We have grown GaN films on atomically-flat LiTaO3 substrates by using pulsed laser deposition (PLD), and we then investigated the effect of the use of low-temperature AlN (LT-AlN) buffer layers on the structural properties of GaN. The full-width at half-maximum (FWHM) values for the crystal orientation distribution of the GaN films in the tilt directions were reduced from 0.48 degrees to 0.17 degrees, and those in the twist directions were reduced from 0.40 degrees to 0.17 degrees by the incorporation of AlN buffer layers grown at 580 degrees C. The surface morphology of GaN has also been improved by the insertion of LT-AlN buffer layers. X-ray reflectivity measurements have revealed that the interfacial layer thickness between LT-AlN and LiTaO3 is as thin as 1.7 nm, and that the increase in the interfacial layer thickness caused by annealing at up to 700 degrees C is quite small. These results indicate that the PLD growth of GaN on atomically flat substrates using LT-AlN buffer layers is quite promising for achieving GaN on LiTaO3. (c) 2006 Elsevier B.V. All rights reserved.