Electronic configuration of indium antimonide surfaces

Abstract

Large signal alternating current field effect experiments previously performed on the {111} A and B “real” surfaces of n and p-type InSb were extended to cleaved {110} and {100} “real” surfaces of n-type InSb. Discrete “fast” states were observed in the energy gap near the valence as well as near the conduction band edge on all surfaces. The discrete state near the conduction band edge exhibited essentially the same density on all surfaces, ~ 4 × 10 11/cm 2, while the state near the valence band edge was found to be 2 to 6 times more dense, increasing in the order: {110} cleaved, {111} A, {100}, and {111} B. All surfaces were found to be p-type; the degree of p-type character correlated directly with the state density near the valence band edge. The present results were found to be consistent with a model according to which the discrete “fast” states near the valence and conduction band edges are acceptor-like, characteristic of the antimony and indium species, respectively. This model was extended to emphasize the importance of sub-surface states. The electrical properties of these surfaces were correlated with their chemical and structural characteristics and were found to be consistent with the Gatos-Lavine model of the dangling bonds on the III–v compound surfaces.