SET and RESET states of As2Se3 doped GeTe4 bulk glasses probed by Raman spectroscopy

Abstract

Te based chalcogenide glasses are being explored for non-volatile memory applications. We report the electrical switching studies on bulk Ge0.20Te0.80 glass alloyed with As0.40Se0.60 in different proportions. The addition of As0.40Se0.60 increases the electrical resistivity and the threshold voltage of (As0.4Se0.6)x(Ge0.2Te0.8)1−x glasses in the composition range 0 ≤ x ≤ 0.40. Glasses in the range 0 ≤ x ≤ 0.10 are found to exhibit memory switching, whereas glasses with x ≥ 0.15 exhibit threshold switching. The memory (SET) state can be brought back to RESET state by passing a current of 3–5 mA. Particularly, the glass with x = 0.10 is identified to be very stable, and it can be cycled between the SET and RESET state consistently with 3 mA current. The Raman spectra of SET and RESET states indicate that the SET sample has GeTe and Te crystalline units while the structure of RESET state is analogous to the as-quenched glass. Interestingly, the variation in the local structure is minimal for SET and RESET states for x = 0.10. And also the resistance of the SET state is relatively high. So they can be set to RESET state with less current and can be explored for low power phase change memory applications.