Structural, optical, and electrical properties of laser deposited FeTiO3 films on C- and A-cut sapphire substrates

FeTiO3 (FTO) thin films were epitaxially grown on two kinds of alpha-Al2O3 substrates [(0001) and (11 (2) over bar 0)] through pulsed laser deposition under a mixtured gas ambient of 5% oxygen with argon used as the balance. The x-ray diffraction (XRD) and XRD pole figure measurements show parallel growth relationships of the films on these two kinds of substrates, (0006) parallel to (0006), (11 (2) over bar 0) parallel to (11 (2) over bar 0), re spectively. The interplane XRD pole texture measurement also shows that a p arallel relationship exists. Rutherford backscattering spectrometry and Aug er electron spectrometry analyses show that the films are stoichiometric an d without distinguishable impurities. The optical properties were character ized in the ultraviolet-visible region, and 3.55 eV was obtained for the fi rst time as the band gap of these epitaxial and stoichiometric FTO films. T his value in the present high quality films is higher than the band gap rep orted for bulk material, 2.58 eV. The measurement of the electrical resista nce in a quite wide temperature range shows typical semiconductor propertie s. (C) 1999 American Institute of Physics. [S0021-8979(99)00710-0].