Broadband-spectrum high-uniformity black silicon integrated nanogold quadrant detector and preparation method thereof

Abstract

The invention discloses a wide-spectrum high-uniformity black silicon integrated nanogold quadrant detector and a preparation method thereof, the wide-spectrum high-uniformity black silicon integrated nanogold quadrant detector comprises a substrate base material, a micro-nano conical B-Si structure is etched on the substrate base material, gold nanoparticles are deposited and covered on the surface of the micro-nano conical B-Si structure, the photoelectric detector is a double-four-quadrant photoelectric detector, and the thickness of the double-four-quadrant photoelectric detector is larger than that of the micro-nano conical B-Si structure. And the boundary area of the double four quadrants is electrically isolated by etching deep grooves and filling oxygen-silicon compounds to form isolation grooves. The gold nanoparticles are compounded on the surface of B-Si, hot electrons can be excited through a localized surface plasma resonance mechanism and injected into a black silicon conduction band to participate in the photoelectric conversion process, the band gap limitation of the B-Si material is broken through, wide spectral response is achieved, the response capability in a near-infrared region is improved, and the photoelectric conversion efficiency is improved. And meanwhile, a silicon oxide and silicon nitride passivation film is introduced to the surface of the black silicon and gold nanoparticle composite structure, and a surface carrier recombination process is inhibited by filling dangling bonds and defect states on the surface of the black silicon pointed cone structure, so that the dark current level of the device is reduced.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and more specifically, to a wide-spectrum, highly uniform black silicon integrated nano-gold quadrant detector and its fabrication method. Background Technology

[0002] With the development of nano-optical structure design technology, black silicon (B-Si) materials have been widely used in PIN structure optoelectronic devices due to their excellent light absorption properties, significantly improving the photoelectric response of the devices. However, the response capability of traditional B-Si above 1064 nm is still limited, restricting its application expansion in a longer wavelength range.

[0003] Currently, plasma-enhanced photodetectors have expanded into the near-infrared band, and nanoparticles based on the principle of localized surface plasmon resonance (LSPR) have attracted much attention due to their strong absorption in specific wavelength bands. However, most plasma structures suffer from problems such as narrow resonance bands and difficulties in fabrication, making it difficult to achieve wide-band enhanced response. In particular, achieving large-area, uniform distribution on silicon substrates remains a technical challenge.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] The problem with existing technologies is that traditional B-Si has limited response capabilities above 1064 nm wavelength. Therefore, this invention provides a broadband, highly uniform black silicon integrated nano-gold quadrant detector and its fabrication method. By composite gold nanoparticles on the surface of B-Si, hot electrons can be excited in the near-infrared region or even below the silicon bandgap energy through the localized surface plasmon resonance mechanism. These hot electrons overcome the potential barrier between the metal and the semiconductor and are injected into the conduction band of the black silicon to participate in the photoelectric conversion process, achieving a broadband response and improving the response capability of the photodetector in the near-infrared region.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a broad-spectrum, highly uniform black silicon integrated gold nanomaterial, comprising a substrate, wherein a micro / nano cone-shaped B-Si structure is etched on the substrate, and gold nanoparticles (AuNPs) are deposited on the surface of the micro / nano cone-shaped B-Si structure.

[0007] This invention introduces gold nanoparticles into the surface of B-Si to form a composite structure. The black silicon structure with its pointed, conical microstructure enhances the ability to capture incident light. The gold nanoparticles can excite hot electrons in the near-infrared band or even below the silicon bandgap energy (<1.12 eV) through localized surface plasmon resonance. These hot electrons have sufficient energy to overcome the potential barrier between the metal and the semiconductor and are effectively injected into the conduction band of the black silicon to participate in the photoelectric conversion process. This converts the sub-bandgap light energy that cannot be absorbed by silicon into a measurable electrical signal, breaking through the bandgap limitation of B-Si materials, achieving a broad spectral response, and improving the response capability of the photodetector in the near-infrared region.

