Temperature independent Er3+ photoluminescence lifetime in a-Si:H<Er> and a-SiOx:H<Er>

The photoluminescence (PL) lifetime of Er3+ in a-Si:H<Er> and a-SiOx:H<Er> was measured between 15 and 300 K in a set of samples containing ∼1 at.% Er and up to ∼10 at.% O. The room temperature PL intensity increased and the temperature quenching decreased with O content. The maximum PL intensity at 15 K, however, is obtained from samples with no intentional oxygen added. The PL lifetimes were obtained using the quadrature frequency resolved spectroscopy (QFRS) technique. The QFRS signal was well fitted supposing two lifetimes, the fast decay in the 20–150 μs range and the slow decay in the 200–830 μs range, consistently increasing with the O content of the samples. For all samples both the fast and the slow lifetimes did not depend on the temperature within experimental incertitude. Our results are interpreted supposing two different lattice sites for Er3+ in the hosts. Moreover, the de-excitation of the Er3+ ions by multiple phonon emission is negligible in this class of materials.