Wideband polarization photoelectric detector and preparation method thereof

Abstract

The application discloses a wide-band polarized photoelectric detector and a preparation method thereof, and belongs to the technical field of semiconductor photoelectricity.The wide-band polarized photoelectric detector is formed on the surface of a single crystal silicon substrate, and sequentially forms an embedded plasmonic nanoparticle layer and a plasmonic grating layer through ion beam irradiation and femtosecond laser direct writing; and then an electrode layer is formed on the surface of the plasmonic grating layer.The wide-band polarized photoelectric detector provided by the application is a new multifunctional photoelectric detector with super-wide-band response, high polarization sensitivity and high detection sensitivity, and can realize polarized light signal detection in a super-wide range from deep ultraviolet to mid-infrared band.Compared with a method of hetero-integrated anisotropic nanostructure, the application has good repeatability, high device stability and stable performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic technology, and specifically to a wide-band polarization photodetector and its fabrication method. Background Technology

[0002] As a core functional component of modern optoelectronic sensing systems, the performance of polarization photodetectors directly determines the technological ceiling in key fields such as remote sensing imaging, precise biomedical detection, all-weather safety monitoring, and high-speed optical communication. They hold irreplaceable application value in emerging industries such as aerospace, intelligent sensing, precision medicine, and 5G / 6G communication. With downstream applications rapidly evolving towards miniaturization, integration, and low power consumption, unprecedentedly stringent requirements are being placed on the spectral coverage, polarization resolution accuracy, system integration, and long-term reliability of polarization detection technology. For example, deep space remote sensing requires broad-spectrum polarization detection covering the deep ultraviolet to mid-infrared to identify complex celestial signals; portable biological detection devices require high-sensitivity polarization analysis without external power supplies and optical components; and industrial safety monitoring requires devices to maintain stable polarization response performance in harsh environments. Traditional polarization detection systems generally employ a discrete architecture of photodetectors and external polarization optical components (polarizers, waveplates, etc.), severely restricting the development of polarization detection technology towards miniaturization, integration, and high reliability, becoming a core technological obstacle to the implementation of high-end downstream applications. Therefore, polarization-sensitive ultrawideband photodetectors that do not require external polarization elements and can directly respond to the polarization state of light have become a core research direction for breaking through traditional technical bottlenecks, and their performance improvement and technological innovation have attracted widespread attention from global research institutions and industries.

[0003] Currently, the core approach to polarization-sensitive detection is to utilize the anisotropic micro / nanostructures of optoelectronic materials to directly convert the polarization information of light into electrical signals. The main technical solutions can be categorized into three main types: first, one-dimensional semiconductor nanowire arrays, which achieve shape anisotropy through the orientation and arrangement of nanowires, utilizing the difference in transmission efficiency of light with different polarization directions within the nanowires to achieve polarization resolution; second, two-dimensional layered material heterojunction stacks, which leverage the inherent crystal anisotropy of two-dimensional materials and optimize polarization response characteristics by adjusting the stacking angle; and third, subwavelength metal / dielectric grating structures, which utilize the polarization-selective diffraction effect of gratings to efficiently absorb light with specific polarization directions and convert it into electrical signals. However, existing technical approaches have fundamental limitations and cannot meet the high-performance requirements of practical applications. For example, the response bands are narrow and discontinuous, limited by the intrinsic optical band gap of materials (such as the band gap of semiconductor materials determining their response threshold) or structural resonance modes (such as the limited resonant wavelength range of grating structures). The effective response bands of existing polarization detectors are mostly concentrated in a single range of visible light (400nm~700nm) or near-infrared (700nm~2500nm), with bandwidths typically less than 600nm. They cannot simultaneously cover key application scenarios such as the deep ultraviolet band (200nm~400nm, used for high-precision spectral analysis and ultraviolet monitoring) and the mid-infrared band (2.5μm~25μm, used for gas sensing, infrared thermal imaging, and trace substance detection), which is far from meeting the practical requirements of modern sensing systems for wide-spectrum, multi-band collaborative detection. Furthermore, there are shortcomings in polarization sensitivity and performance stability. Specifically, the polarization ratio (i.e., the ratio of the maximum response current to the minimum response current) of existing devices is generally below 10, and the orientation consistency of nanomaterials and the uniformity of micro / nano structure arrangement are difficult to control precisely through traditional processes, resulting in large performance differences between batches of devices, which seriously affects the reliability and consistency in practical applications. In addition, due to the lack of functional integration, existing solutions cannot simultaneously achieve synergistic optimization of self-powered characteristics, ultra-wideband response, and high polarization sensitivity without complex external circuits and external polarization components. Summary of the Invention

[0004] This invention provides a wideband polarization photodetector and its fabrication method, which effectively solves the technical problems of existing polarization photodetectors, such as narrow and discontinuous response bands, insufficient polarization sensitivity and performance stability, and lack of functional integration. This invention provides a deep ultraviolet to mid-infrared ultrawideband polarization photodetector that combines a deep ultraviolet to mid-infrared ultrawideband response, high polarization sensitivity, and high detection sensitivity.

[0005] The first objective of this invention is to provide a wideband polarization photodetector, wherein an embedded plasmonic nanoparticle layer, a plasmonic grating layer and an electrode layer are sequentially formed on the surface of a single-crystal silicon substrate.

[0006] The embedded plasmonic nanoparticle layer is formed by implanting at least one ion selected from copper, gold, silver, iron, yttrium, zinc and oxygen into a single-crystal silicon substrate through ion beam irradiation to create plasmonic nanoparticles embedded in the substrate.

[0007] The thickness of the embedded plasmonic nanoparticle layer is 50nm~200nm; the plasmonic nanoparticles are spherical, with an outer diameter of 2nm~50nm and a spacing of 1nm~10nm; the size and spacing of the nanoparticles affect the position and intensity of the resonance peak of the local surface plasmon resonance (LSPR), which has a significant impact on the device response band.

[0008] The plasmonic grating layer is formed by micro- and nano-etching and modifying an embedded plasmonic nanoparticle layer after laser-induced annealing, while simultaneously melting the plasmonic nanoparticles and reconstructing them into nanorods.

