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

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. The electronic properties in two‐dimensional MoS2 in contact with gate oxide are susceptible to the interface properties. Ab‐initio calculations show that amorphous SiO2 and HfO2 form different interfaces with MoS2 in atomistic scale. The SiO2 strongly interacts with MoS2 by forming interface chemical bonds and severely affects the electronic band structure of MoS2. In contrast, the HfO2 shows weak interaction and maintains the properties of MoS2. The differences are explained by the short‐range order in amorphous oxide.