“Surface/Phase/Interface Engineering for van der Waals Heterostructures”

Dr. Gwan-Hyoung Lee
Materials Science and Engineering, Seoul National University

Sep. 11 (Fri.), 04:00 PM
Online seminar

Abstract:
Van der Waals (vdW) materials and their heterostructures, weakly combined by vdW force, have attracted extensive interests because of their unique properties and large degree of freedom in the design of new materials. In the vdW materials, all properties can be dramatically changed by modifying the surface, interface, and phase (crystal structure).
In this talk, I will introduce how to modify the surface and interface of vdW heterostructures for practical device applications. We modify the surfaces of 2D materials by using plasma or highly active gas, leading to control of surface properties, such as hydrophilicity, conductivity, and band structure, which can be applied for fabrication of bio-template, low resistance contact, and passivation/dielectric layer. We also discovered abnormal thickness-dependent phase transition in MoTe2, which shows a great promise in engineering characteristics of 2D materials and unveil the mysterious phase stability of 2D materials. Further, by engineering band alignment of the stacked 2D materials and utilizing work function tunability of graphene, light emitting devices with exceptional multi-functions were fabricated. The electrically tunable light emitting transistors and tunnel devices can emit a strong light with modulation of charge (or trion) density. Our surface/phase/interface engineering techniques provide a deeper insight in understanding behavior and properties of 2D materials and abundant choices in manipulation of 2D materials for advanced optoelectronics.