavelengths such as 375 nm, 532 nm, 1064 nm, and 1550 nm. By reading the change in response current under the applied bias voltage, real-time detection of the incident light signal intensity and broadband imaging applications can be achieved.

[0018] Further, the fabrication of the metal micro-basin array structure involves: spin-coating photoresist onto the surface of a silicon layer or insulating dielectric layer, and removing the solvent from the photoresist through pre-baking; subsequently, exposing and developing the photoresist using a photomask to form a periodically distributed photoresist pattern. By controlling the development time, the photoresist pattern is changed from an underdeveloped state to a fully developed or overdeveloped state, thereby forming a special contour structure with undercut, inclined sidewalls, or arc-shaped sidewalls at the edge of the photoresist. Then, a gold layer is deposited on the photoresist pattern and the exposed silicon layer or insulating dielectric layer surface using magnetron sputtering or physical vapor deposition, allowing the gold layer to be deposited along the photoresist sidewalls and the substrate surface, replicating the developed photoresist contour. Subsequently, the photoresist is removed using an organic solvent and stripped, removing the gold layer above the photoresist, leaving only the gold layer structure on the surface of the silicon layer or insulating dielectric layer, ultimately obtaining a three-dimensional metal micro-basin array composed of multiple concave metal micro-basin units.

[0019] Furthermore, the structural parameters of the metal micro-basin array are controlled according to actual needs by adjusting the photolithographic mask pattern, photoresist spin coating thickness, development time, developer concentration, metal sputtering time, and metal sputtering power. After the metal micro-basin array is formed, the graphene layer is transferred to the metal micro-basin array and its surrounding area, and the top electrode and bottom contact electrode are prepared, finally forming a three-dimensional composite Schottky photodetector structure composed of the graphene layer, the metal micro-basin array, the silicon layer, and the electrode.

[0020] Furthermore, the structural unit pattern of the metal micro-basin array is designed as a circular, elliptical, polygonal, or annular cavity structure, and multiple metal micro-basin units can be distributed in a periodic, quasi-periodic, or non-periodic array; the opening diameter of the metal micro-basin unit can be 0.5 μm-100 μm, the array period can be 1 μm-200 μm, the basin depth or sidewall height can be 100 nm-5000 nm, and the gold layer thickness can be 10 nm-500 nm.

[0021] Furthermore, the graphene layer is a macroscopically assembled graphene nanofilm or a multilayer graphene nanofilm. The macroscopically assembled graphene nanofilm can be a multilayer graphene film with consistent crystal orientation stacking angles, or a macroscopically assembled graphene nanofilm modified, composited, or doped with two-dimensional materials. The materials include bromine, molybdenum chloride, copper chloride, molybdenum disulfide, or metal nanoparticles. The macroscopically assembled graphene nanofilm is prepared by mechanical exfoliation, filtration sintering, liquid phase assembly, chemical vapor deposition, or transfer assembly, and then transferred onto the metal micro-basin array. Its thickness is controlled according to the actual light absorption and carrier transport requirements, and the thickness range is 5 nm-500 nm.

[0022] Furthermore, the bottom contact electrode forms an ohmic contact with the semiconductor substrate; the material of the bottom contact electrode is any one of gallium-indium alloy, aluminum, nickel silicide, titanium silicide, and cobalt silicide; the material of the top electrode is any one of gold, aluminum, platinum, titanium / gold composite metal layer, chromium / gold composite metal layer, nickel / gold composite metal layer, or indium tin oxide; the arrangement of the top electrode relative to the window structure is any one of symmetrical distribution, quadrangular distribution, interdigitated distribution, herringbone distribution, surrounding distribution, or plum blossom distribution; the fabrication process of the top electrode and / or the bottom contact electrode adopts any one of thermal evaporation, electron beam evaporation, magnetron sputtering, physical vapor deposition, or screen printing.

