The oxide growth of rf sputtered polycrystalline Si1-xGex films was found not sensitive to the Ge concentration in the films. The infrared results showed that the oxide grown on Si0.61Ge0.39 film mainly contained GeO2 and the oxide contained Ge–O–Ge and Si–O–Ge bonds when grown on Si0.73Ge0.27 film. X-ray photoelectron spectroscopy results showed the absence of Ge in the bulk of the oxides for Si1-xGex films with x≪0.27 and no pile-up of Ge at the SiO2/Si1-xGex interface. The electrical breakdown fields of oxides grown on Si1-xGex films were lower than the oxide breakdown field of polysilicon. The Dit and Qf values of the SiO2/Si1-xGex system were found to be rather high at ∼2.1–2.6×1012 eV-1 cm-2 and ∼1.1–2.7×1012 cm-2, respectively. © 2002 American Institute of Physics.