Synthesis of SiC/SiO2 core–shell nanowires with good optical properties on Ni/SiO2/Si substrate via ferrocene pyrolysis at low temperature

Abstract

In this study, the high-density SiC/SiO2 core–shell nanowires were synthesized on the nickel coated SiO2 (100 nm)/Si substrate by chemical vapor deposition (CVD) method with ferrocene precursor at temperature 1000 °C compared to previous studies (1300–1600 °C). The present work provides an efficient strategy for the production of SiC/SiO2 nanowires with uniform morphology and good optical properties, where the Ni layer plays important roles for this fabrication at low temperature which reduces the decomposition temperature of hydrocarbon gases and improves the growth quality of SiC nanowires. The as-synthesized SiC/SiO2 nanowires consist of single crystal 3C structures as well as 3C structures with defects along [111] direction. In the photoluminescence (PL) spectrum, the SiC/SiO2 core–shell nanowires revealed an obvious blueshift. The blueshift is due to the formation of nanoscale silicon carbide polytypism caused by the stacking faults in 3C–SiC and the nanoscale polytypism also caused the transition from indirect to direct bandgap which explains why the stacking faults percentage in SiC confirmed from X-ray diffraction (XRD) is 19%, but ultimately makes the strongest emission intensity. Finally, the PL characteristics are further improved by changing the diameter of the SiC nanowire and etching and an approximate model followed by the vapor–liquid–solid (VLS) mechanism was proposed to explain the possible growth mechanism of the SiC/SiO2 nanowires.

High-Yield Synthesis of SiC@SiO2 Core–Shell Nanowires on Graphite Substrates for Energy Applications

“…Previously, Tateyama et al and Pujar and Cawley reported that the SFs peak increases while the one related to (200) planes decreases with an increase in SFs density. The SFs content (χ) in SiC can be determined according to χ = I SFs / I (200) , where I SFs and I (200) are peak intensities related to SFs and (200) planes, respectively. , Moreover, Seo et al calculated the SFs density ( Y ) in terms of χ using eq . , Y = χ a χ + b + c χ 3 .25em ( % ) where χ presents the SF’s content, with values of a = 6.82 × 10 –2 , b = 2.27 × 10 –2 , and c = 1.7. Figure b shows the magnified XRD patterns from 32 to 44°, and the χ values are 0.79, 1.24, 1.81, and 1.32 for SiC@SiO 2 NWs-0, SiC@SiO 2 NWs-5, SiC@SiO 2 NWs-15, and SiC@SiO 2 NWs-30, respectively (Figure c), corresponding to SFs densities of 11.2, 14.8, 22.5, and 15.6%.…”

“…Various methods have been explored for the synthesis of SiC@SiO 2 NWs, including sol–gel, , chemical vapor deposition (CVD), , carbon thermal reduction, chemical etching, molten salt, , and thermal evaporation. , For example, Tian et al synthesized SiC@SiO 2 NWs by the CVD method using coconut cell and silicon (Si) as carbon (C) and Si sources, respectively, which emit strong violet-blue light and have good application prospects in optoelectronic devices. However, the productivity and purity are not satisfactory .…”

“…1,2 In addition, they have potential applications in these areas, including field emitters, photocatalysis, electromagnetic stealth, composites, and supercapacitors, due to their high tensile strength (53.4 GPa), high plasticity (elongation > 200%), high melting temperature (2700 °C), wide band gap (2.3−3.2 eV), high Young's modulus (600 GPa), and low coefficient of thermal expansion (4.0 × 10 −6 K −1 ). 3−6 Various methods have been explored for the synthesis of SiC@SiO 2 NWs, including sol−gel, 7,8 chemical vapor deposition (CVD), 9,10 carbon thermal reduction, 11 chemical etching, 12 molten salt, 13,14 and thermal evaporation. 15,16 For example, Tian et al synthesized SiC@SiO 2 NWs by the CVD method using coconut cell and silicon (Si) as carbon (C) and Si sources, respectively, which emit strong violet-blue light and have good application prospects in optoelectronic devices.…”

Effect of Reinforcement Size on Mechanical Behavior of SiC-Nanowires-Reinforced 6061Al Composites

“…According to previous research [ 43 ], the diffraction peak at 33.7° is caused by stacking faults on the (111) surface of 3C-SiC. Chen et al [ 44 ] evaluated the stacking fault density ( X ) by the intensity ratio of the SFs peak to the SiC (200) peak, as shown in Equation (1): …”

Defect-Induced Luminescence Quenching of 4H-SiC Single Crystal Grown by PVT Method through a Control of Incorporated Impurity Concentration

“…The PL spectra in 4H-SiC originate from a combination of phonon-instigated electronic transitions caused by defects in SiC [9][10][11]. This observation of luminescence quenching is not evidence of electronic doping [12,13]. Therefore, it is necessary to determine the additional factors that affect the PL quenching and luminescence properties of 4H-SiC by characterizing it fully.…”