Properties of Ga2O3thin films deposited by electron‐beam evaporation from a high‐purity single‐crystal Gd3Ga5O12source are reported. As‐deposited Ga2O3films are amorphous, stoichiometric, and homogeneous. Excellent uniformity in thickness and refractive index was obtained over a 2 in. wafer. The films maintain their integrity during annealing up to 800 and 1200 °C on GaAs and Si substrates, respectively. Optical properties including refractive index (n=1.84–1.88 at 980 nm wavelength) and band gap (4.4 eV) are close or identical, respectively, to Ga2O3bulk properties. Reflectivities as low as 10−5for Ga2O3/GaAs structures and a small absorption coefficient (≊100 cm−1at 980 nm) were measured. Dielectric properties include a static dielectric constant between 9.9 and 10.2, which is identical to bulk Ga2O3, and electric breakdown fields up to 3.6 MV/cm. The Ga2O3/GaAs interface demonstrated a significantly higher photoluminescence intensity and thus a lower surface recombination velocity as compared to Al2O3/GaAs structures. ©1995 American Institute of Physics.