[0009] The thickness of the plasmonic grating layer is 30nm~100nm, and the grating period of the plasmonic grating layer is 200nm~800nm; the long axis length of the nanorod is 50nm~100nm, the long axis / short axis ratio is 5~10, and the long axis direction is consistent with the grating direction.

[0010] In a preferred embodiment, the wide-band polarization photodetector has a response band of 200 nm to 25 μm, ranging from deep ultraviolet to mid-infrared. When the wide-band polarization photodetector responds in the 200 nm to 25 μm range, the localized surface plasmon resonance effect of the embedded plasmon nanoparticles enables continuous and efficient capture and absorption of incident light in the deep ultraviolet to mid-infrared band. Combined with the nanorod plasmon grating structure formed by femtosecond laser reconstruction, the device generates a highly sensitive electrical signal response to the polarization state of light. Thus, without relying on external polarization elements, it simultaneously achieves the functional integration of ultra-wide-band response and high polarization sensitivity. This invention verifies its wide-band polarization detection capability by conducting photoelectric performance tests on the device in the 850 nm near-infrared, 637 nm visible, and 380 nm deep ultraviolet bands. The device exhibits regular current-incident light polarization angle curves in all three typical bands, proving that it can stably respond to the polarization state of light in the visible, near-infrared, and even deep ultraviolet regions.

[0011] In a preferred embodiment, the thickness of the ion beam irradiation region on the surface of the single-crystal silicon substrate is 100nm~300nm; and the short axis length of the nanorod is 20nm~50nm.

[0012] In a preferred embodiment, the electrode layer is shaped as a parallel electrode or an interdigitated electrode; the thickness of the electrode layer is 30 nm to 100 nm; and the material of the electrode layer is at least one of gold, nickel, titanium, and chromium.

[0013] In a preferred embodiment, when the electrode layer is a parallel electrode, the thickness of the parallel electrode is 50 nm, the electrode spacing is 70 μm to 200 μm, and the electrode width is 30 μm to 50 μm.

[0014] Alternatively, when the electrode layer is shaped as an interdigitated electrode, the thickness of the interdigitated electrode is 35 nm and the electrode spacing is 70 μm to 200 μm.

[0015] In a preferred embodiment, the thickness of the single-crystal silicon substrate is 0.1 mm to 10 mm.

[0016] A second objective of this invention is to provide a method for fabricating a broadband polarization photodetector as described in any of the preceding claims, comprising the following steps: ≤5×10 -4 Under a vacuum of Pa, at a distance of 50 nm to 200 nm from the surface of a single-crystal silicon substrate, at least one of copper, gold, silver, iron, yttrium, zinc and oxygen is used to irradiate the surface of the single-crystal silicon substrate to form an embedded plasmonic nanoparticle layer, thus obtaining an ion-beam irradiated silicon substrate. In a vacuum (vacuum degree ≤ 5 × 10⁻⁶) -4 Under a protective atmosphere (Pa), the silicon substrate irradiated by the ion beam is heated to 300℃~1000℃ and annealed for 0.5h~1h to obtain an annealed silicon substrate; the annealing process involves heating to 300℃~1000℃ at a rate of 5℃ / min~10℃ / min, and after annealing, cooling to room temperature at a rate of 3℃ / min~5℃ / min.

[0017] Laser-induced micro-nano etching and modification of the surface of the annealed silicon substrate is performed, while the plasmonic nanoparticles are melted and reconstituted into nanorods to form a plasmonic grating layer, thus obtaining a silicon substrate with a grating layer. An electrode layer is deposited on the surface of the plasmonic grating layer to obtain a broadband polarization photodetector.

[0018] In a preferred embodiment, the parameters of the ion beam radiation are: the ion injection angle is normal incidence and the angle with the normal is less than 7°; the beam current density during the injection process is less than 10 nA / cm². 2 The ion implantation energy is 120keV~200keV, and the ion implantation dose is 2×10⁻⁶. 16 ions / cm 2 ~8×10 16 ions / cm2 .

[0019] Furthermore, when the implanted ions are copper and gold, and the implantation is performed in two sequential implantations, the implantation energy of copper ions is 120 keV~140 keV, preferably 120 keV, and the implantation dose is 2×10⁻⁶. 16 ions / cm 2 ~6×10 16 ions / cm 2 Preferably 5×10 16 ions / cm 2 The implantation energy of gold ions is 150 keV to 160 keV, preferably 160 keV, and the implantation dose is 6 × 10⁻⁶. 16 ions / cm 2 ~8×10 16 ions / cm 2 Preferably 8×10 16 ions / cm 2 .

[0020] Furthermore, when the implanted ions are silver and yttrium, the implantation is performed in two sequential implantations at an energy of 120 keV to 200 keV, with the preferred silver ion implantation energy being 180 keV and the preferred yttrium ion implantation energy being 160 keV, and the implantation dose being 5 × 10⁻⁶. 16 ions / cm 2 ~1×10 17 ions / cm 2 The preferred silver ion implantation dose is 8×10⁻⁶. 16 ions / cm 2 The preferred yttrium ion implantation dose is 8 × 10⁻⁶. 16 ions / cm 2 .

[0021] Furthermore, when the implanted ions are zinc and oxygen, and the implantation is performed in two sequential implantations, the zinc ion implantation energy is 100keV~150keV, preferably 130keV, and the implantation dose is 3×10⁻⁶. 16 ions / cm 2 ~7×10 16 ions / cm 2 Preferably 5×10 16 ions / cm 2 The oxygen ion implantation energy is 100 keV~150 keV, preferably 100 keV, and the implantation dose is 4 × 10⁻⁶. 16 ions / cm 2 ~8×10 16 ions / cm 2 Preferably 6×1016 ions / cm 2 .

[0022] As a preferred implementation, micro / nano etching and modification are performed using femtosecond laser direct writing. The parameters for femtosecond laser direct writing are: linearly polarized laser pulses with a width < 300 fs, a center wavelength of 343 nm, 515 nm, or 1030 nm, a focused spot diameter of 2 μm to 10 μm, a scanning rate of 10 μm / s to 10 mm / s, and a single pulse energy of 10 mJ / cm². 2 ~300mJ / cm 2 The repetition frequency of the laser pulse is 0.05MHz~5MHz; furthermore, the center wavelength of the femtosecond laser is preferably 1030nm, the scanning rate is preferably 3mm / s~6mm / s, and the single pulse energy is preferably 20mJ / cm². 2 ~50mJ / cm 2 .

