Temperature-Induced Semiconductingc(4×2)⇔Metallic(2×1)Reversible Phase Transition on theβ-SiC(100) Surface

We use combined variable temperature scanning tunneling microscopy and spectroscopy, and angle-resolved photoemission spectroscopy experiments to study transition between two β-SiC(100) surface structures. We observe a reversible temperature-dependent phase transition from a semiconducting $c(4\times 2)$ surface at 25 °C to a metallic $2\times 1$ structure at 400 °C. This transition results from temperature-induced disruption of the $c(4\times 2)$ structure composed of alternately up and down dimers into a structure having all dimers at the same height giving a $2\times 1$ symmetry. This arrangement favors electronic orbital overlap between Si top surface atoms leading to surface metallization.