Abstract: As a two-dimensional transition-metal dichalcogenide (TMDC), few-layer molybdenum disulfide (MoS2) possesses excellent optical and electrical properties and thus shows a great prospect in the field of optoelectronic functional devices.In this work, mechanically exfoliated few-layer MoS2 flakes were treated by a novel soft hydrogen plasma followed by post annealing and the resultant variations in both optical and electrical properties were systematically investigated.It has been demonstrated that hydrogen atoms may penetrate into MoS2 lattices with the help of soft hydrogen plasma and consequently change pristine lattice structure as well as lattice vibration, leading to fluorescence quenching and at the same time making n-type few-layer MoS2 become intrinsic or p-type doping.Post annealing after soft hydrogen plasma treatment may induce the bonding of a very few MoS2 molecules with hydrogen atoms, giving rise to the bule shift of optical band gap.

Key words: As a two-dimensional transition-metal dichalcogenide (TMDC), few-layer molybdenum disulfide (MoS2) possesses excellent optical and electrical properties and thus shows a great prospect in the field of optoelectronic functional devices.In this work, mechanically exfoliated few-layer MoS2 flakes were treated by a novel soft hydrogen plasma followed by post annealing and the resultant variations in both optical and electrical properties were systematically investigated.It has been demonstrated that hydrogen atoms may penetrate into MoS2 lattices with the help of soft hydrogen plasma and consequently change pristine lattice structure as well as lattice vibration, leading to fluorescence quenching and at the same time making n-type few-layer MoS2 become intrinsic or p-type doping.Post annealing after soft hydrogen plasma treatment may induce the bonding of a very few MoS2 molecules with hydrogen atoms, giving rise to the bule shift of optical band gap.