First-principles simulations of local structure contrast for liquid Ge<sub>1sub>Sb<sub>2sub>Te<sub>4sub>, Ge<sub>2sub>Sb<sub>2sub>Te<sub>5sub>, and Ge<sub>4sub>Sb<sub>1sub>Te<sub>5sub> alloys
- 作者：Feng-Chun Pang<sup>asup><sup> ; sup><sup>bsup> ; Dan Wang<sup>bsup> ; Nian-Ke Chen<sup>bsup> ; Sheng-Yi Xie<sup>asup><sup> ; sup><sup>bsup> ; Xing Meng<sup>asup><sup> ; sup><sup>mengxing@jlu.edu.cnsup> ; Cheng-Song Huo<sup>csup> ; Hai Yang<sup>csup> ; Xiao-Ping Su<sup>csup> ; Wen-Quan Wang<sup>asup><sup> ; sup><sup>wangwq@jlu.edu.cnsup> ; Hai-Ling Tu<sup>csup>
- 关键词：Phase-change memory ; Ge&ndash ; Sb&ndash ; Te alloys ; Liquid phase ; First-principles molecular dynamics ; Compositional disorder number
- 刊名：Computational Materials Science
- 出版年：2012
- 期刊代码：31_09270256
- 类别：et
- 出版时间：August, 2012
- 卷：61
- 期：Complete
- 页码：287-290
- 文件大小：582 K
摘要
Ge-Sb-Te alloys have played a critical role in present nonvolatile optical and electrical storages. It is generally accepted that their 鈥渄ata encoding鈥?(i.e. amorphization) needs the crystal melting and subsequent quenching. Therefore, liquid should be an important intermediate state during the storage. In this study, based on first-principles molecular dynamics we compared the structural properties of liquid Ge-Sb-Te alloys with three compositions: Ge<sub>1sub>Sb<sub>2sub>Te<sub>4sub>, Ge<sub>2sub>Sb<sub>2sub>Te<sub>5sub>, and Ge<sub>4sub>Sb<sub>1sub>Te<sub>5sub>. In long timescale mean square displacements (MSD), we observe that the element coupled state for Ge<sub>1sub>Sb<sub>2sub>Te<sub>4sub> and Ge<sub>2sub>Sb<sub>2sub>Te<sub>5sub> is significantly better than that of Ge<sub>4sub>Sb<sub>1sub>Te<sub>5sub>. The careful analyses by pair correlation functions (PCF) and compositional disorder numbers (CDN) show that Ge<sub>2sub>Sb<sub>2sub>Te<sub>5sub> has the best stability among the three liquids. Bond angle distributions (BAD) further reflect that all the three liquids essentially retain the crystalline character of local structure with 90藲 bond angle. The present results are helpful to understand the rapid storage technique based on Ge-Sb-Te alloys.