Structures of GaAs and GaP, prepared by an ion-beam-epitaxy system having two ion sources and a rf coil, have been studied. GaAs and GaP films were deposited onto the cleavage surfaces of rock salt (001) and silicon (111) surfaces by the ion-beam-deposition system. Film structures have been studied under the electron microscope. Good epitaxy was found and the epitaxial temperature was lower than that found in ordinary deposition. These effects seem to have resulted from the ionized portion in the vapor beam.