STM and XPS studies of early stages of carbon nanotube growth by surface decomposition of 6H–SiC(000-1) under various oxygen pressures

The effects of oxygen on the early stage of carbon nanocap and nanotube growth by surface decomposition of 6H–SiC(000-1) were investigated, using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Our results showed that the presence of oxygen enhances the decomposition of the SiC surface, promoting carbon nanocap and nanotube growth. We also observed active-to-passive oxidation transition below 10− 1 Pa, which is consistent with the pressure–temperature phase diagram previously estimated from experimental results above 10− 1 Pa.