Wang Xue-Peng, Chen Nian-Ke, Li Xian-Bin, Cheng Yan, Liu X Q, Xia Meng-Jiao, Song Z T, Han X D, Zhang S B, Sun Hong-Bo
State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun, China.
Phys Chem Chem Phys. 2014 Jun 14;16(22):10810-5. doi: 10.1039/c3cp55476g.
The nano amorphous interface is important as it controls the phase transition for data storage. Yet, atomic scale insights into such kinds of systems are still rare. By first-principles calculations, we obtain the atomic interface between amorphous Si and amorphous Sb2Te3, which prevails in the series of Si-Sb-Te phase change materials. This interface model reproduces the experiment-consistent phenomena, i.e. the amorphous stability of Sb2Te3, which defines the data retention in phase change memory, and is greatly enhanced by the nano interface. More importantly, this method offers a direct platform to explore the intrinsic mechanism to understand the material function: (1) by steric effects through the atomic "channel" of the amorphous interface, the arrangement of the Te network is significantly distorted and is separated from the p-orbital bond angle in the conventional phase-change material; and (2) through the electronic "channel" of the amorphous interface, high localized electrons in the form of a lone pair are "projected" to Sb2Te3 from amorphous Si by a proximity effect. These factors set an effective barrier for crystallization and improve the amorphous stability, and thus data retention. The present research and scheme sheds new light on the engineering and manipulation of other key amorphous interfaces, such as Si3N4/Ge2Sb2Te5 and C/Sb2Te3, through first-principles calculations towards non-volatile phase change memory.
纳米非晶界面很重要，因为它控制着数据存储的相变。然而，对于这类系统的原子尺度洞察仍然很少见。通过第一性原理计算，我们获得了非晶硅与非晶 Sb2Te3 之间的原子界面，这种界面在 Si-Sb-Te 系列相变材料中普遍存在。该界面模型再现了与实验一致的现象，即 Sb2Te3 的非晶稳定性，它决定了相变存储器中的数据保持能力，并且通过纳米界面得到了极大增强。更重要的是，这种方法提供了一个直接的平台来探索理解材料功能的内在机制：（1）通过非晶界面的原子“通道”产生的空间效应，Te 网络的排列被显著扭曲，并且与传统相变材料中的 p 轨道键角分离；（2）通过非晶界面的电子“通道”，孤对形式的高度局域化电子通过近邻效应从非晶硅“投射”到 Sb2Te3 上。这些因素为结晶设置了有效屏障并提高了非晶稳定性，从而提高了数据保持能力。本研究和方案通过对非易失性相变存储器的第一性原理计算，为其他关键非晶界面（如 Si3N4/Ge2Sb2Te5 和 C/Sb2Te3）的工程设计和操控提供了新的思路。
