Silver-assisted Chemical Etching Research Articles

Composition-adjustable silicon-germanium alloy films based on porous silicon matrices

Morphology and crystalline structure of silicon-germanium alloys formed by rapid thermal processing of germanium-filled porous silicon layers are evaluated. Two types of porous silicon are employed as matrices for electrochemical pore filling using GeO2 aqueous solutions and subsequently compared, the first one formed by electrochemical anodization and the second by silver-assisted chemical etching of monocrystalline silicon. The resulting alloys’ structure and composition are investigated using scanning electron microscopy, energy-dispersive X-ray analysis, Raman spectroscopy and X-ray powder diffraction. It is shown that by varying the porosity of the initial matrix (by adjusting anodization current density for anodic porous silicon or changing silver deposition time for structures produced by metal-assisted etching) in the range from 55 to 75%, Si1-xGex alloys with germanium fractions of x = 0.31 to x = 0.83 can be formed, as indicated by Raman spectroscopy. It is concluded that composition-adjustable layers of silicon-germanium can be successfully formed on either type of porous silicon layer. While an increase in porosity generally leads to a decrease in silicon fractions in the alloy, the steepness of this effect varies heavily depending on the type of porous matrix used and should be considered independently for anodic porous silicon and silicon nanowires.

Three-Dimensional Porous Si@SiOx/Ag/CN Anode Derived from Deposition Silicon Waste toward High-Performance Li-Ion Batteries.

The application of photovoltaic (PV) solid waste to the field of lithium-ion batteries is deemed to be an effective solution for waste disposal, which can not only solve the problem of environmental pollution but also avoid the loss of secondary resources. Herein, based on the volatile deposited waste produced by electron beam refining polysilicon, a simple and environmentally friendly method was designed to synthesize P-Si@SiOx/Ag/CN as an anode material for lithium-ion batteries. Remarkably, the presence of silver and the formation of a carbon-nitrogen network can enhance the electrical conductivity of the composite and boost the transport efficiency of lithium ions. Furthermore, the porous Si@SiOx structure is generated by silver-assisted chemical etching (Ag-ACE), and the carbon-nitrogen grid architecture is formed after lyophilization with NaCl as a template, which can jointly provide sufficient buffer space for the volume change of silicon during lithiation/delithiation. Benefitting from these advantages, the P-Si@SiOx/Ag/CN anode exhibits outstanding cycling performance with 759 mA h g-1 over 300 cycles at 0.5 A g-1. Meanwhile, the lithium-ion batteries employing the P-Si@SiOx/Ag/CN anodes present a superior rate capability of 950 mA h g-1 at 2 A g-1 and retain a high reversible specific capacity of 956 mA h g-1 at 1 A g-1 after 50 cycles. This work opens up a new economic strategy for the fabrication of high-performance silicon anodes and affords a promising avenue for the recycling of PV silicon waste.

Silicon-Based Superslippery/Superhydrophilic Striped Surface for Highly Efficient Fog Harvesting.

Fog-harvesting performance is influenced by surface wettability, patterned structure and the heat transfer coefficient. In this work, we have prepared different surfaces with a stripe array of superhydrophilic, superslippery and superslippery/superhydrophilic surfaces for fog harvesting on silicon substrates using photolithography and silver-assisted chemical etching. The surface wettability and heat transfer coefficients of the above samples have been investigated. We analyzed the contact angle, sliding angle and transport state of droplets on these surfaces. The fog-harvesting rate of all samples under different voltages of the cooling pad (V = 0, 2.0, 2.5, 3.0, 3.5 V) was measured. Results showed that the superslippery/superhydrophilic striped surface could achieve rapid droplet nucleation, directional transport and efficient collection due to its superhydrophilic striated channels and the Laplace pressure difference between different wettability regions. At a condensation voltage of 3.5 V, the fog-harvesting rate efficiencies of the uniformly striped superhydrophilic and superslippery surface were 1351 mg·cm-2·h-1 and 1265 mg·cm-2·h-1, respectively, while the fog-harvesting rate of the superslippery/superhydrophilic striped surface was 1748 mg·cm-2·h-1. Compared with the original silicon surface, the maximum fog-harvesting rate of the superslippery/superhydrophilic striped surface was improved by 86.9%. This study offers significant insights into the impact of heat transfer and silicon surface wettability on the process of fog collection.

