Electronic structure of quasi free 2 dimensional HfS_2 clusters

TL;DR

This paper introduces a novel method to grow and analyze quasi free 2D HfS_2 clusters, enabling detailed study of their electronic structure and size-dependent properties using angle-resolved photoemission and microscopy.

Contribution

It presents a new growth technique for weakly bound, oriented 2D transition metal dichalcogenide clusters, facilitating electronic structure investigations.

Findings

k_parallel-dispersion observed in clusters >100 nm

First correlation between cluster size and electronic structure

Demonstration of weakly bound, oriented 2D cluster growth

Abstract

Cluster research so far only dealt with either 3D free clusters or clusters on substrates with strong electronic coupling at the interface. Preparation of free and orientated 2D clusters is usually not possible because one of these conditions generally excludes the other. We demonstrate a new way to grow 2D clusters of transition metal dichalcogenides which are only weakly bound to the substrate, i.e. quasi free, but all show the same orientation thus allowing angle resolved photoemission experiments. In combination with scanning tunneling microscopy this provides for the first time the possibility to investigate the correlation between the size of quasi free 2D clusters and its associated electronic structure. For 2D HfS_2 clusters grown by van der Waals epitaxy we demonstrate that k_parallel-dispersion of electronic states already occurs for cluster diameters above ~100 nm.