INFLUENCE OF RESONANT-TUNNELING ON THE IMAGING OF ATOMIC DEFECTS ON INAS(110) SURFACES BY LOW-TEMPERATURE SCANNING-TUNNELING-MICROSCOPY

We have used a low-temperature scanning tunneling microscope (STM) to study the surface of heavily doped semiconductor InAs crystals. The cr ystals are cleaved in situ along the (110) plane. Apart from atomicall y flat areas, we also observe two major types of atomic-scale defects which can be identified as S dopant atoms and As vacancies, respective ly. The strong bias voltage dependence of the STM image of the impurit ies can be explained in terms of resonant tunneling through localized states which are present near the impurity.