GeSb2Te4纳米薄膜的原位透射电子显微学研究

相变材料GeSbTe亚稳相中的局域结构长期以来一直是研究的热点,特别是亚稳相中Ge原子的分布对相变过程的进行具有重要作用.本文主要利用透射电子显微学,电子衍射技术和基于电子衍射技术的径向分布函数对不同时效温度时效过程中GeSb2Te4亚稳相的原子结构进行了深入研究.通过对径向分布函数的研究表明:250℃时效60min时GeSb2Te4亚稳相中几乎所有的Ge原子都位于四面体位置,局域形成类尖晶石结构;而时效温度为150℃、200℃下分别时效60min时发现没有或者几乎没有Ge原子位于四面体位置,时效后的结构以岩盐矿结构为主,部分晶化为六方结构.

In-situ aging TEM study of GeSb2Te4 Nano-films

The local structure of phase change material GeSbTe metastable phase has been widely studied for a long time. The configuration of Ge in metastable phase plays an important role in the phase transition process. In this paper, the atomic structure of GeSb2Te4 metastable phase in different aging temperatures were studied by advanced in-situ transmission electron microscopy. The results show that almost all of the Ge atoms in the GeSb2Te4 metastable phase are located in the tetrahedral position after aging for 60 min at 250 ℃, which is named as the pseudo-spinel structure. In contrast, there is no tetrahedral Ge if the aging temperature is below 250°C. The crystalline phases are mainly presented as rocksalt structure and partially hexagonal structure.