Plasmonic-enhanced silicon-based near-infrared photodetection material, preparation method and application thereof

Abstract

This invention relates to the field of optoelectronic materials and photodetectors, providing a plasmon-enhanced silicon-based near-infrared photodetector material, its preparation method, and its applications. The invention constructs a silicon nanostructure array on a silicon substrate and deposits a metal layer on the surface of the silicon nanostructure array. The metal layer is formed by dispersed metal nanoparticles or metal nanoclusters. The metal layer and the silicon nanostructure array form a Schottky barrier, achieving interfacial barrier modulation and directional separation of charge carriers, significantly suppressing recombination and reducing dark current noise. Simultaneously, the localized surface plasmons generated by the metal nanoparticles or metal nanoclusters significantly enhance near-field light intensity and promote the effective separation and injection of hot electrons or photogenerated charge carriers, thereby improving the interfacial photoelectric conversion efficiency. The efficient light-trapping structure of the silicon nanostructure array further enhances its broad-spectrum absorption capability. The photodetector material provided by this invention exhibits high responsivity, low noise, and excellent photoelectric conversion performance.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials and photodetectors, and in particular to a plasmonic-enhanced silicon-based near-infrared photodetector material, its preparation method, and its applications. Background Technology

[0002] Near-infrared photoelectric detection technology has significant application value in fields such as communication, biomedical imaging, and environmental monitoring. However, existing silicon-based photoelectric detection materials still have many limitations in terms of performance and practical application, making it difficult to achieve efficient and broadband near-infrared detection. The band gap of silicon materials is approximately 1.12 eV, and it hardly absorbs near-infrared light with wavelengths greater than 1100 nm. This results in extremely low photogenerated carrier generation efficiency in the near-infrared band for traditional silicon-based photodetectors, severely limiting the photoelectric detection performance of silicon-based platforms.

[0003] Plasmon enhancement is considered an effective strategy to improve the near-infrared response of silicon-based materials. Metal nanostructures can generate strong localized optical fields and hot electrons through localized surface plasmons, achieving additional absorption of near-infrared light. However, the plasmon resonance wavelength and enhancement range of plasmon structures are limited by the particle size and structure of metal nanoparticles, resulting in insufficient absorption of broadband near-infrared light. Furthermore, the number of hot electrons generated is limited, making efficient injection and separation at the interface with the silicon substrate difficult, leading to a still relatively low overall photoelectric conversion efficiency.

[0004] On the other hand, while silicon micro- and nanostructures built on silicon surfaces can reduce reflection and enhance light capture, their intrinsic absorption still struggles to cover a broad near-infrared spectrum, and they lack an effective carrier separation mechanism. Relying solely on silicon micro- and nanostructures cannot significantly improve near-infrared detection performance.

[0005] Therefore, how to achieve the synergistic effect of plasmon enhancement, silicon-based light trapping, and Schottky interface separation to construct silicon-based photodetector materials with broadband near-infrared absorption, efficient carrier separation, and low noise characteristics is a problem that urgently needs to be solved in current technology. Summary of the Invention

[0006] In view of this, the present invention provides a plasmonic-enhanced silicon-based near-infrared photodetector material, its preparation method, and its application. The plasmonic-enhanced silicon-based near-infrared photodetector material provided by the present invention can significantly improve the absorption of near-infrared light and the separation efficiency of photogenerated carriers in silicon, achieving high responsivity, low noise, and broadband near-infrared photodetection, suitable for various photodetector application scenarios.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A plasmonic-enhanced silicon-based near-infrared photodetector material, comprising: A silicon substrate; one side surface of the silicon substrate is provided with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array; the metal layer is formed by dispersed metal nanoparticles or metal nanoclusters; the metal layer and the silicon nanostructure array form a Schottky heterojunction interface.

[0008] Preferably, the silicon nanostructure array is formed by silicon nanostructure units, the morphology of which is a nanocone, a nanopillar, or a textured silicon structure; the upper surface diameter of the nanocone is 50~1000nm, the lower surface diameter is 300~1000nm, and the height is 200nm~20μm; the diameter of the nanopillar is 200~1200nm, and the height is 0.2~20μm; the textured silicon structure is a micron-scale pyramid structure with a height of 1~10μm. The silicon substrate is a single-crystal silicon wafer or a textured silicon wafer, and the silicon substrate is n-type silicon or p-type silicon.

[0009] Preferably, the average particle size of the metal nanoparticles or metal nanoclusters is 1~100 nm; The metal layer is made of one or more of Au, Ag, Pt, Pd, and Cu.

