K. Teker, D. Abdurazik
Istanbul Sehir University,
Keywords: SiC nanowires, FTIR, CVD
Summary:Silicon carbide is a wide band-gap semiconductor material with many superior properties, such as high electron mobility, high thermal conductivity, high mechanical strength, and high radiation resistance. 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, e.g. solid state transformers and inverters), and biomedical applications. Furthermore, nanoscale materials exhibit unique properties differing from bulk materials. Due to these unique properties, SiC nanostructures present even more advantages in some applications such as gas sensors, blue LEDs, UV photodetectors, field emission devices, and field-effect transistors due to their superior properties at nanoscale. However, integration of these nanostructures to the large-scale manufacturing is still a challenge for researchers and engineers. Owing to the very promising applications, significant research has been devoted to the synthesis of 1D-SiC nanostructures with various fabrication methods. This work presents chemical vapor deposition (CVD) growth of SiC nanowires using hexamethyldisilane (HMDS) as the single source material with various catalyst materials. Various catalyst materials, including iron film (0.8 nm), nickel film (20 nm), and cobalt nanoparticles (25 nm) have been used. We provide a comparative Fourier transform infrared spectroscopy investigation of the SiC nanowires grown with various catalyst materials. FTIR provides valuable and practical information about the chemical bond states of the materials. Further, we will discuss the differences of phonon states of SiC nanowires compared to the bulk materials. Moreover, the study also investigates the decomposition temperature of the HMDS precursor with the presence of the catalysts to achieve high-density SiC nanowires. Figure 1 shows SEM image of the dense SiC nanowires grown at 1100oC on Ni-film. Large quantities of SiC nanowires with high aspect ratio have been synthesized with different catalysts. Nanowires are relatively long with typical lengths of several tens of microns. Figure 4.2 shows the FTIR spectra of the SiC nanowires formed on Si substrate with catalyst Ni-film at temperatures of 1100oC, 1050oC, 1000oC, and 900oC, respectively. As seen in Figure 4.2, the spectra of the SiC nanowires have revealed strong absorption bands with a very small variation. In fact, the transverse optical (TO) Si-C bond ranges from 782 to 784 cm-1, the longitudinal optical (LO) Si-C bond ranges between 930 and 950 cm-1. The sharp and consistent TO modes indicate very good bonding uniformity of the SiC nanowires. In summary, a detailed comparative FTIR spectroscopy analysis of the SiC nanowires will be provided.