Vapor Phase Synthesis and Doping in Two-Dimensional MoS 2 Monolayer

Silicon based semiconductor electronics has long-reached its threshold. As other III-V semiconductors take over the semiconductor industry, a new breed of two-dimensional nanomaterials has emerged which promise intriguing morphology dependent properties that can be tailored for specific applications. The potential of 2D nanomaterials is exemplified by graphene and its derivatives. However, the spectrum of 2D materials has now widened to overcome the limitations of graphene. Notably, it's intrinsic zero band-gap which is a concern for low-power applications. Transition metal dichalogenides (TMDCs), trichalcogenides, silicene, and Boron nitride (BN) are some of the emerging materials with similar layered 3D structure as graphite. The focus of this thesis is on monolayer Molybdenum disulfide (MoS2) from the TMDC family of compounds, which has been identified as a direct band-gap semiconductor with wide range of applications in planar and flexible field-effect transistors, photovoltaics, phototransistor and sensors.;Successful realization of monolayer as well as few layer MoS2 in electronic devices hinges upon two factors: reliable synthesis of wafer-scale high quality MoS2 films and effective doping techniques to enhance the intrinsic carrier concentration. In this study, experimental efforts have been made towards resolution of both factors. We have explored both top-down and bottom-up techniques to achieve monolayer and few layer MoS2 films. The as-synthesized MoS2 films have been extensively characterized with the help of Atomic Force Microscopy (AFM), Raman spectroscopy and Photoluminescence (PL) spectroscopy. A molecular doping technique has been adopted for doping 2D MoS2 to tune the intrinsic band gap. The effect of doping has been analyzed with PL and Electrostatic Force Microscopy (EFM) techniques which have been employed in previous studies for reliable doping measurements.