The effect of annealing on the electrical conduction of amorphous Bi0.5Se99.4Zn0.1 thin films

The electrical conductivity of as-evaporated and thermally annealed films of a-Bi0.5Se99.4Zn0.1, grown by vacuum evaporation technique, has been measured in the temperature range of 80-260 K. The experimental data suggest that conduction in the high temperature range 200-260 K is due to thermally assisted tunneling of charge carriers in localized states near the band edge; while conduction in low temperature range 80-200 K takes place through variable range hopping of charge carriers in the localized states near the Fermi level. The activation energy for both the processes is found to decrease with increase in annealing temperature. In case of conduction near the Fermi level, the density of states decreases, average hopping distance increases and average hopping energy decreases with increase in annealing temperature. (c) 2007 Published by Elsevier B.V.