[0023] Furthermore, the window or opening pattern in the insulating dielectric layer is any one of a rectangle, circle, triangle, polygon, plum blossom shape, ring, or irregular closed pattern; the material of the insulating dielectric layer is any one of silicon dioxide, silicon nitride, boron nitride, silicon oxynitride, aluminum oxide, hafnium oxide, titanium oxide, or rutile titanium dioxide; the preparation method of the insulating dielectric layer is any one of thermal oxidation, plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, atomic layer deposition, electron beam evaporation, magnetron sputtering, or spin coating of insulating dielectric material.

[0024] On the other hand, the present invention also provides a method for fabricating a silicon-based metal micro-basin array graphene photodetector, the method comprising the following steps:

[0025] (1) Preparation of silicon substrate: forming an insulating dielectric layer on the surface of silicon layer;

[0026] (2) Spin coating of photoresist: spin coating, pre-baking, exposure and development of photoresist are performed on the surface of silicon layer and insulating dielectric layer to form a special photoresist outline at the edge of the photoresist;

[0027] (3) Deposition of metal gold layer: A metal gold layer is deposited on the surface of a photoresist template with a special contour and an exposed silicon layer or insulating dielectric layer. After being peeled off, it can form a concave micro-basin structure.

[0028] (4) Peeling and shaping of metal micro basin array: The sample is peeled off, and only the metal structure located on the surface of the silicon layer or insulating dielectric layer is retained to obtain a metal micro basin array composed of multiple concave metal micro basin units.

[0029] (5) Fabrication of the top gold electrode: After the metal micro-basin array is fabricated, the sample surface is subjected to photoresist spin coating, pre-baking, exposure and development again to form the top electrode area pattern. Then, metal electrode material is deposited to obtain the top electrode.

[0030] (6) Transfer of macroscopically assembled graphene nanofilm: The pre-prepared macroscopically assembled graphene nanofilm is transferred to the metal micro-basin array and the top electrode; the transferred macroscopically assembled graphene nanofilm forms an electrical connection with the top electrode and forms a graphene / silicon Schottky junction in contact with the silicon layer.

[0031] (7) Fabrication of bottom contact electrode: The bottom contact electrode is fabricated on the back side of the silicon layer to realize the electrical connection between the silicon layer and the external test circuit.

[0032] The beneficial effects of this invention are:

[0033] This invention possesses excellent silicon-based process compatibility and on-chip integration potential. By combining macroscopically assembled graphene nanofilms, metal micro-basin arrays, and silicon-based Schottky junction structures, a three-dimensional composite photosensitive structure is constructed. This structure utilizes the reflection, scattering, and localized light field enhancement effects of the metal micro-basin array to improve the light absorption efficiency and carrier separation and collection efficiency near the graphene / silicon interface, thereby addressing the weakness of existing planar silicon-based graphene photodetectors in a wide spectral range, especially in the near-infrared band. Furthermore, this invention enables ultraviolet, visible, and near-infrared detection at room temperature without additional cryogenic cooling, reducing system complexity and operating costs. Under an applied bias voltage, the device achieves a stable photoelectric response, demonstrating promising applications in wide-spectral detection, array fabrication, and on-chip integration. This invention combines the advantages of silicon-based process compatibility, structural tunability, and array fabrication, providing a novel technical solution for wide-spectral silicon-based photodetection. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the overall structure of a silicon-based metal micro-basin array graphene photodetector provided by the present invention;

[0036] Figure 2 A magnified view of a local detail of the metal micro-basin array in a silicon-based metal micro-basin array graphene photodetector provided by the present invention;

[0037] Figure 3 A schematic diagram illustrating the working principle of a silicon-based metal micro-basin array graphene photodetector provided by the present invention;

[0038] Figure 4A flowchart illustrating the fabrication process of a silicon-based metal micro-basin array graphene photodetector provided by this invention;

[0039] Figure 5 The graphs show the responsivity and specific detectivity of the photodetector of this invention in the ultraviolet, visible and near-infrared bands.

[0040] Figure 6 This is a diagram showing the surface morphology and partial structure of the photodetector of the present invention;

[0041] Figure 7 This is a photograph of the silicon-based photodetector array fabricated according to the present invention.

