Luminescence enhancement in inelastic tunnelling of electrons by changing the geometry of the tunnelling contact
We have experimentally investigated the light emission resulting from inelastic electron tunneling in the transition with hemispherical gold nanoantennas (d = 400 nm, h = 300 nm) created by direct fs-laser ablation. We found two characteristic modes of luminescence: standard - increased signal is observed in the region of nanoantennas at tunneling currents below 2.25 nA and inverted-anomalous, where the gold surface is mainly luminescent, while dark spots are observed on the antennas on the contrary. In the inverted-anomalous mode we observe record signal values of 5·104 photons per second. We attribute the anomalous effect to the realization of a conditionality for resonant tunneling of electrons with excitation of optical states.