Directional and controllable edge-emitting ZnO ultraviolet random laser diodes

Abstract

Room-temperature ultraviolet random lasing action is demonstrated from a $p\text{-GaN}$ /annealed $i\text{-ZnO}:\text{Al}\left(3\mathrm{\%}\right)/n\text{-ZnO}:\text{Al}\left(5\mathrm{\%}\right)$ buried heterojunction diode with a $2\mu \text{m}$ rib waveguide. Excellent electrical-to-optical conversion efficiency is achieved by strong electrical and optical confinement of a buried heterojunction rib waveguide structure. Hence, emission intensity (threshold current) can be enhanced (reduced) by $\sim 9$ times $\left(\sim 40\mathrm{\%}\right)$ . Directional emission as well as controllability on the number of the random lasing modes can also be achieved.