The authors have demonstrated the epitaxial growth of Sc2O3 films on GaN (0001) using pulsed laser deposition (PLD) (with KrF excirner laser). The ' characteristics of these Sc2O3 films Were found to be highly dependent on. the substrate temperature (T-s) and the oxygen partial pressure (P) during the PLD process. Under optimized deposition conditions (T-s of 700 degrees C and, P-0 of 10 mTorr), highly c-axis oriented Sc2O3 films have been epitaxially grown on GaN (0001) ternpldte with fine film crystallinity, smooth surface morphology, good film stoichiometry, and a refractive index close to that of the bulk material. Cross-sectional transmission electron microscopy measurements confirmed the heteroepitaxial nature of the Sc2O3 films on the GaN template and revealed an epitaxial relationship of [112]Sc2O3 parallel to [21 (3) over bar0](GaN) and (222)(Sc2O3)parallel to(0002)(GaN). (c) 2007 American Vacuum Society.