Graphene and related two-dimensional (2-D) materials have recently emerged as a topical area in which atomic layer control is possible. However, their successful integration into useful applications is heavily reliant on a complete understanding of their physical properties, together with their response when subject to different environments. For graphene-based devices that are processed and operated in ambient, the environmental humidity has an unpredictable influence on the device performance and reliability. In this talk, I will first review our recent scanning Kelvin probe microscopy studies highlighting the impact of relative humidity variation on the electronic properties of graphene and the relevance to chemical sensors applications.
I will then discuss the role of graphene in tuning the electronic and optical properties of other 2-D materials when integrated in vertical heterostructures, giving rise to novel excitonic effects. In particular, I will show that the thickness of the supporting graphene substrate is crucial in modulating the light emission in WS2 on graphene heterostructures, as supported by scanning Kelvin probe microscopy, which proved to be extremely valuable in unravelling the underlying nature of excitonic effects associated with such heterostructures.