We report on structural and optical properties for the (0001)-oriented α-(CrxFe1-x)2O3 (0 ≤ x ≤ 1) epitaxial films prepared on c-sapphire substrates by using pulsed-laser deposition. Pure corundum phase with atomically flat surface was obtained in the entire composition range. Optical absorption spectra for the films with 0.2 < x < 0.9 showed a nearly constant band-gap (1.7 eV), which is narrower than those of α-Fe2O3 (2.1 eV) and α-Cr2O3 (3.0 eV). The result suggests that the band-gap narrowing arises from a type-II band alignment of these oxides and the fundamental band-gap lies between the Cr t2g and O 2p occupied states and the Fe t2g* empty state.
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