时间：2018年5月25日13:30-14：30
地点：教十一318会议室
报告题目：The phase transition in transition metal dichalcogenides on metallic substrates
报告人：张文静 教授
报告摘要: The emergence of two-dimensional transition metal dichalcogenides (2D-TMDs) and their unique polymorphic features such as the semiconducting 1H and quasi-metallic 1T' phases exhibits intriguing optical and electronic properties, which can be used in novel electronic and photonic device applications. With the favorable quasi-metallic nature of 1T’-phase of 2D-TMDs, the 1H to 1T’ phase engineering process has been exploited for novel device applications. Here, we report a high-yield 1H-1T’ phase transition of monolayer-MoS2on Cu and monolayer-WSe2 on Au after a simple annealing process. A comprehensive study involving Raman, photoluminescence and synchrotron-based photoemission spectroscopies, spectroscopic ellipsometry, and first-principles calculations is performed to elucidate the phase transition process and understand the underlying mechanisms. Moreover, a general trend for the high-yield phase transition process of 2D-TMDs on metallic substrates is derived. While each 2D-TMD possess different intrinsic 1H-1T’ energy barriers, the use of an metallic substrate with high chemical reactivity plays a more pivotal role in increasing the 1H-1T’ phase transition yield. As demonstrated by the first-principles study, this increased in yield is brought about through the enhancement of the interfacial hybridization by the means of increased interfacial binding energy, larger charge transfer, shorter interfacial spacing and weaker bond strength. This study provides new insights into the fundamental understanding of how phase transition dynamics of 2D-TMDs is mediated by interfacial hybridization, it further opens up the field of 2D-TMD on metallic substrate systems to further inquiry and research, thereby unlocking new possibilities for 2D-TMD-based device applications.
个人简介：张文静，2008年北京大学电子学系博士毕业，2008-2014年分别于新加坡南洋理工大学、台湾中央研究院、新加坡国立大学做博士后研究工作，2014年深圳大学教授。从2008年至今，一直致力于新型二维光电材料及器件的研究。在本领域取得了一系列的原创性成果，部分研究国际领先，在材料与光电子学期刊上共发表论文50篇。论文在Science、Nature、Nature Physics、Nature Photonics、Nature Nanotechnology、Physical Review Letters等国际著名学术刊物上被引用了5500多次，篇均引用次数120多次，单篇最高引用次数为1300次。代表性成果为： 1) 研发出二维半导体原子晶体的可控制备方法：三篇代表论文共被引用2200余次，该制备方法成为国际上制备二维半导体原子晶体的主要方法。2) 构建基于二硫化钼-石墨烯垂直异质结的新型光电子器件：一篇代表论文被引用次数300多次，被美国科学专家评论员在Nature News发表的前瞻性论文给予肯定。3) 建立并完善原子尺寸的金属-半导体接触模型，优化基于二维半导体原子晶体光电器件的性能：三篇代表论文目前被引用共400多次。4) 拓展了拉曼光谱在表征新型光电子器件中的应用范围：一篇代表论文以research highlight形式，被Nature Physics报道。
