Effect of HfO2 and Al2O3 on monolayer MoS2 electronic structure

Transition metal dichalcogenides (TMDs) are novel, and unlike graphene, gapped 2D materials with unique electrical and optical properties that are being explored for novel device applications. Their 2D nature also makes their properties sensitive to the surrounding environment. For example, a free standing monolayer of MoS₂ - which has an experimentally reported direct band gap of E_g ≈ 1.8 eV¹ - has a very low reported mobility (μ<;3 cm²/(V-s)),² but exhibits significant enhancement of its mobility (μ~200 cm²/(V-s)) when superposed with a high-k dielectric like HfO₂.³ Here, we study the effect of HfO₂ and Al₂O₃ on monolayer MoS₂ using density functional theory (DFT).