Abstract
We report the synthesis of single-crystalline silicon nanowires on a SiO x film-covered Si substrate in supercritical benzene without using metal nanocrystals as catalysts. Prior to synthesis, a 9 nm thick reactive SiO x 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 SiO x 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 SiO x layer, and these clusters most likely serve as nuclei for silicon nanowire growth. We refer to the SiO x -assisted Si nanowire growth as a supercritical fluid-solid mechanism. © 2010 American Chemical Society.