[0010] Preferably, the height of the Schottky barrier formed between the metal layer and the silicon nanostructure array is 0.2~1.2 eV.

[0011] Preferably, the plasmon-enhanced silicon-based near-infrared photodetector material further includes a top electrode and a back electrode; the top electrode is disposed on one side of the metal layer, and the back electrode is disposed on the back side of the silicon substrate.

[0012] The present invention also provides a method for preparing the plasmonic-enhanced silicon-based near-infrared photodetector material described above, comprising the following steps: Provides a silicon substrate with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array to obtain the plasmon-enhanced silicon-based near-infrared photodetector material.

[0013] Preferably, when the morphology of the silicon nanostructure unit is a textured silicon structure, the silicon substrate with the silicon nanostructure array is a textured silicon wafer. When the morphology of the silicon nanostructure unit is not a textured silicon structure, the silicon substrate with the silicon nanostructure array is prepared by metal-assisted chemical etching. The metal-assisted chemical etching method includes: preparing a template on the surface of the silicon substrate, depositing a metal film on the surface of the template to obtain a silicon substrate with a deposited metal film; performing metal-assisted chemical etching on the silicon substrate with the deposited metal film, and then removing the template and the residual metal film to obtain the silicon nanostructure array. The etching solution used in the metal-assisted chemical etching is a mixed solution of hydrofluoric acid and hydrogen peroxide, wherein the concentration of hydrofluoric acid is 35~45wt%, the concentration of hydrogen peroxide is 30~40wt%, and the volume ratio of hydrofluoric acid to hydrogen peroxide is 1:1~20:1. The template is prepared by methods including microsphere self-assembly, nanoimprinting, photolithography, or electron beam exposure. The method for depositing the metal thin film includes one or more of electron beam evaporation, magnetron sputtering, physical vapor deposition, chemical vapor deposition, atomic layer deposition, and electroplating; the material of the metal thin film is one or more of Au, Ag, Pt, and Cu.

[0014] Preferably, the method for depositing the metal layer includes one or more of cluster beam deposition, physical vapor deposition, chemical vapor deposition, atomic layer deposition, electrodeposition solvent reaction, and gas aggregation.

[0015] Preferably, after depositing the metal layer, the method further includes fabricating a top electrode on one side of the metal layer and a back electrode on the back side of the silicon substrate.

[0016] The present invention also provides the application of the plasmon-enhanced silicon-based near-infrared photodetector material described in the above-described scheme or the plasmon-enhanced silicon-based near-infrared photodetector material prepared by the preparation method described in the above-described scheme in photoelectric detection, near-infrared photoelectric conversion, spectral detection, surface-enhanced spectroscopy, optical signal sensing or optical imaging.

[0017] This invention provides a plasmonic-enhanced silicon-based near-infrared photodetector material, comprising a silicon substrate; a silicon nanostructure array disposed on one side surface of the silicon substrate; a metal layer deposited on the surface of the silicon nanostructure array; the metal layer being formed by dispersed metal nanoparticles or metal nanoclusters; and the metal layer forming a Schottky heterojunction interface with the silicon nanostructure array. This invention utilizes the Schottky heterojunction interface formed by the metal layer and the silicon nanostructure array, where the plasmonic modes provided by the metal nanoparticles or metal clusters synergistically interact with the light-trapping modes provided by the silicon nanostructures, achieving multiple optical field couplings such as plasmonic mode-platinum mirror mode coupling and plasmonic mode-nanostructure light-trapping mode coupling. This multi-mode synergy significantly enhances the local optical field intensity and absorption efficiency; simultaneously, the hot electrons generated by plasmonic decay can be effectively injected into silicon through the metal-silicon Schottky contact, improving the excitation and transport efficiency of photogenerated carriers, resulting in higher photoresponsivity and a wider absorption range in the near-infrared band, overcoming the problem of insufficient absorption above 1100 nm in traditional silicon-based materials.

[0018] This invention employs a silicon nanostructure array, which can significantly reduce surface reflection and enhance light-harvesting capability, forming a gradient refractive index structure to achieve broadband light absorption and improve near-infrared light utilization. The Schottky barrier formed by metal / silicon provides an effective carrier separation mechanism, reducing the recombination of photogenerated carriers, and the device has low dark current and high signal-to-noise ratio characteristics.

[0019] In summary, the plasmon-enhanced silicon-based near-infrared photodetector material provided by this invention has the advantages of broadband absorption, high photogenerated carrier generation efficiency, low noise and high responsivity, and is suitable for different types of near-infrared photodetector applications.