[0023] In a preferred embodiment, before depositing an electrode layer on the surface of the plasmonic grating layer, photoresist is spin-coated on the silicon substrate with the grating layer, and a mask pattern is prepared on the silicon substrate with the grating layer using photolithography to obtain a photolithographic silicon substrate, and then an electrode layer is deposited on the surface of the photolithographic silicon substrate.

[0024] It should be noted that when depositing electrodes, when the electrode is a nickel electrode, a 50nm thick layer of metallic nickel is deposited on the photolithographic silicon substrate to form a parallel nickel electrode; when the electrode is a chromium / gold interdigitated electrode, a 5nm thick layer of metallic chromium is first deposited on the photolithographic silicon substrate, followed by a 30nm thick layer of gold to form a chromium / gold interdigitated electrode; when depositing a titanium / gold interdigitated electrode, a 10nm thick layer of metallic titanium is first deposited on the photolithographic silicon substrate, followed by a 50nm thick layer of gold to form a titanium / gold interdigitated electrode.

[0025] In addition, before ion beam irradiation on the monocrystalline silicon substrate, the present invention sequentially performs ultrasonic cleaning on the monocrystalline silicon substrate using acetone, anhydrous ethanol, and deionized water. Each ultrasonic cleaning lasts for 15 to 20 minutes, with an ultrasonic power of 80 W to 100 W, to thoroughly remove organic contaminants, oil stains, and particulate impurities from the substrate surface. After cleaning, the silicon substrate is dried in a nitrogen atmosphere (nitrogen purity ≥ 99.99%, airflow rate 5 L / min to 10 L / min), and then placed in a high-temperature annealing furnace for pre-annealing. Annealing treatment (annealing temperature of 800℃~1000℃, holding time of 2h~3h, heating rate of 5℃ / min~10℃ / min, nitrogen atmosphere) eliminates internal stress in the substrate; finally, double-sided mechanical polishing process is used to obtain a flat, clean, and low-stress pretreated silicon substrate with a surface roughness Ra≤0.5nm on both sides of the substrate, and then ion beam irradiation is performed on the pretreated silicon substrate. The thickness of the ion beam irradiation region 2 on the single crystal silicon substrate 1 is 100nm~300nm, preferably 170nm.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a wide-band polarization photodetector, which is obtained by sequentially forming an embedded plasmon nanoparticle layer and a plasmon grating layer on the surface of a single-crystal silicon substrate; and then depositing an electrode layer on the surface of the plasmon grating layer. The wide-band polarization photodetector provided by this invention is a novel multifunctional photodetector that combines ultra-wideband response, high polarization sensitivity, and high detection sensitivity, enabling the detection of polarized light signals over an ultra-wide range from deep ultraviolet to mid-infrared.

[0027] To address the technical problems of narrow and discontinuous response bands, insufficient polarization sensitivity and performance stability, and lack of functional integration in existing polarization photodetectors, this invention employs ion beam irradiation and femtosecond laser direct writing technology. The plasmonic nanoparticles formed by ion implantation exhibit a strong localized surface plasmon resonance (LSPR) effect, effectively enhancing light absorption and broadening the absorption wavelength, enabling the device to achieve a continuous ultra-wideband response. The plasmonic nanoparticles formed by ion implantation are embedded in a single-crystal silicon substrate, not directly exposed to air, greatly avoiding nanoparticle deterioration and damage, and improving device stability. Because femtosecond laser processing melts the nanoparticles and reconstitutes them into nanorods, the plasmon resonance mode becomes highly sensitive to the polarization direction of the incident light. This invention simultaneously achieves self-powered characteristics, ultra-wideband response, and high polarization sensitivity through functional integration.

[0028] Compared to traditional polarization photodetectors, the wideband polarization detector provided by this invention significantly improves integration and reduces device size by more than a thousand times. It has irreplaceable application value in emerging industries such as aerospace, intelligent sensing, precision medicine, and 5G / 6G communications. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the wideband polarization photodetector of the present invention; wherein, 1 is a single crystal silicon substrate, 2 is an ion beam irradiation region, 3 is an embedded plasmonic nanoparticle layer, 4 is a plasmonic grating layer, and 5 is an electrode layer.

[0030] Figure 2 This is a schematic diagram of the process of ion beam radiation and femtosecond laser direct writing used in the fabrication of the wide-band polarization photodetector of the present invention. In the diagram, a is a schematic diagram of ion implantation, 6 is a schematic diagram of ion implantation; b is a schematic diagram of femtosecond laser processing.

[0031] Figure 3 This is a graph showing the distribution of ion concentration with implantation depth in Example 1, simulated using SRIM software according to the present invention.

[0032] Figure 4 The current-incident light polarization angle curves of the wideband polarization photodetector provided in Embodiment 1 of the present invention under different polarization states of light in the deep ultraviolet band, visible light band, and near-infrared band are shown, where a is the 850nm near-infrared band, b is the 637nm visible light band, and c is the 380nm deep ultraviolet band.

[0033] Figure 5 The current-time curves of the wideband polarization photodetector provided in Embodiment 1 of the present invention at wavelengths of 261nm, 637nm, 1900nm and 4μm are shown, where (a) is 261nm, (b) is 637nm, (c) is 1900nm and (d) is 4μm.

[0034] Figure 6 The current-incident light polarization angle curves of the wideband polarization photodetector provided in Embodiment 2 of the present invention under different polarization states of light in the deep ultraviolet band, visible light band, and near-infrared band are shown, where a is the 850nm near-infrared band, b is the 637nm visible light band, and c is the 380nm deep ultraviolet band.

[0035] Figure 7 The current-time curves of the wideband polarization photodetector provided in Embodiment 2 of the present invention at wavelengths of 261nm, 637nm, 1900nm and 4μm are shown, where (a) is 261nm, (b) is 637nm, (c) is 1900nm and (d) is 4μm.

