Influence of indium content on the optical, electrical and crystallization kinetics of Se100-xInx thin films deposited by flash evaporation technique

Thin films of Se100-xInx (x=10, 20 and 30 at%) have been prepared by the flash evaporation technique. The effect of the indium content on optical band gap of the Se100-xInx films has been investigated by the optical characterization. The optical band gap values of the Se100-xInx thin films were determined and are found to decrease with increasing indium content. This indium content changes the width of localized states in the optical band gaps of the thin films. It was found that the optical band gap. E-g, of the Se100-xInx films changes from 1.78 to 1.37 eV with increasing indium content from 10 to 30 at%, while the width of localized states in optical band gap changes from 375 to 342 meV. The temperature dependence of the dark electrical conductivity were studied in the temperature range 303-433 K and revealed two activation energies providing two electrical conduction mechanisms. The activation energy of the Se100-xInx films in the high temperature region changes from 0.49 to 0.32 eV with increasing indium content from 10 to 30 at%, while the hopping activation energy in the lower temperature region changes from 0.17 to 0.22 meV. The change in the electrical conductivity with time during the amorphous-to-crystalline transformation is recorded for amorphous Se100-xInx films at two points of isothermal temperatures 370 and 400 K. The formal crystallization theory of Avrami has been used to calculate the kinetic parameters of crystallization. (C) 2011 Elsevier B.V. All rights reserved.