Effect of indium concentration on the electrical properties of InSe alloy

In(x)Sel(1-x)(x=0.4, 0.5, 0.6) thin films are deposited at room temperature on glass substrates by thermal evaporation technique. The X-ray diffraction analysis showed that both the as-deposited films In2Se3 and InSe (x=0.4 and 0.5) are amorphous in nature while the as-deposited films of In3Se2 are polycrystalline. Scanning electron microscopy (SEM) photographs of these samples have been taken. The dc measurements are made on the InxSe1-x films at all concentrations, in the temperature range 100-400 K. The obtained results revealed three distinct regions. Temperature dependence of conductivity are analyzed by three mechanisms: extended state conductivity, conduction in band tail and conduction in localized sites. It is clear from the results that at high temperatures conductivity mechanism obeys the law In sigma proportional to 1/T and at low temperatures: In sigma proportional to T-1/4, indicating variable range hopping energy in the localized states near the Fermi level N (E-F). The incorporation of In atoms in Se matrix leads to an increase in the electrical conductivity and decrease in the thermal activation energy. The change in the above parameters will be discussed in terms of the phase transition, which takes place in InxSe1-x thin films. (C) 2010 Elsevier B.V. All rights reserved.