Morphology Of Silicon Nanowires Research Articles

Morphological studies of Si nanowires effect on the photovoltaic s

Silicon nanowires (SiNWs) were produced by an electroless method on FZ-Si (100) wafer, in HF/AgNO3 solution. The influence of etching time and temperature on SiNWs morphology were studied using FESEM images. Optical properties were also investigated by optical absorption spectroscopy and low-temperature photoluminescence at 4.2 K. Considering their role as active regions, photo- voltaic properties of SiNWs solar cells were studied for their different lengths. Photovoltaic measurements were taken in 1 sun condition under AM 1.5 illumination supplied by a solar simulator. Measurements indicated a reduction in effi ciency as SiNWs length increased, which might be attributed to increased dangling states on nanowires surfaces.

Silicon Nanowires Decorated with Silver Nanoparticles for Photoassisted Hydrogen Generation

Highly n-doped silicon nanowires (SiNWs) decorated with silver nanoparticles (AgNPs) at the top, middle, and bottom were produced using electroless silver deposition (ELD), silver mirror reaction (MR), and native AgNPs as a reference, respectively. Subsequently, hydrogen generation on SiNWs decorated with and without AgNPs was evaluated. Our results show that SiNWs decorated with native and MR AgNPs produce the highest and the lowest hydrogen amount under white light irradiation in 3 h, respectively. Moreover, for SiNWs with native AgNPs, the morphology of SiNWs after hydrogen generation was almost the same as the original array of SiNWs before hydrogen release, even after 24 h in water/ethanol (4:1; v/v) solution. However, the geometry of SiNWs decorated without and with AgNPs by ELD and MR was collapsed after hydrogen evolution. The detailed surface studies show that the sidewall surface of SiNWs with native AgNPs has a rougher topology and formed a stable layer of SiOx in water. Our observations strongly suggest that two hydrogen generation possibilities, i.e., SiNW oxidation and photostimulation, are jointly responsible for the efficient hydrogen generation. Additionally, the presence of AgNPs on the sidewall of the SiNW matrix can enhance the hydrogen generation rate. Our results open novel perspectives for the effective hydrogen generation based on nanostructured silicon.

Morphological studies of Si nanowires effect on the photovoltaic s

Silicon nanowires (SiNWs) were produced by an electroless method on FZ-Si (100) wafer, in HF/AgNO3 solution. The influence of etching time and temperature on SiNWs morphology were studied using FESEM images. Optical properties were also investigated by optical absorption spectroscopy and low-temperature photoluminescence at 4.2 K. Considering their role as active regions, photo- voltaic properties of SiNWs solar cells were studied for their different lengths. Photovoltaic measurements were taken in 1 sun condition under AM 1.5 illumination supplied by a solar simulator. Measurements indicated a reduction in effi ciency as SiNWs length increased, which might be attributed to increased dangling states on nanowires surfaces.

Laser Assisted Catalytic Growth of Silicon Nanowires Using Gold and Nickel Catalysts.

Laser assisted synthesis of silicon nanowires (SiNWs) was successfully achieved through the use of gold and nickel as catalysts. The diameter of the resulting SiNWs was found to be dependent on that of the catalyst in the case of gold catalyst. The gold catalysed silicon nanowires were unevenly curved and branched owing to the high kinetic energy possessed by gold nanoparticles (AuNPs) at relatively high processing temperature. The use of nickel as catalyst resulted in the formation of several SiNWs on a single nickel catalyst crystallite due to interconnection of the nickel metal crystallites at processing temperature. The morphology of SiNWs catalysed by both nickel and gold was controlled by optimising the laser energy during ablation.

