Diffusion, electric transport, and effect of a silver impurity on the electrical and optical properties of As2Se3

Abstract

The diffusion and electric transport of silver in glassy As2Se3 was studied in the range 110 to 160 °C with the radioactive tracer 110mAg. It is shown, that the temperature dependence of the silver diffusivity can be described by the formula D = 5.9 × 10−6 exp (−0.41/kT), and that the effective mobility of the silver ions in the range 134 to 155 °C vary within (1.7 to 5.0) × 10−9 cm2/Vs. At temperatures below 134 °C silver is found to migrate in glass in the form of positive ions with an effective charge qeff ≧ + 1, the experimentally measured charge above 134 °C is qeff ≧ +2. This anomalous increase of qeff with temperature is shown to be associated with the formation of inclusions of a second phase (apparently Ag2Se, Ag3AsSe3, or AgAsSe2) in the course of the electric transport at T > 134 °C. A discussion based on the experimental data obtained is made of the mechanism of silver diffusion involving the migration of arsenic selenide through the interlayer space. Further an effect of white light illumination on the concentration profile of silver introduced by diffusion in As2Se3 is revealed. The results obtained are considered on the basis of photochemical reactions occurring at the silver–As2Se3 interface. A study is also made of the effect of silver impurities introduced by diffusion in As2Se3 glasses on the electrical and optical properties of this material. [Russian Text Ignored]