Time: 14:00 (Monday, June 21, 2021)
Venue: Meeting room on the third floor of the South Building
Online Tencent meeting, ID: 400 699 204; https://meeting.tencent.com/s/DJ6ABYmF3ANC
Host: Prof. Qing Dai
Speaker：Ricky L.K.Ang, Professor, Singapore University of Technology and Design
Title：Electron Emission from Two-Dimensional Materials and Applications
Abstract：Electron emission from a material through an interface to vacuum or another material is a fundamental process in cathode, diode, ionization, electric contact, interface physics and many other areas. Depending on the energy used for electron emission, it can be broadly characterized into 3 different processes known as thermionic emission TE (by thermal energy), field emission FE (by quantum tunneling) and photoemission PE (by absorption of photons or optical tunneling). Regardless of the emission mechanism, the emission current density may all become saturated, known as space charge limited emission (SCLE). The basic models for these processes (TE, PE, PE, SCLE) have been formulated many decades ago, known as the Richardson law, Child-Langmuir (CL) law, Fowler-Nordheim (FN) law, and the Keldysh model, etc. With the development of two-dimensional (2D) atomic scale materials in the 2000’s, the above-mentioned classical laws may require revisions to account for new material properties, as well as novel operating regimes in nanometer dimensions and in ultrashort time scales. In this talk, some recent and self-consistent emission models will be presented, with applications to 2D materials such as graphene and topological materials. These new models exhibit smooth transition to the classical models and also new scaling laws are obtained. The models have been used to compare with experimental results with better agreements. Some applications on using such new materials with its interaction of electrons and lights will be discussed.
Biography：Lay Kee (Ricky) Ang received his BS degree from National Tsing Hua University, Taiwan, in 1994, and his MS and PhD degrees from University of Michigan, in 1996 and 1999, respectively. He is currently the Head of the Science, Mathematics and Technology, Singapore University of Technology and Design (SUTD), and also the Ng Teng Fong chair Professor under the SUTD–ZJU (Zhejiang University) IDEA (Innovation, Design and Entrepreneurship Alliance). Before joining SUTD, he was with the Nanyang Technological University, Singapore (2002-2011), and with the Los Alamos National Laboratory (LANL) as a LANL director funded postdoctoral fellow (1999-2001). His research interests are in the formulation of basic scaling laws and theoretical models for the interaction of electrons and light with surrounding materials and structures in any user-inspired research topics related to applied physics and engineering. In applied mathematics and computational physics, he is currently applying fractional calculus to analyze complexity and disordered systems, and also AI-assisted design of complex meta-surfaces. His research has been funded by Singapore (MOE, ASTAR, SUTD) and USA (AFOSR and ONRG). He is a fellow UK IOP and an IEEE NPSS Distinguished Lecturer.
Speaker：Yee Sin ANG, Assistant Professor, Singapore University of Technology and Design
Title：Physics of Contact Heterostructures in 2D Semiconductor Devices
Abstract：Charge transport physics in the contact heterostructures to 2D semiconductor play a central role in designing of novel nanodevices. Despite much research attentions have been devoted to the study of contact heterostructures to 2D semiconductor devices in recent years, the physics of interface formation, charge injection and tunneling phenomena remains an open question thus far. In this talk, we will introduce our research efforts in generalized the charge injection theory into the quantum mechanical tunneling regime in 2D-material-based contact heterostructures. Our recent density functional theory (DFT) simulations of novel metal contacts to 2D semiconductors will also be introduced.
Biography：Yee Sin ANG is currently an Assistant Professor at the Science, Mathematics and Technology (SMT) at the Singapore University of Technology and Design (SUTD). He received his PhD degree in condensed matter physics from the University of Wollongong (Australia) in 2014. He is a Lindau Alumni to the 69th Lindau Nobel Laureate Meeting. His current research is focused on the device physics and modeling of electronic, optoeletronic, photonic and valleytronic devices using 2D and topological materials and heterostructures, particularly focusing on the design of novel high-performance and low-energy solid state devices for beyond-CMOS computing architecture.
You are all welcome!