Photoluminescence of Eu3+ in Si/SiO2 Nanostructure Films

Abstract

ABSTRACTEu3+ -doped Si/SiO2 nanocomposites were successfully prepared by Ar sputtering deposition on quartz substrates. The optical properties were studied using time-resolved photoluminescence spectroscopy. Excited by intense picosecond laser pulses with energy greater than1GW/cm2 and wavelength at 532nm the observed photoluminescence consists of a rapidly decaying component with life time of ∼1 s and a slowly component with life time of ∼ 2 ms. The former was recognized as coming from Si/SiO2 nanostructures matrix while the latter as coming from the impurity Eu3+ ions. Using the intense laser excitation a two-photon absorption by silicon matrix occurred, resulting in photo-induced carriers produced in conduction band. A direct recombination from Si/SiO2 nanostructure host gives a weak but fast emission, and creates a large number of nonequilibrium phonon. For Eu3+ emission a set of 5D0 to 7F multiplet transitions were identified. In addition to the direct excitation by 532nm the excited state 5D0 of Eu3+ ions was also found to be populated due to energy transfer from silicon matrix. The mechanism of phonon-assisted energy transfer is discussed.