The electronic properties of devices based on two-dimensional materials are significantly influenced by interactions with substrate and electrode materials. Here, we use photoemission electron microscopy to investigate the real- and momentum-space electronic structures of electrically contacted single-layer WS2 stacked on hBN, SiO2 and TiO2 substrates. Using work function and X-ray absorption imaging we single-out clean microscopic regions of each interface type and collect the valence band dispersion. We infer the alignments of the electronic band gaps and electron affinities from the measured valence band offsets of WS2 and the three substrate materials using a simple electron affinity rule and discuss the implications for vertical band structure engineering using mixed three- and two-dimensional materials.
@article{arxiv.1903.10400,
title = {Imaging microscopic electronic contrasts at the interface of single-layer WS$_2$ with oxide and boron nitride substrates},
author = {Søren Ulstrup and Roland J. Koch and Daniel Schwarz and Kathleen M. McCreary and Berend T. Jonker and Simranjeet Singh and Aaron Bostwick and Eli Rotenberg and Chris Jozwiak and Jyoti Katoch},
journal= {arXiv preprint arXiv:1903.10400},
year = {2020}
}