[0020] The present invention also provides a method for preparing the plasmonic-enhanced silicon-based near-infrared photodetector material described above. The preparation method provided by the present invention is simple, highly controllable, suitable for large-area preparation, and highly compatible with silicon-based processes, and can be used in various silicon-based optoelectronic device platforms.

[0021] This invention also provides the application of the plasmon-enhanced silicon-based near-infrared photodetector material described in the above-described technical solutions, or the plasmon-enhanced silicon-based near-infrared photodetector material prepared by the preparation method described in the above-described solutions, in photoelectric detection, near-infrared photoelectric conversion, spectral detection, surface-enhanced spectroscopy, optical signal sensing, or optical imaging. The plasmon-enhanced silicon-based near-infrared photodetector material provided by this invention possesses broad-spectrum absorption capability, plasmon enhancement characteristics, and efficient carrier separation capability, and also exhibits low noise and high responsivity, demonstrating significant advantages in near-infrared detection and other applications. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the plasmon-enhanced silicon-based near-infrared photodetector material provided by the present invention, wherein 1 is a silicon substrate, 2 is a silicon nanostructure array, 3 is a metal cluster layer, 4 is a top electrode, and 5 is a back electrode. Figure 2 SEM surface morphology image of the plasmonic-enhanced silicon-based near-infrared photodetector material prepared in Example 1; Figure 3 SEM surface morphology image of the plasmonic-enhanced silicon-based near-infrared photodetector material prepared in Example 2; Figure 4 SEM surface morphology image of the plasmonic-enhanced silicon-based near-infrared photodetector material prepared in Example 3; Figure 5 The photocurrent response curves (top) and (bottom) of the plasmonic-enhanced silicon-based near-infrared photodetector material obtained in Example 1 under 1550nm light irradiation with a power of 2mW are shown. Figure 6The photocurrent response curve of the plasmon-enhanced silicon-based near-infrared photodetector material obtained in Example 2 under irradiation with 1550nm light at a power of 2mW is shown. Figure 7 The photocurrent response curve of the plasmon-enhanced silicon-based near-infrared photodetector material obtained in Example 3 under irradiation with 1550nm light at a power of 2mW is shown. Figure 8 The photocurrent response curve of the planar silicon material without deposited metal clusters in Comparative Example 1 under 1550 nm light irradiation with a power of 2 mW is shown. Figure 9 The photocurrent response curve of the planar silicon material with deposited metal clusters obtained in Comparative Example 2 under 1550 nm light irradiation with a power of 2 mW is shown. Figure 10 The image shows the morphology of gold nanoclusters prepared on the substrate surface using cluster beam deposition. Figure 11 This is a morphology image of the gold film after thermal annealing, in the case of depositing a continuous gold film. Detailed Implementation

[0023] This invention provides a plasmonic-enhanced silicon-based near-infrared photodetector material, comprising: A silicon substrate; one side surface of the silicon substrate is provided with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array; the metal layer is formed by dispersed metal nanoparticles or metal nanoclusters; the metal layer and the silicon nanostructure array form a Schottky heterojunction interface.

[0024] Figure 1 This is a schematic diagram of the structure of the plasmon-enhanced silicon-based near-infrared photodetector material provided by the present invention. In the diagram, 1 is a silicon substrate, 2 is a silicon nanostructure array, 3 is a metal cluster layer, 4 is a top electrode, and 5 is a back electrode. This structure achieves broadband light capture through the micro-nano structures on the silicon surface, achieves localized surface plasmon enhancement through the metal clusters, and forms a Schottky barrier at the metal-silicon interface to improve the separation efficiency of near-infrared photogenerated carriers.

[0025] The following is combined Figure 1 The technical solution of the present invention will be described in detail below.

[0026] The plasmon-enhanced silicon-based near-infrared photodetector material provided by this invention includes a silicon substrate. In this invention, the silicon substrate is preferably n-type silicon or p-type silicon, and the silicon substrate is a single-crystal silicon wafer or a textured silicon wafer.

[0027] A silicon nanostructure array is disposed on one side surface of the silicon substrate, the silicon nanostructure array being formed by silicon nanostructure units; the morphology of the silicon nanostructure units is a nanocone, a nanopillar, or a textured silicon structure; the nanocone can specifically be a cone, an inverted cone, a parabolic cone, or an irregular cone-like shape; the upper surface diameter of the nanocone is preferably 50~1000nm, more preferably 50~800nm, specifically 50nm, the lower surface diameter is preferably 300~1000nm, more preferably 500~800nm, specifically 350nm, and the height is preferably 200nm~20μm, more preferably 500nm~5μm, specifically 4μm; the diameter of the nanopillar is preferably 200~1200nm, specifically 200nm, the height is preferably 0.2~20μm, specifically 3μm, and the distance between the centers of two nanopillars is specifically 500nm. nm; the textured silicon structure is a micron-level quadrangular pyramid structure (also known as a micron-level pyramid structure), with a height preferably 1~10μm, specifically 5~10μm.

