ZnO film was grown on GaN/Si by one-step hydrothermal technique at low temperature in this paper. It was found that the GaN buffer layer played an important role in depositing ZnO films. ZnO nanorod arrays with a hexagonal wurtzite structure were grown on undoped GaN/Si substrate, whereas film structure was achieved on p-doped GaN/Si. The mechanism could be attributed to the defect-rich p-GaN/Si that propagates dislocation-driven growth. The high density of dislocations provided more nucleation sites than undoped GaN/Si; thus ZnO film could be formed by aggregation of nanorods. The results will provide opportunities for the fabrication of ZnO/GaN optoelectronic devices by simple catalyst-free dislocation-driven growth. (C) 2013 Elsevier B.V. All rights reserved.