On the origin of the ultraviolet photoluminescence in the Ce3+-doped epitaxial films of multicomponent (Lu,Gd)(3)(Ga,Al)(5)O-12 garnets
Abstract
The characteristics of a relatively weak ultraviolet photoluminescence of Ce3+-doped epitaxial films of the multicomponent Lu3-xGdxGayAl5-yO12 garnets (x: 0.14-3; y: 0-3.54) are investigated by the steady-state and time-resolved spectroscopy methods in the 77-300K temperature range. In the low-temperature steady-state emission spectrum, a complex emission band is observed with the maximum position depending on the sample and located in the 3.13-3.22eV energy range.
The excitation spectrum of this emission has the maxima around 3.95, 4.5, and 5.2eV. The broad emission bands with the decay times of 1.25 and 6.76ns, peaking at about 3.13 and 3.0eV, respectively, and, in some samples, also the slow (approximate to 1.39ms) narrow Tb3+-related 3.23eV emission band are found to contribute into the steady-state emission spectrum.
The fast ultraviolet emission is suggested to arise from two types of the antisite CeAl3+-related centers (the Ce3+ ions substituting for the Al3+ ions in the crystal lattice of (Lu,Gd)(3)(Ga,Al)(5)O-12).