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Nanoparticle Emissions from Metal-Assisted Chemical Etching of Silicon Nanowires for Lithium Ion Batteries
摘要： As one of the most promising anode materials for high-capacity lithium ion batteries (LIBs), silicon nanowires (SiNWs) have been studied extensively. The metal-assisted chemical etching (MACE) is a low-cost and scalable method for SiNWs synthesis. Nanoparticle emissions from the MACE process, however, are of grave concerns due to their hazardous effects on both occupational and public health. In this study, both airborne and aqueous nanoparticle emissions from the MACE process for SiNWs with three sizes of 90 nm, 120 nm, and 140 nm are experimentally investigated. The prepared SiNWs are used as anodes of LIB coin cells, and the experimental results reveal that the initial discharge and charge capacities of LIB electrodes are 3636 and 2721 mAh g-1 with 90 nm SiNWs, 3779 and 2712 mAh g-1 with 120 nm SiNWs, and 3611 and 2539 mAh g-1 with 140 nm SiNWs. It is found that, for 1 kW h of LIB electrodes, the MACE process for 140 nm SiNWs produces a high concentration of airborne nanoparticle emissions of 2.48 × 109 particles/cm3; the process for 120 nm SiNWs produces a high mass concentration of aqueous particle emissions, with a value of 9.95 × 105 mg/L. The findings in this study can provide experimental data of nanoparticle emissions from the MACE process for SiNWs for LIB applications, and can help the environmental impact assessment and life cycle assessment of the technology in the future.
关键词： Lithium ion batteries (LIBs),Metal-assisted chemical etching (MACE),Nanoparticle emissions,Silicon nanowires (SiNWs)
更新于2025-09-23 15:23:52
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Study of the relationship between metal-assisted chemical etching and direction of the applied electric field
摘要： Metal-assisted chemical etching (MACE) has been proposed as a promising alternative for the fabrication of micro/nano-structures on silicon with simple process and low cost. Electric field can be applied during the reaction to control the motion of charged particles so as to accelerate the reaction and form uniform vertical trenches with high aspect ratio. In this paper, boron doped p-type (100) silicon wafers with resistivity of 20～30 Ω·cm was used as substrates. After coated with layers of 5 nm Ti and 10 nm Au, the silicon substrate was immersed into the etchant containing hydrofluoric acid (HF) and hydrogen peroxide (H2O2) with high HF-to-H2O2 concentration ratio (ρ) and an applied voltage of 40 volts. It was found that the direction of the applied electric field had a great influence on morphologies of the trenches. Deeper trenches with vertical sidewalls and relatively smoother bottom were observed when silicon substrate was connected to cathode of the power supply. Possible interpretation to these phenomena was proposed, and the effect of the electric field intensity and doping concentration was further studied.
关键词： trench morphology,metal-assisted chemical etching,electric field,HF-to-H2O2 ratio,electrode connection
更新于2025-09-23 15:23:52
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Optical properties of ZnO deposited by atomic layer deposition (ALD) on Si nanowires
摘要： In this work, we report proof-of-concept results on the synthesis of Si core/ ZnO shell nanowires (SiNWs/ZnO) by combining nanosphere lithography (NSL), metal assisted chemical etching (MACE) and atomic layer deposition (ALD). The structural properties of the SiNWs/ZnO nanostructures prepared were investigated by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies. The X-ray diffraction analysis revealed that all samples have a hexagonal wurtzite structure. The grain sizes are found to be in the range of 7–14 nm. The optical properties of the samples were investigated using reflectance and photoluminescence spectroscopy. The study of photoluminescence (PL) spectra of SiNWs/ZnO samples showed the domination of defect emission bands, pointing to deviations of the stoichiometry of the prepared 3D ZnO nanostructures. Reduction of the PL intensity of the SiNWs/ZnO with the increase of SiNWs etching time was observed, depicting an advanced light scattering with the increase of the nanowire length. These results open up new prospects for the design of electronic and sensing devices.