A detailed study on the growth of silicon nanowires by hot wire chemical vapor process: concept of critical size of Sn catalyst

The size of silicon nanowires (SiNWs) plays an important role for their application in nanoelectronic and nanophotonic systems. Therefore, it is of great interest to study the synthesis conditions of SiNWs in order to grow SiNWs with well-controlled manner to be integrated into a device. This paper includes a systematic study of the dependence of diameter and length of the SiNWs on the growth conditions. SiNWs were synthesized via vapor–liquid–solid (VLS) mechanism using a catalyst film of Sn nanoparticles on stainless steel (SS) substrate. The morphology and microstructure of SiNWs synthesized at different parameters were investigated with scanning electron microscopy and Raman spectroscopy. In this study, we have observed that there exists a minimum size of the catalyst to initiate the growth of SiNWs for a given set of process parameters. Furthermore, this work also addresses the difficulties associated with the growth of long SiNWs. Effect of filament temperature on the morphology of SiNWs has also been studied. It is observed that their dimensions and geometrical orientation are greatly influenced by the filament temperature. At filament temperatures between 1400 and 1600 °C, short SiNWs with random distributions are observed. Long and vertical SiNWs are found if the filament temperature was raised to 1800–1950 °C.

Enhanced photocatalytic activities of silicon nanowires/graphene oxide nanocomposite: Effect of etching parameters

Homogeneous and vertically aligned silicon nanowires (SiNWs) were successfully fabricated using silver assisted chemical etching technique. The prepared samples were characterized using scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Photocatalytic degradation properties of graphene oxide (GO) modified SiNWs have been investigated. We found that the SiNWs morphology depends on etching time and etchant composition. The SiNWs length could be tuned from 1 to 42 µm, respectively when varying the etching time from 5 to 30 min. The etchant concentration was found to accelerate the etching process; doubling the concentrations increases the length of the SiNWs by a factor of two for fixed etching time. Changes in bundle morphology were also studied as function of etching parameters. The SiNWs diameter was found to be independent of etching time or etchant composition while the size of the SiNWs bundle increases with increasing etching time and etchant concentration. The addition of GO was found to improve significantly the photocatalytic activity of SiNWs. A strong correlation between etching parameters and photocatalysis efficiency has been observed, mainly for SiNWs prepared at optimum etching time and etchant concentrations of 10 min and 4:1:8. A degradation of 92% was obtained which further improved to 96% by addition of hydrogen peroxide. Only degradation efficiency of 16% and 31% has been observed for bare Si and GO/bare Si samples respectively. The obtained results demonstrate that the developed SiNWs/GO composite exhibits excellent photocatalytic performance and could be used as potential platform for the degradation of organic pollutants.

Electrical characterisation of Ag/poly(3-hexylthiophene)/silicon nanowires Schottky diode

The electrical properties of Ag/Poly(3-hexylthiophene)/Silicon nanowires heterostructure (Ag/P3HT/SiNWs) were investigated. Silicon nanowires (SiNWs) were obtained by metal-assisted chemical etching method in one-step process. P3HT polymer was deposited on SiNWs surfaces by electroless deposition method for different immersion durations (dim). The morphology of SiNWs before and after deposition of P3HT polymer has been examined by scanning electron microscope (SEM). The formation of nanowires as well as the presence of P3HT on their surfaces can be seen in SEM images. Current–voltage (I–V) measurements were carried out on Ag/P3HT/SiNWs by varying dim from 30 to 210 min. The electrical measurements on the different junctions at room temperature showed a rectifying effect. For 30 min, the ideality factor of the Schottky diode was reduced from 4 to 1,4. By using the Cheung method, the diode parameters of the different structures are determined and discussed. The different hetrostructures have been annealed at 100 °C, 200 and 300 °C. The characteristic parameters were calculated as a function of annealing temperature. The optimum temperature for these heterostructures characteristics is 100 °C. The interface states, the trapping levels and the thermal activation of the free carriers are the main factors involved in the conduction phenomenon through Ag/P3HT/SiNWs heterostructures.

