Size dependent photoluminescence from Si nanoclusters produced by laser ablation

We report a photoluminescence study of silicon nanoclusters deposited by la ser ablation. This technique allows to obtain clusters with a reduced size dispersion. Taking advantage of that as well as of the possibility to tune selectively the cluster size relatively to the preparation parameters, we a re able to make a fine correlation between the emission band and the corres ponding emitting size. The photoluminescence band can be tuned in a wide sp ectral region spreading from the near ultraviolet to the near infrared depe nding on preparation conditions. The correlation with atomic force microsco py measurements provides a size dependence of the luminescence which is ful ly consistent with the quantum confinement interpretation. To our knowledge , we present here the first observation of a wide spectral range tuning of the emission bands of nanocrystalline silicon by using a dry technique comp atible with clean vacuum processing. (C) 1999 Elsevier Science B.V. All rig hts reserved.