Trap-mediated excitation of Er3+ photoluminescence in Er-implanted GaN

Site-selective photoluminescence (PL) spectra obtained at 6 K from the 1540 nm I-4(13/2)-->I-4(15/2) emissions characteristic of four distinct Er3+ centers in Er-implanted films of GaN are compared with the Er3+ FL excited by 325 nm above-gap pump light, Two of the site-selective 1540 nm Er3+ PL spectra pumped by below-gap, trap-mediated excitation bands dominate the Er3+ PL spectrum excited by above-gap light. A third broad band-excited spectrum and a fourth spectrum pumped by direct Er3+ 4f-band absorption are apparently not strongly excited by above-gap light. These results indicate that trap-mediated excitation dominates above-gap pumping of Er3+ emission in GaN:Er, and suggest an explanation for the reduced thermal quenching of Er3+ emission in GaN. (C) 1997 American Institute of Physics.