Gallium nitride has been reactive-ion etched with SF6 and argon plasmas. Th
e Ar-etched samples show a striking transition from a dominant blue lumines
cence band to a dominant yellow luminescence band after less than 5 min of
low power illumination. The observation of metastable defects which are ass
ociated with both the yellow and blue bands has important consequences for
our understanding of defect-related luminescence in gallium nitride. (C) 19
99 American Institute of Physics. [S0003-6951(99)00747-0].