THERMOANALYSIS OF QUASI-TERNARY AS2(S, SE, TE)3 SEMICONDUCTOR GLASSES

In comparison with other chalcogenide glassy systems, less attention h as been paid to the quasi-ternary (quaternary) system As2(S, Se, Te)3. In this paper, thermal methods were used to characterize ten differen t quaternary homogeneous semiconductor glasses that were prepared by m ixing the stoichiometric binary systems As2S3, As2Se3 and As2Te3. The ratios of the constituent binaries in the quasi-ternary glasses exerte d a great influence on their thermal spectrum. The samples poor in As2 Te3 showed neither the exothermic nor the endothermic peak due to crys tallization (T(c) and melting (T(m)), respectively, but only the glass transition (T(g)). Three transition temperatures, T(g)), T(c) and T(m ), were detected for other compositions. On the other hand, a phase se paration was observed in the samples rich in As2Te3. A cyclic scanning technique was used to investigate the thermally-induced phases during two consecutive heating-cooling cycles covering the temperature range T(g)-T(m). The energy of decomposition E(d) decreased on increase of the ratio As2S3/As2Se3 (at constant As2Te3), whereas it increased on i ncrease of the ratio As2Te3/As2Se3 (at constant As2Se3 or As2S3).