Emergent Physics at the Metal / Layered Semiconductor Interface

In most cases, metals grown upon non-reactive surfaces will tend to ball up into nanoclusters to minimize surface free energy. However, for noble metals grown on layered dichalcogenide semiconductors, film gorwth follows a very different set of rules Despite weak bnding and a lattice mismatch exceeding 8%, noble metals form well-deinfeed and quantized nanostructures. The sizes of these feaatures are not only discrete, but correlated with the electronic structure of the given metal. The sturctural sizes, which correspons to integer multiples of a Fermi wavelength, induce energy gaps and reduce the overall electronic energy in these systems. Usually, such energy savings are trivial compared to other rowth parameters like strain, interfacial bonding, and surface free energy. In order to achieve such electornic growth modes, the normal energetics fo film growth must be minimal in these noble metal / layered semiconductor systems. We find that bonding is almost equally viable at multiple surface sites, leading to a drastic reduction of strain which enables quantum effects to actually control feature sizes. Despite the overall weak bonding, we find that there is significnat hybridization with the surface molecular layer, which leads to semi-metallic behavior in a sinlge layer of the substrate. While weak, this hybridization leads to novel interface propoerties, particularly for ferromagnetic films. These discoveries can lead to the development of better electrical contact formation with layered materials and also induce novel 2D states at the interface.