Optical absorption and oxygen passivation of surface states in III-nitride photonic devices

III-nitride surface states are expected to impact high surface-to-volume ratio devices, such as nanoand micro-wire light-emitting diodes, transistors, and photonic integrated circuits. In this work, reversible photoinduced oxygen desorption from III-nitride microdisk resonator surfaces is shown to increase optical attenuation of whispering gallery modes by 100 cm(-1) at lambda-450 nm. Comparison of photoinduced oxygen desorption in unintentionally and n(+)-doped microdisks suggests that the spectral changes originate from the unpinning of the surface Fermi level, likely taking place at etched nonpolar III-nitride sidewalls. An oxygen-rich surface prepared by thermal annealing results in a broadband Q improvement to state-of-the-art values exceeding 1 x 10(4) at 2.6 eV. Such findings emphasize the importance of optically active surface states and their passivation for future nanoscale III-nitride optoelectronic and photonic devices. (C) 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.