关键词： nanosphere lithography (NSL),atomic layer deposition (ALD),Silicon nanowires (SiNWs),metal-assisted chemical etching (MACE),ZnO
更新于2025-09-23 15:21:21
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Development of additive-assisted Ag-MACE for multicrystalline black Si solar cells
摘要： The uniform distribution of silver nanoparticles on the surfaces of diamond-wire sawn multicrystalline silicon (mc-Si) is critical for the texturing of mc-Si by the Ag metal-assisted chemical etching method (Ag-MACE). In this study, an additive containing alkylphenol polyoxyethylene is developed to improve the Ag-MACE process. It enables an even deposition of the silver nanoparticles over the surface of the silicon wafer, so that the entire wafer surface can be uniformly textured with nanostructures. The experimental results show that the additive improves the appearance and performance of solar cells, including their reflectivity, efficiency, internal quantum efficiency and external quantum efficiency. Mass-produced mc-Si solar cells textured using Ag-MACE with this additive have achieved a maximum efficiency of 19.51%, compared with an efficiency of 19.16% for cells fabricated without the additive.
关键词： metal-assisted chemical etching,additive,diamond wire saw,uniform textures,solar cell,multicrystalline silicon
更新于2025-09-23 15:19:57
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Controllable Patterning of Hybrid Silicon Nanowire and Nanohole Arrays by Laser Interference Lithography
摘要： Metal-assisted chemical etching (MACE) is a cost-effective method to fabricate Si nanostructures including silicon nanowires (SiNWs) and silicon nanoholes (SiNHs). However, the preparation of metallic template for MACE would require complex experimental conditions including strict cleaning process and multiple steps. In our study, we applied superlens-enhanced laser interference lithography to directly fabricate complicated metallic patterns and then used MACE to obtain hybrid SiNW and SiNH arrays. Ag films were firstly deposited on Si substrates, and then a 1064 nm high power laser source was utilized to generate two-beam interference electric fields. Since Ag molecules are very sensitive to any input energy change, they tend to break up or aggregate and form different Ag patterns which have a specific energy threshold in order to lower its free energy. By manipulating the distribution of input electric field, we are able to obtain complicated metallic patterns and their corresponding Si nanostructures with feature sizes that range from tens of nanometers to several micrometers.
关键词： silicon nanowires and silicon nanoholes,silicon nanostructures,nanofabrication,metal-assisted chemical etching
更新于2025-09-23 15:19:57
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Metal-Assisted Silicon Chemical Etching Using Self Assembled Sacrificial Nickel Nanoparticles Template for Anti-Reflection Layers in Photovoltaic and Light-Trapping Devices
摘要： Thin film de-wetting is a simple patterning approach that provides a straight forward method for fabricating silicon structures using metal-assisted chemical etching (MacEtch). Currently, this has been mainly demonstrated with gold (Au) or silver (Ag) catalyst for MacEtch and to accomplish this, an extra Au or Ag nanoparticles lift-off step is required. The uncertain success with the lift-off process is potentially a major hindrance to achieve low-cost, large-scale and uniform Si nanostructures. In this work, we report on the use of nickel (Ni) as an alternative sacrificial metal for the de-wetting process. The de-wetting phenomenon of Ni on silicon dioxide is investigated to show that controllable sizes and density are achievable for this material system. A physical model to describe the relationship among Ni film thickness, particle interspacing and density is proposed. Using the Ni nanoparticles as a starting mask template, an improved approach for the large scale fabrication of silicon nanowires without the use of lithography methods is demonstrated. This not only eliminates problems associated with lift-off but also allows for scaling up of such fabrication using the proposed self-assembly approach, which holds great potential in furthering the versatility of the MacEtch technique in anti-reflection surfaces and light-trapping devices applications.
