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Ab Initio Calculations of Crystalline and Amorphous In2Se3 Compounds for Chalcogenide Phase Change Memory

Published online by Cambridge University Press:  01 February 2011

Renyu Chen  and
Scott T Dunham
Renyu Chen
Affiliation:
[email protected], University of Washington, Electrical Engineering, Seattle, Washington, United States
Scott T Dunham
Affiliation:
[email protected], University of Washington, Electrical Engineering, Seattle, Washington, United States
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Abstract

Ab Initio calculations of various configurations of In2Se3 compounds are used to gain insight into the transition from crystalline to amorphous phase. The structures considered are based on wurzite structures with 1/3 of indium sites vacant as observed experimentally. From extensive calculations for possible vacancy configurations in In2Se3 compounds, predictions based on the local coordination of In/Se atoms are made for the energetically favorable vacancy ordering structures. Results indicate that in the most stable In vacancy configurations, Se atoms have coordination of either 2 or 3 (In atoms have coordination of 4). Other coordinations lead to significantly higher formation energies. Results from analyzing the total energy and electronic structure of a range of off-stoichiometry, including vacancies, interstitials and anti-site, configurations, suggest that the energetically most favorable way to form In-rich material is via incorporation of Se vacancies, while Se occupying a vacant site is the most favorable for formation of Se-rich phase. Based on these calculations, predictions are made on how stoichiometry deviations impact structural evolution during phase change.

Keywords

phase transformationmemorysimulation
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1251: Symposium H – Phase-Change Materials for Memory and Reconfigurable Electronics Applications , 2010 , 1251-H03-34
Copyright
Copyright © Materials Research Society 2010

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