Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 20: Nanostructures at Surfaces II

O 20.7: Talk

Monday, March 31, 2014, 17:30–17:45, WIL B321

Field effect and charging in layered 2D materials — •Thomas Brumme, Matteo Calandra, and Francesco Mauri — Institut de minéralogie et de physique des milieux condensés, Université Pierre & Marie Curie, Paris, France

In recent years, materials with reduced dimensionality such as graphene, dichalcogenides or chloronitrides have attracted a lot of attention because of their interesting physical properties. Particularly challenging is the possibility of doping these systems by using a field-effect transistor (FET). In an ion-liquid based FET configuration the charging of the nanolayers is substantial and thus allows for the investigation of the transition from a band insulator, to a metal and, eventually, to a superconductor [1]. Despite the extensive use of such FETs, many questions remain open. It is, e.g., unclear what changes are induced in the nanolayer by the large electric field. Furthermore the distribution of the induced charge is usually obtained from simple Thomas-Fermi models, that can be inappropriate. In this work [2], we develop a first-principles framework to describe nanolayers in FET configuration. We include the external electric field and the charging in the calculations of the geometric and electronic structure of different nanolayer systems. In the case of ZrNCl we show that the charge doping profile in the nanolayer is very different from what has been proposed in previous analysis based on simple screening models.
Nat Mater 9, 125 (2010). Science 338, 1193 (2012).
T. Brumme, M. Calandra, and F. Mauri, in preparation.