Quasi-equilibrium size distribution of subcritical nuclei in amorphous phase change AgIn-Sb2Te

Kristof Darmawikarta, Bong Sub Lee, Robert M. Shelby, Simone Raoux, Stephen G. Bishop, John R. Abelson

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the effect of low temperature annealing or of extended storage at room temperature on the subsequent nucleation behavior of amorphous AgIn-incorporated Sb2Te (AIST), a material for phase change memories. Time-resolved reflectivity measurements during pulsed laser crystallization reveal the rates of solid-phase transformation, while fluctuation transmission electron microscopy detects the nanoscale order in the amorphous phase prior to crystallization. The nanoscale order is postulated to consist of subcritical nuclei that coarsen upon annealing at temperatures ranging from 25°C (for months) or 100°C (for hours). Samples that have been annealed remain fully amorphous as evaluated by conventional diffraction experiments. Shorter nucleation times are consistently associated with the observation of increased nanoscale order. The effect of annealing is observed to saturate: there is no further reduction in nucleation time or increase in nanoscale order for annealing at 100°C beyond three hours. This result supports the general prediction of classical nucleation theory that the size distribution of subcritical nuclei increases from the as-deposited state to a quasi-equilibrium.

Original languageEnglish (US)
Article number034904
JournalJournal of Applied Physics
Volume114
Issue number3
DOIs
StatePublished - Jul 21 2013

ASJC Scopus subject areas

  • General Physics and Astronomy

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