Disorder enhancement due to structural relaxation in amorphous Ge2Sb2Te5

Abstract

This work investigates the atomic structural relaxation accounting for the resistance drift of the amorphous phase of the Ge2Sb2Te5 (α-GST) chalcogenide alloy. A joint electrical and optical characterization over time on both the phase change memory cell in the reset state and the as-deposited amorphous GST film has been performed to elucidate the origin of the drift phenomenon. We highlight that the drift mechanism is ascribed to the removal of residual resonant-like bonding in the amorphous network, lowering the electronic component of the dielectric constant (ɛ∞) and leading to a progressive loosing of any medium-range order.