[0042] Figure 8 This is a diagram showing the broadband imaging test and imaging results of the photodetector of the present invention.

[0043] in:

[0044] Macroscopically assembled graphene nanofilm 1, three-dimensional metal micro-basin array 2, top electrode 3, insulating dielectric layer 4, silicon layer 5, bottom contact electrode 6. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are merely illustrative and not intended to limit the invention.

[0046] This invention provides a silicon-based metal micro-basin array graphene photodetector, such as... Figure 1 and Figure 6 As shown, it includes a macroscopically assembled graphene nanofilm 1, a three-dimensional metal micro-basin array 2, a top electrode 3, an insulating dielectric layer 4, a silicon layer 5, and a bottom contact electrode 6.

[0047] The insulating dielectric layer 4 is disposed above the silicon layer 5, together forming the main body of the device. The insulating dielectric layer 4 has an opening window exposing the silicon layer 5. The three-dimensional metal micro-basin array 2 is disposed in or adjacent to the opening window region and is adjacent to the silicon layer 5. The three-dimensional metal micro-basin array 2 is composed of multiple concave metal micro-basin units, used to form a three-dimensional light field modulation structure. The top electrode 3 is disposed above the insulating dielectric layer 4 and arranged around the three-dimensional metal micro-basin array 2 and the opening window region. The macroscopically assembled graphene nanofilm 1 is disposed above the top electrode 3, the insulating dielectric layer 4, and the three-dimensional metal micro-basin array 2, and is in direct contact with the top electrode 3. At the same time, it contacts the silicon layer 5 in the opening window region to form a graphene / silicon Schottky junction. The three-dimensional metal micro-basin array is located in the photosensitive region between the macroscopically assembled graphene nanofilm and the silicon layer, and is used to enhance the effect of incident light near the Schottky junction interface. The bottom contact electrode 6 is disposed below the silicon layer 5, and is used to achieve ohmic contact between the silicon layer 5 and the external test circuit. The silicon layer can be made of silicon-based semiconductor materials or other semiconductor materials with photoelectric conversion capabilities, including but not limited to any one of silicon, germanium, indium gallium arsenide, gallium arsenide, cadmium telluride, indium phosphide, silicon carbide, or gallium nitride. The semiconductor layer is used to form a graphene / semiconductor Schottky junction with the macroscopically assembled graphene nanofilm. In this invention, silicon material is used as a preferred embodiment for description, but the application of other semiconductor materials in the structure of this invention is not limited. The bottom contact electrode realizes a low-resistance electrical connection between the silicon layer and the external circuit, and its material can be any one of gallium indium alloy, aluminum, nickel silicide, titanium silicide, cobalt silicide, or other conductive materials that can form ohmic contact with the silicon layer. The top electrode is used to collect and output photogenerated carriers, and its material can be any one of gold, aluminum, platinum, titanium / gold composite metal layer, chromium / gold composite metal layer, transparent indium tin oxide, or other conductive thin film materials. The top electrode can be prepared using thermal evaporation, electron beam evaporation, magnetron sputtering, or other physical vapor deposition processes. The shape of the opening window of the insulating dielectric layer can be any one of rectangular, circular, triangular, quincunx, polygonal, or other closed shapes. The arrangement of the top electrode can be any one of symmetrical distribution, herringbone distribution, interdigitated distribution, ring distribution, or quincunx distribution. The material of the insulating dielectric layer can be any one of silicon dioxide, silicon nitride, boron nitride, silicon oxynitride, aluminum oxide, hafnium oxide, or rutile titanium dioxide. The insulating dielectric layer can be prepared using thermal oxidation, plasma-enhanced chemical vapor deposition, atomic layer deposition, electron beam evaporation, or magnetron sputtering processes.

