Well-aligned GaN nanorods were synthesized on Si substrates to form heterojunctions with potential applications in photovoltaic (PV) cells. Transmission electron microscopy images, selected area electron diffraction pattern images, and photoluminescence spectra showed that the GaN crystalline nanorods were preferentially oriented along the [0 0 0 1] direction and were very well-aligned perpendicular to the Si (1 1 1) substrate. An ultraviolet (UV) PV cell based on GaN nanorod/n-Si heterojunctions was fabricated, and current-voltage curves under an illumination with UV light exhibited obvious PV effect with a power conversion efficiency of about 1%. (C) 2010 Elsevier B.V. All rights reserved.