High Q light-emitting Si-rich Si_3N_4 microdisks

We report on the optical properties of active silicon (Si)-rich Si₃N₄ microdisk cavities in the visible range. We have studied the correlation between the quality (Q) factor of the cavities and the active material deposition parameters. Microphotoluminescence measurements revealed subangstrom whispering galley modes resonances and a maximum Q of 10⁴ around 760 nm. These values improve significantly the best results reported so far for Si-based light-emitting circular resonators in the visible range. In contrast to what is reported for Si-rich SiO₂-based microcavities, we demonstrate the absence of a spectral widening at high pump fluxes associated to carrier absorption mechanisms, which allows high emitted power without degrading the Q of the cavity. These results open the route toward the monolithic integration of those structures into more complex circuits including Si photodetectors.