[0036] Figure 8The current-incident light polarization angle curves of the polarization photodetector provided in Comparative Example 1 of this invention under different polarization states of light in the deep ultraviolet, visible, and near-infrared bands are shown, where a is the 850nm near-infrared band, b is the 637nm visible band, and c is the 380nm deep ultraviolet band. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0038] Regarding the existing polarization photodetectors, firstly, their response bands are narrow and discontinuous. The effective response bands of existing polarization detectors are mostly concentrated in a single range of visible light (400nm~700nm) or near-infrared (700nm~2500nm), with bandwidth typically less than 600nm. This makes it impossible to simultaneously cover key application scenarios such as the deep ultraviolet band (200nm~400nm, used for high-precision spectral analysis and ultraviolet monitoring) and the mid-infrared band (2.5μm~25μm, used for gas sensing, infrared thermal imaging, and trace substance detection), which is far from meeting the practical requirements of modern sensing systems for wide-spectrum, multi-band coordinated detection. Secondly, their polarization sensitivity and performance stability are insufficient. The polarization ratio (i.e., the ratio of the maximum response current to the minimum response current) of existing devices is generally less than 10, and the orientation consistency of nanomaterials and the uniformity of micro-nano structures are difficult to control precisely through traditional processes, resulting in large performance differences between batches of devices, which seriously affects the reliability and consistency in practical applications. Third, there is a lack of functional integration. Existing solutions struggle to simultaneously achieve synergistic optimization of self-powered characteristics, ultra-wideband response, and high polarization sensitivity without complex external circuitry and external polarization elements. To address these technical problems, this invention provides a wideband polarization photodetector and its fabrication method.

[0039] The technical solution of the present invention will be described in detail below.

[0040] The present invention first provides a wide-band polarization photodetector, wherein an embedded plasmonic nanoparticle layer, a plasmonic grating layer and an electrode layer are sequentially formed on the surface of a single-crystal silicon substrate.

[0041] The embedded plasmonic nanoparticle layer is formed by implanting at least one ion selected from copper, gold, silver, iron, yttrium, zinc and oxygen into a single-crystal silicon substrate through ion beam irradiation to create plasmonic nanoparticles embedded in the substrate.

[0042] The thickness of the embedded plasmonic nanoparticle layer is 50nm~200nm; the plasmonic nanoparticles are spherical, with an outer diameter of 2nm~50nm and a spacing of 1nm~10nm; the size and spacing of the nanoparticles affect the position and intensity of the resonance peak of the local surface plasmon resonance (LSPR), which has a significant impact on the device response band.

[0043] The plasmonic grating layer is formed by micro- and nano-etching and modifying an embedded plasmonic nanoparticle layer after laser-induced annealing, while simultaneously melting the plasmonic nanoparticles and reconstructing them into nanorods.

[0044] The thickness of the plasmonic grating layer is 30nm~100nm, and the grating period of the plasmonic grating layer is 200nm~800nm; the long axis length of the nanorod is 50nm~100nm, the long axis / short axis ratio is 5~10, and the long axis direction is consistent with the grating direction.

[0045] In the above technical solution, ion beam irradiation and femtosecond laser direct writing technology are used. The plasmonic nanoparticles formed by ion implantation exhibit a strong localized surface plasmon resonance (LSPR) effect, which effectively enhances light absorption and broadens the absorption wavelength, enabling the device to achieve a continuous ultra-wideband response. The plasmonic nanoparticles formed by ion implantation are embedded in a single-crystal silicon substrate and are not directly exposed to air, greatly avoiding nanoparticle deterioration and damage, and improving device stability. Because femtosecond laser processing melts the nanoparticles and reconstitutes them into nanorods, the plasmon resonance mode becomes highly sensitive to the polarization direction of the incident light. This invention simultaneously achieves the functional integration of self-powered characteristics, ultra-wideband response, and high polarization sensitivity.

[0046] This invention utilizes ion beam irradiation and femtosecond laser direct writing technology to fabricate a deep ultraviolet to mid-infrared ultrawide-band polarization photodetector. The ion irradiation region, the embedded plasmon nanoparticle layer, and the plasmon grating layer can be controlled by the ion irradiation parameters and femtosecond laser direct writing parameters, thereby customizing the device's performance characteristics in different optical response bands, exhibiting extremely high controllability. Compared to methods using heterogeneous integrated anisotropic nanostructures, this method offers better repeatability, higher device stability, and more stable performance.

[0047] The technical effects of the present invention will be described below through specific embodiments and comparative examples.

[0048] Example 1 A wide-band polarization photodetector, such as Figure 1As shown, from bottom to top, the structure consists of a single-crystal silicon substrate 1 with a thickness of 0.5 mm, an ion irradiation region 2 with a thickness of 170 nm, an embedded plasmonic nanoparticle layer 3 with a thickness of 150 nm, a plasmonic grating layer 4 with a thickness of 80 nm, and a double parallel gold electrode layer 5 with a thickness of 50 nm, an electrode channel spacing of 50 μm, and an electrode width of 50 μm.

[0049] The fabrication method of the aforementioned broadband polarization photodetector specifically includes the following steps: S1. A single-crystal silicon substrate was selected and ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. Each ultrasonic cleaning lasted 20 minutes, and the ultrasonic power was 100W to thoroughly remove organic contaminants, oil, and particulate impurities from the substrate surface. After cleaning, the silicon substrate was dried in a nitrogen atmosphere (nitrogen purity ≥99.99%, airflow rate 10L / min), and then placed in a high-temperature annealing furnace for pre-annealing treatment (annealing temperature 800℃, holding time 2h, heating rate 5℃ / min, nitrogen atmosphere) to eliminate internal stress in the substrate. Finally, a double-sided mechanical polishing process was performed to achieve a surface roughness Ra ≤0.5nm on both sides of the substrate, resulting in a flat, clean, and low-stress pre-treated silicon substrate.