[0028] In a specific embodiment of the present invention, when the silicon nanostructure unit has a textured silicon structure, textured silicon can be directly used as the silicon substrate; when the silicon nanostructure unit has a non-textured silicon structure, a single crystal silicon wafer is preferably used as the silicon substrate, and the silicon nanostructure array is prepared by metal-assisted chemical etching (MACE).

[0029] The plasmon-enhanced silicon-based near-infrared photodetector material provided by this invention includes a metal layer deposited on the surface of a silicon nanostructure array; the metal layer is formed by dispersed metal nanoparticles or metal nanoclusters; the metal layer and the silicon nanostructure array form a Schottky heterojunction interface. In this invention, the coverage of the metal layer on the surface of the silicon nanostructure array is preferably 50% or more, preferably greater than or equal to 50% and less than 100%, and specifically 50-80%; the coverage is specifically the percentage of the total projected area of ​​the metal nanoparticles or nano-metal nanoclusters in a SEM top view to the projected area of ​​the silicon nanostructure array region; the density of the metal nanoparticles or metal nanoclusters in the metal layer is such that it can form local plasmon hotspots on the surface of the silicon nanostructure array to enhance light absorption.

[0030] In this invention, the average particle size of the metal nanoparticles or metal nanoclusters is preferably 1 to 100 nm, specifically 10 or 15 nm. This invention preferably shortens the effective transport path of hot electrons in the metal and reduces scattering thermal loss by controlling the particle size of the metal nanoparticles or metal nanoclusters, which is beneficial to improving the probability of hot electrons reaching the metal / silicon interface and their injection efficiency across the Schottky barrier.

[0031] In this invention, the material of the metal layer preferably includes one or more of Au, Ag, Pt, Pd and Cu; in this invention, when the material of each metal nanoparticle or metal nanocluster in the metal layer is one or more of the above-mentioned metals, it can be called an alloy; when the materials of different metal nanoparticles or metal nanoclusters are different, it is a metal mixture; if each metal nanoparticle or metal nanocluster is a single metal, it is called a metal element.

[0032] In this invention, a metal / semiconductor heterojunction interface is formed between the silicon nanostructure array and the metal layer. This interface provides a Schottky barrier with a height of 0.2~1.2 eV, which is used to suppress dark current and achieve effective separation and transport of photogenerated carriers.

[0033] In this invention, the plasmon-enhanced silicon-based near-infrared photodetector material further includes a top electrode and a back electrode; the top electrode is disposed on one side of the metal layer, and the back electrode is disposed on the back side of the silicon substrate; the top electrode may be a ring, grid, or finger-like structure, and the electrode materials of the top electrode and the back electrode are preferably gold, chromium, titanium, or aluminum.

[0034] The present invention also provides a method for preparing the plasmonic-enhanced silicon-based near-infrared photodetector material described above, comprising the following steps: Provides a silicon substrate with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array to obtain the plasmon-enhanced silicon-based near-infrared photodetector material.

[0035] This invention first provides a silicon substrate with an array of silicon nanostructures. In this invention, when the morphology of the silicon nanostructure units is a textured silicon structure, the silicon substrate with the array of silicon nanostructures can be directly used as a textured silicon wafer.

[0036] In this invention, when the morphology of the silicon nanostructure unit is not a textured silicon structure, the silicon substrate with the silicon nanostructure array is prepared by metal-assisted chemical etching. The metal-assisted chemical etching preferably includes: preparing a template on the surface of the silicon substrate, depositing a metal film on the surface of the template to obtain a silicon substrate with a deposited metal film; performing metal-assisted chemical etching on the silicon substrate with the deposited metal film, and then removing the template and the residual metal film to obtain the silicon nanostructure array.

[0037] In this invention, the silicon substrate is preferably cleaned before template preparation. The cleaning method is not specifically limited, as long as it removes impurities and oxide films. The template is specifically a patterned template, and the pattern size can be set according to actual needs. The template preparation method preferably includes microsphere self-assembly, nanoimprinting, photolithography, or electron beam lithography. The template material is preferably a polymer material, an inorganic dielectric material, or a metal material. The polymer material is preferably PS microspheres, PMMA, SU-8, or nanoimprint adhesive. The inorganic dielectric material is preferably SiO2, Si3N4, or Al2O3. The metal material is preferably Cr, Ti, Al, or Ni.

