Spectroscopic studies of Er-centers in MOCVD grown GaN layers highly doped with Er

We report on the high-resolution photoluminescence (PL) and electron spin resonance (ESR) studies of highly Er-doped (2 × 1020 to 2 × 1021 cm−3) MOCVD grown GaN epilayers. The high-resolution Fourier transform of the 4I13/2 → 4I15/2 PL of Er3+ near 1.5 μm, site-selective PL and PL excitation measurements show that in MOCVD grown GaN only one type of Er-centers exists. This conclusion has been confirmed by ESR measurements. In ESR the axial Er3+ spectrum was observed with g|| = 2.861 and g⊥ = 7.645 characteristic for substitutional Er ions at Ga sites (C3V symmetry). Angular dependence of the ESR did not point to the existence of other centers.