Effect of composition on the electrical and structural properties of As-Te-Ga thin films

As(30)Te(70-x)GaA (x = 0.5, 1, 3, 6 and 10 at.%) chalcogenide thin films were studied. Specimens of thickness 2500 Angstrom were used for resistivity (p) measurements as a function of temperature (7 in the temperature range from 300 to 443 K. The resistivity (p) exhibits an activated temperature dependence in accordance with the relation rho(T) = rho(0) exp(DeltaE/kT). It was found that the activation energy for conduction (DeltaE) and room temperature resistivity (rho(300)) decrease with increasing Ga content up to 3 at.%. For x greater than 3 at.%, it was found that DeltaE and rho(300) increase with increasing Ga content. The results were discussed according to the valence alternation pair (VAP) model and the alloying effect. Thermal annealing above T-g was found to decrease rho and DeltaE. The decrease of rho and DeltaE after annealing at T > T-g was attributed to the amorphous-crystalline transformation. XRD, SAED, TEM and DSC were used to study the structure of the as-deposited and annealed films. (C) C 2001 Elsevier Science B.V. All rights reserved.