High mobility field-effect transistors based on MoS 2 crystals grown by the flux method

Abstract Two-dimensional (2D) molybdenum disulphide (MoS 2 ) transition metal dichalcogenides (TMDs) have great potential for use in optical and electronic device applications; however, the performance of MoS 2 is limited by its crystal quality, which serves as a measure of the defects and grain boundaries in the grown material. Therefore, the high-quality growth of MoS 2 crystals continues to be a critical issue. In this context, we propose the formation of high-quality MoS 2 crystals via the flux method. The resulting electrical properties demonstrate the significant impact of crystal morphology on the performance of MoS 2 field-effect transistors. MoS 2 made with a relatively higher concentration of sulphur (a molar ratio of 2.2) and at a cooling rate of 2.5 °C h −1 yielded good quality and optimally sized crystals. The room-temperature and low-temperature (77 K) electrical transport properties of MoS 2 field-effect transistors (FETs) were studied in detail, with and without the use of a hexagonal boron nitride (h-BN) dielectric to address the mobility degradation issue due to scattering at the SiO 2 /2D material interface. A maximum field-effect mobility of 113 cm 2 V −1 s −1 was achieved at 77 K for the MoS 2 /h-BN FET following high-quality crystal formation by the flux method. Our results confirm the achievement of large-scale high-quality crystal growth with reduced defect density using the flux method and are key to achieving higher mobility in MoS 2 FET devices in parallel with commercially accessible MoS 2 crystals.