High-permittivity spinel Zn2TiO4 thin films were grown on GaN (0 0 1) by rf-sputtering. Grazing-angle, powder, and pole-figure X-ray diffractometries (XRD) were performed to identify the crystallinity and the preferred orientation of the Zn2TiO4 films. Lattice image at the Zn2TiO4 (1 1 1)/GaN (0 0 1) interface was obtained by high-resolution transmission-electron microscopy (HR-TEM). An oxygen atmosphere in sputtering and post heat-treatment using rapid thermal annealing effectively enhanced the epitaxy. The epitaxial relationship was determined from the XRD and HR-TEM results: (1 1 1)(Zn2TiO4)parallel to(0 0 1)(GaN), (2 0 (2) over bar)(Zn2TiO4 parallel to)(1 1 0)(GaN) and [2 (1) over bar(1) over bar](Zn2TiO4)parallel to[0 (1) over bar 1 0](GaN). Finally, the relative permittivity, interfacial trap density and the flat-band voltage of the Zn2TiO4 based capacitor were similar to 18.9, 8.38 x 10(11) eV(-1) cm(-2), and 1.1 V, respectively, indicating the potential applications of the Zn2TiO4 thin film to the GaN-based metal-oxide-semiconductor capacitor. (c) 2012 Elsevier Ltd. All rights reserved.