Amorphous chalcogenide Se1−xy TexPy semiconducting alloys: thermal and mechanical properties


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Abstract

Thermal and mechanical properties of ternary Se rich Se1−xyTexPy semiconducting glasses (Te < 20 at % and P < 10 at %) in vitreous bulk and film form have been studied by differential scanning calorimetry (DSC) and microhardness measurements. Bulk vitreous samples were prepared by conventional melt quenching techniques and the amorphous photoreceptor films were prepared by vacuum deposition onto oxidized aluminum substrates whose electrophotographic properties were reported previously. We measured the glass transition temperature Tg starting from a well defined thermal history and using both heating and cooling scans as a function of composition. Tg increases monotonically with both Te and P content. Both bulk and film samples evince similar compositional Tg dependence. The increase in Tg with the P content in the glasses follows the Tanaka rule, that is, P addition has a networking effect due to the trivalent nature of the P atom and increases the mean coordination number. Both Te and P additions initially inhibit crystallization but at high Te contents (∼20 at %) the crystallization behavior is comparable to the pure a-Se case. Glasses with ∼10 at % Te seem to have the greatest resistance to crystallization. The crystallization behavior does not correlate with the Tg behavior over the whole composition range. The Vickers microhardness HV increases with both Te and P content. HV vs. Te and P behavior is similar to that of Tg vs. Te and P content. The compositional dependence of both HV and Tg can be explained by the same factors that reduce Se chain mobility.

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