"Impurity Doping into Semiconductor Nanocrystals"

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The aims of this research project are, i) to establish the method of doping impurity atoms into semiconductor nanocrystals, ii) develop the analytical tools for verifying the doping and estimate the degree of doping, and iii) investigate the change in physical properties pf nanocrystals caused by doping, in particular, the optical properties.We could successfully dope B and P atoms into Si nanocrystals by applying the cosputtering technique. The success in doping could be verified by the appearance of Fano-type interference in Raman spectra. We could also successfully observe the change in the photoluminescence spectra caused by doping. The change in the photoluminescence spectra is believed to arise from the creation of excitons bound to the impurity states.Er and Yb ions could also be doped into SiO2 thin films containing Si nanocrystals. In the presence of Si nanocrystals, Er and Yb exhibited strong light emission, while the light emission was very weak, in the absence of Si nanocrystals. The strong light emission is caused by the energy transfer from Si nanocrystals to Er and Yb ions. The present results suggest the possibility of Si-based light emitting devices.