Choi, Min Sup Cheong, Byung-ki Ra, Chang Ho Lee, Suyoun Bae, Jee-Hwan Lee, Sungwoo Lee, Gun-Do Yang, Cheol-Woong Hone, James Yoo, Won Jong 2024-01-20T00:03:27Z 2024-01-20T00:03:27Z 2021-09-03 2017-11-13 0935-9648 https://pubs.kist.re.kr/handle/201004/122070 An unconventional phase-change memory (PCM) made of In2Se3, which utilizes reversible phase changes between a low-resistance crystalline phase and a high-resistance crystalline gamma 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, beta and gamma 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-to-insulator transition accompanying the beta-to-gamma 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. English WILEY-V C H VERLAG GMBH CHANGE MEMORY BAND-STRUCTURE TRANSITIONS METAL TRANSFORMATION GAMMA-IN2SE3 Electrically Driven Reversible Phase Changes in Layered In2Se3 Crystalline Film Article 10.1002/adma.201703568 1 ADVANCED MATERIALS, v.29, no.42 ADVANCED MATERIALS 29 42 scie scopus 000414756700019 2-s2.0-85032983053 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article CHANGE MEMORY BAND-STRUCTURE TRANSITIONS METAL TRANSFORMATION GAMMA-IN2SE3 indium selenides layered materials metal-to-insulator transition phase changes vacancy layers