Epitaxial growth of hierarchical PbS nanowires

Growth of extensively aligned hierarchical lead sulfide (PbS) nanowires with hyperbranched morphology has been achieved by synthesizing nanowires epitaxially on single crystal NaCl, rutile TiO₂ (001), and muscovite mica in a chemical vapor deposition process. The morphology of as-grown PbS nanowires has been examined using scanning electron microscopy. Epitaxial match with the (100) plane of PbS has been observed on all substrates, and epitaxial match with PbS (111) was also observed on mica. In addition, the preferred orientation of nanowires led to particularly strong (200) reflections from PbS in powder X-ray diffraction. The potential epitaxial relationship and lattice match are proposed and discussed. PbS nanowires of the pine tree morphology can only be formed non-epitaxially in the presence of epitaxial hyperbranched clusters. The difficulty of forming epitaxial nanowire pine trees suggested that epitaxial growth might not be conducive to the creation of dislocations that drive the formation of pine tree nanowires. Electrical properties of PbS nanowires have also been investigated.