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Supercritical Fluid−Solid Growth of Single-Crystalline Silicon Nanowires: An Example of Metal-Free Growth in an Organic Solvent

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journal contribution
posted on 03.11.2010, 00:00 by Fang-Wei Yuan, Hsing-Yu Tuan
We report the synthesis of single-crystalline silicon nanowires on a SiOx film-covered Si substrate in supercritical benzene without using metal nanocrystals as catalysts. Prior to synthesis, a 9 nm thick reactive SiOx film on a silicon wafer was generated by etching a Si substrate with boiling ultrapure water, followed by annealing at 1100 °C for 30 min in Ar ambient. Si nanowires were synthesized on the 9 nm SiOx film-covered silicon substrate at temperatures ranging from 430 to 500 °C at 1500 psi; conditions were in supercritical fluid. A large amount of Si clusters with sizes ranging from 2 to 3 nm formed in the reactive SiOx layer, and these clusters most likely serve as nuclei for silicon nanowire growth. We refer to the SiOx-assisted Si nanowire growth as a supercritical fluid−solid mechanism.