Sensitization of erbium through silicon nanocrystals in silicon rich oxide

The process of erbium sensitization through silicon nanocrystals (Si-nc) in silicon rich oxide host is analyzed through a model involving five levels of Er energy states. Energy transfer processes from Si-nc to Er, and mechanisms involving deteriorating effects in Er sensitization are studied. It is proposed that Er atoms are excited through quasi-direct processes involving excitonic recombinations in Si-nc. An effective range of 1.3 nm is estimated for erbium sensitization through Si-nc. Effects of multiple excitation of Si-nc during an erbium lifecycle is analyzed. It is shown that, the fraction of Si-nc that is repeatedly excited at every alternate cycle of excitation increases from small fractions to percentage levels for incident flux levels above 10(18)/cm(2)-s. For typical values of Er and Si-nc incorporation, saturating effects in Er luminescence is found to start at flux levels much lower than that for Si-nc excitation. Occurrence of multiple excitation of Si-nc is correlated with the deteriorating effects in Er sensitization at higher flux incidence. Simulated results with our model are in good agreement with reported data of Er luminescence through Si-nc sensitization.