Porous silicon doped by erbium electrodeposition or from spin-on silica gel film followed by rapid thermal processing at 950 °C or higher exhibited liquid-nitrogen and room-temperature luminescence at 1.54 μm. The full width at half maximum was about 0.01 eV at 77 K. The mechanism of light emission from erbium-doped porous silicon is proposed. The direct bandgap of nanocrystallites in porous silicon is considered to provide an effective pumping media.

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.