Synthesis of Tin nitride Sn xN y nanowires by chemical vapour deposition

Abstract

Tin nitride (Sn xN y) nanowires have been grown for the first time by chemical vapour deposition on n-type Si(111) and in particular by nitridation of Sn containing NH 4Cl at 450 °C under a steady flow of NH 3. The Sn xN y nanowires have an average diameter of 200 nm and lengths ≥5 μm and were grown on Si(111) coated with a few nm's of Au. Nitridation of Sn alone, under a flow of NH 3 is not effective and leads to the deposition of Sn droplets on the Au/Si(111) surface which impedes one-dimensional growth over a wide temperature range i.e. 300-800 °C. This was overcome by the addition of ammonium chloride (NH 4Cl) which undergoes sublimation at 338 °C thereby releasing NH 3 and HCl which act as dispersants thereby enhancing the vapour pressure of Sn and the one-dimensional growth of Sn xN y nanowires. In addition to the action of dispersion, Sn reacts with HCl giving SnCl 2 which in turn reacts with NH 3 leading to the formation of Sn xN y NWs. A first estimate of the band-gap of the Sn xN y nanowires grown on Si(111) was obtained from optical reflection measurements and found to be ≈2.6 eV. Finally, intricate assemblies of nanowires were also obtained at lower growth temperatures. © to the authors 2009.