SiC NW Research Articles

Solution Processed Schottky Diodes Enabled by Silicon Carbide Nanowires for Harsh Environment Applications.

Silicon carbide nanowires (SiC NWs) exhibit promising features to allow solution-processable electronics to be deployed in harsh environments. By utilizing a nanoscale form of SiC, we were able to disperse the material into liquid solvents, while maintaining the resilience of bulk SiC. This letter reports the fabrication of SiC NW Schottky diodes. Each diode consisted of just one nanowire with an approximate diameter of 160 nm. In addition to analyzing the diode performance, the effects of elevated temperatures and proton irradiation on the current-voltage characteristics of SiC NW Schottky diodes were also examined. The device could maintain similar values for ideality factor, barrier height, and effective Richardson constant upon proton irradiation with a fluence of 1016 ion/cm2 at 873 K. As a result, these metrics have clearly demonstrated the high-temperature tolerance and irradiation resistance of SiC NWs, ultimately indicating that they may provide utility in allowing solution-processable electronics in harsh environments.

SiCnw@SiC foam prepared based on vapor-solid mechanism for efficient microwave absorption

A SiC nw @SiC foam with highly efficient microwave absorption (MA) performance was successfully synthesized based on Vapor-Solid (V–S) growth mechanism. SiC nanowire (SiC nw ) and SiC foam skeleton efficiently form a double network coupling structure, which gives additional interface polarization and dielectric loss for the SiC foam, significantly enhancing the MA capacity of the foam. In this study, the SiC nw @SiC foam has a minimum reflection loss (RL min ) of −86.31 dB and an effective absorption bandwidth (EAB) of 12.55 GHz in room-temperature environment. However, the MA performance of SiC nw @SiC foam decreases with increasing temperature, which may be due to the thickening of the SiO 2 layer in the SiC nw at high temperature. At 600 °C, it has no effective absorption bandwidth, while at 1000 °C, the EAB and RL min were 0.6 GHz and −13.04 dB, respectively. As the temperature reaches 1000 °C, the defects in the material further increase, leading to a recovery in the MA performance.

3D printing and in situ transformation of SiCnw/SiC structures

Successful preparation of photopolymerizable ceramic slurries using non-oxide ceramics and their 3D printing is highly challenging as the ceramic powders often possess high UV-light absorbance. Even though pre-oxidation of the powders could improve the slurry printability, the residual oxygen element in the material would eventually deteriorate the material purity and performance. In this study, a separated redox route (pre-oxidation, 3D printing and carbothermal reduction) was proposed to overcome these challenges. SiC ceramic powder was pre-oxidized into SiC@SiO 2 core-shell form to lower the UV-light absorbance. It was found that the ultraviolet (UV) light absorbance value of SiC powder at 405 nm decreased 20% from 0.357 to 0.284 after pre-oxidation process. The UV-light penetration depth of SiC@SiO 2 ceramic slurries at 40 ~ 55 vol% solid loading ranging from 14.81 to 12.82 µm, which surpassed two times that for 40 vol% raw SiC ceramic slurry. Different-shaped structures of SiC@SiO 2 /resin green ceramic bodies were successfully fabricated by vat photopolymerization 3D printing. The oxygen element resided was then eliminated by carbothermal reduction to avoid detriment of SiO 2 to the mechanical performance of the SiC ceramics. Phenolic epoxy acrylate resin with 14 wt% pyrolytic carbon (PyC) yield was chosen as the carbon source and thus the SiC@SiO 2 /resin green body pyrolyzed into SiC@SiO 2 /PyC ceramics after 1200 °C. It was found that after the heating temperature was further raised to 1600 °C, most of the pre-introduced SiO 2 shells on the surface of SiC particles were in situ transformed into SiC nanowires through carbothermal reduction reaction between SiO 2 and PyC, and the content of oxygen element in the ceramic matrix sharply dropped from 20.21% to 2.08%. The results demonstrated that through the proposed redox route, the photopolymerization-related issues including high UV-light absorbance and pre-oxidation-induced impurity for 3D printing of SiC ceramic slurries can be tackled. Finally, high purity porous SiC nw /SiC ceramic components with different structures were produced. This study provides a promising route for the preparation and 3D printing of photopolymerization ceramic slurries using non-oxide ceramics possessing high UV-light absorbance. • UV-light absorbance of SiC powder at 405 nm decreased 20% after pre-oxidation. • UV-light penetration depth of SiC@SiO 2 slurries (40 ~ 55 vol%) surpassed two times that for 40 vol% raw SiC slurry. • Pre-introduced SiO 2 shells on SiC particles in situ transformed into SiC nanowires through carbothermal reduction. • SiC nw /SiC components with complex structures successfully fabricated by photopolymerization 3D printing.

