Luminescence-center-mediated excitation as the dominant Er sensitization mechanism in Er-doped silicon-rich SiO(2) films
Abbreviated Journal Title
Phys. Rev. B
SI NANOCRYSTALS; ENERGY-TRANSFER; WAVE-GUIDE; MU-M; OPTICAL-PROPERTIES; ELECTRONIC STATES; POROUS SILICON; ERBIUM; PHOTOLUMINESCENCE; IONS; Physics, Condensed Matter
The structural and optical properties of erbium-doped silicon-rich silica samples containing 12 at. % of excess silicon and 0.63 at. % of erbium are studied as a function of annealing temperature in the range 600-1200 degrees C. Indirect excitation of Er(3+) ions is shown to be present for all annealing temperatures, including annealing temperatures well below 1000 degrees C for which no silicon nanocrystals are observed. Two distinct efficient (eta(tr)>60%) transfer mechanisms responsible for Er(3+) excitation are identified: a fast transfer process (tau(tr)< 80 ns) involving isolated luminescence centers (LCs), and a slow transfer process (tau(tr)similar to 4-100 mu s) involving excitation by quantum confined excitons inside Si nanocrystals. The LC-mediated excitation is shown to be the dominant excitation mechanism for all annealing temperatures. The presence of a LC-mediated excitation process is deduced from the observation of an annealing-temperature-independent Er(3+) excitation rate, a strong similarity between the LC and Er(3+) excitation spectra, as well as an excellent correspondence between the observed LC-related emission intensity and the derived Er(3+) excitation density for annealing temperatures in the range of 600-1000 degrees C. The proposed interpretation provides an alternative explanation for several observations existing in the literature.
Physical Review B
"Luminescence-center-mediated excitation as the dominant Er sensitization mechanism in Er-doped silicon-rich SiO(2) films" (2007). Faculty Bibliography 2000s. 7616.