[0008] In one specific embodiment, the diameter of the gold nanoparticles (AuNPs) is 5~50 nm.

[0009] In one specific embodiment, the surfaces of the micro / nano cone-shaped B-Si structure and the gold nanoparticles AuNPs are sequentially deposited and covered with a SiO2 passivation layer and a Si3N4 passivation layer.

[0010] This invention introduces a double passivation film of silicon oxide (SiO2) and silicon nitride (Si3N4) on the surface of a black silicon and gold nanoparticle composite structure. This double passivation film can play the role of interface passivation. By filling the dangling bonds and defect states on the surface of the black silicon cone structure, it suppresses the surface carrier recombination process and reduces the dark current level of the device.

[0011] In one specific embodiment, the thickness of the SiO2 passivation layer is 5-15 nm, and the thickness of the Si3N4 passivation layer is 110-130 nm. This invention first deposits a thin SiO2 passivation layer on the black silicon surface, followed by a thicker Si3N4 passivation layer. This effectively passivates dangling bonds on the black silicon surface, reduces surface recombination, and decreases dark current. Then, based on the antireflection film design principle, a thicker Si3N4 passivation layer and a thinner SiO2 passivation layer are designed to increase the near-infrared photon incident rate, thereby improving the device's quantum efficiency.

[0012] In one specific embodiment, a PIN junction is constructed on the substrate, and the micro / nano tapered B-Si structure is etched in the photosensitive region of the PIN junction.

[0013] In one specific embodiment, the thickness of the P region of the PIN junction is 5~8 μm, the thickness of the I region is 250 μm, and the thickness of the N region is 3~5 μm.

[0014] In one specific embodiment, the substrate is an intrinsic silicon wafer with a resistivity of 3000 Ω·cm.

[0015] Secondly, the present invention provides a method for preparing a broadband, highly uniform black silicon integrated gold nanomaterial, comprising the following steps: (1) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, and a back electrode is formed by depositing metal on the back side of the silicon substrate; (2) The sample with PIN junction obtained in step (1) is placed in SF6 gas, and a micro-nano cone-shaped B-Si structure is formed by etching the photosensitive area of ​​the PIN junction using a femtosecond laser. (3) The sample with the obtained micro-nano cone-shaped B-Si structure is placed in the thermal evaporation chamber, and gold nanoparticles are deposited on the B-Si surface by thermal evaporation under vacuum to form a B-Si / AuNPs composite structure. (4) SiO2 passivation layer and Si3N4 passivation layer were sequentially deposited on the surface of B-Si / AuNPs by chemical vapor deposition.

[0016] Single AuNPs (independent gold nanoparticles) have narrow-band absorption characteristics, while double AuNPs (two connected gold nanoparticles) can achieve multimodal resonant absorption. In this invention, gold nanoparticles are deposited on a micro-nano conical B-Si structure using a thermal evaporation process. The resulting gold nanoparticles are randomly interconnected on the surface of the B-Si, and the internal interconnections are of different sizes, which can form a broad-spectral resonant absorption peak and generate local electric field enhancement, thereby broadening the spectral response range of the device.

[0017] In a specific implementation, the parameters of the femtosecond laser in step (2) are as follows: wavelength 750~850 nm, pulse width 100 fs, power density 3.0~6.0 kJ / m². 2 The scanning speed is 0.5~2 mm / s.

[0018] In a specific implementation, in step (3), in 1×10 -3 ~5×10 -3 Gold nanoparticles were thermally evaporated under a vacuum of Pa at a temperature range of 350–400 K using a sputtering power of 800–6000 W.

[0019] Thirdly, the present invention provides a wide-spectrum, highly uniform black silicon integrated nano-gold quadrant detector, comprising the black silicon integrated nano-gold material or the black silicon integrated nano-gold material prepared by the method. The photodetector adopts a dual four-quadrant structure. The boundary regions of the dual four-quadrants are electrically isolated by etching deep trenches and filling them with silicon oxide compounds to form isolation trenches.

