Electrical-driven Plasmon Source on Silicon based on Quantum Tunneling
An efficient silicon based light source presents an unreached goal in the field of photonics, due to Silicons indirect electronic band structure preventing direct carrier recombination and subsequent photon emission. Here we utilize inelastically tunneling electrons to demonstrate an electrically driven light emitting silicon based tunnel junction operating at room temperature. We show that such a junction is a source for plasmons driven by the electrical tunnel current. We find that the emission spectrum is not given by the quantum condition where the emission frequency would be proportional to the applied voltage, but the spectrum is determined by the spectral overlap between the energy dependent tunnel current and the modal dispersion of the plasmon. Experimentally we find the highest light outcoupling efficiency corresponding to the skin depth of the metallic contact of this metal insulator semiconductor junction. Distinct from LEDs, the temporal response of this tunnel source is not governed by nanosecond carrier lifetimes known to semiconductors, but rather by the tunnel event itself and Heisenbergs uncertainty principle.