Three primary color luminescence from nanocrystalline silicon (nc-Si) prepared by hydrofluoric (HF) acid solution and subsequent oxidation treatments were studied using photoluminescence and Fourier transform infrared spectroscopy measurements. HF-treated nc-Si exhibited stable and strong red luminescence in the air. When the HF-treated nc-Si surface was oxidized by native and/or thermal treatment, the luminescence color varied continuously from red to blue. The reason is the enlargement of the effective band gap energy because of a reduced particle size caused by surface oxidation. The blue and green luminescence of thermally oxidized nc-Si could be distinctly seen in the air with the naked eye. These results suggest that the HF and post-thermal oxidation treatments can realize good stability and higher brightness in the air for three primary color luminescence from nc-Si. (c) 2006 American Vacuum Society.