Surface and interface states of GaSb: A photoemission study

Abstract

Photoemission experiments at $h\ensuremath{\nu}<11.8$ eV indicate that there are no filled or empty surface states in the bandgap of GaSb. Small amounts of oxygen or alkali metals pin the Fermi level (${E}_{F}$) on $n$-type samples and move it down to near the valence band maximum, showing that Schottky barrier pinning is possible without intrinsic surface states in the band gap. When GaSb is cesiated to give maximum "white light" yield, the cesium coverage is unstable and partially desorbs. The electronic structure as seen in photoemission also appears to be different at this stage of cesiation. These and other results provide a new insight on the GaSb surface.