Morphological and electrical study of p-type silicon nanowires synthesised by Ag-assisted electroless chemical etching

Fabrication of Silicon nanowires (SiNWs) by electroless etching of p-type (100) Silicon wafer using silver (Ag) particles as catalyst at room temperature has been reported in this paper. Dependence of SiNWs formation on Ag electroplating and etching time was investigated. Surface morphology of SiNWs has been studied using scanning electron microscope (SEM) for different samples. The length of SiNWs increased with time of etching and decreased with electroplating time. A systematic study regarding the surface topography of fabricated SiNWs was performed using atomic force microscope (AFM). A 3D profile of the surface on a nanoscale were analysed and compared with SEM images. The average diameter of 73.9 nm for SiNWs was measured using as-obtained AFM images. Electroplating and etching time had minimum effect on the diameter of as-fabricated SiNWs. Fourier transform infrared spectroscopy was used to extract the bonding information for SiNWs. Electrical properties were evaluated using two-probe source measuring unit. Resistivity of 0.11 Ω-cm was obtained for synthesised SiNWs. A cost-effective, environment friendly electroless metal assisted chemical etching process was used to successfully develop SiNWs from the bulk Silicon wafer.

Silicon Nanowires as Sensory Material for Surface-Enhanced Raman Spectroscopy

This paper shows steps for silicon nanowires substrates synthesis in detail. The research is focused on experimental techniques optimization while the targeted application was a fabrication of highly sensitive substrates for surface-enhanced Raman spectroscopy (SERS). Horizontal silicon nanowires on top of two-inch wafers were obtained by vapour-liquid-solid growth inside the low-pressure chemical vapour deposition reaction tube. The silicon nanowires morphology was monitored by scanning electron microscope after a short and long growth period which defined an adequate deposition time for SERS applications. Surface-enhanced Raman spectroscopy features were tested on silver nanoparticles decorated substrates and the detection concentration limit of 10− 9 M of rhodamine 6G molecules was reached. Raman spectroscopy showed that the 532 nm laser excitation powers of less than 4 mW (∼0.57 kW/cm2) do not widen the phonon peak or shift its frequency and the nanostructure distribution parameter of 3.7 nm was calculated. The horizontally placed Ag decorated nanowires are proved to be sensitive substrates for surface-enhanced Raman spectroscopy only if the silicon nanowires thickness, length, volume density as well as metal nanoparticle size and distribution are carefully designed.

Growth of silicon nanowires from bio-templated gold nanoparticles

Silicon nanowires (SiNWs) have recently attracted considerable interest in a wide range of fields due to their quantum confinement effects and specific structures. Synthesis of silicon nanowires with high density and low diameter and also control over their growth direction and location are necessary to attain desired properties for applying in electronic devices. So, in this research a biological template was used to array nanoparticles catalyst and high density growth of nanowires. For this purpose, S-layers of Deinocaccus radiodurans have been used as template to pattern 4.5 nm Au nanoparticles (AuNPs) and arrayed nanoparticles have been utilized as catalyst to grow SiNWs by vapor-liquid-solid (VLS) procedure. Biotemplated SiNWs revealed low diameters, higher densities compared to SiNWs grown from nontemplated AuNPs on the silicon substrate. The results showed the protein template effect on the SiNWs morphology and grown SiNWs were analyzed by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS).

Study the effect of plasma power density and gold catalyst thickness on Silicon Nanowires growth by Plasma Enhanced Chemical Vapour Deposition

Gold (Au) metal catalysed tapered Silicon Nanowires (SiNWs) of diameter 50–150 nm at the base and length of 0.8–2.5 µm are synthesised by VLS mechanism using Silane (SiH4) as a precursor gas in Plasma Enhanced Chemical Vapour Deposition (PECVD) reactor at a substrate temperature of 650 °C. In this work, the effect of plasma power on the growth morphology of SiNWs is studied with two different thicknesses of Au catalyst layer. The catalyst layers are deposited using thermal evaporation system. Field Emission Scanning Electron Microscopy (FESEM) images confirm the growth of randomly oriented tapered nanowires. From the FESEM studies, it is clear that the density and the length of SiNWs increases with the increase of plasma power. High-resolution Transmission Electron Microscopy (HRTEM) demonstrated that the SiNWs are highly crystalline with (1 1 1) and (2 2 0) plane orientation. Raman spectra of SiNWs have been analysed and the first order optical phonons for SiNWs is observed at 519 cm−1 with 1 nm and 514.82 cm−1 with 2 nm Au catalyst.

