Trap-mediated, site-selective excitation of photoluminescence from multiple Er3+ sites in Er-implanted GaN

Site-selective photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been carried out at 6 K on the ~1540 nm ⁴I_13/2→⁴I_15/2 emissions of Er³⁺ in Er-implanted MOCVD GaN. The PLE spectroscopy has detected several independent, site-selective excitation mechanisms which demonstrate the existence of four different Er³⁺ sites in Er-implanted GaN. Each of these four Er³⁺ 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 Er³⁺ PL spectra pumped by trap-mediated excitation bands dominate the Er³⁺ PL spectrum excited by above-gap light. The PLE spectra demonstrate that the Er³⁺ 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 Er³⁺ PL spectra was studied to examine thermal quenching properties of these site-specific Er³⁺ PL centers