Effects of concentration and thermal annealing on the optical activation of Er implanted into GaN layers

The wide band gap semiconductor, GaN, has emerged as an important host for rare earth-electroluminescence. The annealing behaviour and lattice site location of Er implanted into GaN were studied with the Rutherford Backscattering Spectrometry (RBS)/channelling and photoluminescence (PL) techniques. Also Er site dependence on the annealing temperature and implantation dose has been studied in detail. The optical properties of the Er-doped GaN system, evidencing their dependence on the parameters adopted during the synthesis procedure (Er implantation dose, annealing temperature) have been discussed. RBS/channelling measurements suggested that mostly Er occupy substitutional site and depends on the Er concentration. The main result is the activation of a typical Er giving rise to PL emission in the 1450-1650nm range, related to radiative 4I 13/2→ 4I 15/2 transitions. Depending on the Er dose, we observe a specific behaviour linked to variation of the annealing temperature that strongly determines PL emission band. We observed a PL spectral shape with the main peak located at 1542nm and shoulder peak at 1558nm (and full width at half maximum (FWHM) of 33nm) with a series of weaker PL structures at 1519, 1572 and 1591nm, due to the Stark sub-level splitting. © 2012 Copyright Taylor and Francis Group, LLC