The first results are reported on Si1-xGex epitaxial layers grown on Si(100) by ion beam sputter deposition in ultrahigh vacuum. Growth temperatures were varied from 300 to 700°C, for compositions in the range 0.05 < x < 0.5. The properties of the grown films, such as morphology and structure, were studied by scanning electron microscopy and reflection high-energy electron diffraction respectively. Results indicate good monocrystallinity for the entire range of deposition temperature used. For deposition temperatures over 300°C, the films have smooth surfaces for all compositions and thicknesses. The distorted lattice parameters of epitaxial Si0.7Ge0.3 layers were measured by double-crystal diffractometry and the tetragonal strain was calculated. Increasing deposition temperature results in strain relaxation. Layers 3000 Å thick grown at 400°C still retain a larger strain than that measured in a similar layer grown by molecular beam epitaxy. All these results may show the effects of energetic bombardment on the growing film.