Structural study of bismuth films and its consequences on their electrical properties

Abstract

The structure of bismuth thin films prepared according to three different deposition techniques is inspected by : reflection electron diffraction, X-ray diffraction, scanning electron microscopy, transmission microscopy and electron diffraction. The electrical conduction properties, R H and conductance measurements, of these films are then discussed. It appears that surface states play a major role in dictating the properties of both RH and conductivity. This is clearly confirmed with the aid of the conclusions of the structural study. By comparing size effect theories with the conductivity data the carrier mean free path can be estimated to be of the order of 1 000 A in good agreement with the observation of the film structure. The surface state density and the energy barrier that controls the carrier transport across the grain boundaries have also been evaluated as a function of the preparation technique.