Elaboration of Silicon Nanostructures with Vapor-Phase Silver Assisted Chemical Etching: Correlation between Structural and Optical Properties.

Based on the widely used wet metal-assisted electroless etching, we develop in this work a novel vapor-phase silver-assisted chemical etching (VP-Ag-ACE) suitable for the elaboration of highly doped p-silicon (Si) nanostructures with strong, visible, and multi-peak photoluminescence (PL) emissions. The lateral and vertical etching rates (LER and VER) were discussed based on the etching mechanism of the VP-Ag-ACE. The antireflective suitability of the vapor-etched layer has been evaluated by a reflectivity measurement and exhibits reflectivity values lower than 3%. The PL emission at both room and low temperatures emissions were deeply discussed and correlated with the structural properties of the Si morphologies and their surface states based on the FTIR results.

A Simple Method for the Fabrication of Silicon Inverted Pyramid Substrates for Surface-Enhanced Raman Spectroscopy.

Silicon inverted pyramids have been shown to exhibit superior SERS properties compared to ortho-pyramids, yet low-cost, simple preparation processes are lacking at present. This study demonstrates a simple method, silver-assisted chemical etching combined with PVP, to construct silicon inverted pyramids with a uniform size distribution. Two types of Si substrates for surface-enhanced Raman spectroscopy (SERS) were prepared via silver nanoparticles deposited on the silicon inverted pyramids by electroless deposition and radiofrequency sputtering, respectively. The experiments were conducted using rhodamine 6G (R6G), methylene blue (MB) and amoxicillin (AMX) molecules to test the SERS properties of the Si substrates with inverted pyramids. The results indicate that the SERS substrates show high sensitivity to detect the above molecules. In particular, the sensitivity and reproducibility of the SERS substrates with a denser silver nanoparticle distribution, prepared by radiofrequency sputtering, are significantly higher than those of the electroless deposited substrates to detect R6G molecules. This study sheds light on a potential low-cost and stable method for preparing silicon inverted pyramids, which is expected to replace the costly commercial Klarite SERS substrates.

Highly efficient photodegradation of methylene blue by a composite photocatalyst of bismuth nanoparticles on silicon nanowires

When synthetic dyes are used to embellish the world, the wastewater holding these hazardous materials is wantonly released into the biosphere. Appropriate treatment for such effluents is thereby indispensable. In this context, the present study was conducted to fabricate an eco-friendly, cost-effective and new bismuth modified silicon nanowires (Bi@SiNWs)-based photocatalysts toward superior photocatalytic degradation of methylene blue (MB) dye under both UV and solar irradiations. SiNWs were synthesized by silver-assisted chemical etching while Bi nanoparticles were anchored onto the NWs via thermal evaporation. By assessing the morphology, elemental composition, structure and crystallinity characteristics, these Bi@SiNWs nanocomposites are systematically identified. Extensive investigations of blank SiNWs and Bi@SiNWs optical properties — reflectance, transmittance, absorption coefficient, absorbance and optical band-gap — are presented. Near-perfect absorbance above 97%, over the visible wavelength region, has been achieved owing to the synergistic effect of Bi decoration on SiNWs. Accordingly, Bi@SiNWs showed remarkable photocatalytic ability for the degradation of MB up to 44% and 89% under UV and solar irradiation, respectively, only within 120 min. Repeated cycle runs revealed that the Bi@SiNWs composite photocatalyst exhibits strong reusability and photo-stability. Lastly, we will thoroughly provide the plausible mechanism for the photocatalytic degradation of MB over Bi@SiNWs. Our outcomes validate the potent role of Bi@SiNWs photocatalysts for effective environmental remediation.

Construction of porous Si/Ag@C anode for lithium-ion battery by recycling volatile deposition waste derived from refining silicon

