  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.
