Kinetics of phase transitions in vitreous chalcogenide semiconductors As sub(x)Se sub(100-x-y)Bi sub(y) as studied by the differential thermal analysis and exoelectron emission methods

Kinetics of glass transition (retrification) in chalcogenide semiconductors As sub(x)Se sub(100-x-y)B sub(y) (x = 20 or 30, and y = 0 and 1) has been investigated by parallel differential thennal analysis (DTA) and exoelectron emission (EEE) measurements. EEE is a surface effect accompanying the structural transformations in the surface layer, whereas the DTA technique gives information about the transformations occurring in the volume of the sample. Temperature dependencies of the DTA signal and of the EEE intensity have been determined and the values of the activation energy for both the volume and the surface retrification have been determined by the Ozawa method for each of the four investigated materials. It has been found that addition of Bi into the vitreous As sub(x)Se sub(100-x) glass changes distinctly the kinetics of both the surface and volume retrification. Addition of Bi causes a distinct decrease in the value of the activation energy for retrification process in both the surface layer and in the volume, i.e. reduces the thermal stability of investigated materials.