Liu Cheng, Tang Qiongyan, Zheng Yonghui, Zhao Jin, Song Wenxiong, Cheng Yan
Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, People's Republic of China.
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
Nanotechnology. 2023 Feb 2;34(15). doi: 10.1088/1361-6528/acb446.
GeSbTe(GST) is the most widely used matrix material in phase change random access memory (PCRAM). In practical PCRAM device, the formed large hexagonal phase in GST material is not preferred, especially when the size of storage architecture is continually scaling down. In this report, with the aid of spherical-aberration corrected transmission electron microscopy (Cs-TEM), the grain growth behavior during theheating process in GST alloy is investigated. Generally, the metastable face-centered-cubic (f-) grain tends to grow up with increasing temperature. However, a part of f-phase nanograins with {111} surface plane does not grow very obviously. Thus, the grain size distribution at high temperature shows a large average grain size as well as a large standard deviation. When the vacancy ordering layers forms at the grain boundary area in the nanograins, which is parallel to {111} surface plane, it could stabilize and refine these f-phase grains. By elaborating the relationship between the grain growth and the vacancy ordering process in GST, this work offers a new perspective for the grain refinement in GST-based PCRAM devices.
