Trap-mediated, site-selective excitation of photoluminescence from multiple Er/sup 3+/ sites in Er-implanted GaN

Site-selective photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been carried out at 6 K on the /spl sim/1540 nm /sup 4/I/sub 13/2//spl rarr//sup 4/I/sub 15/2/ emissions of Er/sup 3+/ in Er-implanted MOCVD GaN. The PLE spectroscopy has detected several independent, site-selective excitation mechanisms which demonstrate the existence of four different Er/sup 3+/ sites in Er-implanted GaN. Each of these four Er/sup 3+/ sites exhibits a distinctive PL spectrum characteristic of that center's environment when pumped by the appropriate wavelengths of below-gap light. Two of the site-selective Er/sup 3+/ PL spectra pumped by trap-mediated excitation bands dominate the Er/sup 3+/ PL spectrum excited by above-gap light. The PLE spectra demonstrate that the Er/sup 3+/ PL spectra are excited by below gap absorption attributable to both implantation damage-induced defects and defects and impurities characteristic of the as-grown GaN. The temperature dependence of the Er/sup 3+/ PL spectra was studied to examine thermal quenching properties of these site-specific Er/sup 3+/ PL centers.