SCANNING-TUNNELING-MICROSCOPY STUDY OF INSB(110)

The (110) cleavage surface of InSb has been studied with scanning tunneling microscopy. A variety of surface defects has been observed, including those that appear to be simple vacancies and Schottky defects. Atomic-resolution images have been obtained of both the occupied- and unoccupied-state densities concentrated on the Sb anion and In cation, respectively. By simultaneously imaging both the occupied- and unoccupied-state densities, the relative positions of the In and Sb dangling bonds within the unit cell have been determined. As expected, the In state density is shifted with respect to the Sb state density by approximately one-half of a unit cell along the [11»0] direction. Along the [001] direction, the In state density is displaced by approximately one-third of a unit cell, in good agreement with surface electronic structure and surface-buckling calculations. Measurements of the tunnel current versus voltage reveal conductance within the band gap associated with dopant-induced occupation of the conduction band. © 1990 The American Physical Society.