Résumé
Deep ultra-violet semiconductor lasers have numerous applications for optical storage, biochemistry or optical interconnects. UV-emitting ridge lasers usually embed nitride heterostructures grown on complex buffer layers or expensive substrates – an approach that cannot be extended to nano-photonics and microlasers. We demonstrate here the first deep ultra-violet microlaser operating at 275nm at room temperature under optical pumping. It is based on binary GaN/AlN thin quantum wells (QWs) grown on a silicon substrate and embedded in microdisk resonators. Those QWs indeed combine UV-C emission with a good emission efficency even at room temperature thanks to the huge band offset beetwen GaN and AlN. They form the active layer of state-of-the-art microdisk resonators, which electromagnetic modes, the so-called Whispering-Gallery Modes (WGMs), present a low modal volume and a high quality factor (Q=6000). This active layer can form free-standing membranes and is further compatible with future developments of nitride nanophotonic platforms on silicon.