Elimination of interface states in the GaAs band-gap by cyanide treatment: XPS measurements under bias

Energy distribution of interface states for GaAs-based metal-oxide-semiconductor structure with an ultra-thin silicon oxide layer is obtained from "XPS measurements under bias." The interface state spectra have peaked-structure at 0.7 and 0.9 eV above the valence band maximum and they are attributed to (++/+) and (+/0) transitions of As_Ga antisite defects at the interface. When cyanide treatment (i.e., the immersion in a KCN aqueous solution followed by the rinse in boiling water) is performed after the deposition of the silicon oxide layer, the interface state density is decreased to ∼ 50%, resulting in the partial unpinning of the Fermi level.