Quasiparticle Band Gap Tunability in Mono- to Few Layer Molybdenum Disulfide

Quasi two-dimensional molybdenum disulfide (MoS 2 ) has emerged as an attractive candidate for next generation 2D semiconductor devices due to its substantial and tunable band gap 1,2 . Controlling the band gap of single layer MoS 2 has been the focus of significant research effort as it offers complimentary functionality to metallic or semi-metallic 2D materials. In this work, we investigate the effect of various tuning knobs, such as crystallographic orientation 3 and strain 4 , on the magnitude of the quasiparticle band gap of MoS 2 . We employ low temperature scanning tunneling microscopy and spectroscopy (STM/STS) to obtain quantitative measurements of the local electronic density of states on the atomic scale. Measurements were performed on mono- to few layer MoS 2 films grown by ambient pressure chemical vapor deposition (AP-CVD). Additionally, Green’s function based electronic structure calculations were carried out in order to shed light on the mechanisms at play responsible for changes in the band gap. \\ \\In Collaboration With: Yuan Zhang (2), Aleksei V. Putilov (2) , Cinzia Di Giorgio (2) , Boakai Wang (3) , Xiaoxing Xi (2) , Fabrizio Bobba (2,4) , Saw Hla (1) , Jouko Nieminen (3,5) , Arun Bansil (3) , Maria Iavarone (2). \\ \\1. Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, United States. 2. Physics Department, Temple University, Philadelphia, PA, United States. 3. Physics Department, Northeastern University, Boston, Massachusetts 02115, United States 4. Physics Department, Salerno University, Salerno, Italy. 5. Computational Physics Laboratory, Tampere University, Tampere 33014, Finland