J. Phys. Colloques
Volume 42, Numéro C4, Octobre 1981Proceedings of the Ninth International Conference on Amorphous and Liquid Semiconductors
|Page(s)||C4-167 - C4-170|
J. Phys. Colloques 42 (1981) C4-167-C4-170
CONTRIBUTION OF SINGLE POLARON HOPPING TO AC CONDUCTION IN AMORPHOUS CHALCOGENIDESK. Shimakawa
Department of Physics, University of Leicester, Leicester, England.
Although it is now fairly well established that defects in amorphous chalcogenide semiconductors are normally charged (D+ and D-), it is proposed that neutral defects D0 (generated by the reverse reaction of 2D0 → D+ + D-) can be important for a.c. conductivity. It is shown that the contribution to σ(ω,T) from correlated barrier hopping of single polarons exceeds that of bipolarons at high temperatures (T) and/or low frequencies (ω). An expression for σ(ω,T), which includes terms due to electrons hopping between D0 and D+ and holes between D0 and D-, as well as two electrons hopping between D- and D+ (bipolarons), is able to account for all the features observed in many materials. The energy levels and densities of the defect states for Se, two Se-Te alloys, As2Te3 and As2Se3 are deduced from a comparison of the theory with experimental data.