[0020] In one specific embodiment, the width of the isolation groove is 10~100 μm and the depth is 5~10 μm.

[0021] This invention, based on a PIN structure, employs trenches with a width of approximately 100 μm and a depth of approximately 10 μm etched at the quadrant boundary positions, and further fills these trenches with silicon oxide compounds. This passivates defects on the trench sidewalls, prevents the diffusion and migration of photogenerated carriers between different quadrants, reduces signal crosstalk between quadrants, achieves quadrant structure isolation, and improves consistency and response balance between quadrants, thereby enhancing spatial resolution. It is suitable for high-precision scenarios such as laser alignment and spatial positioning.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a broadband, highly uniform black silicon integrated nano-gold quadrant detector and its fabrication method. AuNPs are introduced on the surface of B-Si to form a composite structure. The black silicon structure of B-Si with its pointed cone-shaped microstructure can enhance the ability to capture incident light, while AuNPs can excite hot electrons in the near-infrared band or even below the silicon bandgap energy (<1.12 eV) through the local surface plasmon resonance effect. Through the synergistic effect of B-Si and AuNPs, a broadband response of silicon-based photodetector can be achieved. 2. The embodiments of the present invention provide a broadband, highly uniform black silicon integrated nano-gold quadrant detector and its fabrication method. By injecting hot electrons with sufficient energy to overcome the metal-semiconductor barrier into the conduction band of black silicon to participate in the photoelectric conversion process, it can convert sub-bandgap light energy that cannot be absorbed by silicon into a measurable electrical signal, breaking through the bandgap limitation of B-Si material. It enables the photodetector to effectively respond to the 1310 nm and 1550 nm near-infrared bands from the 400~1100 nm band of ordinary silicon material. 3. The embodiments of the present invention provide a wide-spectrum, highly uniform black silicon integrated nano-gold quadrant detector and its fabrication method. Gold nanoparticles are deposited on a micro-nano conical B-Si structure using a thermal evaporation process. The gold nanoparticles formed are randomly interconnected on the surface of B-Si, which can form a wide-spectrum resonant absorption peak and generate local electric field enhancement, thereby broadening the spectral response range of the device. 4. The embodiments of the present invention provide a wide-spectrum, high-uniformity black silicon integrated nano-gold quadrant detector and its fabrication method. By introducing silicon oxide and silicon nitride to form a double-layer passivation film on the surface of the black silicon and gold nanoparticle composite structure, it can play the role of interface passivation. By filling the dangling bonds and defect states on the surface of the black silicon cone structure, the surface carrier recombination process is suppressed, and the dark current level of the device is reduced. 5. The embodiments of the present invention provide a wide-spectrum, high-uniformity black silicon integrated nano-gold quadrant detector and its fabrication method. On the PIN basic structure, by etching trenches with a depth of about 100 μm at the quadrant boundary positions and further filling them with silicon oxide compounds, the defects on the trench sidewalls can be passivated, preventing the diffusion and migration of photogenerated carriers between different quadrants, reducing signal crosstalk between quadrants, achieving isolation of the quadrant structure, improving the consistency and response balance between each quadrant, and improving spatial resolution. It is suitable for high-precision scenarios such as laser alignment and spatial positioning. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the black silicon integrated gold nanoparticle material provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the photodetector provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the quadrant structure of the photodetector provided in Embodiment 1 of the present invention; Figure 4 The results show a comparison of the responsivity of the photodetectors provided in Embodiment 1 and Comparative Example 1 of the present invention. Figure 5 The results show the comparison of dark current of the photodetectors provided in Embodiment 1 and Comparative Example 2 of this invention. Figure 6 The results show the comparison of non-uniformity of the photodetectors provided in Embodiment 1 and Comparative Example 3 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0026] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0027] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this document; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0029] Black silicon (B-Si) materials are widely used in PIN structure optoelectronic devices due to their excellent light absorption properties, significantly improving the photoelectric response of these devices. However, the response capability of traditional B-Si above 1064 nm remains limited, restricting its application in longer wavelength ranges. Plasma-enhanced photodetectors have expanded into the near-infrared band, and nanoparticles based on the principle of localized surface plasmon resonance (LSPR) have attracted much attention due to their strong absorption in specific wavelength bands. However, most plasmonic structures suffer from narrow resonance bands and difficulties in fabrication, making it difficult to achieve wide-band enhanced response. Achieving large-area, uniform distribution, especially on silicon substrates, remains a technical challenge.