[0048] The fabrication process of the metal micro-basin array graphene composite structure in this invention is as follows: First, photoresist is spin-coated onto the surface of silicon layer 5 or insulating dielectric layer 4, and a patterned photoresist template is formed by exposure and development using a photomask. By controlling the development time, the photoresist edges are made to form tilted sidewalls, arc-shaped sidewalls, or undercut contour structures in underdeveloped, fully developed, or overdeveloped states. Subsequently, a gold layer is deposited on the photoresist template and the exposed substrate surface (silicon layer or insulating dielectric layer) using magnetron sputtering, electron beam evaporation, or thermal evaporation processes, so that the gold layer is deposited along the photoresist sidewalls and the substrate surface and replicates the photoresist contour. Then, the photoresist and the metal layer above it are removed by peeling with organic solvents such as acetone, finally obtaining a three-dimensional metal micro-basin array 2 composed of multiple concave metal micro-basin units, such as... Figure 1 and Figure 2 As shown in the diagram, the macroscopically assembled graphene nanofilm is then transferred onto the three-dimensional metal micro-basin array and the silicon layer, forming a three-dimensional Schottky photosensitive structure composed of the three-dimensional metal micro-basin array and the macroscopically assembled graphene nanofilm. The structural unit pattern of the metal micro-basin unit can be designed as a circular, elliptical, polygonal, or annular cavity structure, and multiple metal micro-basin units can be distributed in a periodic, quasi-periodic, or non-periodic array. The opening size, array period, basin depth, sidewall height, and metal layer thickness of the metal micro-basin unit can be controlled according to actual needs through photolithography mask pattern, photoresist thickness, development time, and metal deposition process. The basin depth or sidewall height can range from 100 to 5000 nm, and the gold layer thickness can range from 10 to 500 nm.

[0049] Due to the limited absorption rate of single-layer graphene to incident light, the light absorption and photoelectric conversion efficiency of ordinary planar graphene / silicon photodetectors remain limited across a wide spectral range, especially in the near-infrared band. This invention constructs a three-dimensional graphene / silicon Schottky junction photosensitive structure by compositing a macroscopically assembled graphene nanofilm 1, a three-dimensional metal micro-basin array 2, and a silicon layer 5. This achieves high-performance detection across a wide spectral range in the ultraviolet-visible-near-infrared band, enhancing the detection response of planar macroscopically assembled graphene silicon-based photodetectors in this band. The macroscopically assembled graphene nanofilm can be a multilayer graphene film with a consistent crystal orientation stacking angle, or a macroscopically assembled graphene nanofilm doped or modified with bromine, molybdenum chloride, copper chloride, molybdenum disulfide, or other functional materials. The macroscopically assembled graphene nanofilm can be prepared by mechanical exfoliation, filtration sintering, chemical vapor deposition, or transfer assembly. Its thickness can be controlled according to the requirements of light absorption and carrier transport, preferably 30–60 nm. The macroscopically assembled graphene nanofilm 1 has a multilayer stacked structure and broad-spectrum absorption characteristics, which can increase the interaction between incident light and graphene material and improve the absorption capacity of graphene layers for photons of different wavelengths. The three-dimensional metal micro-basin array 2 has a concave microcavity structure, which can reflect, scatter, extend optical path multiple times and enhance local optical field of incident light, so that the incident light can act multiple times in the photosensitive region and concentrate more photons on the graphene / silicon Schottky junction interface and near the silicon layer 5, thereby improving the generation efficiency of photogenerated electron-hole pairs and the effective utilization rate of photogenerated carriers. When incident light irradiates the device, some photons are absorbed by the macroscopically assembled graphene nanofilm 1 and generate photogenerated carriers in the graphene layer. The other photons penetrate the graphene layer and enter the three-dimensional metal micro-basin array 2 and silicon layer 5 region. Under the three-dimensional microcavity modulation of the three-dimensional metal micro-basin array 2, the light absorption process is further enhanced. Simultaneously, the macroscopically assembled graphene nanofilm 1 and silicon layer 5 contact to form a graphene / silicon Schottky junction, with band bending and a built-in electric field at the interface. Under an applied bias voltage, the Schottky junction barrier and interface electric field distribution are modulated, facilitating the rapid separation of photogenerated electrons and holes. The separated carriers are transported along the macroscopically assembled graphene nanofilm 1, silicon layer 5, and their interface, and are ultimately collected by the top electrode 3 and the bottom contact electrode 6 to form a response current. By reading the change in the response current under the applied bias voltage, real-time detection of the incident light signal and intensity can be achieved, such as... Figure 3 and Figure 5As shown. Simultaneously, the three-dimensional metal micro-basin array enhances the light's path and local light field distribution within the photosensitive region. This invention enables broadband detection of wavelengths such as 375 nm, 532 nm, 1064 nm, and 1550 nm at room temperature without additional cryogenic cooling and can be used for multi-band imaging testing. Furthermore, the synergistic effect of the three-dimensional metal micro-basin array 2 with the macroscopically assembled graphene nanofilm 1 and silicon layer 5 enhances the device's photoelectric response in different wavelength bands, improving the weak response of traditional planar silicon-based graphene photodetectors in the near-infrared band and enhancing its applicability in broadband detection, on-chip integration, and multi-band imaging applications.

