Thin photoluminescent silicon films are fabricated by means of a purely wet-chemical process using, as a starting material, a fine powder obtained by ball milling p- and n-type silicon wafers. The reaction is characterized by a coalescence phenomenon and produces photoluminescent films whose physical properties depend on the material type. Samples fabricated by processing a mixture of p- and n-type powders exhibit different photoluminescent spectra, have lower reactivity towards oxidating environments, and show the longest emission lifetimes. In order to explain those properties, we propose that, as long as the reaction proceeds and consumes the silicon powders, nanostructures containing both p- and n-type silicon form. Suppression of the Auger recombination in such structures can account for the experimental findings. © 2001 American Institute of Physics.

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