Abstract
The sub-threshold electron transport properties of amorphous (a-) germanium telluride (GeTe) phase change material (PCM) ultra-thin films are investigated by using ab initio molecular dynamics, density function theory, and Green’s function simulations. The simulation results reproduce the trends in measured electron transport properties, e.g. current-voltage curve, intra-bandgap donor-like and acceptor-like defect states, and p-type conductivity. The underlying physical mechanism of electron transport in ultra-scaled a-PCM is unraveled. We find that, though the current-voltage curve of the ultra-scaled a-PCM resembles that of the bulk a-PCM, their physical origins are different. Unlike the electron transport in bulk a-PCM, which is governed by the Poole-Frenkel effect, the electron transport in ultra-scaled a-PCM is largely dominated by tunneling transport via intra-bandgap donor-like and acceptor-like defect states.
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acknowledgments
This work was supported by U.S. National Science Foundation (NSF) under Grant Award 1006182. We acknowledge the Pacific Northwest National Laboratory (PNNL) for providing computational resources on the PNNL Chinook supercomputers. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575. This work was facilitated through the use of advanced computational, storage, and networking infrastructure provided by the Hyak supercomputer system, supported in part by the University of Washington’s eScience Institute. We acknowledge J. Akola and R.O. Jones (for discussion about AIMD simulations). This article uses results from our previous journal article in reference.
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Liu, J., Xu, X. & Anantram, M.P. Ab Initio Study of the Sub-threshold Electron Transport Properties of Ultra-scaled Amorphous Phase Change Material Germanium Telluride. MRS Online Proceedings Library 1697, 1–6 (2014). https://doi.org/10.1557/opl.2014.423
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DOI: https://doi.org/10.1557/opl.2014.423