Grains, grain boundaries in single and few layer MoS₂

This study investigates the chemical vapour deposition (CVD) of molybdenum disulfide (MoS 2 ) on SiO 2 , examining the formation of various grains and grain boundaries (GBs) in single- to few-layer MoS 2 . The material, optical, and electronic properties of the resulting MoS 2 were evaluated through Raman and photoluminescence (PL) spectroscopy. Notably, both Raman and photoluminescence intensities were quenched at the GBs. Moreover, a consistent redshift in the photoluminescence peak positions at the grain boundaries indicating local strain or defect-induced modifications. Electrical characterization of lateral 2-terminal backgated devices on individual grains exhibited lower carrier mobility than those fabricated on continuous few-layers MoS 2 , with the highest measured mobility reaching 18.6 cm 2 V −1 s −1 . Additionally, the back-gated field effect transistors (FET) on individual grains and continuous fewlayered showed pronounced clockwise hysteresis in their transfer characteristics, revealing the distinctive contribution of MoS 2 surface and MoS 2 /SiO 2 interface defects and their associated traps-as primary sources of hysteresis.