Abstract
Ternary compositions Ge1Te4 (In. or Cu.) with x= 0.05 and 0.1 were prepared by conventional melt-quenching. Thin films of these compositions were deposited by thermal evaporation with thickness 300 nm. Dependence of d.c conductivity on compositions has been reported. It was found that the activation energy decreases with increasing additive (In or Cu). The obtained results have been interpreted in the frame of the model proposed by Mott and Davis (1979). The ac electrical properties of adding Cu or In to amorphous GeTe system have been measured in the frequency range from 100 Hz to 100KHz and temperature range (303-208)K. It is found that, in Ge1Te4 (In. or Cu. ) compositions where x is limited to x=0.05 and x=0.1, the change of conductivitycracdeFends linearly on the frequency and temperature. The value of the exponent (S) in all this system is reasonably interpreted by the correlated barrier-hopping model (CBH). The analysis of the results reveals that electronic conduction of Ge1Te4 (Inx or Cu.) takes place via bipolaron hopping. The dielectric investigation provides a fundamental method for studying the rotational and hopping electron processes involved in conduction. Conductivity values, which depend on the glass microstructure, are observed as a term of cohesive energy, expre-ssed by the force of binding ions. An attempt has been made to evaluate this correlation. The experimental results support to some extent the above criterion in the case of Ge1Te4 (In. or Cu.) ternary alloy.
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