Growth Mechanism and Photoluminescence Properties of In2O3 Nanotowers

To elucidate the growth mechanism of In 2 O 3 nanotowers synthesized via a Au-catalyzed vapor transport process, the structural evolution of In 2 O 3 nanotowers was carefully examined during the synthesis process. It was found that Au catalysts only play a role at the initial stage, where they facilitate the formation of In 2 O 3 nanoparticles and nanorods. After the Au atoms are consumed by the formation of Au−In compound(s), the liquid In droplets will form on the tips of In 2 O 3 nanoparticles or nanorods, and the self-catalytic vapor−liquid−solid (VLS) growth mechanism will dominate the subsequent one-dimensional (1D) growth of In 2 O 3 nanopillars. Since the supply of In 2 O may not be sufficient for the continuous 1D growth, the lateral growth of In 2 O 3 nanopillars governed by the vapor−solid (VS) mechanism will occur. The periodical axial and continuous lateral growth leads to the formation of In 2 O 3 nanotowers with a truncated octahedron structure of 4-fold symmetry {111} accumulated planes along the [100] direction. The photoluminescence (PL) spectrum of In 2 O 3 nanotowers exhibited an intense green-yellow luminescence at the wavelength of 580 nm, which can be ascribed to the possible recombination of electrons on singly ionized oxygen vacancies and holes on the valence band or doubly ionized oxygen vacancies.