Xia Mengjiao, Ding Keyuan, Rao Feng, Li Xianbin, Wu Liangcai, Song Zhitang
1] State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China [2] Graduate University of the Chinese Academy of Sciences, Beijing 100080, China.
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
Sci Rep. 2015 Feb 24;5:8548. doi: 10.1038/srep08548.
Group IIIA elements, Al, Ga, or In, etc., doped Sb-Te materials have proven good phase change properties, especially the superior data retention ability over popular Ge2Sb2Te5, while their phase transition mechanisms are rarely investigated. In this paper, aiming at the phase transition of Al-Sb-Te materials, we reveal a dominant rule of local structure changes around the Al atoms based on ab initio simulations and nuclear magnetic resonance evidences. By comparing the local chemical environments around Al atoms in respective amorphous and crystalline Al-Sb-Te phases, we believe that Al-centered motifs undergo reversible tetrahedron-octahedron reconfigurations in phase transition process. Such Al-centered local structure rearrangements significantly enhance thermal stability of amorphous phase compared to that of undoped Sb-Te materials, and facilitate a low-energy amorphization due to the weak links among Al-centered and Sb-centered octahedrons. Our studies may provide a useful reference to further understand the underlying physics and optimize performances of all IIIA metal doped Sb-Te phase change materials, prompting the development of NOR/NAND Flash-like phase change memory technology.
ⅢA族元素铝（Al）、镓（Ga）或铟（In）等掺杂的锑碲（Sb-Te）材料已被证明具有良好的相变特性，尤其是相较于广为人知的Ge2Sb2Te5，其数据保持能力更为优异，然而它们的相变机制却鲜有研究。本文针对Al-Sb-Te材料的相变，基于第一性原理模拟和核磁共振证据，揭示了Al原子周围局部结构变化的主导规律。通过比较非晶态和晶态Al-Sb-Te相中Al原子周围的局部化学环境，我们认为以Al为中心的结构单元在相变过程中经历了可逆的四面体-八面体重构。与未掺杂的Sb-Te材料相比，这种以Al为中心的局部结构重排显著提高了非晶相的热稳定性，并且由于以Al为中心和以Sb为中心的八面体之间的弱连接而促进了低能量非晶化。我们的研究可能为进一步理解所有ⅢA族金属掺杂的Sb-Te相变材料的潜在物理机制和优化其性能提供有用的参考，推动类NOR/NAND闪存相变存储技术的发展。
