Thickness Thinning of Epitaxial Graphene Grown on Carbon-Terminated 6H-SiC by Using Oxygen Plasma Etching

Abstract

Oxygen plasma was utilized to etch the epitaxial graphene films grown on carbon-terminated 6H-SiC substrate. XPS spectra show that the intensity ratio between the graphene peak and SiC peak decreases with oxygen plasma etching time. It indicates that with increasing etching time from 0 to 42 s, the thickness of graphene dramatically decreases from eight to one monolayers following a first-order exponential decay function. Meanwhile, AFM images show that the ridges among domains are preferred to be etched by oxygen plasma and they will almost disappear after etched for 42 s. It indicates that the oxygen plasma will not decrease the mobility of graphene layer obviously when the graphene thickness is over two monolayers; however, further etching the graphene with thickness less than two monolayers will leads to significantly decrease the mobility due to the formation of many more defects.