Fabrication of Ultra-Clean Interfaces Between Atomically Thin Semiconductors and High k Dielectrics

Atomically thin semiconductors based on transition metal dischalcogenides (TMDs) such MoS₂ are now on the roadmaps of major semicondcutor manufacturers for ultra-scaled devices. To realise the potential of 2D TMDs for electronics, how quality high k dielectrics must be deposited on top of the semiconductors. However, this is not straightforward as 2D materials are chemically inert and nucleation and growth high k amorphous oxide dielectrics is challenging. Here, I will describe deposition of high k dielectrics - in particular ZrO₂ - on top of 2D MoS₂. Atomic resolution imaging of the interface shows that it is clean and free of defects. These observations are correlated with photoluminescence and x-ray photoelectron spectroscopy results that show minimal doping from the oxide. Field effect transistors with top gates show excellent device properties with small and positive threhold voltage for n-type devices. Our results suggest that is possible to achieve clean van der Waals interfaces between high k dielectric on top of 2D TMDs, which allows for realization of FETs operating in enhancement mode.