Erbium luminescence in porous silicon doped from spin-on films

Erbium photoluminescence at room temperature and at 77 K has been observed from porous silicon doped with erbium from a spin-on silica gel film. Erbium incorporation into silicon dioxide at the surface of porous silicon and rapid thermal processing at temperatures higher than 1223 K were found to be a necessary prerequisite for erbium-related luminescence in porous silicon. No erbium diffusion into monocrystalline silicon from the spin-on films was observed. The depth-dependent erbium concentration in the bulk of porous silicon was determined by secondary-neutral- and secondary-ion-mass spectrometry depth profiling. The laterally resolved erbium distribution in the porous silicon was derived from energy-dispersive x-ray analysis. Possible mechanisms of erbium-related luminescence in porous silicon are discussed.