Synthesis of calcium monosilicide nanowires by a reactive deposition technique

CaSi nanowires were synthesized on a Si substrate by a reactive deposition technique. A large amount of Ca vapor reacted with the surface of the cleaned Si substrate, and CaSi nanowires were grown on the as-synthesized CaSi film. The diameter of the nanowires reached a minimum value of about 25 nm. The CaSi nanowires were self-oriented along the 001 direction. We can control the length of the nanowires, to a maximum of 4 mu m, by adjusting the experimental parameter settings, such as the amount of Ca source, duration and temperature. The mechanism of formation of Ca silicides on a Si substrate is discussed in detail. Raman spectroscopy confirmed the nanosized character of the CaSi phase. These results give us greater expectations for the application of CaSi, not only in hydrogen storage but also as a new inorganic semiconductor.