关键词： MacEtch,Nickel nanoparticles,Silicon,MACE,De-wetting,Metal-assisted chemical etching
更新于2025-09-19 17:13:59
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Low Reflection and Low Surface Recombination Rate Nano-Needle Texture Formed by Two-Step Etching for Solar Cells
摘要： In this study, needle-like and pyramidal hybrid black silicon structures were prepared by performing metal-assisted chemical etching (MACE) on alkaline-etched silicon wafers. E?ects of the MACE time on properties of the black silicon wafers were investigated. The experimental results showed that a minimal re?ectance of 4.6% can be achieved at the MACE time of 9 min. The height of the nanostructures is below 500 nm, unlike the height of micrometers needed to reach the same level of re?ectance for the black silicon on planar wafers. A stacked layer of silicon nitride (SiNx) grown by inductively-coupled plasma chemical vapor deposition (ICPCVD) and aluminum oxide (Al2O3) by spatial atomic layer deposition was deposited on the black silicon wafers for passivation and antire?ection. The 3 min MACE etched black silicon wafer with a nanostructure height of less than 300 nm passivated by the SiNx/Al2O3 layer showed a low surface recombination rate of 43.6 cm/s. Further optimizing the thickness of ICPCVD-SiNx layer led to a re?ectance of 1.4%. The hybrid black silicon with a small nanostructure size, low re?ectance, and low surface recombination rate demonstrates great potential for applications in optoelectronic devices.
关键词： passivation,black silicon,metal-assisted chemical etching
更新于2025-09-16 10:30:52
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A silicon-based quantum dot random laser
摘要： Herein, a quantum dot random laser was achieved using a silicon nanowire array. The silicon nanowire array was grown by a metal-assisted chemical etching method. A colloidal quantum dot solution was spin-coated on silicon nanowires to form the random laser. The performance of the random laser was controlled by the resistivity of silicon wafers and the length of silicon nanowires. A transition from incoherent random lasing to coherent random lasing was obtained by increasing the resistivity of the silicon wafers. The random lasing threshold increased with an increase in the length of the silicon nanowires. These results may be useful to explore high-performance silicon-based random lasers.
关键词： metal-assisted chemical etching,silicon nanowire array,coherent random lasing,quantum dot,random laser
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - The damage mitigation process for Si nanopillar structure using silica nanosphere lithography and metal assisted chemical etching
摘要： This work focuses on mitigating the damage from nanostructure fabrication using silica nanosphere lithography (SNL) and metal assisted chemical etching (MACE). Metal contamination and plasma damage are the two main factors to limit the Si wafer's minority carrier lifetime. Ni/Au and Ti/Au metal layers on bare Si wafer are compared using lifetime recovery test. Ti/Au shows to be more suitable for the MACE process. Samples deposited with Ni/Au and Ti/Au show lifetimes of 7 μs and 1200μs, respectively. The silicon surface is degraded significantly by the RIE plasma during the nanosphere etching process. SiO2 protective layer was added to the process, mitigating significantly the plasma damage on the silicon surface. Lifetime measurements shows an improvement over 1 ms when SiO2 protective layer on planar Si wafer is used. Lifetimes of 353 μs and implied open circuit voltages of 651mV were accomplished on nanopillar structured wafers using SiOx protective layer and Ti/Au.
关键词： lifetime recovery,silica nanosphere lithography,metal assisted chemical etching,Si nanopillar structure,damage mitigation
更新于2025-09-11 14:15:04
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Combined metal-assisted chemical etching and anisotropic wet etching for anti-reflection inverted pyramidal cavities on dendrite-like textured substrates
摘要： A simple and low-cost method using the combination of metal-assisted chemical etching (MacEtch) and anisotropic wet etching was performed to fabricate anti-reflection inverted pyramidal cavities on dendrite-like textured silicon substrates. To achieve this, a thin Ag film was deposited on an n-type (100) silicon substrate to form agglomerated Ag particles and MacEtch was performed to obtain vertically aligned etching holes on Si substrate. Subsequently, anisotropic wet etching was conducted and the etchant would penetrate the porous structure to form inverted pyramidal cavities on the dendrite-like structure. Using this two-step etching, excellent anti-reflection behavior was obtained for our textured substrates.
关键词： Anisotropic wet etching,Metal-assisted chemical etching,Textured substrate,Anti-reflection
更新于2025-09-10 09:29:36