[0050] S2, the pretreated silicon substrate from S1 is smoothly adhered to the target disk in the vacuum chamber using high-temperature conductive adhesive, ensuring a tight, gap-free, and bubble-free fit between the pretreated silicon substrate and the target disk to avoid localized temperature unevenness during irradiation; the target disk is then moved into the ion beam irradiation vacuum chamber, and the chamber is closed and evacuated to a vacuum level ≤5×10⁻⁶. -4 Pa ensures the purity and uniformity of ion implantation; the ion implantation method is single-stage implantation, the ion type is copper, the implantation energy is 160 keV, and the implantation dose is 7 × 10⁻⁶. 16 ions / cm 2 During irradiation, the target disk is kept rotating at a constant speed to ensure uniform ion implantation into the silicon substrate surface, such as... Figure 2 In step a, the thickness of the ion irradiation region 2 is controlled to be 250 nm. After irradiation, the substrate is left to stand in a vacuum chamber for 24 hours to eliminate radiation hazards. Finally, an embedded plasmonic nanoparticle array with a size of 2 nm to 50 nm and a spherical morphology is formed in a region 10 nm to 150 nm away from the surface of the pretreated silicon substrate, resulting in an embedded plasmonic nanoparticle layer. See details. Figure 3 The concentration distribution of implanted ions in silicon is shown.

[0051] S3. The embedded plasmonic nanoparticle layer is placed in an annealing furnace and heated to 800°C at a rate of 5°C / min in a nitrogen atmosphere, and held for 2 hours to further optimize the crystallinity and size uniformity of the nanoparticles. At the same time, it repairs the lattice damage to the silicon substrate caused by ion irradiation, constructs an efficient carrier transport channel, and obtains the annealed silicon substrate.

[0052] S4. Fix the annealed silicon substrate onto a high-precision electric displacement stage and place the stage in the working area of ​​the femtosecond laser processing system; adjust the laser path so that the femtosecond laser focus is on the surface of the silicon substrate; the laser pulse width is 210 fs, the center wavelength of the femtosecond laser is 1030 nm, the focused spot diameter is 8 μm, the scanning rate is 3 mm / s, and the single pulse energy is 35 mJ / cm². 2 The repetition frequency is 1MHz; the laser pulse is linearly polarized, with the polarization direction aligned with the processing direction. The coordinated control program between the displacement stage and the laser system is initiated, and line-by-line scanning and direct writing are performed according to the preset periodic grating pattern, such as... Figure 2 b) By laser-induced micro-nano etching and modification of the silicon substrate surface, a regular plasmonic grating layer is formed; after direct writing is completed, the silicon substrate is placed in deionized water for ultrasonic cleaning to remove surface etching residues, and then dried with nitrogen to obtain a silicon substrate with a plasmonic grating layer.

[0053] S5. Positive photoresist (AR-P 5350) was uniformly coated onto the surface of a silicon substrate with a plasmonic grating layer using a spin-coating process. After spin-coating, the silicon substrate was pre-baked on a 100°C hot plate for 1 minute to remove the solvent from the photoresist. Subsequently, the silicon substrate with photoresist was placed in a photolithography machine, and ultraviolet lithography was used to precisely expose a pre-designed electrode pattern mask, controlling the mask diameter to 0.6 μm and the exposure power density to 60 mJ / cm². 2 After exposure, a development process is performed, and the residual developer is rinsed with deionized water. After drying with nitrogen, a post-baking process is carried out at 100°C for 1 minute to enhance the adhesion between the photoresist and the substrate. Finally, a photoresist mask consistent with the preset electrode pattern is formed on the surface of the silicon substrate, and the photolithographic silicon substrate is obtained.

[0054] S6. Place the photolithographically etched silicon substrate into a vacuum coating machine and deposit metal electrodes using magnetron sputtering to obtain the wideband polarization photodetector.

[0055] The photoelectric performance of the broadband polarization photodetector prepared in Example 1 above was tested. Figure 4 The current-incident light polarization angle curves are shown under different polarization states of light in the ultraviolet, visible, and infrared bands. The device exhibits excellent polarization-sensitive photoelectric detection performance in the ultraviolet to infrared bands. Figure 5The figures show the current-time curves of the photodetector excited at wavelengths of 261 nm, 637 nm, 1900 nm, and 4 μm. Furthermore, the photocurrent decrease was less than 0.1% after one year of storage, demonstrating excellent environmental stability.

[0056] Example 2 Unlike Example 1, in S2, the ion implantation method was sequential implantation, with silver and yttrium ions implanted sequentially. The silver ion implantation energy was 160 keV, and the implantation dose was 8 × 10⁻⁶. 16 ions / cm 2 The yttrium ion implantation energy was 130 keV, and the implantation dose was 8 × 10⁻⁶. 16 ions / cm 2 .

[0057] The photoelectric performance of the device prepared in Example 2 was tested. Figure 6 These are the current-incident light polarization angle curves under different polarization states of light in the ultraviolet, visible, and infrared bands. For example... Figure 7 The figures show the current-time curves generated at wavelengths of 261 nm, 637 nm, 1900 nm, and 4 μm. Compared to Example 1, the polarization sensitivity and photoresponsivity under the same wavelength excitation are different, demonstrating that by changing the ion beam irradiation method and irradiation parameters, the device performance can be controlled and adjusted, exhibiting extremely high controllability.

[0058] Example 3 Unlike Example 1, the femtosecond laser processing parameters in S4 are different: the scanning rate is 5 mm / s and the single pulse energy is 20 mJ / cm². 2 The repetition frequency is 2MHz. The electrode channel spacing in S6 is 70μm, and the electrode width is 20μm.

[0059] The photoelectric performance of the polarization photodetector prepared in Example 3 was tested. Compared with Example 1, the polarization sensitivity and photoelectric responsivity under the same wavelength excitation are different. It can be seen that by changing the femtosecond laser processing parameters and the processing rate, the performance of the device can be controlled and adjusted, which has extremely high controllability.

[0060] Example 4 Unlike Example 2, the femtosecond laser processing parameters in S4 are different: the scanning rate is 5 mm / s and the single pulse energy is 30 mJ / cm². 2 The repetition frequency is 2.5 MHz. The electrode channel spacing in S6 is 70 μm, and the electrode width is 20 μm.

[0061] The photoelectric performance of the polarization photodetector prepared in Example 4 was tested. Compared with Example 1, the polarization sensitivity and photoelectric responsivity under the same wavelength excitation are different. It can be seen that by changing the femtosecond laser processing parameters and the processing rate, the performance of the device can be controlled and adjusted, exhibiting extremely high controllability.

