Model for Hydrothermal Growth of Rutile Wires and the Associated Development of Defect Structures

Crystal defects play a major role in determining the electrical properties of semiconductors. Hydrothermally grown TiO₂ rutile nanowire arrays are frequently used as electrodes in photovoltaic devices. However, they exhibit a characteristic defect structure that may compromise performance. A detailed scanning and transmission electron microscopy study of these defects reveals their internal structure and is suggestive at their origin. We propose an anisotropic layer-by-layer growth model, which combined with steric effects and Coulombic repulsion on high atom-density facets, can explain the observed V-shaped defect cascade in the nanowires.