Self-assembly of photoluminescent silicon films: Influence of doping on the physical properties

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 physica l properties depend on the material type. Samples fabricated by processing a mixture of p- and n-type powders exhibit different photoluminescent spect ra, have lower reactivity towards oxidating environments, and show the long est emission lifetimes. In order to explain those properties, we propose th at, as long as the reaction proceeds and consumes the silicon powders, nano structures containing both p- and n-type silicon form. Suppression of the A uger recombination in such structures can account for the experimental find ings. (C) 2001 American Institute of Physics.