Excitation of plasmonic nanoantennas with nonresonant and resonant   electron tunnelling
  A rigorous theory of photon emission accompanied inelastic tunnelling inside the gap of plasmonic nanoantennas has been developed. The disappointingly low efficiency of the electrical excitation of surface plasmon polaritons in these structures can be increased by orders of magnitude when a resonant tunnelling structure is incorporated inside the gap. Resonant tunnelling assisted surface plasmon emitter may become a key element in future electrically-driven nanoplasmonic circuits. 
Alexander V. Uskov, Jacob B. Khurgin, Igor E. Protsenko, Igor V.   Smetanin, Alexandre Bouhelier
physics.optics cond-mat.mes-hall