Manipulating 3C-SiC Nanowire Morphology through Gas Flow Dynamics
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Manipulating 3C-SiC Nanowire Morphology through Gas Flow Dynamics Kasif Teker1 and Jesse M. Otto1 1 Department of Physics and Engineering, Frostburg State University, 101 Braddock Road, Frostburg, MD 21532, U.S.A. ABSTRACT Creation of nanoscale building blocks with various sizes and shapes are critical for the progress of nanotechnology. Silicon carbide nanostructures attract interest due to their applications in optoelectronic devices, sensors, high-power/high temperature electronics, and thermoelectrics. This paper presents a detailed study of SiC nanowire morphology change through gas flow dynamics. SiC nanowire synthesis has been carried out by chemical vapor deposition using hexamethyldisilane (HMDS) as source material on SiO2/Si substrate. The study has been limited to several catalyst materials, including nickel (nanoparticle and thin film), cobalt nanoparticles, and gold thin film. The growth runs have been carried out at 1000oC under H2 as carrier gas with flow rates varying from 100 to1000 sccm. A significant change in morphology has been observed. At high flow rates, the nanowires are highly curved and contain sharp kinks, while the nanowires are straight and longer at lower flow rates. Moreover, it is important to note that the flow rate has influenced the nanowire growth-yield significantly. As small as 8nm-diameter SiC nanowire has been observed, as determined by transmission electron microscopy (TEM). These findings will help in controlling the morphology of the SiC nanowires. The fabricated nanowires have also been characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). INTRODUCTION Silicon carbide is a wide band-gap semiconductor material (2.39 – 3.33 eV) with many superior properties, such as high electron mobility, high thermal conductivity, high mechanical strength, and high radiation resistance [1-4]. These superior properties make SiC an excellent material for applications in many areas including optoelectronics, thermoelectric devices, microelectronics (high temperature, high power, and high frequency), and biomedical applications [5]. Furthermore, nanoscale materials exhibit excellent physical properties. SiC nanostructures present even more advantages in some applications such as gas sensors, blue LEDs, UV photodetectors, field emission devices [6-8], and field-effect transistors [9] due to their superior properties at nanoscale. However, controlling the synthesis and fabrication of these nanostructures has been a major challenge for researchers. Synthesis of SiC nanostructures with various fabrication methods has been reported. These fabrication methods include chemical vapor deposition [10-11], carbon thermal reduction [12], metalorganic chemical vapor deposition (MOCVD) [13-14]. CVD has been the most widely used method to fabricate nanostructured materials due to its low cost, high yield, simplicity of operation, and possibility of enabling direct device fabrication on pre- patterned substrates. This paper presents
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