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Improvement of Laser Processing for Colloidal Silicon Nanocrystal Formation in a Reactive Solvent

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journal contribution
posted on 01.04.2017, 00:00 by Ze Yuan, Toshihiro Nakamura, Sadao Adachi, Kiyoto Matsuishi
We report the highly improvement of colloidal Si nanocrystal (Si-nc) formation by pulsed-UV-laser irradiation of porous silicon in a HF-contained organic solvent. The Si-nc in such reactive organic solvent exhibits higher photoluminescence quantum yield (∼50–70%) than that in an ordinary organic solvent without HF (∼20%). This enhancement of the quantum yield is caused by HF-induced removal of the surface oxidation layer and subsequent hydrogen termination of the Si surface. These reaction kinetics promote an efficient hydrosilylation between the hydrogen-terminated surface and an organic solvent, resulting in oxygen-free surface terminated by alkyl groups. Furthermore, the preparation yield in the HF-contained solvent is higher and the size distribution of Si-nc becomes more homogeneous than those in the ordinary solvent. These results can be attributed to efficient pulsed-laser-induced fragmentation by the removal of the oxidation layer on the porous Si target surface.