THE EFFECT OF TE ISOELECTRONIC SUBSTITUTION ON THE ELECTRICAL AND OPTICAL-PROPERTIES OF THE GE-S-SE AMORPHOUS-CHALCOGENIDE SYSTEM STUDIED IN THIN-FILMS

The results are presented of a study of the electrical and optical pro perties of vacuum evaporated amorphous thin films in the Ge-S-Se syste m. The effect of Te isoelectronic substitution either completely for S to give Ge-2.5 Te-2.5 Se-95 and Ge-5 Te-5 Se-90 or partially for Se t o yield Ge-2.5 S-2.5 Te-2.5 Se-92.5 and Ge-5 S-5 Te-5 Se-85 is discuss ed. The changes recorded for the electrical conductivity, the thermal activation energy and for the red shift of the absorption band edge ar e interpreted in terms of some physical properties such as connectedne ss, electronegativity, bond strength and atomic size. Correlation betw een the Tg and E-04 values for samples with the same average coordinat ion number is also given. (C) 1998 Elsevier Science Ltd. All rights re served.