[0030] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a broad-spectrum, highly uniform black silicon integrated gold nanomaterial, comprising a substrate, wherein a micro / nano cone-shaped B-Si structure is etched on the substrate, and gold nanoparticles (AuNPs) are deposited on the surface of the micro / nano cone-shaped B-Si structure.

[0031] This invention introduces gold nanoparticles into the surface of B-Si to form a composite structure. The black silicon structure with its pointed, conical microstructure enhances the ability to capture incident light. The gold nanoparticles can excite hot electrons in the near-infrared band or even below the silicon bandgap energy (<1.12 eV) through localized surface plasmon resonance. These hot electrons have sufficient energy to overcome the potential barrier between the metal and the semiconductor and are effectively injected into the conduction band of the black silicon to participate in the photoelectric conversion process. This converts the sub-bandgap light energy that cannot be absorbed by silicon into a measurable electrical signal, breaking through the bandgap limitation of B-Si materials, achieving a broad spectral response, and improving the response capability of the photodetector in the near-infrared region.

[0032] In one specific embodiment, the diameter of the gold nanoparticles (AuNPs) is 5~50 nm.

[0033] In one specific embodiment, the surfaces of the micro / nano cone-shaped B-Si structure and the gold nanoparticles AuNPs are sequentially deposited and covered with a SiO2 passivation layer and a Si3N4 passivation layer.

[0034] This invention introduces a double passivation film of silicon oxide (SiO2) and silicon nitride (Si3N4) on the surface of a black silicon and gold nanoparticle composite structure. This double passivation film can play the role of interface passivation. By filling the dangling bonds and defect states on the surface of the black silicon cone structure, it suppresses the surface carrier recombination process and reduces the dark current level of the device.

[0035] In one specific embodiment, the thickness of the SiO2 passivation layer is 5-15 nm, and the thickness of the Si3N4 passivation layer is 110-130 nm. This invention first deposits a thin SiO2 passivation layer on the black silicon surface, followed by a thicker Si3N4 passivation layer. This effectively passivates dangling bonds on the black silicon surface, reduces surface recombination, and decreases dark current. Then, based on the antireflection film design principle, a thicker Si3N4 passivation layer and a thinner SiO2 passivation layer are designed to increase the near-infrared photon incident rate, thereby improving the device's quantum efficiency.

[0036] In one specific embodiment, a PIN junction is constructed on the substrate, and the micro / nano tapered B-Si structure is etched in the photosensitive region of the PIN junction.

[0037] In one specific embodiment, the thickness of the P region of the PIN junction is 5~8 μm, the thickness of the I region is 250 μm, and the thickness of the N region is 3~5 μm.

[0038] In one specific embodiment, the substrate is an intrinsic silicon wafer with a resistivity of 3000 Ω·cm.

