The photoluminescence and light absorption of Er-doped amorphous hydrogenated material were studied at temperatures ranging from 77 to 300K. In the linear pumping regime, the intensity of the Er-induced luminescence decreased by a factor of about 15 over the above temperature range. Frequency-resolved spectroscopy showed that, within the same temperature range, the lifetime of excited Er ions in the amorphous matrix decreased by a factor of only 2.5. Excitation spectroscopy proved that the primary step of excitation was absorption and free carrier generation in the amorphous matrix. The emission was effectively excited by sub-gap light within the range of the Urbach edge and even within the range of defect absorption. On the basis of the experimental results, a defect-related Auger excitation mechanism for Er luminescence was proposed. The probabilities of defect-related Auger excitation, and of the competing radiative defect recombination processes (D0 + e → D-), were calculated. It was shown that the probability of defect-related Auger excitation was greater by an order of magnitude. According to this model, a temperature quenching of the Er luminescence which was observed above 200K resulted from competition between defect-related Auger excitation and multi-phonon non-radiative recombination at the defects.

W.Fuhs, I.Ulber, G.Weiser, M.S.Bresler, O.B.Gusev, A.N.Kuznetsov, V.K.Kudoyarova, E.I.Terukov, I.N.Yassievich: Physical Review B, 1997, 56[15], 9545-51