Owing to the rapid advancement of the photovoltaic industry, a lot of photovoltaic (PV) silicon waste will be generated. Thus, the recycling and reuse of waste silicon have become particularly important, both for environmental remediation and economic benefits. In this work, a special structure of porous Si nanoparticles embedded nano-Ag and coated carbon layer (P-SiNPs/Ag@C) was produced by silver-assisted chemical etching (Ag-ACE) the deposited silicon waste. The special porous structure and carbon layer coating can effectively address the volume expansion issues during charge/discharge. The intercalated Ag nanoparticles greatly reduced the transfer impedance and enhanced the electrical conductivity of the anode material. As a result, the novel-designed P-SiNPs/Ag@C anode can maintain a prominent reversible capacity (1521 mAh·g−1 at 0.2 A g−1 after 50 cycles) and outstanding rate performance (1099 mAh·g−1 at 2 A g−1). When the current density at 1 A g−1, the specific capacity still maintains at 706 mAh·g−1 over 300 cycles. The superiority of the prepared P-SiNPs/Ag@C structures was further confirmed by Comsol Multiphysics software. Impressively, the synthesis route provides a novel avenue for value-added utilization of residual silicon waste resources from EB refining silicon and the preparation of high-performance lithium battery silicon-based anode.

Efficient Diode Performance with Improved Effective Carrier Lifetime and Absorption Using Bismuth Nanoparticles Passivated Silicon Nanowires.

In this paper, we report a novel design of bismuth nanoparticle-passivated silicon nanowire (Bi@SiNW) heterojunction composites for high diode performances and improved effective carrier lifetime and absorption properties. High-density vertically aligned SiNWs were fabricated using a simple and cost-effective silver-assisted chemical etching method. Bi nanoparticles (BiNPs) were then anchored in these nanowires by a straightforward thermal evaporation technique. The systematic study of the morphology, elemental composition, structure, and crystallinity provided evidence for the synergistic effect between SiNWs and BiNPs. Bi@SiNWs exhibited an eight-fold enhancement of the first-order Raman scattering compared to bare silicon. Current-voltage characteristics highlighted that bismuth treatment dramatically improved the rectifying behavior and diode parameters for Bi-passivated devices over Bi-free devices. Significantly, Bi wire-filling effectively increased the minority carrier lifetime and consequently reduced the surface recombination velocity, further indicating the benign role of Bi as a surface passivation coating. Furthermore, the near-perfect absorption property of up to 97% was achieved. The findings showed that a judicious amount of Bi coating is required. In this study the reasons behind the superior improvement in Bi@SiNW's overall properties were elucidated thoroughly. Thus, Bi@SiNW heterojunction nanocomposites could be introduced as a promising and versatile candidate for nanoelectronics, photovoltaics and optoelectronics.

Enhancing Detection Reproducibility of Surface-Enhanced Raman Scattering by Controlling Analytes under One Laser Spot.

Surface-enhanced Raman scattering (SERS), as a sensitive analytical technique, is expected to be used for quantification of trace analytes. At the current stage, high detection reproducibility should be guaranteed for realizing quantification analysis of trace analytes. The main obstacle to achieving high detection reproducibility is the nonuniform distribution of analyte molecules on substrates, particularly, the "coffee-ring" effect introduced by the flow of solute to the pinning of the contact line. Herein, we report a method to tackle this problem by controlling the location of analytes through tuning the wettability of the SERS substrate. With the combination of silver-assisted chemical etching and photolithography, the ordered Si patterns grafted silver nanoparticles with tunable wettability were integrated into a SERS substrate. With this substrate, high detection reproducibility was achieved by confining all the analyte molecules on the area of active plasmonic hot-spots within one laser, and the quantitative analysis was realized with ultrahigh sensitivity. Furthermore, the substrate is applicable for high-throughput detection.

Preparation and electrochemical properties of porous SiO/Ni anode materials for lithium-silicon batteries

To alleviate the volume expansion and improve the electrical conductivity of silicon monoxide (SiO) anode materials for lithium-silicon batteries, porous SiO (P-SiO) was prepared by silver-assisted chemical etching, and then porous SiO/Ni (P-SiO/Ni) composites were prepared by electroless Ni plating. The effect of SiO particle size on the microstructure of P-SiO and its electrochemical properties and the effect of Ni+ concentration in the plating solution on the microstructure of P-SiO/Ni and its electrochemical properties were systematically investigated, and the process mechanism of the preparation porous SiO by silver assisted chemical etching was firstly clarified. The results show that both the refinement and porosity of the SiO raw material are beneficial to alleviate the volume expansion of the P-SiO electrodes during the lithiation and delithiation process, and thus improve their the electrochemical performance. The electroless plating of nickel on the surface of P-SiO is also beneficial to further alleviate the volume expansion and increase the electrical conductivity of P-SiO electrode, thus further improving its specific capacity and cycling stability, the P-SiO/Ni anode with 3.03 wt% Ni content prepared at the Ni2+ concentration of 13 g/L has the best electrochemical performance, which the first discharge specific capacity reaches 1725.67 mAh/g, the first coulomb efficiency reaches 69.53%, and the reversible specific capacity after 200 cycles reaches 811.34 mAh/g at 1 A g−1 with a capacity retention rate of 62.39%.

