Colloquium

December 9, 2019 - 3:30pm to 4:30pm
301 VAN

Professor Andrew Stollenwerk; Department of Physics; University of Northern Iowa

"Self-assembled nanostructures on MoS2 induced by quantum size effects"

Abstract: The energy associated with quantum well states was found to play a critical role in determining the geometric structure of Au(111) and Ag(111) islands grown on the surface of MoS2. Under this growth mode, the wave nature of electrons cause the total energy to oscillate with island dimensions. Island stability increases as quantum states shift farther from the Fermi level, lowering the energy of the island. The preferred dimensions observed in Au and Ag on MoS2 have relatively large periodicities and persist to higher temperatures than have been observed in previous systems exhibiting quantum growth modes. This is likely due to the weak van der Waals interface, which can induce epitaxial growth with minimal stress in the absence of a wetting layer or significant lattice matching. The abrupt van der Waals gap at the interface also gives rise to strong electronic confinement, ideal for the formation of quantum well states. These findings indicate the potential to explore electronic growth modes in a new class of systems based on metal - layered semiconductor interfaces.