[0038] In this invention, the method for depositing the metal thin film preferably includes one or more of electron beam evaporation, magnetron sputtering, physical vapor deposition, chemical vapor deposition, atomic layer deposition, and electroplating; the material of the metal thin film is preferably one or more of Au, Ag, Pt, and Cu; and the thickness of the metal thin film is preferably 10~100 nm.

[0039] In this invention, the etching solution used for the metal-assisted chemical etching is preferably a mixed solution of hydrofluoric acid and hydrogen peroxide. The concentration of hydrofluoric acid is preferably 35-45 wt%, more preferably 40 wt%, and the concentration of hydrogen peroxide is preferably 30-40 wt%, more preferably 35 wt%. The volume ratio of hydrofluoric acid to hydrogen peroxide is preferably 1:1-20:1, preferably 1:1-10:1, more preferably 3:1-6:1, and specifically 3:1 or 5:1. The time for the metal-assisted chemical etching is preferably 10-6000 seconds, more preferably 30-3000 seconds, and specifically 600 seconds. This invention does not specifically limit other etching parameters, as long as the silicon nanostructure array with the required morphology and size can be obtained.

[0040] In this invention, the preferred method for removing the template and residual metal film is a combination of solvent stripping, selective wet etching and / or dry etching, and plasma ashing and cleaning treatment may be used if necessary.

[0041] After obtaining a silicon substrate with a silicon nanostructure array, the present invention deposits a metal layer on the surface of the silicon nanostructure array to obtain the plasmon-enhanced silicon-based near-infrared photodetector material. In the present invention, the method for depositing the metal layer preferably includes one or more of cluster beam deposition, physical vapor deposition, chemical vapor deposition, atomic layer deposition, electrodeposition solvent reaction, and gas aggregation. The present invention does not limit the specific parameters of the above deposition methods, as long as a metal layer with the required particle size and coverage can be obtained. The metal layer coverage is preferably 50% or more, preferably 50% to 80%. In a specific embodiment of the present invention, when a continuous metal film is deposited, the present invention preferably further includes thermal annealing of the metal film to form dispersed metal nanoclusters or metal nanoparticles. The present invention does not specifically limit the heat treatment process, as long as dispersed metal nanoclusters or metal nanoparticles can be obtained. In a specific embodiment of the present invention, annealing can be performed at 400°C for 20 minutes. In a specific embodiment of the present invention, when using cluster beam deposition or gas aggregation, a metal cluster layer can be directly obtained without heat treatment.

[0042] In this invention, after depositing the metal layer, it is preferable to further prepare a top electrode on one side of the metal layer and a back electrode on the back side of the silicon substrate. This invention does not impose special requirements on the preparation methods of the top and back electrodes; methods well-known to those skilled in the art can be used.

[0043] This invention also provides applications of the plasmon-enhanced silicon-based near-infrared photodetector material described in the above-described scheme, or the plasmon-enhanced silicon-based near-infrared photodetector material prepared by the preparation method described in the above-described scheme, in photoelectric detection, near-infrared photoelectric conversion, spectral detection, surface-enhanced spectroscopy, optical signal sensing, or optical imaging. In this invention, the photoresponse wavelength range of the plasmon-enhanced silicon-based near-infrared photodetector material is 450~1550 nm. This invention does not specifically limit the specific application of the plasmon-enhanced silicon-based near-infrared photodetector material; those skilled in the art can make adjustments as needed.

[0044] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Example 1 (1) Single-crystal Si was selected as the substrate material. Silicon nanocone structures were prepared on one side of the substrate by template-assisted metal-assisted chemical etching. The specific steps are as follows: PS microsphere templates were prepared on the surface of the silicon substrate. PS microsphere dispersion was spread on the surface of the silicon substrate and self-assembled to form a monolayer microsphere array. Then, oxygen plasma was used to etch and shrink the PS microspheres to reduce the microsphere particle size and control the gap size to obtain the desired patterned template. A metal thin film was prepared on the template surface by magnetron sputtering. The metal thin film was made of Au and had a thickness of 20 nm. The silicon substrate was formed into a silicon nanocone structure array by metal-assisted chemical etching. The etching solution was an HF / H2O2 system. The concentration of hydrofluoric acid used in the etching solution was 40 wt%, the concentration of hydrogen peroxide was 35%, the volume ratio of hydrofluoric acid to hydrogen peroxide was 5:1, the etching time was 600 s, and the top diameter of the obtained nanocones was about 50 nm, the bottom diameter was about 350 nm, and the height was about 4 μm. The template and residual metal film were then removed by immersion in a KI and I2 mixed solution (KI and I2 mass ratio of 4:1) for 5 min, resulting in a well-structured silicon nanocone array. (2) Au clusters were prepared on the surface of the silicon nanocone array obtained in step (1) by cluster beam deposition. During the deposition process, the sputtering gas flow rate was 60 sccm, the buffer gas flow rate was 65 sccm, the working pressure was 88 Pa, the sputtering power was 40 W, the cluster beam deposition rate was 0.3 Å / s, the average particle size of the clusters was 10 nm, and they were dispersed. The coverage of the Au clusters on the surface of the silicon nanocone array was 70%.

