学术报告（5月23日）

主持人：佘峻聪  教授

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 摘要：

 As the feature size of integrated circuit technology (IC) continues downward scaling, it is imperative to introduce new materials in ICs to enable the continuous downward scaling. The unique physical properties of two-dimensional (2D) layered materials make them a promising candidate for future nanoelectronics applications. Atomic-level-thick semiconducting Transition Metal Dichalcogenides (TMDs) have been shown with effective electrostatic control and high-resistance to short-channel effect. We develop a CVD method to controllably grow monolayer MoS2 from triangular islands to continuous thin films. Large crystalline grain (>200 µm) and high surface coverage can be obtained simultaneously by optimizing the growth. We also investigated the growth dynamics of MoS2 using in-situ transmission electron microscopy. A record small equivalent oxide thickness of ~1.1 nm has been obtained by using ultra high-k Pb(Zr0.52Ti0.48)O3 gate dielectric for a MoS2 transistor. The low threshold voltage (< 0.5 V) is comparable to that of the liquid/gel gated MoS2 transistor. The small subthreshold swing of 85.9 mV/dec, high on/off ratio of ~ 108 and negligible hysteresis ensure a high performance MoS2 transistor operated at 1V. We also present carrier type control in WSe2 field-effect transistors via thickness engineering and solid-state oxide doping, which are compatible with state-of-the-art integrated circuit (IC) processing. A new type of group-10 TMD (PtS2) is also investigated for future field-effect transistor applications.

 报告人简介：

Dr. Yang Chai received his PhD degree from the Hong Kong University of Science and Technology in 2009. After he conducted his Postdoctoral studies at Stanford University and University of Illinois at Urbana & Champaign, he joined the Department of Applied Physics in the Hong Kong Polytechnic University in 2012 as an Assistant Professor. He received Early Career Award from the Research Grant Council of Hong Kong in 2014. He is an IEEE senior member and an IEEE distinguished lecturer in Electron Device Society. His current research interest includes low-dimensional material and electron devices and flexible electronics.