Electrically Driven Reversible Phase Change in Layered In2Se3 Crystalline Film

Title
Electrically Driven Reversible Phase Change in Layered In2Se3 Crystalline Film
Authors
정병기이수연Min Sup ChoiChang Ho RaJee-Hwan BaeSungwoo LeeGun-Do LeeCheol-Woong YangJames HoneWon Jong Yoo
Keywords
Reversible Phase Changes; Phase-Change Memory; indium selenides; layered materials; metal-to-insulator transition; phase changes; vacancy layers
Issue Date
2017-10
Publisher
Advanced materials
Citation
VOL 2017-1703568-8
Abstract
An unconventional phase-change memory (PCM) made of In2Se3, which utilizes reversible phase changes between a low-resistance crystalline β phase and a high-resistance crystalline γ phase is reported for the first time. Using a PCM with a layered crystalline film exfoliated from In2Se3 crystals on a graphene bottom electrode, it is shown that SET/RESET programmed states form via the formation/annihilation of periodic van der Waals’ (vdW) gaps (i.e., virtual vacancy layers) in the stack of atomic layers and the concurrent reconfiguration of In and Se atoms across the layers. From density functional theory calculations, β and γ phases, characterized by octahedral bonding with vdW gaps and tetrahedral bonding without vdW gaps, respectively, are shown to have energy bandgap value of 0.78 and 1.86 eV, consistent with a metal-toinsulator transition accompanying the β-to-γ phase change. The monolithic In2Se3 layered film reported here provides a novel means to achieving a PCM based on melting-free, low-entropy phase changes in contrast with the GeTe– Sb2Te3 superlattice film adopted in interfacial phase-change memory.
URI
http://pubs.kist.re.kr/handle/201004/66316
ISSN
0935-9648
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KIST Publication > Article
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