[0050] To further verify the application potential of the present invention in on-chip integrated devices, this embodiment fabricated the silicon-based metal micro-basin array graphene photodetector in an array configuration. Figure 7 The photograph shows a physical image of the silicon-based photodetector array after its fabrication, demonstrating that the device can be integrated into a multi-unit array on a silicon wafer. Based on the wide spectral response performance of this array device, further imaging tests were conducted. Figure 8 The invention demonstrates broadband imaging tests and imaging results. By collecting the photoresponse current of different pixel units and mapping grayscale, real-time grayscale images can be obtained under illumination conditions of wavelengths such as 375 nm, 532 nm, 1064 nm and 1550 nm, indicating that the invention has the potential for broadband imaging and on-chip integration applications.

[0051] According to the second aspect of this specification, such as Figure 4 As shown, the present invention also provides a method for fabricating a silicon-based metal micro-basin array graphene photodetector, comprising the following steps:

[0052] (1) Preparation of silicon substrate: An N-type lightly doped silicon wafer is used as silicon layer 5. The thickness of the silicon wafer can be 100-500 μm and the resistivity can be 1-10 Ω·cm. After the silicon wafer is cut to the required size, it is ultrasonically cleaned in acetone, isopropanol and deionized water in sequence to remove organic contaminants, particulate impurities and residues on the surface of the silicon wafer. Then it is taken out and dried with nitrogen. After that, an insulating dielectric layer 4 is formed on the surface of silicon layer 5. The insulating dielectric layer 4 can be an insulating material such as silicon dioxide, silicon nitride, aluminum oxide, etc., to define the device area and realize electrical isolation between the top electrode and the silicon layer.

[0053] (2) Spin coating of photoresist: Photoresist is spin-coated onto the cleaned and treated silicon layer 5 and insulating dielectric layer 4 to uniformly cover the area where the metal micro-basin array is to be prepared. After spin coating, the sample is pre-baked to remove the solvent in the photoresist and improve the adhesion between the photoresist and the substrate. Subsequently, the photoresist is exposed through a photomask to obtain a preset pattern in the area where the metal micro-basin array is to be formed, providing a basis for subsequent development to form a special photoresist outline.

[0054] (3) Formation of photoresist contours: The exposed sample is placed in a developer for development. By controlling the development time, developer concentration, and development temperature, the photoresist forms a periodically distributed patterned structure. By controlling the underdevelopment, full development, or overdevelopment states, the photoresist edges can form inclined sidewalls, arc-shaped sidewalls, or undercut structures. The special photoresist contours serve as sacrificial templates for subsequent metal deposition and stripping to form metal micro-basin structures.

[0055] (4) Deposition of a gold layer: A gold layer is deposited on the surface of the photoresist template with a special contour and the exposed silicon layer 5 or insulating dielectric layer 4. The metal deposition process can be magnetron sputtering, electron beam evaporation or thermal evaporation, with magnetron sputtering being preferred, so that the gold layer can be continuously deposited along the sidewalls, top and substrate surface of the photoresist, and replicate the sidewall contour of the developed photoresist template. Since the photoresist contour has an arc-shaped or undercut structure, the deposited gold layer can form a concave micro-basin structure after being peeled off.

