First-principles simulations of crystallization of phase-change materials
讲座名称：
First-principles simulations of crystallization of phase-change materials
讲座时间：
2015-06-05
讲座人：
Riccardo Mazzarello
形式：
校区：
兴庆校区
实践学分：
讲座内容：
报告题目：First-principles simulations of crystallization of phase-change materials
报告人： Prof. Dr. Riccardo Mazzarello( RWTH Aachen University 德国亚琛工业大学)
报告时间：6月5日 （周四）上午10:30-11:30
报告地点：材料学院205会议室
Abstract:
Phase-change materials (PCMs) are capable of switching very rapidly and reversibly between the amorphous and crystalline phase at high temperatures. Yet, the two phases are stable at room temperature and exhibit pronounced optical and electrical contrast. These unique properties have resulted in applications in rewritable optical devices and electronic non-volatile random access memories (PRAM), where heating is induced by laser irradiation and the Joule effect, respectively. Recently, sub-nanoseconds crystallization of phase-change memory cells of size of less than 10 nanometers has been reported. These time and length scales are almost within reach of first-principles methods based on density functional theory.
In this talk, I will present our ab initio molecular dynamics simulations of crystallization of two technologically important PCMs, namely Ag,In-doped Sb2Te [1] and Ge2Sb2Te5 [2]. I will first discuss the links between the fragility of the supercooled liquid phase of these materials and the ability of the glass to crystallize rapidly at high temperature and yet to be extremely stable at room temperature. I will then show that high-temperatures simulations yield crystal growth velocities in good agreement with experimental data. They indicate that fast crystal growth stems from the large diffusion constants and sticking coefficients and the presence of a sharp crystalline-liquid interface.
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