Thickness effect of catalyst layer on silicon nanowires morphology and features

Silicon nanowires (SiNWs) have been synthesized on gold layer-coated silicon substrates via plasma enhanced chemical vapor deposition method (PECVD). Various thicknesses of Au layers were coated on Si (111) substrates using radio frequency magnetron sputtering. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to characterize the morphology, compositions, and structures of the samples. The results show that the sample consisted of single-crystalline SiNWs with the diameters ranging from 40 to 160nm and length up to 3μm. It was observed that the diameter of SiNWs increases with increasing of Au catalyst layers thickness. Raman spectra display peaks with narrow and asymmetric shape at 518cm−1 for the SiNWs, indicating the high crystalline nature of the samples. A possible growth mechanism is proposed for the formation of nanowires (NWs). It has been found that the features of SiNWs depend on the thickness of Au layers.

Growth and Morphology Modulation of Needle-like Silicon Nanowires for SERS Application

Abstract Semiconductor nanowires are attracting intense interest as a promising substrate material for surface enhanced Raman spectroscopy (SERS). Based on vapor-liquid-solid (VLS) procedure using Au as a catalyst, silicon nanowires (SiNWs) with controllable diameters were developed by the plasma enhanced chemical vapor deposition (PECVD) system. Inspired by the fact that the morphology of SiNWs can be effectively modulated by tuning the size of catalyst droplets, we designed a needle-like SiNWs owing to the shrink and consumption of Si-Au catalyst droplets. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses reveal that crystalline Si phase is possessed of amorphous SiO2 in the as-prepared coaxial nanowires. The morphology of the prepared SiNWs was examined by scanning electron microscope (SEM). As SERS active substrates, Ag nanoparticles were synthesized on surface of SiNWs by galvanic displacement. Results show that enhancement factor (EF) of SERS achieved on the prepared needle-like SiNWs/Ag is more than 10 times than that of cylindrical-shaped SiNWs/Ag for R6G molecules detection. It is supposed that needle-like SiNWs composited with Ag nanoparticles can be exploited as a new type nanosensor, environmental monitoring or biomedical diagnostics. In addition, many other needle-like semiconductor nanowires such as germanium needle-like nanowires also can be prepared by similar method in the present study.

Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs.

Morphology, structure and magnetic study of permalloy films electroplated on silicon nanowires

We report the effect of deposition potential on the morphology, structure and magnetic properties of Ni80Fe20 (Permalloy: Py) deposits, elaborated by electrochemical process onto silicon nanowires (SiNWs). The morphology of SiNWs and Py/SiNWs were performed with scanning electron microscopy (SEM). The SEM micrographs reveal the formation of SiNWs and clearly show a change in the morphology with the deposition potential. The analysis of X-ray diffraction spectra shows a change in the texture with the deposition potential. The grain size, the lattice parameter and the strain were studied as a function of the deposition potentials. From hysteresis loops, we have shown that the magnetization easy axis is the plane of the samples.

Stability and Performance of Heterogeneous Anode Assemblies of Silicon Nanowires on Carbon Meshes for Lithium-Sulfur Battery Applications

ABSTRACTSi is a promising anode material for Li storage due to its high theoretical specific capacity surpassing 4200 Ah/kg. Si based anodes exhibit an extreme instability upon electrochemical incorporation of Li given the accompanied large volume expansion of about 400%. We show innovative anode assemblies composed of a forest of free standing Si nanowires conformally integrated on carbon meshes. The morphology of silicon nanowires allows a volume expansion and compression lowering strain incorporation. In this paper, we demonstrate the utilization of SiNW grown on top of a current collector made of a carbon fiber network. This leads to an increase of stability of Si with a remaining effective capacitance above 2000 Ah/kg(Si) after 225 full charge/discharge cycles. This is significantly better compared to previous results shown in literature. The anodes are fabricated by a simple and inexpensive method promising for a transfer into industrial integration.