Selective electrochemical deposition of indium in-between silicon nanowire arrays fabricated by metal-assisted chemical etching

Indium electrodeposition in-between silicon nanowire arrays fabricated by silver-assisted chemical etching of lightly-doped (100)-oriented silicon wafers is evaluated. It is concluded based on SEM and EDX analysis of indium's distribution that, by utilizing pulsed-mode electrodeposition and maintaining a sufficiently low duty cycle value, indium particles can be formed exclusively at the very bottom of each consecutive pore on the residual silver particles left over from metal-assisted etching. This result differs significantly from irregular pore filling along with surface and subsurface deposition observed in the cases of continuous galvanostatic deposition regimes at prolonged durations or in the absence of residual silver particles. Bottommost fusible metal deposit localization, which is unattainable on porous silicon fabricated by electrochemical anodization, is presumed to be optimal for the growth of germanium crystallites inside the pores via the electrochemical liquid-liquid-solid approach and subsequent silicon-germanium alloy formation through thermal annealing.

Optical Monitoring of the Biodegradation of Porous and Solid Silicon Nanoparticles.

Silicon nanoparticles (SiNP) are currently of great interest, especially in biomedicine, because of their unique physicochemical properties combined with biodegradability. SiNPs can be obtained in various ways and can have either a non-porous solid (sol-) or porous (por-) structure. In this work, we carry out detailed optical monitoring of sol- and por-SiNP biodegradation using Raman and photoluminescence (PL) micro-spectroscopy. SiNPs were obtained by ultrasound grinding of sol- or por-silicon nanowires, created by silver-assisted chemical etching of crystalline Si with different doping levels. In this case, sol-SiNPs consist of nanocrystals 30 nm in size, while por-SiNPs consist of small 3 nm nanocrystals and 16 nm pores. Both SiNPs show low in vitro cytotoxicity towards MCF-7 and HEK293T cells up to 800 μg/mL. The appearance of the F-band (blue–yellow) PL, as well as a decrease in the intensity of the Raman signal, indicate the gradual dissolution of the sol-SiNPs during 20 days of incubation. At the same time, the rapid dissolution of por-SiNP within 24 h is identified by the quenching of their S-band (red) PL and the disappearance of the Raman signal. The obtained results are important for development of intelligent biodegradable drug delivery systems based on SiNPs.

Recycling of photovoltaic silicon waste for high-performance porous silicon/silver/carbon/graphite anode.

The rapid development photovoltaic industry has generated a huge amount of waste ultra-fine silicon cutting powder. The management and value-added recovery of silicon cutting waste is highly important for both environmental remediation and economic efficiency. In this work, silicon waste was used as a cost-effective raw material for the preparation of silicon/graphite anode for lithium-ion batteries. First, porous Si embedded with Ag particles (pSi/Ag) was produced by silver-assisted chemical etching (Ag-ACE). Then, pSi/Ag was loaded on a micron-sized graphite matrix (pSi/Ag/G), and organic carbon (C) produced by the pyrolysis of polyvinylpyrrolidone (PVP) acted as a link to closely connect pSi/Ag and graphite to form the pSi/Ag/C/G composite. The incorporated Ag particles and the porous structure improve electron transfer and mitigate the volume expansion effect of silicon. The novel design and structure of the anode can maintain the integrity of the electrode during cycling, and thus strongly improve cycling stability. The prepared pSi/Ag/C/G composite exhibited a large initial discharge capacity of 2353 mAh/g at 0.5 A/g and good initial coulombic efficiency of 83%, delivering a high capacity of 972 mAh/g at 1 A/g after 200 cycles. This work confirmed the possibility of the preparation of lithium battery silicon-carbon anode from silicon waste and provides a promising new avenue for value-added utilization of silicon cutting waste materials.

