Stable photoluminescence in low-temperature annealed porous silicon

The low-temperature annealing of porous silicon (PS) has been studied in am bient air and vacuum. After air-annealed samples were again stored in air f or a period of time, their luminescence exhibited improved stability in com parison to fresh samples. But their luminescence intensity is much weaker t han that of fresh samples, and their peak position moves to shorter wavelen gths. A stoichiometric oxide SiO2 can easily be formed on PS surfaces if th e annealing is performed in vacuum. The SiO2 layer prevents nc-Si from furt her oxidation and guarantees the luminescence intensity and that peak posit ion remains unchanged with air storage.