Strong and stable photoluminescence from sputtered silicon nanoparticles

Silicon nanoparticles have been prepared by means of direct de sputtering o f the silicon material onto the liquid nitrogen-cooled surface of the stain less-steel trap. By periodically harvesting the deposits followed by ultras onic agitation in 2-propanol it was possible to produce nanometre-size sili con crystals of less than 10 nm in diameter, and in which the silicon parti cle surfaces were barely oxidized. XPS measurements of the samples so prepa red revealed that the oxidization states of their surface layers were chang ed in different significant ways when the as-prepared sample was annealed i n air or in a vacuum. However, all these chemical changes have very little effect on the photoluminescence level of the samples. Its intensity remains strong and stable in the region of 300-550 nm, both before and after annea ling either in the atmosphere or in an ultra-high vacuum at up to 500 degre es C and for up to 6 h. Moreover, the photoluminescence intensity stays con stant even after the samples were aged in the atmosphere at room temperatur e (300 K) for 22 days. The photoluminescence stability of our silicon nanop articles, regardless of changes in their surface chemical structure, enhanc es their conduciveness for commercial applications.