Site selective excitation of Er-implanted GaN

The photoluminescence (PL), and PL excitation studies of Er-implanted GaN reveal a variety of Er centers with different excitation mechanisms. The PL of the centers dominating under above band-gap illumination is mediated primarily by donor-acceptor pair recombination, and subject to temperature quenching. Evidence is found for significant energy migration among Er centers dominating under direct excitation into the 4f-shell, which leads to a stronger quenching. The PL intensity of centers excited by a broad, below-gap absorption band, associated with deep traps is temperature independent.