Selective enhancement of 1540 nm Er³⁺ emission centers in Er-implanted GaN by Mg codoping

The ∼1540 nm ⁴I_13/2 to ⁴I_15/2 Er³⁺ photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Er-implanted Mg-doped GaN reveal a selective enhancement of one of the nine different Er³⁺ centers observed previously in PL and PLE studies of Er-implanted undoped GaN. These Er³⁺ PL spectra are excited selectively by pump wavelengths that correspond to broadband, below-gap absorption bands associated with different Er³⁺ centers. In the Er-implanted, Mg-doped GaN, both the 1540 nm PL spectrum characteristic of the so-called violet-pumped Er³⁺ center and the ∼2.8-3.4 eV (violet) PLE band that enables its selective excitation are significantly enhanced by Mg doping. In addition, the violet-pumped PL center dominates the above-gap-excited Er³⁺ PL spectrum of Er-implanted Mg-doped GaN, whereas it was nearly unobserveable under above-gap excitation in Er-implanted undoped GaN. These results confirm our hypothesis that appropriate codopants can increase the efficiency of trap-mediated above-gap excitation of Er³⁺ emission in Er-implanted GaN.