Title: Two-Dimensional Materials: Interfaces, Edges, and Dopants
Speaker: Geert Brocks (CCER, Twente)
Time: Feb. 13, 2020, 10:00–11:00
Location: Differ, Alexander-zaal
In the wake of graphene, many different types of two-dimensional (2D) materials have been grown or isolated. Monolayers of transition metal di-chalcogenides (TMDCs) MX2, with M=Mo,W, X=S,Se,Te, are direct semiconductors with sizeable band gaps in the range of 1 to 2 eV. Applications in devices not only demand a control over the 2D material’s quality, but also call for carefully designed interfaces with the surroundings, such as metal contacts. I will explain a strategy for making zero-barrier contacts, based upon theoretical insight and DFT calculations, which has meanwhile been verified experimentally. Edges and grain boundaries of TMDC islands often display a one-dimensional (1D) metallic character, which is robust against reconstructions or stoichiometric variations of the edges, and can lead to catalytic activity. I will discuss the origin and type of such 1D metals, and show how to manipulate them. The catalytic activity of a 2D material can be enhanced by transition metal (TM) doping. Time permitting, I will show you how this is done in TM-doped GaN.