I n s i t u electrical conductivity and amorphous-crystalline transition in vacuum-deposited amorphous thin films of a Se50Te50 alloy

Abstract

In situ electrical conductivity measurements have been made on vacuum‐deposited amorphous thin films of various thicknesses of a Se₅₀Te₅₀ alloy in the temperature range 300–430 K. From the electrical conductivity, x‐ray studies, and electron diffraction studies it is found that the as‐grown films are amorphous and undergo an irreversible amorphous‐crystalline transition on heating in situ. The amorphous‐crystalline transition takes place in the temperature range 320–360 K for the different films. However, no systematic variation of the transition temperature with the thickness of the films is observed. All the films except the thinnest ones have a sharp transition temperature. X‐ray and electron diffraction analyses show that the Se₅₀Te₅₀ films above 360 K are polycrystalline. Above 360 K the electrical conductivity of the polycrystalline Se₅₀Te₅₀ films varies as an exponential function of reciprocal temperature.