Influence of doping concentration on the photoluminescence of silicon nanocrystals

Photoluminescent silicon films have been fabricated starting from p-type silicon powders, by means of a purely wet-chemical process at different doping concentrations. Their light emission properties have been investigated by means of continuous wave and time-resolved photoluminescence measurements. In all the samples Auger saturation has been observed, showing that light emission from quantum confined Si nanocrystals occurs. The doping level influences the spectra, the decay times and the reactivity towards oxidizing environment. The same features are observed in samples obtained from simultaneously processing p- and n-type silicon powders. Hence, our results support the hypothesis that, during the chemical reaction, merging of p- and n-type silicon nanocrystals and subsequent doping neutralization occurs.