High yield–low temperature growth of indium sulphide nanowires via chemical vapor deposition

Indium sulphide nanowires (NWs) have been grown on Si via the reaction of In and InCl3 with H2S using chemical vapor deposition at temperatures as low as 250 °C. We find that the growth of InxSy NWs via the direct reaction of In with H2S is hindered by the formation of InxSy around the source of In which limits its vapor pressure. Thus a low yield of InxSy NWs with diameters of ≈100 nm, lengths up to ≈5 μm and hexagonal crystals measuring ≈500 nm across, were obtained between 500 and 600 °C, but their growth was not uniform or reproducible. These exhibited weak, but nevertheless clear peaks, in the X-ray diffraction (XRD) spectrum corresponding to tetragonal β-In2S3 and orthorhombic InS. No NWs were obtained for TG≤500 °C while for TG>600 °C we obtained a polycrystalline layer with oriented grains of triangular shape. In contrast, a high yield of InS NWs with diameters ≤200 nm and lengths up to ≈2 μm were obtained at temperatures as low as 250 °C via the reaction of In and InCl3 with H2S. The sublimation of InCl3 enhances the vapor pressure of In and the growth of InS NWs, which organize themselves in urchin like structures at 300 °C, exhibiting very intense peaks in the XRD spectrum, corresponding mainly to orthorhombic InS. Optical transmission measurements through the InS NWs gave a band-gap of 2.4 eV.