[0056] (5) Lifting and shaping of the metal micro-basin array: After metal deposition, the sample is placed in an organic solvent such as acetone for lift-off treatment to remove the photoresist and the gold layer attached above it, leaving only the metal structure on the surface of the silicon layer 5 or the insulating dielectric layer 4. After lift-off, a three-dimensional metal micro-basin array 2 composed of multiple concave metal micro-basin units can be obtained. The opening size, array period, basin depth, sidewall height and metal thickness of the three-dimensional metal micro-basin array 2 can be controlled by the photolithographic mask pattern, photoresist thickness, development time and metal sputtering thickness;

[0057] (6) Fabrication of the top gold electrode: After the three-dimensional metal micro-basin array 2 is fabricated, the sample surface is again subjected to photoresist spin coating, pre-baking, exposure and development to form the top electrode region pattern. Subsequently, metal electrode material is deposited using thermal evaporation, electron beam evaporation or magnetron sputtering processes. The material of the top electrode 3 can be any one of gold, aluminum, platinum, titanium / gold composite metal layer, chromium / gold composite metal layer or indium tin oxide. After deposition, the non-electrode region metal is removed by acetone stripping to obtain the top electrode 3 located above the insulating dielectric layer 4 and distributed on both sides or around the three-dimensional metal micro-basin array 2.

[0058] (7) Transfer of macroscopically assembled graphene nanofilm: The pre-prepared macroscopically assembled graphene nanofilm 1 is transferred onto the three-dimensional metal micro-basin array 2 and the top electrode 3. During the transfer process, a small amount of ethanol and deionized water mixture can be dropped onto the device surface. Then, the macroscopically assembled graphene nanofilm 1 is spread evenly on the droplet surface, and the mixture is blown away with nitrogen or argon gas, so that the macroscopically assembled graphene nanofilm 1 tightly covers the three-dimensional metal micro-basin array 2, the top electrode 3, and the silicon window region. After transfer, the macroscopically assembled graphene nanofilm 1 forms an electrical connection with the top electrode 3 and contacts the silicon layer 5 to form a graphene / silicon Schottky junction.

[0059] (8) Fabrication of the bottom contact electrode: A bottom contact electrode 6 is fabricated on the back side of the silicon layer 5 to realize the electrical connection between the silicon layer 5 and the external test circuit. Taking gallium-indium alloy as the bottom contact electrode 6 as an example, gallium-indium alloy can be dotted on the back side of the silicon layer 5 to form a good ohmic contact with the silicon layer 5; alternatively, materials such as aluminum, nickel silicide, titanium silicide, or cobalt silicide can be used as the bottom contact electrode. Thus, a silicon-based metal micro-basin array graphene broadband photodetector is formed, consisting of a macroscopically assembled graphene nanofilm 1, a three-dimensional metal micro-basin array 2, a top electrode 3, an insulating dielectric layer 4, a silicon layer 5, and a bottom contact electrode 6.

[0060] In summary, the embodiments of this invention provide a silicon-based metal micro-basin array graphene photodetector and its fabrication method. A three-dimensional metal micro-basin array is prepared through controlled development, metal deposition, and exfoliation processes. This array is then combined with a macroscopically assembled graphene nanofilm and a silicon-based Schottky junction structure to form a three-dimensional composite photosensitive structure with optical field modulation and interface enhancement effects. This device possesses silicon-based process compatibility, structural tunability, and array fabrication capabilities. It can improve photoelectric response performance in the ultraviolet, visible, and near-infrared bands and can operate at room temperature, making it suitable for broadband detection and imaging applications.

