Effects of temperature and crucible height on the synthesis of 6H-SiC nanowires and nanoneedles

6H-SiC has been produced via catalyst-free chemical vapor growth method using Si wafer and activated carbon powder as the respective Si and C sources. The effects of heating temperature (1250, 1300, and 1350 °C) and crucible height (9, 13, and 16 cm) on the formation of nanowires and nanoneedles have been systematically investigated. Scanning and transmission electron microscopy, X-ray diffraction (XRD), Raman and photoluminescence (PL) spectroscopy have been employed in this study. The reasons for the transformation of nanoneedles to nanowires have also been proposed.