[0062] To further illustrate the technical effects of the present invention, comparative examples are also provided, as follows.

[0063] Comparative Example 1 A polarization photodetector comprises, from bottom to top, a single-crystal silicon substrate with a thickness of 0.5 mm, an ion irradiation region with a thickness of 140 nm, an embedded plasmonic nanoparticle layer with a thickness of 100 nm, and a double parallel gold electrode layer with a thickness of 50 nm, an electrode channel spacing of 50 μm, and an electrode width of 50 μm.

[0064] The fabrication method of the above-mentioned polarization photodetector specifically includes the following steps: S1. A single-crystal silicon substrate was selected and ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. Each ultrasonic cleaning lasted 20 minutes, and the ultrasonic power was 100W to thoroughly remove organic contaminants, oil, and particulate impurities from the substrate surface. After cleaning, the silicon substrate was dried in a nitrogen atmosphere (nitrogen purity ≥99.99%, airflow rate 10L / min), and then placed in a high-temperature annealing furnace for pre-annealing treatment (annealing temperature 800℃, holding time 2h, heating rate 5℃ / min, nitrogen atmosphere) to eliminate internal stress in the substrate. Finally, a double-sided mechanical polishing process was performed to achieve a surface roughness Ra ≤0.5nm on both sides of the substrate, resulting in a flat, clean, and low-stress pre-treated silicon substrate.

[0065] S2, the pretreated silicon substrate is smoothly adhered to the target disk in the vacuum chamber using high-temperature resistant conductive adhesive, ensuring a tight, gap-free, and bubble-free fit between the substrate and the target disk to avoid localized temperature unevenness during irradiation; the target disk is then moved into the ion beam irradiation vacuum chamber, the chamber is closed, and a vacuum level of ≤5×10⁻⁶ is evacuated. -4 Pa ensures the purity and uniformity of ion implantation; the ion implantation method is single-stage implantation, the ion type is copper, the implantation energy is 160 keV, and the implantation dose is 7 × 10⁻⁶. 16 ions / cm 2 During irradiation, the target disk is kept rotating at a constant speed to ensure that ions are uniformly injected into the surface of the silicon substrate. After irradiation, the substrate is placed in a vacuum chamber for 24 hours to eliminate radiation hazards. Finally, an array of embedded plasmonic nanoparticles with a size of 2-50 nm and a spherical morphology is formed in a region 10 nm to 150 nm away from the surface of the silicon substrate, thus obtaining an ion beam irradiated silicon substrate.

[0066] S3. The silicon substrate irradiated by the ion beam is placed in an annealing furnace and heated to 800°C at a rate of 5°C / min in a nitrogen atmosphere, and held for 2 hours to further optimize the crystallinity and size uniformity of the nanoparticles. At the same time, the lattice damage of the silicon substrate caused by the ion irradiation process is repaired, and an efficient carrier transport channel is constructed to obtain the annealed silicon substrate.

[0067] S4. A positive photoresist (AR-P 5350) is uniformly coated onto the annealed silicon substrate using a spin-coating process. After spin-coating, the silicon substrate is pre-baked on a 100°C hot plate for 1 minute to remove the solvent from the photoresist. Subsequently, the silicon substrate with photoresist is placed in a photolithography machine, and ultraviolet lithography is used to precisely expose a pre-designed electrode pattern mask, controlling the mask diameter to 0.6 μm and the exposure power density to 60 mJ / cm². 2 After exposure, a development process is performed, and the residual developer is rinsed with deionized water. After drying with nitrogen, a post-baking process is carried out at 100°C for 1 minute to enhance the adhesion between the photoresist and the substrate. Finally, a photoresist mask consistent with the preset electrode pattern is formed on the surface of the silicon substrate, and the photolithographic silicon substrate is obtained.

[0068] S5. The photolithographically etched silicon substrate is placed in a vacuum coating machine, and a metal electrode is deposited using a magnetron sputtering method to obtain the polarization photodetector.

[0069] The photoelectric performance of the polarization photodetector prepared in Comparative Example 1 was tested. Figure 8 As shown, the device did not exhibit polarization-sensitive photoelectric detection performance in the deep ultraviolet to mid-infrared band.

[0070] Comparative Example 2 A polarization photodetector comprises, from bottom to top, a single-crystal silicon substrate with a thickness of 0.5 mm, a grating layer with a thickness of 30 nm, and a double parallel gold electrode layer with a thickness of 50 nm, an electrode channel spacing of 50 μm, and an electrode width of 50 μm.

[0071] The fabrication method of the above-mentioned polarization photodetector specifically includes the following steps: S1. A single-crystal silicon substrate was selected and ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. Each ultrasonic cleaning lasted 20 minutes, and the ultrasonic power was 100W to thoroughly remove organic contaminants, oil, and particulate impurities from the substrate surface. After cleaning, the silicon substrate was dried in a nitrogen atmosphere (nitrogen purity ≥99.99%, airflow rate 10L / min), and then placed in a high-temperature annealing furnace for pre-annealing treatment (annealing temperature 800℃, holding time 2h, heating rate 5℃ / min, nitrogen atmosphere) to eliminate internal stress in the substrate. Finally, a double-sided mechanical polishing process was performed to achieve a surface roughness Ra ≤0.5nm on both sides of the substrate, resulting in a flat, clean, and low-stress pre-treated silicon substrate.

[0072] S2, fix the pretreated silicon substrate on a high-precision electric displacement stage and place the stage in the working area of ​​the femtosecond laser processing system; adjust the laser path so that the femtosecond laser focus is on the surface of the silicon substrate; the laser pulse width is 210 fs, the center wavelength of the femtosecond laser is 1030 nm, the focused spot diameter is 8 μm, the scanning rate is 3 mm / s, and the single pulse energy is 35 mJ / cm². 2 The repetition frequency is 1MHz; the laser pulse is linearly polarized, and the polarization state direction is consistent with the processing direction. The coordinated control program of the displacement stage and the laser system is started, and the linear scanning is performed according to the preset periodic grating pattern. The laser induces micro-nano etching and modification of the silicon substrate surface to form a regular plasmonic grating structure. After the linear writing is completed, the silicon substrate is ultrasonically cleaned in deionized water to remove surface etching residues. After being dried with nitrogen, a silicon substrate with a surface plasmonic grating layer is obtained.

