Ac conductivity and dielectric properties of amorphous In2Se3 films

In2Se3 films of different thicknesses were prepared by thermal evaporation technique. X-ray diffraction measurements showed that the as-deposited In2S e3 films and those annealed at 373, 423. and 473 K are in the amorphous sta te. The composition of the investigated films is checked using energy dispe rsive X-ray spectroscopy (EDX) technique. The ac conductivity and dielectri c properties of the amorphous In2Se3 films have been investigated in the fr equency range 100 Hz-100 kHz. The ac conductivity sigma (ac)(omega) is foun d to be proportional to omega (S) where s < 1. The temperature dependence o f both ac conductivity and the parameter s is reasonably well interpreted b y the correlated barrier hopping (CBH) model. Values of dielectric constant <epsilon>(1) acid dielectric loss epsilon (2) were found to decrease with frequency and increase with temperature. The maximum barrier height W-M cal culated from dielectric measurements according to Guintini equation agrees with that proposed by the theory of hopping of charge carriers over potenti al barrier as suggested by Elliot in case of chalcogenide glasses. The effe ct of annealing at different temperatures on the ac conductivity and dielec tric properties is also investigated. Values of sigma (ac) (omega), epsilon (1) and epsilon (2) were found to increase with higher annealing temperatu re due to the increase of the degree of ordering of the investigated films. (C) 2001 Elsevier Science Ltd. All rights reserved.