One-Step Fabrication of Inverted Pyramid Textured Silicon Wafers via Silver-Assisted Chemical Etching Combing with Synergism of Polyvinylpyrrolidone (PVP)

Inverted pyramid-texturing of silicon surface has been proven to have great application potential in silicon solar cells. In this paper, we utilized Ag-assisted chemical etching (Ag–ACE) technology combing with polyvinylpyrrolidone (PVP) to fabricate an inverted pyramid textured Si surface. We call it Ag@PVP–ACE. The effect of different experimental parameters on etching results was observed. We show that the microstructure of the Si surface exhibited two states as the concentration of NH4HF2 and PVP concentration changed: polishing and inverted pyramid texturing. Meanwhile, we found inverted pyramids easier to form at the high temperature and low H2O2 concentration of the etching system. Consequently, compared to inverted pyramid structures fabricated by nanostructure rebuilding (NSR) technology and Ag@PVP–ACE, we consider that Ag@PVP–ACE technology could become a viable strategy for fabricating inverted pyramid textured Si wafers in Si solar cells production.

Thermolytically grafted silicon particles with ultrathin carbonaceous coating rich of phenyl moieties as lithium-storage anode material

The most critical bottleneck of Si anode materials is an inevitable cracking and pulverization of Si nanostructure during electrochemical cycling process, resulting in a significant loss of electrical contact and rapid capacity fading. The low-temperature thermolytic grafting process at 360–400 °C was employed to produce a conformal carbon coating on a bundle-like porous silicon (por-Si) prepared by silver-assisted chemical etching. During the thermolytic grafting process, polystyrene infiltrated in the por-Si was depolymerized into styrenic carbon fragments rich of phenyl moieties. The styrenic carbon fragments were subsequently grafted uniformly on the por-Si surface as an ultrathin carbonaceous film of 5 nm, which was confirmed by transmission electronic microscope, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The polystyrene grafted por-Si (por-Si@PS) was employed as a lithium-storage anode material. After 100 cycles at a current rate of 0.5C, the por-Si@PS anode exhibited an excellent reversible capacity of 1938.82 mAh g−1, when compared to those of por-Si and pristine Si anodes with 1228.57 mAh g−1 and 117.43 mAh g−1. The por-Si@PS exhibited a good recovery capability of 93.1% in the C-rate test. The ultrathin carbonaceous coating rich of phenyl moieties not only prevents the rapid pulverization of nanostructured Si, but also enhances the interfacial properties of por-Si@PS as lithium-storage anode material. Notably, the thermolytically grafted Si-C species rich of phenyl moieties played as a strong adhesive passivation layer against the corrosive electrochemical agents during cycling.

Formation of silver nanoparticles and their application for suppressing surface reflection of n-type silicon

In this paper silver-assisted chemical etching (SACE) was studied to increase roughness and reduce light reflection from the surface of n-type (100) mono-crystalline silicon. SACE process includes two basic steps which are silver deposition and chemical etching step. Simple electroless silver deposition step using mixture of AgNO3 and HF was utilized to form silver nanoparticles onto n-type silicon surface. Following chemical etching step was carried out by immersing samples in mixture of HF and H2O2. Concentration of AgNO3 in eletroless deposition step and concentration of HF in chemical etching step were investigated to get minimum reflectance. The surface of sample was characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and sample reflectance was measured at the wavelength range from 350–1100 nm. The results show that reflectance depends on AgNO3 concentration in electroless deposition step and HF concentration in etching step and the minimum solar-weighted reflectance is 1.74%. This method can be considered as simple, inexpensive method to effectively increase roughness and suppress light reflection for photovoltaic, optoelectronic, sensor, photonic applications.

Structural and Optical Properties of Silicon Nanowire Arrays Fabricated by Metal Assisted Chemical Etching With Ammonium Fluoride.

Here we report on the metal assisted chemical etching method of silicon nanowires (SiNWs) manufacturing, where the commonly used hydrofluoric acid (HF) has been successfully replaced with ammonium fluoride (NH4F). The mechanism of the etching process and the effect of the pH values of H2O2: NH4F solutions on the structural and optical properties of nanowires were studied in detail. By an impedance and Mott-Schottky measurements it was shown that silver-assisted chemical etching of silicon can be attributed to a facilitated charge carriers transport through Si/SiOx/Ag interface. It was shown that the shape of nanowires changes from pyramidal to vertical with pH decreasing. Also it was established that the length of SiNW arrays non-linearly depends on the pH for the etching time of 10 min. A strong decrease of the total reflectance to 5–10% was shown for all the studied samples at the wavelength <800 nm, in comparison with crystalline silicon substrate (c-Si). At the same time, the intensities of the interband photoluminescence and the Raman scattering of SiNWs are increased strongly in compare to c-Si value, and also they were depended on both the length and the shape of SiNW: the biggest values were for the long pyramidal nanowires. That can be explained by a strong light scattering and partial light localization in SiNWs. Hereby, arrays of SiNWs, obtained by using weakly toxic ammonium fluoride, have great potential for usage in photovoltaics, photonics, and sensorics.

