报告题目：Electrical transport behavior of 2D semiconductor
2D layered transition metal dichalcogenides (TMDs) with the chemical formula MX2 (where M=group IVB-VIIB metal and X=chalcogen) have brought new possibility for the applications in ultralow-power electronics than the zero-bandgap graphene. However, their low carrier mobilities at ambient conditions have limited their practical applications. Therefore, many researchers are paying much attention on seeking and synthesizing new member of the 2D TMDs. In the same time, some researchers are trying to further explore the carrier transport mechanism enabling to design new electronics. Except metallic and insulate property, many 2D layered materials exhibit semiconducting behavior including n-type, p-type or ambipolar, which could be used to fabricate various electronics. Compared with unipolar (n-type or p-type) transistors, ambipolar transistors, which can easily switch between n-type and p-type behavior by applying an electric field, are most promising candidates since they can effectively simplify circuit design and save the layout area in CMOS. In this presentation, scanning probe technique including electric field microscopy, kelvin probe force microscopy and current atomic force microscopy, will be introduced to study the local electronic property of 2D layered semiconductor. The surface potential, aligned energy band in p-n junctions and local carrier transport property of CVD-grown PtSe2 will be talked. Furthermore, the dimensionality dependent ambipolar WSe2 will be introduced from locally field screening and tuned work function under external electric field.
相对于零带隙石墨烯而言，具有MX2（其中M = IVB-VIIB族金属和X =硫属元素）结构的二维层状过渡金属二硫化物（TMD）因具有可观的带隙而有望应用于超低功率电子器件。然而，TMD[美高梅官网]的载流子迁移率较低，这不利于它的实际应用。因此许多研究人员正在尝试寻找并合成新型的TMD[美高梅官网]。于此同时，探索并优化TMD电子器件的结构也受到越来越多的关注。除金属和绝缘特性外，大多数二维TMD[美高梅官网]具有半导体特性，包括n型，p型或双极性。与单极性（n型或p型）晶体管相比，通过施加电场可以在n型和p型行为之间轻松切换的双极晶体管是最有希望的候选者，因为它们可以有效地简化电路设计并节省CMOS中的布局区域。在本报告中，我将介绍扫描探针技术，包括电场显微镜，开尔文探针力显微镜和导电原子力显微镜在研究二维层状半导体局部电子特性中的应用。将讨论表面电位，p-n结中的对准能带和局部载流子传输特性。
Dr. Zegao Wang obtained his Ph.D. in Microelectronics and Solid-State Electronics from University of Electronic Science and Technology of China in 2014. Since 2014, he is a postdoctoral fellow in the Bio-SPM group, Aarhus University. He has published more than 70 papers, including first-authored Advanced Materials, ACS Nano, Nano Energy, et al. His current research interest focuses on two dimensional nanomaterials and their applications in electronic devices, biosensors and energy devices.