Upcoming Event: Oden Institute Seminar

Defects and Interfaces in Low-Dimensional Materials for Resistive Switching

Wennie Wang, Chemical Engineering, UT Austin

Abstract

Two-dimensional materials have recently been shown to demonstrate non-volatile resistive switching, offering significant advantages such as high-density integration and low energy consumption due to their atomic-scale thinness. Previous experimental work indicates that vertical heterojunctions based on transition metal dichalcogenides (TMDs) sandwiches between metal electrodes exhibit resistive switching and I-V hysteresis. Using first-principles calculations, we develop material-based relationships for resistive switching mechanisms based on the formation and dissolution defects and study the interfacial interactions that give rise to memory effects. 
Our results reveal that defect adsorption energies of transition metals exhibit consistent trends across different TMDs (MoS2, MoSe2, WS2, WSe2), and can be explained using descriptors of the atomic and electronic structure. We next study the effect of an applied electric field on the structural and electronic behavior of MoS2/Au(111)-based heterostructures. The applied electric field modulates the interfacial dipole moments, which can explain characteristics of different regions of the hysteresis loop. We also discuss the effects of structural asymmetry of the heterostructure and of the role of point defects on the interfacial characteristics of the system such as coercive voltage, remnant polarization and dissipation ratio.

Biography

Wennie Wang is a computational materials scientist and current assistant professor in the McKetta Department of Chemical Engineering at the University of Texas at Austin. She earned her B.S. degree in Materials Science and Engineering from MIT in 2013, followed by her Ph.D. in Materials at UC, Santa Barbara in 2018 and a postdoctoral appointment at the University of Chicago. Her research focuses on first-principles methods for optical and electronic properties of semiconductors, with an emphasis on defects in transition metal compounds.