Enabling and suppressing quantum growth of Cu(111) nanostructures

Under certain conditions, the energy associated with quantum well states was found to play a critical role in determining the geometric structure of Cu(111) clusters grown on the surface of MoS₂ . This happens when depositions occur on a freshly prepared surface. The wave nature of electrons causes the total energy of the cluster to oscillate with thickness. Island stability increases as quantum states shift farther below the Fermi level, lowering the energy of the cluster. We believe the energy from the quantum states contributes significantly to the total energy due to the weak van der Waals forces at the Cu/MoS₂ interface, which reduces stress without the need for 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. Subsequent depositions cause the Cu clusters to grow in a linear fashion with no evidence of any quantum growth. We believe this is due to the existence of previously deposited clusters hindering additional Cu atoms from reaching their lowest quantum energy state.