[0073] S3. A positive photoresist (AR-P 5350) was uniformly coated onto the surface of a silicon substrate with a surface plasmon grating layer using a spin-coating process. After spin-coating, the silicon substrate was pre-baked on a 100°C hot plate for 1 minute to remove the solvent from the photoresist. Subsequently, the silicon substrate with the photoresist was placed in a photolithography machine, and ultraviolet lithography was used to precisely expose a pre-designed electrode pattern mask, controlling the mask diameter to 0.6 μm and the exposure power density to 60 mJ / cm². 2 After exposure, a development process is performed, and the residual developer is rinsed with deionized water. After drying with nitrogen, a post-baking process is carried out at 100°C for 1 minute to enhance the adhesion between the photoresist and the substrate. Finally, a photoresist mask consistent with the preset electrode pattern is formed on the surface of the silicon substrate, and the photolithographic silicon substrate is obtained.

[0074] S4. The photolithographically etched silicon substrate is placed in a vacuum coating machine, and a metal electrode is deposited using a magnetron sputtering method to obtain the polarization photodetector.

[0075] The photoelectric performance of the polarization photodetector prepared in Comparative Example 2 was tested. Due to the lack of plasmon absorption of the light signal, the device failed to generate photocurrent signals in the deep ultraviolet to mid-infrared bands and showed no polarization response.

[0076] Comparative Example 3 A polarization photodetector comprises, from bottom to top, a single-crystal silicon substrate with a thickness of 0.5 mm, an ion irradiation region with a thickness of 100 nm, an embedded plasmonic nanoparticle layer with a thickness of 50 nm, and a double parallel gold electrode layer with a thickness of 50 nm, an electrode channel spacing of 50 μm, and an electrode width of 50 μm.

[0077] The fabrication method of the above-mentioned polarization photodetector specifically includes the following steps: S1. A single-crystal silicon substrate was selected and ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. Each ultrasonic cleaning lasted 20 minutes, and the ultrasonic power was 100W to thoroughly remove organic contaminants, oil, and particulate impurities from the substrate surface. After cleaning, the silicon substrate was dried in a nitrogen atmosphere (nitrogen purity ≥99.99%, airflow rate 10L / min), and then placed in a high-temperature annealing furnace for pre-annealing treatment (annealing temperature 800℃, holding time 2h, heating rate 5℃ / min, nitrogen atmosphere) to eliminate internal stress in the substrate. Finally, a double-sided mechanical polishing process was performed to achieve a surface roughness Ra ≤0.5nm on both sides of the substrate, resulting in a flat, clean, and low-stress pre-treated silicon substrate.

[0078] S2, the pretreated silicon substrate is smoothly adhered to the target disk in the vacuum chamber using high-temperature resistant conductive adhesive, ensuring a tight, gap-free, and bubble-free fit between the substrate and the target disk to avoid localized temperature unevenness during irradiation; the target disk is then moved into the ion beam irradiation vacuum chamber, the chamber is closed, and a vacuum level of ≤5×10⁻⁶ is evacuated. -4 Pa ensures the purity and uniformity of ion implantation; the ion implantation method is single-stage implantation, the ion type is copper, the implantation energy is 50 keV, and the implantation dose is 5 × 10⁻⁶. 15 ions / cm 2 During irradiation, the target disk is kept rotating at a constant speed to ensure that ions are uniformly injected into the surface of the silicon substrate. After irradiation, the substrate is placed in a vacuum chamber for 24 hours to eliminate radiation hazards. Finally, an embedded plasmonic nanoparticle array with a size of 2nm to 50nm and a spherical morphology is formed in a region 10nm to 150nm away from the surface of the pretreated silicon substrate, thus obtaining an embedded plasmonic nanoparticle layer.

[0079] S3, the silicon substrate with the aforementioned embedded plasmon nanoparticle layer is fixed on a high-precision electric displacement stage, and the stage is placed in the working area of ​​the femtosecond laser processing system; the laser path is adjusted so that the femtosecond laser focus is on the surface of the silicon substrate; the laser pulse width is 210 fs, the center wavelength of the femtosecond laser is 1030 nm, the focused spot diameter is 8 μm, the scanning rate is 3 mm / s, and the single pulse energy is 35 mJ / cm². 2 The repetition frequency is 1MHz; the laser pulse is linearly polarized, and the polarization state direction is consistent with the processing direction. The coordinated control program of the displacement stage and the laser system is started, and the laser performs line-by-line scanning and direct writing according to the preset periodic grating pattern. The surface of the silicon substrate is etched and modified by laser-induced micro-nano etching. After the direct writing is completed, the silicon substrate is ultrasonically cleaned in deionized water to remove surface etching residues. After being dried with nitrogen, a silicon substrate with a surface plasmon grating layer is obtained.

[0080] S4. Using positive photoresist (AR-P 5350), a uniform coating was applied to the surface of a silicon substrate with a surface plasmon grating layer via spin coating. After spin coating, the silicon substrate was pre-baked on a 100°C hot plate for 1 minute to remove the solvent from the photoresist. Subsequently, the silicon substrate with photoresist was placed in a photolithography machine, and ultraviolet lithography was used to precisely expose a pre-designed electrode pattern mask, controlling the mask diameter to 0.6 μm and the exposure power density to 60 mJ / cm². 2 After exposure, a development process is performed, and the residual developer is rinsed with deionized water. After drying with nitrogen, a post-baking process is carried out at 100°C for 1 minute to enhance the adhesion between the photoresist and the substrate. Finally, a photoresist mask consistent with the preset electrode pattern is formed on the surface of the silicon substrate, and the photolithographic silicon substrate is obtained.

[0081] S5. The photolithographically etched silicon substrate is placed in a vacuum coating machine, and a metal electrode is deposited using a magnetron sputtering method to obtain the polarization photodetector.

