Role of the Short-Range Order in Amorphous Oxide on MoS2/a-SiO2 and MoS2/a-HfO2 Interfaces

Abstract

The interface structures between MoS2 and amorphous oxides of SiO2 and HfO2 (MoS2/a-SiO2 and MoS2/a-HfO2) are investigated through ab-initio molecular dynamics simulations. The intrinsic short-range order (SRO) of the amorphous oxide, such as the bond length, coordination number, and connectivity of the oxide polyhedron, is crucial in the interfacial properties. The amorphous SiO2 showing the strict SRO induces a strong interaction with MoS2 and forms interfacial bonds of Si-S, resulting in a significantly increased effective mass of MoS2. By contrast, the amorphous HfO2 has more flexible SRO and weakly interacts with MoS2, which explains the maintenance of the band dispersion and effective mass of MoS2 in contact with amorphous HfO2. These calculation results indicate a possible mechanism of the higher mobility of MoS2/a-HfO2 over MoS2/a-SiO2 by accounting for the interfacial atomic structure.