[0046] (3) An Au electrode (100 nm thick) is prepared on the top of the sample, and an Al back electrode is prepared on the back of the silicon to obtain a plasmonic-enhanced silicon-based near-infrared photodetector material.

[0047] Example 2 (1) Single-crystal Si was selected as the substrate material, and silicon nanopillar structure arrays were prepared on one side of the substrate by MACE. The specific steps are as follows: PS microsphere templates were prepared on the surface of the silicon substrate, and PS microsphere dispersion was spread on the surface of the silicon substrate and self-assembled to form a monolayer microsphere array; then oxygen plasma was used to etch and shrink the PS microspheres to reduce the microsphere particle size and control the gap size to obtain the desired patterned template. A metal thin film was prepared on the template surface by magnetron sputtering, wherein the material of the metal thin film was Au and the thickness was 20 nm; the silicon substrate was formed into a silicon nanopillar structure array by metal-assisted chemical etching; the etching solution was an HF / H2O2 system, the concentration of hydrofluoric acid was 40 wt%, the concentration of hydrogen peroxide was 35%, the volume ratio of hydrofluoric acid to hydrogen peroxide was 3:1, the etching time was 600 s, and the diameter of the obtained nanopillars was about 200 nm, the height was about 3 μm, and the distance between the centers of the two nanopillars was about 500 nm. Subsequently, the template and residual metal film were removed by immersion in a KI and I2 mixed solution (KI to I2 mass ratio of 4:1) for 5 min, resulting in a structurally complete silicon nanopillar array. (2) Au cluster layer was prepared on the surface of the silicon nanopillar structure array obtained in step (1) by cluster beam deposition method. During the deposition process, the sputtering gas flow rate was 60 sccm, the buffer gas flow rate was 65 sccm, the working pressure was 88 Pa, the sputtering power was 40 W, the cluster beam deposition rate was 0.3 Å / s, the average cluster particle size was 10 nm, and the clusters were dispersed. The coverage of the Au cluster layer on the surface of the silicon nanocone structure array was 70%.

[0048] (3) An Au electrode (100 nm thick) is prepared on the top of the sample, and an Al back electrode is prepared on the back of the silicon to obtain a plasmonic-enhanced silicon-based near-infrared photodetector material.

[0049] Example 3 (1) Textured silicon wafers were selected as the substrate material. The textured microstructure consists of micron-level pyramids with a height of about 5~10μm.

[0050] (2) Au cluster layers were prepared on the surface of the structure array obtained in step (1) using the cluster beam deposition method. During the deposition process, the sputtering gas flow rate was 45 sccm, the buffer gas flow rate was 60 sccm, the working pressure was 78 Pa, the sputtering power was 30 W, the cluster beam deposition rate was 0.3 Å / s, the average cluster particle size was 15 nm, and the clusters were dispersed. The coverage of the Au cluster layer on the surface of the silicon nanocone structure array was 70%.

[0051] (3) An Au electrode (100 nm thick) is prepared on the top of the sample, and an Al back electrode is prepared on the back of the silicon to obtain a plasmonic-enhanced silicon-based near-infrared photodetector material.

[0052] Comparative Example 1 The difference from Example 1 is that: instead of preparing silicon nanocone structures on one side of the silicon substrate, planar silicon (without any micro or nanostructures) that has been RCA cleaned is used directly; and no metal cluster layer is deposited.

[0053] The resulting material was used to compare the near-infrared response capability of silicon.

[0054] Comparative Example 2 The difference from Example 1 is that: instead of preparing silicon nanocone structures, Au cluster layers were directly deposited on the surface of a planar silicon substrate using cluster beam deposition, with an average cluster particle size of 10 nm; the top Au electrode and Al back electrode were subsequently prepared, and the other steps were the same as in Example 1.

[0055] The resulting material was used to compare the near-infrared response capability of materials containing only metal clusters but without silicon nanostructure arrays.