[0039] Secondly, the present invention provides a method for preparing a broadband, highly uniform black silicon integrated gold nanomaterial, comprising the following steps: (1) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, and a back electrode is formed by depositing metal on the back side of the silicon substrate; (2) The sample with PIN junction obtained in step (1) is placed in SF6 gas, and a micro-nano cone-shaped B-Si structure is formed by etching the photosensitive area of ​​the PIN junction using a femtosecond laser. (3) The sample with the obtained micro-nano cone-shaped B-Si structure is placed in the thermal evaporation chamber, and gold nanoparticles are deposited on the B-Si surface by thermal evaporation under vacuum to form a B-Si / AuNPs composite structure. (4) SiO2 passivation layer and Si3N4 passivation layer were sequentially deposited on the surface of B-Si / AuNPs by chemical vapor deposition.

[0040] Single AuNPs (independent gold nanoparticles) have narrow-band absorption characteristics, while double AuNPs (two connected gold nanoparticles) can achieve multimodal resonant absorption. In this invention, gold nanoparticles are deposited on a micro-nano conical B-Si structure using a thermal evaporation process. The resulting gold nanoparticles are randomly interconnected on the surface of the B-Si, and the internal interconnections are of different sizes, which can form a broad-spectral resonant absorption peak and generate local electric field enhancement, thereby broadening the spectral response range of the device.

[0041] In a specific implementation, the parameters of the femtosecond laser in step (2) are as follows: wavelength 750~850 nm, pulse width 100 fs, power density 3.0~6.0 kJ / m². 2 The scanning speed is 0.5~2 mm / s.

[0042] In a specific implementation, in step (3), in 1×10 -3 ~5×10 -3 Gold nanoparticles were thermally evaporated under a vacuum of Pa at a temperature range of 350–400 K using a sputtering power of 800–6000 W.

[0043] Thirdly, the present invention provides a wide-spectrum, highly uniform black silicon integrated nano-gold quadrant detector, comprising the black silicon integrated nano-gold material or the black silicon integrated nano-gold material prepared by the method. The photodetector adopts a dual four-quadrant structure. The boundary regions of the dual four-quadrants are electrically isolated by etching deep trenches and filling them with silicon oxide compounds to form isolation trenches.

[0044] In one specific embodiment, the width of the isolation groove is 10~100 μm and the depth is 5~10 μm.

[0045] This invention, based on a PIN structure, employs trenches with a width of approximately 100 μm and a depth of approximately 10 μm etched at the quadrant boundary positions, and further fills these trenches with silicon oxide compounds. This passivates defects on the trench sidewalls, prevents the diffusion and migration of photogenerated carriers between different quadrants, reduces signal crosstalk between quadrants, achieves quadrant structure isolation, and improves consistency and response balance between quadrants, thereby enhancing spatial resolution. It is suitable for high-precision scenarios such as laser alignment and spatial positioning.

[0046] Example 1 This invention provides a method for fabricating a broadband, highly uniform black silicon integrated gold nanoparticle dual four-quadrant photodetector, comprising the following steps: (1) An intrinsic silicon wafer with a resistivity of 3000 Ω·cm was selected as the substrate material for device fabrication. The silicon wafer was cleaned using the RCA standard process, and then immersed in 5% hydrofluoric acid for 1 minute to remove the surface oxide layer. It was then ultrasonically rinsed with deionized water for 10 minutes and dried with 99.99% high-purity nitrogen. (2) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, wherein the P region is 5 μm thick, the I region is 250 μm thick, the N region is 3 μm thick, and the back side is polished, while aluminum is deposited to form the back electrode. (3) Place the sample with PIN junction obtained in step (2) into a container filled with SF6 gas (pressure 8.5 × 10⁻⁶). 4In the reaction cavity of Pa), a femtosecond laser (wavelength 800 nm, pulse width 100 fs, power density 4.5 kJ / m²) is used. 2 Scanning at a speed of 1 mm / s, a micro-nano cone-shaped B-Si structure is etched in the photosensitive region of the PIN junction; (4) The etched sample with the obtained micro / nano cone-shaped B-Si structure was cleaned in 5% hydrofluoric acid for 5 minutes, ultrasonically cleaned for 10 minutes to remove surface oxidation residues, and finally dried with high-purity nitrogen gas and placed in a thermal evaporation chamber at 5×10 -3 Under vacuum of Pa, gold nanoparticles with different diameters of about 10~20 nm were generated on the B-Si surface by thermal evaporation of gold nanoparticles with sputtering power of 800-6000 W within a temperature range of 350 K, forming a B-Si / AuNPs composite structure. (5) A 5 nm SiO2 passivation layer and a 120 nm Si3N4 passivation layer were deposited on the surface of the B-Si / AuNPs composite structure by plasma-enhanced chemical vapor deposition. (6) A deep trench with a width of 50 μm and a depth of 8 μm is etched between the quadrants. Then, the silicon oxide is filled in the deep trench using plasma-enhanced chemical vapor deposition (PECVD) to obtain the photodetector device.

