GaN films have been grown on single-crystalline Mo substrates using lattice-matched HfN buffer layers, and their structural properties have been investigated. Although it is not possible to grow high-quality GaN films on either Mo(110) or (111) substrates, high-quality epitaxial GaN(0001) films with atomically flat surfaces can be grown on the HfN(111)/Mo(110) structure with an in-plane alignment of GaN[11 (2) over bar0] parallel to HfN[1 (1) over bar0] parallel to Mo[001]. We have also found that the HfN/Mo heterointerface is quite abrupt. These results indicate that Mo(110) substrates with HfN buffer layers are promising candidates for the fabrication of future light-emitting devices (LEDs). (C) 2008 Elsevier B.V. All rights reserved.