Synthesis of Tin Nitride Sn(x)N(y)Nanowires by Chemical Vapour Deposition

Tin nitride (Sn(x)N(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(4)Cl at 450 °C under a steady flow of NH(3). The Sn(x)N(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(4)Cl) 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(x)N(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(x)N(y)NWs. A first estimate of the band-gap of the Sn(x)N(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.