Antibonding state on the Ge(111):As surface: Spectroscopy and dynamics

Abstract

The first direct observation of the As derived empty surface state on the Ge(111):As1×1 surface is reported. The state is first populated with a subpicosecond pulse of 2.03 eV light and then probed with equally short pulses of light at 10, 14, 18, and 22 eV which photoemit electrons from the sample. The surface band gap at 300 K is determined to be 0.830.04 eV and compared well with a many-body calculation for this system. Photoexcited electrons are observed to rapidly scatter into the empty As derived state and are trapped for times in excess of 200 ps. The long lifetime is due to a paucity of electrically active defect states within the surface band gap. © 1993 The American Physical Society.