3D printing “wire-on-sphere” hierarchical SiC nanowires / SiC whiskers foam for efficient high-temperature electromagnetic wave absorption

• A materials-independent “wire-on-sphere” hierarchical structure was developed. • 3D printing hierarchical structure for structure design. • A catalyst-free PIP process was first developed to in situ grow SiC nw . • SiC nw /SiC w foam exhibits superior high-temperature EWA performance. • The EWA performance retention of SiC nw /SiC w foam at aeroengine simulation working environment was measured. Electromagnetic wave absorption (EWA) materials for use in extreme environments are of great interest. Herein, SiC nanowires / SiC whiskers (SiC nw /SiC w ) foam with unique “wire-on-sphere” hierarchical structure was developed for efficient high-temperature EWA. SiC w were assembled to porous SiC w spheres via spray drying and then SiC w spheres were 3D printed to SiC w foam. The catalyst-free precursor infiltration pyrolysis process was first developed to ensure that SiC nw can intentionally grow in situ on the surface of SiC w spheres, thereby achieving “wire-on-sphere” hierarchical structure foam. At room-temperature, the maximum electromagnetic wave effective absorption bandwidth (EAB max ) and minimum electromagnetic wave reflection coefficient (RC min ) of SiC nw /SiC w foam can reach 4 GHz and -57 dB, respectively. At 600 °C, the EAB max and RC min were 3 GHz and -15 dB, respectively. Furthermore, even oxidized at 1000–1500 °C, SiC nw /SiC w foam can still retain EAB max ranging from 2.7 to 3.9 GHz and RC min ranging from -16 dB to -64 dB, because the formation of SiO 2 layer with appropriate thickness can boost interfacial polarization and regulate impedance matching. The SiC nw /SiC w foam also shows the flexural strength as high as 17.05 MPa. All results demonstrate that the SiC nw /SiC w foam is a promising EWA material for applications of harsh environments. And the material-independent “wire-on-sphere” hierarchical structure and its novel preparation process should find the widespread use in the design and fabrication of high-efficiency EWA micro-nano materials.

Toughening in low-dimensional nanomaterials high-entropy ceramic nanocomposite

Very recently, high entropy concept has evolved from metal to the ceramic community, named as high entropy ceramics (HEC). The configurational entropy endowed the system with unique structure, performances as well as application potentials such as aerospace, high-speed machining tools, and nuclear reactors. However, the poor densification together with low fracture toughness of HEC significantly limited the practical applications of HEC. Herein, we report for the first time the employment of low-dimensional nanomaterials including multilayer graphene (MLG), carbon nanotube (CNT) and SiC nanowire (SiC nw ) to improve the densification coupled with fracture toughness of HEC through two-step spark plasms sintering. HEC-MLG and HEC-SiC nw exhibited flexural strength of 671.3 MPa and 626.5 MPa, with fracture toughness of 7.1 MPa m 1/2 and 6.2 MPa m 1/2 , respectively. The strength and toughness of HEC nanocomposites were both greater than those of the reported values for high entropy ceramics. The reinforcing mechanisms were discussed in detail for all the three HEC nanocomposites. Overall, this paper demonstrated that the toughening methods for normal ceramics were also feasible for HEC matrix, significantly increasing the freedom to tailor the properties and applications of HEC. • Low-dimensional nanomaterials were proposed for reinforcing high entropy ceramic. • Two-step spark plasms sintering was employed to densify high entropy ceramic. • The compromise between strength and toughness occurred to high entropy ceramic. Graphene and SiC nw performed better roles than CNT in toughening high entropy ceramic.