High performance of symmetric micro-supercapacitors based on silicon nanowires using N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide as electrolyte

This work describes the development and performance of a symmetric micro-supercapacitor made of nanostructured electrodes based on silicon nanowires (SiNWs) deposited using chemical vapor deposition (CVD) on silicon substrates. The performance of the SiNWs micro-supercapacitor employing an aprotic ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide) (PYR13TFSI) as an electrolyte was able to deliver a maximal power density of 182mWcm−2 and a specific energy of 190μJcm−2 operating at a wide cell voltage of 4V with a quasi-ideal capacitive behavior. The lifetime of the device exhibited a remarkable electrochemical stability retaining 75% of the initial capacitance after several million galvanostatic charge–discharge cycles at a high current density of 1mAcm−2. Furthermore, a coulombic efficiency of approximately 99% was obtained after galvanostatic cycling test without structural degradation on the morphology of SiNWs.

Large area fabrication of vertical silicon nanowire arrays by silver-assisted single-step chemical etching and their formation kinetics

Vertically aligned silicon nanowire (SiNW) arrays have been fabricated over a large area using a silver-assisted single-step electroless wet chemical etching (EWCE) method, which involves the etching of silicon wafers in aqueous hydrofluoric acid (HF) and silver nitrate (AgNO3) solution. A comprehensive systematic investigation on the influence of different parameters, such as the etching time (up to 15 h), solution temperature (10–80 °C), AgNO3 (5–200 mM) and HF (2–22 M) concentrations, and properties of the multi-crystalline silicon (mc-Si) wafers, is presented to establish a relationship of these parameters with the SiNW morphology. A linear dependence of the NW length on the etch time is obtained even at higher temperature (10–50 °C). The activation energy for the formation of SiNWs on Si(100) has been found to be equal to ∼0.51 eV . It has been shown for the first time that the surface area of the Si wafer exposed to the etching solution is an important parameter in determining the etching kinetics in the single-step process. Our results establish that single-step EWCE offers a wide range of parameters by means of which high quality vertical SiNWs can be produced in a very simple and controlled manner. A mechanism for explaining the influence of various parameters on the evolution of the NW structure is discussed. Furthermore, the SiNW arrays have extremely low reflectance (as low as <3% for Si(100) NWs and <12% for mc-Si NWs) compared to ∼35% for the polished surface in the 350–1000 nm wavelength range. The remarkably low reflection surface of SiNW arrays has great potential for use as an effective light absorber material in novel photovoltaic architectures, and other optoelectronic and photonic devices.

