Frequency dependent electrical measurements of amorphous GeSbSe chalcogenide thin films

Abstract

A commercial bulk chalcogenide glass (Ge28Sb12Se60) was used as a source to fabricate amorphous thin films via thermal evaporation technique. At low frequencies (<1 MHz) impedance spectroscopy was performed to measure electrical properties. To measure ac conductivity at microwave frequencies, a split resonance cavity technique was applied for which a model based on parallel arrangement of substrate and film capacitors was developed. This model was used to extract tan δ and ac conductivity of the films. Microwave ac conductivity was correlated with the extrapolated low frequency conductivity data confirming applicability of the universal law commonly observed in amorphous semiconductors.