Photo-thermal deflection and electrical switching studies on Ge–Te–I chalcohalideglasses

Abstract

Measurements on thermal diffusivity(α) and electrical switching studies have been undertaken on bulk, melt-quenchedGe22Te78−xIx (3≤x≤10) chalcohalide glasses. The thermal diffusivity values ofGe22Te78−xIx glasses lie inthe range 0.09–0.02 cm2 s−1, and are found to decrease with increase in iodine content. The variation ofα with composition has been understood on the basis of fragmentationof the Ge–Te network with the addition of iodine. The compositionx = 5 (), at which a cusp is seen in the composition dependence of thermal diffusivity,has been identified to be the inverse rigidity percolation threshold of theGe22Te78−xIx system at which the network connectivity is completely lost.Further, Ge22Te78−xIx glasses are found to exhibit memory-type electrical switching. At loweriodine concentrations, a decrease is seen in switching voltages with anincrease in iodine content, in comparison with the switching voltage of theGe22Te78 base glass. The observed initial decrease in the switching voltages with the addition of iodine isdue to the decrease in network connectivity. An increase is seen in switching voltages ofGe22Te78−xIx glasses at higher iodine contents, which suggests the domination of the metallicity factor of theadditive atoms on the switching voltages at higher iodine proportions. It is also interestingto note that the composition dependence of the threshold voltages shows a slope change atx = 5, the inverse rigidity percolation threshold of theGe22Te78−xIx system.