Radio–frequency magnetron sputter epitaxy was employed for the synthesis ofn–type modulation doped Si/Si1−xGexheterostructures. Si channels were grown coherently on sputtered, compositionally graded Si1−xGexbuffers of low defect density, and remotely doped with phosphorus by plasma assisted gas phase doping. Magnetotransport measurements on these films revealed Shubnikov–de Haas oscillations in the longitudinal and the integer quantum Hall effect in the transverse magnetoresistance, demonstrating the presence of a two–dimensional electron gas. AtT=1.6 K and sheet densities of 1012 cm−2, electron mobilities as high as 15 800 cm2/V s give evidence of the excellent structural and electronic properties achievable by the sputter growth technique. ©1995 American Institute of Physics.