Synthesis and properties of Si and Ge nanoclusters produced by pulsed laser ablation

We show that conventional pulsed laser ablation (PLA) of Si and Ge targets in inert buffer gases is an efficient method of nanocluster synthesis. From a photoluminescence study of Si and Ge nanoclusters produced by PLA we hav e demonstrated the possibility of tuning the luminescence band from the nea r infrared to the near ultraviolet regions. The stabilization of the proper ties of Si nanoclusters by reactive (Hz gas) PLA synthesis was proved by ph otoluminescence measurements. Finally, we report a photoluminescence study of gas-suspended Ge nanoclusters during their preparation. They exhibit a b road luminescence spectrum extended from UV to the blue-green region and mo dulated by a molecule-like structure. We propose an interpretation of the v ibronic structure involving Ge-O-Ge vibrations at the surface of photo-exci ted clusters. To the best of our knowledge, we report here the first observ ation of vibrational effects from gas-suspended Ge nanoclusters.