Effect of reactive ion etching on the yellow luminescence of GaN

Photoluminescence spectra of GaN grown by metalorganic chemical-vapor deposition on sapphire show that by reactive ion etching, the intensity of the yellow luminescence (YL) band decreases compared to that of the as-grown GaN, due to nonradiative recombination at the damage-induced defect centers. The intensity of the YL in dry-etched GaN has been found to be dependent on rf power and postetch annealing. No change in intensity is observed with further etching indicating a uniform spread of yellow emitters in the epilayer which supports the view that point defects like V-Ga are the origin of the YL. (C) 1999 American Institute of Physics. [S0003-6951(99)00949-3].