Photoinduced absorption study of carrier dynamics in Ru-doped Bi_(12)SiO_(20) crystals after nanosecond laser pulse excitation

摘要

The charge carrier dynamics in the sillenite type crystal Bi_(12)SiO_(20) (BSO) doped with ruthenium is studied by monitoring the optical density changes after nanosecond laser pulse excitation using a frequency-doubled Nd:yttrium aluminum garnet laser. Ruthenium doping leads to a relatively high density of trap levels that significantly increase the relaxation time of excited charge carriers in comparison with a nondoped BSO. Relaxation dynamics with two different decay time constants is observed in BSO:Ru in the studied submicron to 100 s time range and their dependences on pump intensity and on temperature are investigated. From the observed temperature dependence of the slower and faster of the two decay components, thermal activation energies of E_(a,s) =0.80 ± 0.03 eV and E_(a,f)=0.68 ± 0.03 eV were determined, respectively. The results indicate that in BSO:Ru at least two different traps centers are involved in the long-lived photoinduced carrier dynamics.