Structural dependence of electrical conductivity of thin tellurium films

Abstract

Tellurium films were deposited on glass substrates and maintained in vacuum during the course of the measurement of electrical conductivity. The films were found by electron microscopy to have polycrystalline structure with a grain size dependent on deposition parameters. The electrical conductivity increased with increasing thickness, with increasing rate of deposition, and with the transition from the nonannealed to the annealed state. The increase in deposition rate from 100 to 1000 Å/min led to an increase in both grain size and number of surface defects. Annealing resulted in a further increase in grain size but in a decrease in the number of defects. The conductivity could further be explained in terms of mobility and carrier concentration, the former increasing with increasing grain size and decreasing defects, and the latter increasing with increasing defects. A comparison of quenched and annealed films confirms the dependence of mobility on the number of defects.