Observation of Cleaved GaAs (110) Surfaces by Scanning Tunneling Microscopy

Observation of cleaved GaAs (110) surfaces is performed by scanning tunneling microscopy in ultrahigh vacuum. Monoatomic steps and anomalously large corrugation regions of a few tens of square angstroms in the atomically flat terrace are observed. Since the number of the large corrugations corresponds to the number of the dopant within a few atomic layers, these corrugation regions are probably induced by the dopant. Voltage-dependent morphology, which originates from the local density of states of each constituent at the surface, is also discussed.