cm8b01900_si_001.pdf (4.68 MB)
Genesis and Effects of Swapping Bilayers in Hexagonal GeSb2Te4
journal contribution
posted on 2018-07-02, 00:00 authored by Jiang-Jing Wang, Jun Wang, Hongchu Du, Lu Lu, Peter C. Schmitz, Johannes Reindl, Antonio M. Mio, Chun-Lin Jia, Evan Ma, Riccardo Mazzarello, Matthias Wuttig, Wei ZhangDisorder
plays an essential role in shaping the transport properties
of GeSbTe phase-change materials (PCMs) to enable nonvolatile memory
technology. Recently, increasing efforts have been undertaken to investigate
disorder in the stable hexagonal phase of GeSbTe compounds, focusing
on a special type of swapping bilayer defects. This configuration
has been claimed to be the key element for a new mechanism for phase-change
memory. Here, we report a direct atomic-scale chemical identification
of these swapping bilayer defects in hexagonal GeSb2Te4 together with nanoscale atomic modeling and simulations.
We identify the intermixing of Sb and Te in the bilayer to be the
essential ingredient for the stability of the defects, and elucidate
their abundance as due to the small energy cost. The bilayer defects
are demonstrated to be ineffective in altering the electron localization
nature that is relevant to transport properties of hexagonal GeSb2Te4. Our work paves the way for future studies
of layer-switching dynamics in GeSbTe at the atomic and electronic
level, which could be important to understand the new switching mechanism
relevant to interfacial phase-change memory.