This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si（001） substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er2O3 films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average refiectances （400-1000 nm） is 11.6%. The obtained characteristics indicate that Er2O3 films could be a promising candidate for antireflection coatings in solar cells.
