Two-step growth of 4-inch multilayer MoS2 wafers

Molybdenum disulfide (MoS2) is an emerging two-dimensional (2D) semiconductor and has great potential for high-end applications beyond the traditional silicon-based electronics. Compared to the monolayers, multilayer MoS2 has improved electron mobility and current density, and therefore provides a more promising platform in terms of thin-film transistors, flexible electronic devices, etc. However, the synthesis of large-area, high-quality multilayer MoS2 films with controlled layer number remains a challenge. Here, we develop a two-step oxygen-assisted chemical vapor deposition (OA-CVD) methodology for the synthesis of 4-inch MoS2 films from monolayer to trilayer on sapphire substrates. The influence of critical growth parameters on the growth of multilayer MoS2 is systematically explored, such as the evaporation temperature of MoO3 and the flow rate of O2. Flexible field-effect transistor (FET) devices fabricated from bilayer/trilayer MoS2 show substantial improvements in mobility compared with flexible FETs based on monolayer films.