Thickness dependence of the phase transition temperature in Ag<inf>2</inf>Te thin films

Electrical resistance measurements of Ag2Te thin films of different thicknesses, vacuum deposited on clean glass substrates held at room temperature in a vacuum of 5 × 10-5 Torr, have been carried out from about 300 to 450 K. A semiconducting-to-metallic-phase transition, which takes place during heating, is indicated by a sharp change in the slope of the resistance-vs-temperature curve. For films of different thicknesses the phase transition is found to occur at different temperatures. The size-dependent phase transition is explained by taking into account the varying surface and intergrain surface (interface) energy contributions to the total energy of the stable phase as a function of thickness and the difference in specific surface and integrain surface energies of the two phases. An order of magnitude of the difference in the function of specific surface and interfacial energies of the two phases is also made. © 1985.