Electrically Pumped Whispering Gallery Mode Lasing from Au/ZnO Microwire Schottky Junction

Au/ZnO microwire Schottky diodes are fabricated. The devices exhibit typical Schottky diode I-V behavior with a turn-on voltage of about 0.72 V. The hexagonal ZnO microwires act as whispering gallery mode (WGM) lasing microcavities. Under forward bias, a three-microwire device exhibits WGM ultraviolet lasing spectra with a quality factor of about 1287. Output power of the laser has been measured at various injection currents, indicating threshold behavior with a threshold current of about 59 mA. Due to limited hole injection in the operation of Schottky diode, the lasing is a result of an excitonic recombination within the WGM cavity.