[0056] Test case Figures 2-4 The images show SEM surface morphology images of the plasmon-enhanced silicon-based near-infrared photodetector materials prepared in Examples 1, 2, and 3, respectively. Figures 2-4 As can be seen, the silicon nanocones prepared in Example 1 have a sharp and uniform conical structure with uniformly dispersed metal clusters on the top; the silicon nanopillars obtained in Example 2 are regularly arranged and straight, with metal clusters also loaded on the top; the textured silicon in Example 3 exhibits a typical micron-scale pyramid structure with uniformly distributed metal clusters on the surface. These structures can significantly enhance light scattering and light trapping effects, providing a structural basis for near-infrared absorption.

[0057] Figure 5 The images show the photocurrent response curve (top) of the plasmon-enhanced silicon-based near-infrared photodetector material obtained in Example 1 under 1550nm light irradiation with a power of 2mW, and its photoelectric response curve (bottom) in the 450-1550nm wavelength range. Figure 5 It can be seen that the silicon nanocone and metal cluster synergistically produce the highest photocurrent output, and its response intensity is significantly higher than that of other structures, indicating that the nanocone structure has the strongest light-harvesting ability and plasmon enhancement effect.

[0058] Figure 6 The photocurrent response curve of the plasmon-enhanced silicon-based near-infrared photodetector material obtained in Example 2 under 1550nm light irradiation with a power of 2mW. From... Figure 6 It can be seen that the structure composed of silicon nanopillars and metal clusters also exhibits a significant photocurrent enhancement effect, but its peak value is slightly lower than that of Example 1, indicating that the light-harvesting efficiency and plasmon coupling effect of the nanopillar structure are slightly lower than those of the nanocone structure.

[0059] Figure 7 The photocurrent response curve of the plasmon-enhanced silicon-based near-infrared photodetector material obtained in Example 3 under 1550nm light irradiation with a power of 2mW. From... Figure 7 It can be seen that the combination of textured silicon and metal clusters also exhibits a certain photocurrent enhancement effect, indicating that macroscopic microstructures can also improve light absorption, but the enhancement is lower than that of nanoscale structures.

[0060] Figure 8 The photocurrent response curve of the planar silicon material without deposited metal clusters in Comparative Example 1 under 1550 nm light irradiation with a power of 2 mW is shown. Figure 8 It can be seen that since silicon has extremely weak light absorption above 1100 nm, its near-infrared photocurrent output is significantly lower, proving that metal clusters are the key factor in improving near-infrared response.

[0061] Figure 9 The photocurrent response curve of the planar silicon material with deposited metal clusters obtained in Comparative Example 2 under 1550 nm light irradiation with a power of 2 mW is shown. Figure 9 It can be seen that although the photocurrent is improved when there are only dispersed metal clusters on the planar silicon, it is still far lower than that of materials with nanostructures. This indicates that the plasmonic effect and the light-harvesting effect of the nanostructure need to work together to achieve a significant enhancement.

[0062] Figure 10 and Figure 11 This is a schematic diagram of the surface morphology of the metal nanostructure in the metal layer prepared according to the present invention. Figure 10 The image shows the morphology of gold nanoclusters prepared on the substrate surface using cluster beam deposition (preparation conditions are the same as in Example 1). It can be seen that the nanoclusters are distributed on the substrate surface in the form of discrete particles. The overall distribution is relatively uniform, and there are certain gaps between the particles, forming a typical nanocluster array structure. Figure 11 The image shows the morphology of a continuous gold film after thermal annealing (annealing temperature 400°C, time 20 min) in the case of deposition (deposition using thermal evaporation method). After thermal annealing, the metal film undergoes morphological reconstruction and exhibits granular / island characteristics. A large number of fine particle structures appear on the surface and their distribution becomes more uniform, thereby realizing the transformation from a continuous film to a nanoparticle / nanoisland structure, which facilitates obtaining a nanostructured surface that meets the requirements of the device.

[0063] In summary, this invention provides a photodetector material based on a composite of silicon nanostructure arrays and metal nanoclusters. A high aspect ratio silicon nanostructure array is formed on a silicon substrate surface through template-assisted metal-assisted chemical etching. Metal clusters are then deposited on the surface of the silicon nanostructure array to construct a metal / silicon heterojunction interface. A Schottky barrier is formed between the metal clusters and the silicon nanostructures, enabling the modulation and directional separation of charge carriers at the interface barrier, significantly suppressing recombination and reducing dark current noise. Simultaneously, the localized surface plasmons generated by the metal clusters significantly enhance near-field light intensity and promote the effective separation and injection of hot electrons or photogenerated charge carriers, thereby improving the interface photoelectric conversion efficiency. The efficient light-harvesting structure of the silicon nanostructure array further enhances the broad-spectrum absorption capability. The synergistic effect of these three factors enables the device to exhibit high responsivity, low noise, and excellent photoelectric conversion performance in the visible to near-infrared band. This invention features a simple process, can be fabricated on a large area, and is suitable for applications such as novel photodetectors, surface-enhanced spectroscopy devices, and integrated optoelectronic devices.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A plasmonic-enhanced silicon-based near-infrared photodetector material, characterized in that, include: A silicon substrate; one side surface of the silicon substrate is provided with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array; the metal layer is formed by dispersed metal nanoparticles or metal nanoclusters; the metal layer and the silicon nanostructure array form a Schottky heterojunction interface.

