# Electrical switching and topological thresholds in Ge-Te and Si-Te glasses

Murthy, CN and Ganesan, V and Asokan, S (2005) Electrical switching and topological thresholds in Ge-Te and Si-Te glasses. In: Applied Physics A: Materials Science & Processing, 81 (5). pp. 939-942.

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Melt-quenched $Ge_{x}Te_{100-x}$ glasses and $Si_{x}Te_{100-x}$ glasses (15 \leq x \leq 25) have been found to exhibit memory switching, with threshold fields of the order of 4-11 kV/cm and 6-25 kV/cm, respectively. It is found that the switching voltages of $Ge_{x}Te_{100-x}$ samples increase linearly with Ge content and the composition dependence of threshold voltage $V_{t}$ shows a marked slope change at x=20, which has been earlier identified as the rigidity percolation threshold (RPT) of the system. Above the RPT, $V_{t}$ of Ge-Te glasses continues to increase with composition until the boundary of bulk glass formation (x=28). On the other hand, the switching voltages of $Si_{x}Te_{100-x}$ glasses increase with x, exhibiting abroad maximum around x=20 (RPT). The difference in the composition dependence of $Si_{x}Te_{100-x}$ and $Ge_{x}Te_{100-x}$ glasses has been understood on the basis of separation between the rigidity percolation threshold and the stoichiometric threshold $(CT_{ST})$ in these samples. The present results also indicate that the turn around in the composition dependence of $V_{t}$ and the subsequent minimum observed in the switching voltages of chalcogenide glasses is likely to be due to $CT_{ST}$ and not to the chemical ordering threshold $(CT_{COCRN})$.