Effects of annealing temperature towards surface morphological and optical properties of black silicon fabricated by silver-assisted chemical etching

This paper presents investigation on the effects of annealing temperature towards surface morphological and optical properties of black silicon (b-Si) fabricated by a two-step silver-assisted chemical etching process. Crystalline (c-Si) wafers are deposited with a thin film silver (Ag) layer. The c-Si wafers are annealed in nitrogen atmosphere for 40 min at different temperatures (200–260 ℃) to form Ag nanoparticles. The wafers are then etched in the aqueous solution of HF:H2O2:DI H2O at room temperature for 70 s. The results show that the surface morphologies of all samples are rough due to the presence of b-Si nanotextures. The b-Si wafers demonstrate significantly lower broadband reflection compared to the planar reference. The b-Si wafer annealed at 230 ℃ demonstrates the lowest reflection (3%) and highest absorption (97%) at the wavelength of 600 nm. This sample exhibits b-Si nanotextures with average width less than 50 nm and height of 245 nm. The enhanced broadband light absorption in the best b-Si wafer gives the highest maximum potential short-circuit current density (Jsc(max)) of 39.6 mA/cm2, or enhancement 50.6% compared to the planar c-Si reference wafer, calculated for wavelength region of 300–1100 nm.

Effects of etching time towards broadband absorption enhancement in black silicon fabricated by silver-assisted chemical etching

This paper presents investigation on the effects of etching time towards broadband absorption enhancement in black silicon (b-Si) fabricated by silver-assisted chemical etching. The c-Si wafers are deposited with a thin silver (Ag) layer and annealed in a nitrogen (N2) atmosphere to form Ag nanoparticles (Ag NPs). The wafers are then etched in an aqueous solution of HF:H2O2:H2O at room temperature at different etching times to form the b-Si. All the b-Si wafers show rough surface morphology due to the presence of nanotextures. The b-Si exhibit wafers exhibit significantly lower broadband reflection compared to a planar c-Si reference. The c-Si wafer etched for 70 s demonstrates the lowest broadband reflection, with reflection of 3% at wavelength of 600 nm (i.e. absorption of 97%). This sample exhibits b-Si nanotextures with width of 50–100 nm and height of 300–400 nm. The enhanced broadband light absorption in the b-Si leads to maximum potential short-circuit current density (Jsc (max)) of 39.7 mA/cm2, or 51% enhancement compared to a planar c-Si reference, calculated for wavelength region of 300–1100 nm.

Erratum to: Enhancement of silicon nanowire opto-electric properties by combining acid vapor etching and lithium pore-filling

In this paper, we report a novel method combining acid vapor etching (AVE) and Lithium (Li) pore-filling aiming to enhance the opto-electrical properties of silicon nanowires (SiNWs). Images provided by both scanning and transmission electron microscopies (SEM and TEM) show that, the silver-Assisted Chemical Etching (Ag-ACE) method provides uniform and vertically aligned SiNWs with smooth sidewalls. AVE treatment leads to the formation of thin porous silicon (pSi) layer covering the initially solid SiNW sidewalls without affecting their initial length. The as-prepared porous SiNWs (pSiNWs) exhibit a quite strong photoluminescence (PL) band centered on 2 eV. An additional immersion of pSiNWs in LiBr aqueous solution leads to a significant change in the surface chemistry and a stable PL emission with fourfold increase in the intensity. The total reflectivity decreases with Li concentration and reaches 1% in the visible range. Simultaneously, the minority carrier lifetime (τeff) of pSiNWs is enhanced from 1.48 to 7.1 µs due to the formation of a stable passivation layer and the saturation of dangling bands. The dark I–V measurement shows a significant decrease of the series resistance from 340 to 85 Ω.