Diffusion Mechanisms in Silicon nanowires

In this study we use Fick’s Laws and the properties of bulk silicon (Si) to calculate the diffusion of the dopants, phosphorus and boron, in silicon nanowires (SiNWs). The morphology of SiNWs does not allow the use of the same formulas that are used in the doping and diffusion of bulk Si. While Fick’s Laws still apply, the law as applied is a differential equation and different solutions are used in order to solve this cylindrical problem. An oxidation drive-in is considered in these solutions . This is a study on diffusion doping of Si with boron and phosphorus, fairly well understood processes for the case of planar Si, which could perhaps be improved upon, but for the greater part is mathematically complete (refs). Having a long history, dating back to 185530 , 31, and basis in the science of diffusion, even cylindrical diffusion problems are somewhat well understood. Moving boundary diffusion problems are a bit more complex, as are problems with pre-existing diffusion profiles. Here we conduct an in-depth analysis of the mathematical models of cylindrical diffusion, applying these to the SiNWs. The laws of diffusion are applied to the morphology and physical conditions of the problem to arrive at a better formulation of the calculations than has been provided to date. Figure 1. Pre-dep doping profiles NcB (cylindrical boron), NcP (cylindrical phosphorus), NbB(planar boron), and NbP(planar phosphorus) using Eqs. (5.11) and (5.12) modeled in Mathcad. REFERENCES 1 T. Takagahara and K. Takeda, Phys. Rev. B 46, 15578 - 15581 (1992). 2 T. van Buuren, L. N. Dinh, L. L. Chase, W. J. Siekhaus, and L. J. Terminello, Phy. Rev. Lett., 80, No. 17, (1998). 3 K. Peng, H. Fang, J. Hu, Y. Wu, J. Zhu, Y. Yan, and S. T. Lee, Chem. Eur. J., 12, pp. 7942 – 7947 (2006). 4 T. Qiu, X.L. Wu, Y.F. Mei, G.J. Wan, P. K. Chu, G.G. Siu, J. Cryst. Growth 277, pp. 143–148 (2005). 5 K. Q. Peng, Y.J. Yan, S.P. Gao and J. Zhu, Adv. Func. Mat., 13, No.2, pp. 127-132 (2003). 6 K. Q. Peng, Y-J. Yan, S-P. Gao, J. Zhu, Adv. Mat., 14, 16, pp 1164 – 1167, (2002). 7 D. E. Perea, E. R. Hemesath, E. J. Schwalbach, J. L. Lensch-Falk, P. W. Voorhees and L. J. Lauhon, Nature Nanotechnology Letters, 4(2009). 8 J. E. Allen, D. E. Perea, E. R. Hemesath and L. J. Lauhon, Adv. Mater. 21p. 3067 (2009). 9 G. Imamura, T. Kawashima, M. Fujii, C. Nishimura, T. Saitoh and S. Hayashi, Nano Lett. 8(9) p. 2620 (2008). 10 E. C. Garnett, Y-C. Tseng, D. R. Khanal, J. Wu, J. Bokor and P. Yang, Nature Nanotechnology Letters, 4p. 311 (2009). 11 H. Z. Massoud, J. D. Plummer and E. A. Irene, J. Electrochem. Soc., Nov. pp. 2685-2693 (1985). 12 H. Z. Massoud, ECS Transactions, 2(2), pp. 189-203 (2006). 13 H. Z. Massoud and J. D. Plummer, J. Appl. Phys. 62(8), Oct., pp. 3416-3423 (1987). 14 T. Ohmi, M. Morita, A. Teramoto, K. Makihara and K.S. Tseng, Appl. Phys. Lett. 60pp. 2126 - 2128 (1992). 15 K. Kim, Y. H. Lee, M. H. An, M. S. Suh, C. J. Youn, K. B. Lee and H. J. Lee, Semicond. Sci. Technol. 11pp. 1059–1064 (1996). 16 H. Z. Massoud, J. D. Plummer and E. A. Irene, J. Electrochem. Soc., 132No. 7, pp. 1745-1753 (1985). 17 R. G. Mertens, K. B. Sundaram, Appl. Surf. Sci., 258, (10) pp. 46074613 (2012).

Needles and Haystacks: Influence of Catalytic Metal Nanoparticles on Structural and Vibrational Properties and Morphology of Silicon Nanowires Synthesized by Metal-Assisted Chemical Etching

ABSTRACTMetal-assisted chemical etching (MACE) of silicon (Si) is a simple and low-cost process to fabricate Si nanostructures with varying aspect ratio and properties. In this work, we report on the structural and vibrational properties of Si nanostructures synthesized with varying metal catalyst. The morphology of the synthesized nanowires was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical and vibrational properties of the Si nanostructures were studied by photoluminescence and Raman spectroscopy using three different excitation sources (UV, visible and near-infrared) and are correlated to their microstructures. We propose that the excessive injection of holes into Si at the metal-Si interface and its diffusion to the nanowire surfaces facilitate the etching of Si on these surfaces, leading to a mesoporous network of Si nanocrystallites. When etched with catalytic Au nanoparticles, “hay-stacked” mesoporous Si nanowires were obtained. The straighter nanowires etched with Ag nanoparticles, consisted of a single crystalline core with a thin porous layer that decreased in thickness towards the base of the nanowire. This difference is due to the higher catalytic activity of Au compared to Ag for H2O2 decomposition. The SERRS observed during UV and visible Raman with Ag-etched Si nanowires and near-infrared Raman with Au-etched Si nanowires is due to the presence of the sunken metal nanoparticles. In addition, we explored the influence of varying H2O2 and HF concentration as well as the influence of increased etching temperature on the resultant nanostructured Si morphology. Such Si nanostructures may be useful for a wide range of applications such as photovoltaic and biological and chemical sensing.