[0061] The above embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention. All equivalent substitutions, structural modifications, or process adjustments made based on the technical concept of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicon-based metal micro-basin array graphene photodetector, characterized in that, The photodetector includes: The metal micro-basin array is composed of multiple concave metal micro-basin units; A graphene layer covers the metal micro-basin array and its surrounding area, and forms a Schottky junction with the semiconductor substrate; The top electrode is disposed on the surface of the graphene layer or its edge region and is electrically connected to the graphene layer for collecting and outputting photogenerated carriers; A semiconductor substrate having an insulating dielectric layer disposed on its surface and a window structure forming an exposed substrate in a photosensitive working area, the window structure being used to define a Schottky junction region and a distribution area for a metal micro-basin array; The bottom contact electrode is located on the back side of the semiconductor substrate and is used to realize the electrical connection between the semiconductor substrate and the external test circuit.

2. The silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The metal micro-basin array and the graphene layer are combined to form a three-dimensional heterogeneous photosensitive structure. Through the reflection, scattering, local optical field modulation and optical path enhancement of incident light by the metal micro-basin array, a wide spectrum of incident light detection is achieved, improving the generation, separation and collection efficiency of photogenerated carriers, thereby enhancing the photoelectric response and imaging capabilities of the device in the ultraviolet, visible and near-infrared bands under room temperature conditions.

3. The silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The semiconductor substrate is any one of silicon, germanium, indium gallium arsenide, gallium arsenide, cadmium telluride, indium phosphide, silicon carbide, gallium nitride, gallium oxide, indium selenide, or perovskite semiconductor materials.

4. A silicon-based metal micro-basin array graphene photodetector according to claim 2, characterized in that, The semiconductor substrate is a silicon layer. After the graphene layer contacts the silicon layer, a graphene / silicon Schottky junction is formed at the interface. The Schottky junction interface exhibits band bending, a potential barrier region, and a built-in electric field. When incident light enters the device, some photons are absorbed by the graphene layer, generating photogenerated carriers within it. The remaining photons pass through the graphene layer and enter the metal micro-basin array and the silicon layer region, generating photogenerated electron-hole pairs in the silicon layer. Simultaneously, the metal micro-basin array has a concave microcavity structure, enabling reflection, scattering, and multiple optical path operations of the incident light. The extension and localized light field enhancement increase the intensity of incident light at the graphene / silicon Schottky junction interface and near the silicon layer, thereby improving the light absorption efficiency and the generation efficiency of photogenerated carriers. Under the action of the applied bias voltage, the barrier height, depletion region width and interface electric field distribution of the graphene / silicon Schottky junction are modulated. Photogenerated electrons and holes are effectively separated under the combined action of the built-in electric field and the applied electric field of the Schottky junction, and are transported along the graphene layer, silicon layer and their interface, respectively. Finally, they are collected by the top electrode and the bottom contact electrode to form a photocurrent.

5. A silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The fabrication of the metal micro-basin array structure involves spin-coating photoresist onto the surface of a semiconductor substrate or insulating dielectric layer, and removing the solvent from the photoresist through a pre-baking process; subsequently, the photoresist is exposed and developed using a photomask to form a periodically distributed photoresist pattern. By adjusting the development time, the photoresist pattern changes from an underdeveloped state to a fully developed or overdeveloped state, thereby forming a special contour structure with undercut, inclined sidewalls or arc-shaped sidewalls at the edge of the photoresist. Subsequently, a gold layer is deposited on the photoresist pattern and the surface of the exposed semiconductor substrate or insulating dielectric layer using magnetron sputtering or physical vapor deposition methods, so that the gold layer is deposited along the sidewalls of the photoresist and the surface of the substrate and replicates the developed photoresist outline. Subsequently, organic solvents are used to remove the photoresist and strip it, so that the gold layer above the photoresist is removed, leaving only the gold layer structure on the surface of the semiconductor substrate or insulating dielectric layer, and finally a three-dimensional metal micro-basin array composed of multiple concave metal micro-basin units is obtained.

6. A silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The structural parameters of the metal micro-basin array are controlled according to actual needs by adjusting the photolithographic mask pattern, photoresist spin coating thickness, development time, developer concentration, metal sputtering time, and metal sputtering power. After the metal micro-basin array is formed, the graphene layer is transferred to the metal micro-basin array and its surrounding area, and the top electrode and bottom contact electrode are prepared, finally forming a three-dimensional composite Schottky photodetector structure composed of graphene layer, metal micro-basin array, semiconductor substrate and electrode.

