FWI Seminar: Epitaxial 2D materials beyond graphene

Date

Feb 23, 2023

Time

11:00 AM - 12:00 PM

Speaker

Prof. Dr. Carsten Busse, Universität Siegen

Language

en

Main Topic

Materialien

Host

Dr. Arkady Krasheninnikov

Description

Transition metal dichalcogenides (TMDCs) form a rich family of two-dimensional materials containing metals, semiconductors and insulators. Their tunable chemical composition with the general form MX2 (M: transition metal, X: S, Se, Te) makes them more versatile than monoelemental materials as graphene. Epitaxial growth on well-defined substrates is a method that can produce high-quality TMDC- monolayers, both for applications as well as for fundamental studies of their properties using surface science methods. We grow MoS2, WS2 and TaS2 using molecular beam epitaxy (MBE) under ultra-high-vacuum conditions on weakly interacting substrates Au(111) and graphene / Ir(111) and determine their geometric structure using scanning tunneling microscopy (STM) and the method of x-ray standing waves (XSW) as well as their electronic structure by scanning tunneling spectroscopy (STS) and angle- resolved photoemission spectroscopy (ARPES). For tantalum sulfide, we disover a novel Ta-rich phase when the growth takes place under sulfur-poor conditions. In a laterally stitched heterostructure of the semiconductors MoS2 and WS2, we can map the hybridization of the bands across the junction. We find type-II band alignment and a very narrow electronic transition region.

Last modified: Feb 23, 2023, 7:38:15 AM