Influences of silicon carbide nanowires’ addition on IMC growth behavior of pure Sn solder during solid–liquid diffusion

In this paper, various mass fractions (0, 0.2, 0.4, 0.6, 0.8, 1.0 wt%) of silicon carbide nanowires (SiC NWs) were incorporated into pure Sn solder to enhance the performances of Sn solder joint. The wetting behavior, shear strength, and intermetallic compound (IMC) growth mechanism of Sn–xSiC/Cu solder during solid–liquid diffusion at 250 °C were investigated systematically. The experimental results demonstrated that the wettability of Sn–xSiC/Cu solder had a significant improvement when the addition of SiC NWs was up to 0.6 wt%, and excessive additives would degrade the wettability of the composite solder. The formation of the Cu6Sn5 IMC layer was observed at the Sn–xSiC solder/Cu interface. Meanwhile, SiC NWs as additives were conducive to restraining the growth of interfacial IMC during soldering process and the IMC thickness overtly fell down after doping 0.8 wt% SiC NWs into Sn solder. Moreover, SiC NW addition would contribute to enhancing the mechanical performance of Sn solder joint. The fracture mechanism of solder joint changed from a mix of brittle and ductile fracture to a characteristic of typical ductile fracture.

Effective electromagnetic wave absorption and photoluminescence performances of flexible SiC nanowires membrane

The flexible SiC nanowires (SiC NWs) membrane was prepared by electrostatic spinning technique and pyrolysis using polycarbosilane (PCS) as a precursor. The NW consisted of 3C–SiC nanograins, turbostratic graphite, and amorphous SiOxCy. The microstructure and phase composition of the NW were fine-tuned by controlling the pyrolysis temperature. The photoluminescence of the SiC NW membrane exhibited an evident blue shift, demonstrating its potential for latent application in optoelectronic devices. Additionally, the dielectric loss and electromagnetic wave (EMW) absorption of the nanowire membrane were analyzed between 2 and 18 GHz. An ultra-low content of only 10 wt% SiC NW membrane in the paraffin matrix resulted in excellent dielectric loss, with optimal reflection loss of −41 dB and an effective absorption bandwidth (EBA) of 5 GHz with a 1.5-mm-thick membrane. Herein, the electromagnetic absorption mechanism of a sheet-like, flexible SiC NW membrane in a paraffin matrix is proposed. The unique microstructure of the flexible SiC NW membrane provides excellent light-emitting and EMW absorption performance, enabling it to act as a satisfactory lightweight EMW absorber and optoelectronic device in harsh environments.

Superhydrophobic silicone/SiC nanowire composite as a fouling release coating material

A ceramic superhydrophobic series of polydimethylsiloxane/silicon carbide nanowire (SiC NW) composites was designed for marine fouling release (FR) coatings of the ship hull. Single-crystal SiC NWs with 50–80 nm diameters were grown in {111} crystal plane and employed as nanofillers. Ex situ silicone nanocomposites were facilely developed and cured by a mechanism of hydrosilation. The effects of incorporating different nanofiller concentrations on the surface, mechanical, and FR properties of silicone nanocomposites were extensively studied. Surface properties were studied by nonwettability and free energy and characterized via scanning electron and atomic force microscopes. Nanocomposites’ mechanical features were tested as durability factors. Selected microfoulants of fungi and bacterial progenies were used for biological assessments in the laboratory. A field test was performed on the developed coating samples in natural seawater for 3 months in a tropical area. Excellent distributed SiC NWs (0.5 wt%) showed outstanding hydrophobicity with 153° contact angle, 11.25 mN/m free energy of the surface, micro-/nanoscale roughness, and FR properties.

Effects of SiC nanowire decorated with carbon nanosheet on mechanical, heat-dissipation and anti-ablation properties of carbon/carbon composites

Carbon/carbon (C/C) composites containing SiC nanowires (SiC NW) decorated with carbon nanosheet were prepared with the pyrolytic carbon (PyC) as the matrix, where the nanowires and carbon nanosheet were introduced via electrophoretic deposition and chemical vapor deposition respectively. Their flexural strength, heat-dissipation capacity, and anti-ablation properties were investigated, with C/C composites and carbon nanosheet-C/C composites as comparison. Flexural strength of the SiC NW-Carbon nanosheet-C/C(SiC NW-CN-C/C) composites increased by 40.97% and 65.69% separately due to improvement of the interfacial bonding and bonding between PyC sublayers via SiC NW and carbon nanosheet. Their heat-dissipation performance behaved better due to in-situ grown carbon nanosheet, with lower surface temperature when heated under the same condition. Consequently, the anti-ablation property of such composites was promoted with mass ablation rate decreased by 40.74% and 27.27% respectively, which was attributed to the enhanced bonding, the reduced thermal damage benefitted from better thermal performance, and the formation of SiC NW-Carbon nanosheet-PyC (SiC NW-CN-PyC) micro-rods to prevent debonding under impact of the high-speed gas flow and protect carbon fibers against mechanical ablation.