[0047] Example 2 This invention provides a method for fabricating a broadband, highly uniform black silicon integrated gold nanoparticle dual four-quadrant photodetector, comprising the following steps: (1) An intrinsic silicon wafer with a resistivity of 3000 Ω·cm was selected as the substrate material for device fabrication. The silicon wafer was cleaned using the RCA standard process, and then immersed in 5% hydrofluoric acid for 1 minute to remove the surface oxide layer. It was then ultrasonically rinsed with deionized water for 10 minutes and dried with 99.99% high-purity nitrogen. (2) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, wherein the P region is 5 μm thick, the I region is 250 μm thick, the N region is 3 μm thick, and the back side is polished, while aluminum is deposited to form the back electrode. (3) Place the sample with PIN junction obtained in step (2) into a container filled with SF6 gas (pressure 8.5 × 10⁻⁶). 4 In the reaction cavity of Pa), a femtosecond laser (wavelength 800 nm, pulse width 100 fs, power density 4.5 kJ / m²) is used. 2 Scanning at a speed of 1 mm / s, a micro-nano cone-shaped B-Si structure is etched in the photosensitive region of the PIN junction; (4) The etched sample with the obtained micro / nano cone-shaped B-Si structure was cleaned in 5% hydrofluoric acid for 5 minutes, ultrasonically cleaned for 10 minutes to remove surface oxidation residues, and finally dried with high-purity nitrogen gas and placed in a thermal evaporation chamber at 1×10 -3 Under vacuum of Pa, gold nanoparticles with different diameters of about 20~50 nm were thermally evaporated on the B-Si surface using sputtering power of 800-6000 W within a temperature range of 350 K, forming a B-Si / AuNPs composite structure. (5) A 10 nm SiO2 passivation layer and a 110 nm Si3N4 passivation layer were deposited on the surface of the B-Si / AuNPs composite structure by plasma-enhanced chemical vapor deposition. (6) A deep trench with a width of 100 μm and a depth of 10 μm is etched in the quadrant. Then, the silicon oxide is filled in the deep trench using plasma-enhanced chemical vapor deposition (PECVD) to obtain a photodetector device.