2. The plasmon-enhanced silicon-based near-infrared photodetector material according to claim 1, characterized in that, The silicon nanostructure array is formed by silicon nanostructure units, which have the morphology of nanocones, nanopillars, or textured silicon structures. The upper surface diameter of the nanocones is 50-1000 nm, the lower surface diameter is 300-1000 nm, and the height is 200 nm-20 μm. The nanopillars have a diameter of 200-1200 nm and a height of 0.2-20 μm. The textured silicon structure is a micrometer-scale tetrahedral pyramid structure with a height of 1-10 μm. The silicon substrate is a single-crystal silicon wafer or a textured silicon wafer, and the silicon substrate is n-type silicon or p-type silicon.

3. The plasmon-enhanced silicon-based near-infrared photodetector material according to claim 1, characterized in that, The average particle size of the metal nanoparticles or metal nanoclusters is 1~100 nm. The metal layer is made of one or more of Au, Ag, Pt, Pd, and Cu.

4. The plasmon-enhanced silicon-based near-infrared photodetector material according to claim 1, characterized in that, The Schottky barrier height formed between the metal layer and the silicon nanostructure array is 0.2~1.2 eV.

5. The plasmon-enhanced silicon-based near-infrared photodetector material according to claim 1, characterized in that, The plasmon-enhanced silicon-based near-infrared photodetector material further includes a top electrode and a back electrode; the top electrode is disposed on one side of the metal layer, and the back electrode is disposed on the back side of the silicon substrate.

6. The method for preparing the plasmon-enhanced silicon-based near-infrared photodetector material according to any one of claims 1 to 5, characterized in that, Includes the following steps: Provides a silicon substrate with an array of silicon nanostructures; A metal layer is deposited on the surface of the silicon nanostructure array to obtain the plasmon-enhanced silicon-based near-infrared photodetector material.

7. The preparation method according to claim 6, characterized in that, When the morphology of the silicon nanostructure unit is a textured silicon structure, the silicon substrate with the silicon nanostructure array is a textured silicon wafer. When the morphology of the silicon nanostructure unit is not a textured silicon structure, the silicon substrate with the silicon nanostructure array is prepared by metal-assisted chemical etching. The metal-assisted chemical etching method includes: preparing a template on the surface of a silicon substrate, depositing a metal thin film on the surface of the template to obtain a silicon substrate with a deposited metal thin film; performing metal-assisted chemical etching on the silicon substrate with the deposited metal thin film, and then removing the template and the residual metal thin film to obtain the silicon nanostructure array; The etching solution used in metal-assisted chemical etching is a mixed solution of hydrofluoric acid and hydrogen peroxide, wherein the concentration of hydrofluoric acid is 35-45 wt%, the concentration of hydrogen peroxide is 30-40 wt%, and the volume ratio of hydrofluoric acid to hydrogen peroxide is 1:1-20:

1. The template is prepared by methods including microsphere self-assembly, nanoimprinting, photolithography, or electron beam exposure. The method for depositing the metal thin film includes one or more of electron beam evaporation, magnetron sputtering, physical vapor deposition, chemical vapor deposition, atomic layer deposition, and electroplating; the material of the metal thin film is one or more of Au, Ag, Pt, and Cu.

8. The preparation method according to claim 6, characterized in that, The method for depositing the metal layer includes one or more of cluster beam deposition, physical vapor deposition, chemical vapor deposition, atomic layer deposition, electrodeposition solvent reaction and gas aggregation.

9. The preparation method according to claim 6, characterized in that, After depositing the metal layer, the process also includes fabricating a top electrode on one side of the metal layer and a back electrode on the back side of the silicon substrate.

10. The application of the plasmon-enhanced silicon-based near-infrared photodetector material according to any one of claims 1 to 5 or the plasmon-enhanced silicon-based near-infrared photodetector material prepared by the preparation method according to any one of claims 6 to 9 in photoelectric detection, near-infrared photoelectric conversion, spectral detection, surface-enhanced spectroscopy, optical signal sensing or optical imaging.

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