[0082] The photoelectric performance of the polarization photodetector prepared in Comparative Example 2 was tested. Due to the low ion implantation energy and implantation metering, no nanoparticles were formed, and the lack of plasmon absorption of light signals resulted in the device failing to generate photocurrent signals in the deep ultraviolet to mid-infrared bands, and exhibiting no polarization response.

[0083] In summary, this invention employs a combination of ion beam irradiation and femtosecond laser direct writing to directly construct an embedded plasmonic nanoparticle layer and a plasmonic grating layer within a single-crystal silicon substrate. This eliminates the need for additional semiconductor materials, enabling polarization photodetection across a wide wavelength range from deep ultraviolet to mid-infrared. The fabrication method of this invention offers strong process controllability and repeatability. By adjusting ion implantation parameters (implanted ion type, implantation energy, implantation dose, and implantation method) and femtosecond laser direct writing parameters (laser wavelength, scan rate, and single-pulse energy), the size and distribution of nanoparticles and the morphology of the grating structure can be precisely optimized, thereby controlling the device's light absorption characteristics and polarization response performance, significantly enhancing photoelectric conversion efficiency. Furthermore, this fabrication method is cost-effective, enabling large-scale mass production. The device is an on-chip integrable structure with a simple and compact design, reducing its size by more than a thousand times compared to traditional polarization photodetectors. It is easily integrated with other optoelectronic or photonic devices to construct multifunctional on-chip photonic systems.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A broadband polarization photodetector, characterized in that, The wideband polarization photodetector is formed on the surface of a single-crystal silicon substrate by sequentially forming an embedded plasmonic nanoparticle layer, a plasmonic grating layer and an electrode layer. The embedded plasmonic nanoparticle layer is formed by implanting at least one ion selected from copper, gold, silver, iron, yttrium, zinc and oxygen into a single-crystal silicon substrate through ion beam irradiation to form plasmonic nanoparticles embedded in a single-crystal silicon substrate. The thickness of the embedded plasmonic nanoparticle layer is 50nm~200nm; the plasmonic nanoparticles are spherical, the outer diameter of the plasmonic nanoparticles is 2nm~50nm, and the spacing between the plasmonic nanoparticles is 1nm~10nm. The plasmonic grating layer is formed by micro- and nano-etching and modifying the embedded plasmonic nanoparticle layer after laser-induced annealing, while melting the plasmonic nanoparticles and reconstructing them into nanorods. The thickness of the plasmonic grating layer is 30nm~100nm, and the grating period of the plasmonic grating layer is 200nm~800nm; the long axis length of the nanorod is 50nm~100nm, and the long axis / short axis ratio is 5~10.

2. The broadband polarization photodetector according to claim 1, characterized in that, The response band of the wideband polarization photodetector is the deep ultraviolet to mid-infrared band of 200nm~25μm.

3. The broadband polarization photodetector according to claim 1, characterized in that, The thickness of the ion beam irradiation region on the surface of the single-crystal silicon substrate is 100nm~300nm; the short axis length of the nanorod is 20nm~50nm.

4. The broadband polarization photodetector according to claim 1, characterized in that, The electrode layer is in the shape of a parallel electrode or an interdigitated electrode; the thickness of the electrode layer is 30nm~100nm; the material of the electrode layer is at least one of gold, nickel, titanium and chromium.

5. The broadband polarization photodetector according to claim 4, characterized in that, When the electrode layer is in the shape of a parallel electrode, the thickness of the parallel electrode is 50 nm, the electrode spacing is 70 μm to 200 μm, and the electrode width is 30 μm to 50 μm. Alternatively, when the electrode layer is shaped as an interdigitated electrode, the thickness of the interdigitated electrode is 35 nm and the electrode spacing is 70 μm to 200 μm.

6. The broadband polarization photodetector according to claim 1, characterized in that, The thickness of the single-crystal silicon substrate is 0.1 mm to 10 mm.

7. A method for fabricating a broadband polarization photodetector according to any one of claims 1 to 6, characterized in that, Includes the following steps: ≤5×10 -4 Under a vacuum of Pa, at a distance of 50 nm to 200 nm from the surface of a single-crystal silicon substrate, at least one of copper, gold, silver, iron, yttrium, zinc and oxygen is used to irradiate the surface of the single-crystal silicon substrate to form an embedded plasmonic nanoparticle layer, thus obtaining an ion-beam irradiated silicon substrate. Under vacuum or a protective atmosphere, the silicon substrate irradiated by the ion beam is heated to 300°C to 1000°C and annealed for 0.5 h to 1 h to obtain an annealed silicon substrate. Laser-induced micro-nano etching and modification of the surface of the annealed silicon substrate is performed, while the plasmonic nanoparticles are melted and reconstituted into nanorods to form a plasmonic grating layer, thus obtaining a silicon substrate with a grating layer. An electrode layer is deposited on the surface of the plasmonic grating layer to obtain a broadband polarization photodetector.

8. The method for fabricating a broadband polarization photodetector according to claim 7, characterized in that, The parameters for the ion beam radiation are: the ion injection angle is normal incidence and the angle with the normal is less than 7°; the beam current density during the injection process is less than 10 nA / cm². 2 The ion implantation energy is 120keV~200keV, and the ion implantation dose is 2×10⁻⁶. 16 ions / cm 2 ~8×10 16 ions / cm 2 .

9. The method for fabricating a broadband polarization photodetector according to claim 7, characterized in that, Micro-nano etching and modification are performed using femtosecond laser direct writing. The parameters for femtosecond laser direct writing are: linearly polarized laser pulses with a width < 300 fs, a center wavelength of 343 nm, 515 nm, or 1030 nm, a focused spot diameter of 2 μm to 10 μm, a scanning rate of 10 μm / s to 10 mm / s, and a single pulse energy of 10 mJ / cm². 2 ~300mJ / cm 2 The repetition frequency of the laser pulse is 0.05MHz~5MHz.

10. The method for fabricating a broadband polarization photodetector according to claim 7, characterized in that, Before depositing an electrode layer on the surface of the plasmonic grating layer, photoresist is spin-coated on the silicon substrate with the grating layer, and a mask pattern is prepared on the silicon substrate with the grating layer using photolithography to obtain a photolithographic silicon substrate. Then, an electrode layer is deposited on the surface of the photolithographic silicon substrate.

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