[0048] Example 3 This invention provides a method for fabricating a broadband, highly uniform black silicon integrated gold nanoparticle dual four-quadrant photodetector, comprising the following steps: (1) An intrinsic silicon wafer with a resistivity of 3000 Ω·cm was selected as the substrate material for device fabrication. The silicon wafer was cleaned using the RCA standard process, and then immersed in 5% hydrofluoric acid for 1 minute to remove the surface oxide layer. It was then ultrasonically rinsed with deionized water for 10 minutes and dried with 99.99% high-purity nitrogen. (2) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, wherein the P region is 5 μm thick, the I region is 250 μm thick, the N region is 3 μm thick, and the back side is polished, while aluminum is deposited to form the back electrode. (3) Place the sample with PIN junction obtained in step (2) into a container filled with SF6 gas (pressure 8.5 × 10⁻⁶). 4 In the reaction cavity of Pa), a femtosecond laser (wavelength 800 nm, pulse width 100 fs, power density 4.5 kJ / m²) is used. 2 Scanning at a speed of 1 mm / s, a micro-nano cone-shaped B-Si structure is etched in the photosensitive region of the PIN junction; (4) The etched sample with the obtained micro / nano cone-shaped B-Si structure was cleaned in 5% hydrofluoric acid for 5 minutes, ultrasonically cleaned for 10 minutes to remove surface oxidation residues, and finally dried with high-purity nitrogen gas. It was then placed in a thermal evaporation chamber and heated at 3×10⁻⁶ ppm. -3Under vacuum of Pa, gold nanoparticles with different diameters of about 5~10 nm were generated on the B-Si surface by thermal evaporation of gold nanoparticles with sputtering power of 800-6000 W within a temperature range of 400 K, forming a B-Si / AuNPs composite structure. (5) A 15 nm SiO2 passivation layer and a 130 nm Si3N4 passivation layer were deposited on the surface of the B-Si / AuNPs composite structure by plasma-enhanced chemical vapor deposition. (6) A deep trench with a width of 10 μm and a depth of 5 μm is etched between the quadrants. Then, the silicon oxide is filled in the deep trench using plasma-enhanced chemical vapor deposition (PECVD) to obtain a photodetector device.

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that step (4) is not included, that is, no gold nanoparticles are deposited on the B-Si surface.

[0050] Comparative Example 2 The difference between this comparative example and Example 1 is that step (5) is not included, that is, no SiO2 passivation layer and Si3N4 passivation layer are deposited on the surface of B-Si / AuNPs.

[0051] Comparative Example 3 The difference between this comparative example and Example 1 is that it is a common four-quadrant detector, and in step (6), the boundary area between the four quadrants is not filled with etched deep trenches combined with silicon oxide compound, but is formed by forming physical isolation trenches using deep trench etching.

[0052] Performance testing The relevant performance of the photodetectors prepared in Examples 1-3 and Comparative Examples 1-3 was tested.

[0053] Table 1 As can be seen from Table 1, the spectral response range of Example 1 of the present invention can be extended to 1550 nm, the response at 1550 nm can reach more than 26 mA / W, the non-uniformity is less than 0.6%, and the dark current is less than 1 nA; the spectral response range of Example 2 can be extended to 1550 nm, the response at 1550 nm can reach more than 30 mA / W, the non-uniformity is less than 0.2%, and the dark current is less than 0.5 nA; the spectral response range of Example 3 can be extended to 1550 nm, the response at 1550 nm can reach more than 22 mA / W, the non-uniformity is less than 1%, and the dark current is less than 1 nA. In summary, this invention integrates AuNPs in situ on the black silicon surface of the photosensitive region of a PIN device, extending the device's spectral response range to 1550 nm, with a response of over 22 mA / W at 1550 nm. The invention utilizes a deep trench etching process combined with silicon oxide compound filling to achieve quadrant non-uniformity of less than 1%. Furthermore, by designing a dual-film passivation system using SiO2 and Si3N4, the device's dark current is reduced to less than 1 nA, ultimately enabling the fabrication of a wide-spectrum, highly uniform, low-dark-current dual four-quadrant photodetector.

[0054] from Figure 4 As can be seen, the device in Comparative Example 1 had no gold nanoparticles deposited on its B-Si surface and showed no response at 1550 nm, while the device in Example 1 of this invention had gold nanoparticles deposited, and its spectral response range was extended from the 400-1100 nm band of ordinary silicon material to the 400-1550 nm band.

[0055] from Figure 5 As can be seen from the data, the B-Si / AuNPs device in Comparative Example 2 did not have a SiO2 passivation layer and a Si3N4 passivation layer deposited on its surface. However, after the SiO2 passivation layer and the Si3N4 passivation layer were deposited on the device in Example 2 of this invention, the dark current of the device was reduced from more than 5 nA to less than 1 nA.

