Transition from direct band gap to indirect band gap in fluorinated carbon

Abstract

We studied phase stability, structural properties, and electronic band structures of graphite fluorides ${\mathrm{C}}_{n}\mathrm{F}$ $(n=1,2,\dots{},6)$ using density-functional theory with local density approximation. The calculation shows that ${\mathrm{C}}_{n}\mathrm{F}$ with ${\mathrm{sp}}^{3}$ bonding has a direct gap, when $n=1$ or 2. Even though ${\mathrm{C}}_{n}\mathrm{F}$ with $n>2$ has not been identified experimentally, our calculation predicts that they become an indirect gap semiconductor.