时 间： 2017 年 10 月 9 日 14 : 30 - 16 : 30
地 点： 南五楼 612 学术报告厅
报告人： 张 伟 教授，西安交通大学
邀请人： 徐 明 教授
报告摘要：
非易失性存储器是电子与信息领域重要的研究方向之一，而基于硫系化物（如锗锑碲等）的相变存储器PCM是实现非易失性存储器最为重要的载体之一，目前已经进入存储器市场。在本次报告中，我将从基础材料学方面揭示相变存储器的工作原理，在原子与电子层面讨论相变机制，揭示原子无序在其中起到的重要作用。将从电子显微学实验、电子输运实验以及第一性原理计算等方面揭示原子无序导致巨大电阻差异的根源、纳秒级别的相变机理、高阻态电阻弛豫的机制以及各种调控无序的方式，包括加热、压力、材料组分、离子束辐照、生长界面、生长方式等等。基于无序调控的材料学研究及设计将为器件设计与优化方面提供重要的理论支持。最后，我将总结相变材料领域依旧存在的难点以及未来发展的机遇。
Non-volatile memory is a very important research direction in the field of electronics and informatics. Phase change memory (PCM) based on chalcogenide phase change materials, such as GeSbTe, is one of the most promising candidates to serve as non-volatile memory in practice, and has entered the memory market recently. In this talk, I will discuss the working principle of PCM from the perspective of fundamental materials research, the switching mechanism from the atomic and electronic level, and will elucidate the essential role of atomic disorder in PCM. Through electron microscopy experiments, electrical transport measurements and first-principle simulations to reveal the origin of large electrical resistance difference between different logic states, the mechanism of nanoseconds crystallization kinetics, the mystery of resistance drift of the high resistance state, and various kinds of methods to manipulate disorder, including thermal annealing, pressure, material composition, ion irradiation, interface template, growth method, and so on. The understanding and design of materials properties based on the disorder control concept shall provide important support to the design and optimization of phase change devices. At last, I will review the remaining challenges and future opportunities of phase change materials.
报告人介绍：
张伟，西安交通大学材料科学与工程学院教授，国家“”青年学者，西安交通大学青年拔尖人才入选者。2004-2010年在浙江大学物理系获得学士与硕士学位，2011-2015年在德国亚琛工业大学物理系获得博士学位并从事博士后研究。留德期间获得德国博士学位最高荣誉Summa Cum Laude、亚琛工业大学授予的Borchers-Plakette奖章，并被德意志学术交流中心选为“留学德国”形象代言人。专注于相变数据存储材料的研究，在相变材料的结构特征、电子结构、动力学特性等方面取得重要进展。至今已在Nat Mater, Nat Commun, Adv Mater等国际知名学术期刊上发表论文27篇。
Dr. Wei Zhang is a full professor in the School of Materials Science and Engineering at Xi’an Jiaotong University, and is supported by the Youth Thousand Talents Program of China and the Young Talent Support Plan of Xi'an Jiaotong University. Dr. Zhang obtained his bachelor and master degree in Physics Department at Zhejiang University in 2008 and 2010. From 2011 to 2015, he worked in Physics Department at RWTH Aachen University, Germany, as doctoral and postdoctoral researcher. Dr. Zhang was awarded with the highest honor of German doctor degree “Summa Cum Laude”, was granted with a “Borchers-Plakette” badge by RWTH Aachen University, and was selected to be the celebrity of “Study in Germany” by German Academic Exchange Service (DAAD). Dr. Zhang focuses on the research of phase change materials for electronic memory technology, and has obtained important progress in understanding the structural, electronic and dynamical properties of phase change materials. So far Dr. Zhang has authored and coauthored 27 papers with some of them published on Nat Mater, Nat Commun, Adv Mater, etc.
