  Room-temperature 1535-nm-band photoluminescence in ~126 nm silica films (6
at. % doping), produced by spin-coating an Er2O3 and tetraethylorthosilicate
sol-gel formulation on silicon substrates, was studied as a function of vacuum
furnace annealing (500 to 1050 degrees C). Emission is strongly enhanced for
annealing near 850 degrees C, which is shown by modeling the temperature
dependence as arising from thermally-activated removal of hydroxyl ions.
Suitability of such a process for silicon-based applications is discussed.
