Effect of hydrogen passivation on luminescence-center-mediated Er excitation in Si-rich SiO(2) with and without Si nanocrystals
Abbreviated Journal Title
Phys. Rev. B
ELECTRON-PARAMAGNETIC-RESONANCE; IMPLANTED SILICA GLASS; ENERGY-TRANSFER; OPTICAL-PROPERTIES; DOPED SIO2; POROUS SILICON; QUANTUM; DOTS; SURFACE PASSIVATION; SI-SIO2 INTERFACE; SPIN-RESONANCE; Physics, Condensed Matter
The influence of hydrogen passivation on luminescence-center-mediated excitation of Er(3+) in Er-doped Si-rich SiO(2) films with significantly different microstructures is studied. Photoluminescence measurements are presented for samples containing no detectable silicon nanocrystals (annealed at 600 degrees C) and for samples containing silicon nanocrystals (annealed at 1100 degrees C) as a function of hydrogen passivation temperature. Passivation is found to have little effect on the Er(3+) photoluminescence intensity at 1535 nm in the samples that do not contain nanocrystals. In contrast, a pronounced increase in the Er3+ photoluminescence intensity is observed in the samples containing Si nanocrystals, which is accompanied by a similar increase in the nanocrystal photoluminescence intensity and a gradual increase in the Si nanocrystal emission lifetime. This observation is attributed to two interrelated effects, namely, (a) an increase in the density of fully passivated optically active nanocrystals due to the passivation-induced removal of silicon dangling bonds and (b) a concurrent reduction in nonradiative Er(3+) relaxation from levels above the (4)I(13/2) level due to a direct interaction of excited Er(3+) ions with silicon dangling bonds. In addition, the observed counterintuitive gradual increase in the nanocrystal photoluminescence decay time upon passivation is successfully explained taking into account a passivation-induced change in the concentration of optically active nanocrystals with different sizes and the inhomogeneous nature of the nanocrystal-related emission band. It is shown that the combination of luminescence-center-mediated Er(3+) excitation and silicon-dangling-bond-induced Er(3+) de-excitation can explain at least 14 experimental observations reported by independent authors.
Physical Review B
"Effect of hydrogen passivation on luminescence-center-mediated Er excitation in Si-rich SiO(2) with and without Si nanocrystals" (2008). Faculty Bibliography 2000s. 933.