A High‐Energy Density Asymmetric Supercapacitor Based on Fe2O3 Nanoneedle Arrays and NiCo2O4/Ni(OH)2 Hybrid Nanosheet Arrays Grown on SiC Nanowire Networks as Free‐Standing Advanced Electrodes

AbstractIn this paper, a novel freestanding core‐branch negative and positive electrode material through integrating trim aligned Fe2O3 nanoneedle arrays (Fe2O3 NNAs) is first proposed with typical mesoporous structures and NiCo2O4/Ni(OH)2 hybrid nanosheet arrays (NiCo2O4/Ni(OH)2 HNAs) on SiC nanowire (SiC NW) skeletons with outstanding resistance to oxidation and corrosion, good conductivity, and large‐specific surface area. The original built SiC NWs@Fe2O3 NNAs is validated to be a highly capacitive negative electrode (721 F g−1 at 2 A g−1, i.e., 1 F cm−2 at 2.8 mA cm−2), matching well with the similarly constructed SiC NWs@NiCo2O4/Ni(OH)2 HNAs positive electrode (2580 F g−1 at 4 A g−1, i.e., 3.12 F cm−2 at 4.8 mA cm−2). Contributed by the uniquely engineered electrodes, a high‐performance asymmetric supercapacitor (ASC) is developed, which can exhibit a maximum energy density of 103 W h kg−1 at a power density of 3.5 kW kg−1, even when charging the device within 6.5 s, the energy density can still maintain as high as 45 W h kg−1 at 26.1 kW kg−1, and the ASC manifests long cycling lifespan with 86.6% capacitance retention even after 5000 cycles. This pioneering work not only offers an attractive strategy for rational construction of high‐performance SiC NW‐based nanostructured electrodes materials, but also provides a fresh route for manufacturing next‐generation high‐energy storage and conversion systems.

Hierarchical cobalt oxide-functionalized silicon carbide nanowire array for efficient and robust oxygen evolution electro-catalysis

A hierarchical cobalt oxide (Co3O4)-functionalized silicon carbide nanowire (SiC NW) array electrode is synthesized on 4H–SiC(0001) substrates and investigated for use in the oxygen evolution reaction (OER) of water splitting. Ni-catalyzed chemical vapor deposition is employed to obtain vertically-aligned SiC NWs, and electrodeposition is used to functionalize the nanowires with hierarchical Co3O4 nano-clusters and a thin Co3O4 layer on the top side and the side-walls of the NWs, respectively. By using the Co3O4-functionalized SiC NW electrode for OER, the overpotential required to drive an anodic current density (Janodic) of 10 mA cm−2 is 0.22 V, a value much lower than those of Co3O4 nano-clusters (0.42 V), of bare SiC NWs (1.27 V) electrodes and of Pt foil (0.56 V). The overpotential value of 0.22 V is among the most active for the noble metal-free electro-catalytic electrode to produce Janodic of 10 mA cm−2. The deposition of Co3O4 on the SiC NW substrate produces an extremely hydrophilic surface, which improves the charge transfer characteristics at the interface between the electrode and the aqueous electrolyte. Moreover, the vertically-aligned SiC NWs provide a directional charge transport route along the nanowire length, as seen from a lower charge transfer resistance (Rct) in the Co3O4-functionalized SiC NW electrode compared to the Co3O4-functionalized SiC electrode under the same OER operating conditions. Finally, the Co3O4-functionalized SiC NW electrode maintains stable performance in an alkaline electrolyte (i.e., 1 M KOH aqueous solution) during continuous electrolysis testing over 16 h. The outstanding electro-catalytic performance and stability make the Co3O4-functionalized SiC NW electrode a promising noble metal-free electro-catalytic electrode for the OER and other renewable energy applications.

