Single-molecule light emission at room temperature on a wide-band-gap semiconductor

Abstract

Room-temperature light emission from single chemisorbed perylene based molecules adsorbed on silicon carbide (SiC) is probed by scanning tunnelingmicroscopy (STM).Anewapproach to STM-induced luminescence of a single molecule is explored using a wide-band-gap semiconductor to decouple electronically the molecule from the surface. After molecular adsorption, the lowest unoccupied molecular orbital and the highest occupied molecular orbital (HOMO) both lie within the bulk band gap and below the Fermi level of the substrate. The maximum photon energy of the light emission from the molecule shows a fixed shift of 1.5 eV relative to the maximum energy of the tunnel electrons. This is consistent with the photons being generated by inelastic electron tunneling between the HOMO and the unoccupied electronic states of the STM tip.