Magic Size Effects in the Au/MoS2 Systen

Magic size effects have been seen in a variety of metal/semiconductor thin film systems grown at low temperatures for stability. These electronic growth modes reflect the bulk Fermi wavelength of the metal and result in quantum size effects measuring two or three atomic layers. We have discovered the Au/MoS2 system exhibits quantum size effects that are much more pronounced, measuring several nanometers. Further, these systems can be created at or above room temperature. These results appear to be due to the unique properties arising from the growth of Au on a van der Waals semiconductor. The Au/MoS2 interface provides a weak bonding which is sufficient for epitaxial growth but still allows for sufficient freedom of movement for discrete cluster formation exhibiting a full range of quantum size effects. Interestingly, the integer heights correspond to the necks of the smaller necks of the Au Fermi surface rather than the bulk as is typically seen in these systems. In addition to providing a new set of systems for study of electronic growth modes, these results could impact the development of electronic contacts on MoS2 or other van der Waal surfaces.