Formation of Carbon Nanotube/n-Type 6H-SiC Heterojunction by Surface Decomposition of SiC and Its Electric Properties

Carbon nanotube (CNT)/n-type SiC heterojunctions were formed by surface decomposition of 6H-SiC(0001), where each CNT directly bonded to SiC crystal at the interface without any interlayer. Through heating temperature and heating time, the CNT length could be controlled up to 4 µm. For the sample with CNTs of 180 and 230 nm in thickness, distinct rectifying behavior was observed in the current–voltage measurements, with the forward direction observed at positively biased CNTs. When the CNT length was 1500 nm, the leakage current was increased. From cross-sectional transmission electron microscopy (TEM) observations, we conclude that the increase of the leakage current was due to the deterioration of crystalline quality of CNTs near the interface between CNTs and SiC, which was caused by the obstruction of the desorption of Si atoms by the lengthening of CNTs.