Dynamics of Si plume produced by laser ablation in ambient inert gas and formation of Si nanoclusters

We have performed 1. time-resolved soft X-ray absorption measurements on a time scale up to 15 ms after pulsed-laser ablation of silicon Si. in an ambient Ar gas with a transient pressure of about 10 Torr and 2. investigation of the correlation between 1.6-eV photoluminescence PL. from Si nanocluster-based films and the surface oxidation. No soft X-ray absorption lines corresponding to Si clusters were observed, indicating that it is likely that after 15 ms, significant clustering takes place and then Si nanoclusters can grow. From experiments involving hydrogen termination and hydrogen atom treatment in addition to natural oxidation, it is found that the 1.6-eV PL originates from the interface of a Si nanocluster core and a surface oxide layer and occurs without hydrogen atoms. q1998 Elsevier Science B.V.