Fast phase change speed induced by surface oxidation of phase change material

2014 Fiscal Year Final Research Report

• Project/Area Number: 25630289
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Composite materials/Surface and interface engineering
• Research Institution: Tohoku University
• Principal Investigator: SUTOU Yuji 東北大学, 工学(系)研究科(研究院), 准教授 (80375196)
• Co-Investigator(Renkei-kenkyūsha): KOIKE Junichi 東北大学, 未来科学技術共同研究センター, 教授 (10261588) ; ANDO Daisuke 東北大学, 大学院工学研究科, 助教 (50615820)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 相変化メモリ / 不揮発性メモリ / 表面酸化 / 不均一核生成 / 結晶化

Outline of Final Research Achievements

Phase change random access memory (PCRAM) has attracted much attention as a new class of non-volatile memory because of its low production cost and high scalability. Now, Ge-Sb-Te material is used for PCRAM because of its fast phase change speed and good repeatability. However, the Ge-Sb-Te shows low crystallization temperature (Tc) and consequently insufficient high temperature data retention. Meanwhile, a material with a high Tc shows a slow phase change speed. Therefore, an idea to realize a material with high Tc and fast crystallization speed is desired. In this study, we investigated the effect of preferential surface oxidation on crystallization speed in GeTe-Si phase change material. It was found that the crystallization starting time of the surface-oxidized film by O2 plasma-treatment was about 20% faster than that of a non-oxidized film. This fast crystal nucleation was suggested to be due to the formation of inhomogeneous nucleation sites at the film surface.

Free Research Field

材料工学