Improved ohmic contacts for SiC nanowire devices with nickel-silicide

The effect of annealing temperature has been investigated to obtain a low ohmic contact for silicon carbide nanowire field-effect transistor (SiC NW FET). Fabrication of two types of SiC NW FET has been studied using cylinder and needle shapes of SiC NW. The experimental results show that an annealing temperature of 650 °C leads to the lowest ohmic contact resistance on SiC NW FET. It is believed that the Ni silicide phases formed on SiC NWs make low resistance ohmic contacts. Ni silicide phases begin to intrude into the SiC NW channel after an annealing step at 700 °C for 30 s and consequently, it forms either a SiC/Ni silicide heterostructure or a fully Ni silicidized SiC NW depending on the channel length. A fully silicidized SiC NW exhibits a low channel resistance (740 Ω) and a high current density (1.46 × 107 A cm−2 at 1.4 V). The needle shape of SiC NWs is transformed into a bead necklace like morphology after Ni silicide intrusion.

Synergistically reinforced lithium storage performance of in situ chemically grown silicon@silicon oxide core–shell nanowires on three-dimensional conductive graphitic scaffolds

The silicon material is the most promising candidate for developing new-generation lithium-ion batteries with high energy and power output. However, there remains a significant challenge due to poor electrical conductivity and pulverization of the silicon based anode during cycles. Aiming to solve these problems, in this work we fabricate a novel 3D composite architecture made of a Si@SiOx core–shell nanowire array grown on a 3D graphitic foam (Si CNW–3D GF) substrate by a well-designed multiple-step approach. The prepared Si CNW–3D GF composite shows the integrated advantages for high-performance lithium ion batteries, including its light weight, open macroporosity, high conductivity, high Si NW loading, excellent flexibility as well as SiOx buffer layers. As a result, the Si CNW–3D GF composite exhibits excellent performance such as high reversible lithium storage capacity (3603 mA h g−1 at a current density of 840 mA g−1), excellent cycling performance (up to 100 cycles) and superior rate capability (2299 mA h g−1 at 4200 mA g−1 and 1206 mA h g−1 at 8400 mA g−1), which is 2 times that of the Si CNW electrode where Si CNWs were grown directly on a stainless steel current collector without the presence of 3D GF.

Electrical Transport Properties of Single SiC NW-FET

A single SiC NW-FET (nanowire field effect transistor) was fabricated by FIB (Focus-Ion-Beam) method and the photo-electric properties of the device including I-V characteristic, transfer characteristic and time response et.al. were studied in this paper. SiC NWs (NWs) were prepared by pyrolysis of a polymer precursor with ferrocene as the catalyst by a CVD route. The NWs were suspended in ethanol by ultrasonic, then sprayed onto a silicon wafer with 300nm silicon oxide. Pt electrodes were deposited directly by FEI NanoLab 600i along with the SiC NW on silicon wafer. The transfer characteristic of the device shows that the SiC NW is a n-type semiconductor and photoelectrical measurements of the device show an rapid change of voltage when applied a constant current and explored the device to 254nm UV light. The mechanism of photo-electric properties are discussed in the last. Our results show that the single SiC NW FET could be applied to a harsh environment due to its own excellent electrical and optical properties.

First Experimental Functionalization Results of SiC Nanopillars for Biosensing Applications

DNA biosensors based on silicon carbide nanowire bioFET (SiC NW bioFET) benefit from both biocompatibility and semiconducting properties of SiC. One of the device realization key points is the functionalization of the SiC NW. This process is composed of two main steps: silanization and DNA grafting. It has been successfully carried out on both SiC single crystals and SiC nanopillars. Evidences of DNA detection are given by X-Ray photoelectron Spectroscopy (XPS) and fluorescence microscopy.

Self-irradiation of thin SiC nanowires with low-energy ions: a molecular dynamics study

Irradiation of ultra-thin silicon carbide nanowires (SiC NWs) with low-energy ions was investigated with the molecular dynamics (MD) method. The energies of the incident Si and C ions varied from 0.2 to 5.0 keV. Simulation results show that the ion range predicted by the SRIM code is a little shorter than that obtained from the MD simulation when the incident energy is low and the implanted ions can form a peak-like distribution inside the NW. Compared with bulk material, the sputtering yield of the SiC NW is much higher as a result of the NW's larger surface-to-volume ratio, and for a high ion energy, the sputtering yields show a different dependence to the nuclear stopping power because the NW's limited volume stops the collision cascade from fully evolving. Moreover, the calculated short-range order values indicate that the amorphous degree for most irradiated samples is acceptable and repairable. For a high ion energy range, the SiC NW is more difficult to amorphize compared with bulk SiC. By carefully optimizing the implantation parameters, a desirable distribution of dopants can be achieved in the thin SiC NW while the irradiation damage is kept at an acceptable level.

