%0 Journal Article %K Thin films %K Molecular beam epitaxy %K Substrates %K Spectroscopic ellipsometry %K Bismuth compounds %K Energy gap %K Four-circle x-ray diffraction %K Multiple-angle spectroscopic ellipsometry %K Optical band gap %K Oxygen activity %A J.F Ihlefeld %A N.J Podraza %A Z.K Liu %A R.C Rai %A X Xu %A T Heeg %A Y.B Chen %A J Li %A R.W Collins %A J.L Musfeldt %A X.Q Pan %A J Schubert %A Ramamoorthy Ramesh %A D.G Schlom %B Applied Physics Letters %D 2008 %G eng %R 10.1063/1.2901160 %T Optical band gap of BiFe O3 grown by molecular-beam epitaxy %V 92 %X BiFe O3 thin films have been deposited on (001) SrTi O3 substrates by adsorption-controlled reactive molecular-beam epitaxy. For a given bismuth overpressure and oxygen activity, single-phase BiFe O3 films can be grown over a range of deposition temperatures in accordance with thermodynamic calculations. Four-circle x-ray diffraction reveals phase-pure, epitaxial films with ω rocking curve full width at half maximum values as narrow as 29 arc sec (0.008°). Multiple-angle spectroscopic ellipsometry reveals a direct optical band gap at 2.74 eV for stoichiometric as well as 5% bismuth-deficient single-phase BiFe O3 films. © 2008 American Institute of Physics.