Synthesis, characterization and engineering of two-dimensional transition metal dichalcogenides

In this talk, we first report the controlled vapor phase synthesis of molybdenum disulfide atomic layers and elucidate a fundamental mechanism for the nucleation, growth, and grain boundary formation in its crystalline monolayers. The atomic structure and morphology of the grains and their boundaries in the polycrystalline molybdenum disulfide atomic layers are examined. The electrical properties of the atomic layers are examined and the role of grain boundaries is evaluated. We next demonstrate how self-assembled monolayers with a variety of end termination chemistries can be utilized to tailor the physical properties of single-crystalline MoS2 atomic-layers. Our data suggests that combined interface-related effects of charge transfer, built-in molecular polarities, varied densities of defects, and remote interfacial phonons strongly modify the electrical properties of MoS2, illustrating an engineering approach for local and universal property modulations in two-dimensional atomic-layers.