Silicon nanoparticles were fabricated in both silicon oxide and nitride matrices by using plasmaenhanced chemical vapor deposition, for which a low substrate t emperature belowo 50℃ has been found most favorable. High-density (up to 4.0 ×1012cm-2, from TEM micrograph) amorphous silicon nanoparticles with an averaged size down to 3　nm have been obtained. Strong roomtemperature photoluminescence was observed in the whole visible light range from the deposits that were postannealed at 500 ℃ for two minutes. Careful comparison shows that the Si-SiNx　films provoke a significantly more effective photoluminescence than Si-SiOx films f abricated with similar processing parameters, especially in the green and blue light range. Theis low- temperature procedure for fabricationg light-emitting silicon structures opens up the possibility of manufacturing silicon-based tunable high-efficiency light-e mitting devices.