Optical Detection of Surface States on Cleaved (111) Surfaces of Ge

Abstract

Optical absorption of a cleaved surface of germanium shows a band at energies smaller than the gap, that is removed when the surface is oxidized. The band is assumed to be due to optical excitation of a surface state practically coincident with the top of the valence band to a set of states 0.16 eV below the bottom of the conduction band.