Enhanced electronic property of wafer-scale monolayer MoS2 through S/Mo ratio optimization

Monolayer molybdenum disulfide (MoS2), an emergent two-dimensional (2D) semiconductor, represents the ultimate thickness for scaling down channel materials beyond silicon to overcome the limit of semiconductor technology nodes in the sub-1 nm range. However, despite extensive efforts in the growth of monolayer single-crystal MoS2, growth optimization for higher electronic property and reproducible fabrication for satisfying industrial stability still need to be reported. Here, we report an approach to synthesize wafer-scale monolayer single-crystal MoS2 with high carrier mobility and on/off ratio on sapphire by controlled release of S/Mo precursors ratio during the chemical vapor deposition process. We infer that the main cause of the mismatch in the stoichiometric S/Mo ratio is the oxygen doping. It is found that the MoSx film (x = 1.94) has rather high optimization, as confirmed by the relatively high electronic performances of related devices. Specifically, a fabricated field-effect transistor (FET) array based on the single-crystal monolayer MoS1.94 channels demonstrates significant enhancement in room-temperature mobility (up to 122 cm2 V−1 s−1) and an exceptional on/off ratio (over 1010). This work provides an efficient and reliable approach to produce single-crystal monolayer MoS2 for high-performance microelectronics in the future.