β-SiC NWs Grown on Patterned and MEMS Silicon Substrates

Cubic silicon carbide nanowires (-SiC or 3C-SiC NW) have been grown by Vapour Phase Epitaxy on (001) silicon substrates patterned by conventional photolithography and on Micro Electro Mechanical Systems (MEMS, e.g. cantilevers, springs, bridges) fabricated on (001) Silicon On Insulator (SOI) wafers. The NW morphology was investigated by scanning electron microscopy, showing that the nanowires grew selectively where a nickel thin layer was previously deposited, thanks to its catalytic action. High resolution transmission electron microscopy studies showed that the NWs are predominantly 3C polytype with <111> growth axis and stacking defects on (111) planes.

열 화학기상증착법을 이용한 탄화규소 나노선의 합성 및 특성연구

본 연구에서는 열 화학기상증착법(thermal chemical vapor deposition)을 이용하여 분말 형태의 규소(Si)와 염화니켈 수화물 <TEX>$(NiCl_2{\cdot}6H_2O)$</TEX>을 혼합한 후 탄소공급원인 <TEX>$CH_4$</TEX> 가스를 주입하여 탄화규소 나노선(SiC nanowire)을 합성하였다. 합성 온도와 <TEX>$CH_4$</TEX> 가스 유량 변화에 따른 탄화규소 나노선의 구조적 특성을 분석한 결과, 합성온도가 <TEX>$1,400^{\circ}C$</TEX>, <TEX>$CH_4$</TEX> 가스의 유량이 300 sccm인 경우가 탄화규소 나노선의 합성에 최적화된 조건임을 라만 분광법(Raman spectroscopy)과 X-선 회절(X-ray diffraction), 주사전자현미경(scanning electron microscopy), 그리고 투과전자현미경(transmission electron microscopy) 분석을 통해 확인하였다. 합성된 탄화규소 나노선의 직경은 약 50~150 nm이며, 곧은 방향성과 높은 결정성을 가지는 입방구조(cubic structure)를 지니고 있었다. One-dimensional cubic phase silicon carbide nanowires (<TEX>${\beta}$</TEX>-SiC NWs) were efficiently synthesized by thermal chemical vapor deposition (TCVD) with mixtures containing Si powders and nickel chloride hexahydrate <TEX>$(NiCl_2{\cdot}6H_2O)$</TEX> in an alumina boat with a carbon source of methane <TEX>$(CH_4)$</TEX> gas. SEM images are shown that the growth temperature (T) of <TEX>$1,300^{\circ}C$</TEX> is not enough to synthesize the SiC NWs owing to insufficient thermal energy for melting down a Si powder and decomposing the methane gas. However, the SiC NWs could be synthesized at T><TEX>$1,300^{\circ}C$</TEX> and the most efficient temperature for growth of SiC NWs is T=<TEX>$1,400^{\circ}C$</TEX>. The synthesized SiC NWs have the diameter with an average range between 50~150 nm. Raman spectra clearly revealed that the synthesized SiC NWs are forming of a cubic phase (<TEX>${\beta}$</TEX>-SiC). Two distinct peaks at 795 and <TEX>$970 cm^{-1}$</TEX> in Raman spectra of the synthesized SiC NWs at T=<TEX>$1,400^{\circ}C$</TEX> represent the TO and LO mode of the bulk <TEX>${\beta}$</TEX>-SiC, respectively. XRD spectra are also supported to the Raman spectra resulting in the strongest (111) peaks at <TEX>$2{\Theta}=35.7^{\circ}$</TEX>, which is the (111) plane peak position of 3C-SiC. Moreover, the gas flow rate of 300 sccm for methane is the optimal condition for synthesis of a large amount of <TEX>${\beta}$</TEX>-SiC NW without producing the amorphous carbon structure shown at a high methane flow rate of 800 sccm. TEM images are shown two kinds of the synthesized <TEX>${\beta}$</TEX>-SiC NWs structures. One is shown the defect-free <TEX>${\beta}$</TEX>-SiC NWs with a (111) interplane distance of 0.25 nm, and the other is the stacking-faulted <TEX>${\beta}$</TEX>-SiC NWs. Also, TEM images exhibited that two distinct SiC NWs are uniformly covered with <TEX>$SiO_2$</TEX> layer with a thickness of less 2 nm.