[0056] from Figure 6 As can be seen from the diagram, the device in Embodiment 1 of this invention uses deep trench etching combined with silicon oxide compound filling for quadrant isolation, which improves the uniformity of the device, reducing the non-uniformity from greater than 2% to less than 1%. The device in Comparative Example 3 only utilizes deep trench etching to form physical isolation trenches without silicon oxide filling, resulting in not only higher non-uniformity but also photoresist sputtering during subsequent photolithography processes. Furthermore, the deep trenches alone can lead to defect recombination, affecting the device's dark current.

[0057] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A broadband, highly uniform black silicon integrated gold nanomaterial, characterized in that, The invention includes a substrate on which a micro / nano-conical B-Si structure is etched, and gold nanoparticles (AuNPs) are deposited on the surface of the micro / nano-conical B-Si structure.

2. The broadband, highly uniform black silicon integrated gold nanomaterial according to claim 1, characterized in that, The diameter of the gold nanoparticles (AuNPs) is 5-50 nm.

3. The broadband, highly uniform black silicon integrated gold nanomaterial according to claim 1, characterized in that, The surfaces of the micro / nano cone-shaped B-Si structure and gold nanoparticles (AuNPs) are sequentially coated with SiO2 passivation layers and Si3N4 passivation layers.

4. The broadband, highly uniform black silicon integrated gold nanomaterial according to claim 1, characterized in that, The thickness of the SiO2 passivation layer is 5~15 nm, and the thickness of the Si3N4 passivation layer is 110~130 nm.

5. The broadband, highly uniform black silicon integrated gold nanomaterial according to claim 1, characterized in that, A PIN junction is constructed on the substrate, and the micro / nano tapered B-Si structure is etched in the photosensitive region of the PIN junction.

6. The method for preparing the broadband, highly uniform black silicon integrated gold nanomaterial according to any one of claims 1-5, characterized in that, Includes the following steps: (1) A PIN junction is constructed in the active region of the silicon substrate by photolithography and ion implantation, and a back electrode is formed by depositing metal on the back side of the silicon substrate; (2) The sample with PIN junction obtained in step (1) is placed in SF6 gas, and a micro-nano cone-shaped B-Si structure is formed by etching the photosensitive area of ​​the PIN junction using a femtosecond laser. (3) The sample with the obtained micro-nano cone-shaped B-Si structure is placed in the thermal evaporation chamber, and gold nanoparticles are deposited on the B-Si surface by thermal evaporation under vacuum to form a B-Si / AuNPs composite structure. (4) SiO2 passivation layer and Si3N4 passivation layer were sequentially deposited on the surface of B-Si / AuNPs by chemical vapor deposition.

7. The method for preparing the broadband, highly uniform black silicon integrated gold nanomaterial according to claim 6, characterized in that, In step (2), the parameters of the femtosecond laser are as follows: wavelength 750~850 nm, pulse width 100 fs, power density 3.0~6.0 kJ / m². 2 The scanning speed is 0.5~2 mm / s.

8. The method for preparing the broadband, highly uniform black silicon integrated gold nanomaterial according to claim 6, characterized in that, In step (3), at 1×10 -3 ~5×10 -3 Gold nanoparticles were thermally evaporated under a vacuum of Pa at a temperature range of 350–400 K using a sputtering power of 800–6000 W.

9. A broadband, highly uniform black silicon integrated nano-gold quadrant detector, characterized in that, Includes the black silicon integrated gold nanomaterial according to any one of claims 1 to 5 or the black silicon integrated gold nanomaterial prepared by any one of claims 6 to 8; The photodetector adopts a dual four-quadrant structure. The boundary regions of the dual four-quadrants are electrically isolated by etching deep trenches and filling them with silicon oxide compounds to form isolation trenches.

10. The broadband, highly uniform black silicon integrated nano-gold quadrant detector according to claim 9, characterized in that, The width of the isolation groove is 10-100 μm.

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