7. A silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The graphene layer is a macroscopically assembled graphene nanofilm or a multilayer graphene nanofilm. The macroscopically assembled graphene nanofilm is a multilayer graphene film with consistent crystal orientation stacking angles, or a macroscopically assembled graphene nanofilm modified, composited, or doped with two-dimensional materials. The materials include bromine, molybdenum chloride, copper chloride, molybdenum disulfide, or metal nanoparticles. The macroscopically assembled graphene nanofilm is prepared by mechanical exfoliation, filtration sintering, liquid phase assembly, chemical vapor deposition, or transfer assembly, and then transferred onto the metal micro-basin array. Its thickness is adjusted according to the actual light absorption and carrier transport requirements.

8. A silicon-based metal micro-basin array graphene photodetector according to claim 1, characterized in that, The bottom contact electrode forms an ohmic contact with the semiconductor substrate; the material of the bottom contact electrode is any one of gallium-indium alloy, aluminum, nickel silicide, titanium silicide, and cobalt silicide; the material of the top electrode is any one of gold, aluminum, platinum, titanium / gold composite metal layer, chromium / gold composite metal layer, nickel / gold composite metal layer, or indium tin oxide; the arrangement of the top electrode relative to the window structure is any one of symmetrical distribution, quadrangular distribution, interdigitated distribution, herringbone distribution, surrounding distribution, or plum blossom distribution; the fabrication process of the top electrode and / or the bottom contact electrode adopts any one of thermal evaporation, electron beam evaporation, magnetron sputtering, physical vapor deposition, or screen printing.

9. A silicon-based metal micro-basin array graphene photodetector according to claim 8, characterized in that, The window or opening pattern in the insulating dielectric layer is any one of the following: rectangular, circular, triangular, polygonal, quincunx, annular, or irregular closed pattern; the material of the insulating dielectric layer is any one of the following: silicon dioxide, silicon nitride, boron nitride, silicon oxynitride, aluminum oxide, hafnium oxide, titanium oxide, or rutile titanium dioxide; the preparation method of the insulating dielectric layer is any one of the following: thermal oxidation, plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, atomic layer deposition, electron beam evaporation, magnetron sputtering, or spin coating of insulating dielectric material.

10. A method for fabricating a silicon-based metal micro-basin array graphene photodetector according to any one of claims 1-9, characterized in that, The method includes the following steps: (1) Preparation of silicon substrate: forming an insulating dielectric layer on the surface of silicon layer; (2) Spin coating of photoresist: spin coating, pre-baking, exposure and development of photoresist are performed on the surface of silicon layer and insulating dielectric layer to form a special photoresist outline at the edge of the photoresist; (3) Deposition of metal gold layer: A metal gold layer is deposited on the surface of a photoresist template with a special contour and an exposed silicon layer or insulating dielectric layer. After being peeled off, it can form a concave micro-basin structure. (4) Peeling and shaping of metal micro basin array: The sample is peeled off, and only the metal structure located on the surface of the silicon layer or insulating dielectric layer is retained to obtain a metal micro basin array composed of multiple concave metal micro basin units. (5) Fabrication of the top gold electrode: After the metal micro-basin array is fabricated, the sample surface is subjected to photoresist spin coating, pre-baking, exposure and development again to form the top electrode area pattern. Then, metal electrode material is deposited to obtain the top electrode. (6) Transfer of macroscopically assembled graphene nanofilm: The pre-prepared macroscopically assembled graphene nanofilm is transferred to the metal micro-basin array and the top electrode; the transferred macroscopically assembled graphene nanofilm forms an electrical connection with the top electrode and forms a graphene / silicon Schottky junction in contact with the silicon layer. (7) Fabrication of bottom contact electrode: The bottom contact electrode is fabricated on the back side of the silicon layer to realize the electrical connection between the silicon layer and the external test circuit.

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