We have characterized thin films of and which were grown by molecular beam deposition on Si substrates. Samples of were also grown by pulsed laser deposition on MgO substrates. Using transmission studies between 1.5 and , we have established that low temperature deposition leads to a reduced band gap with respect to the bulk crystal. Furthermore, using spectroscopic ellipsometry from we observe substantial differences in near-band gap absorption between thin and thicker films for both materials. We obtain a band gap of for the thinner film of , whereas we find a band gap of for the thicker film of . Similarly we find band gaps of 5.5 and , respectively, for thin and thick films of .
Optical properties of La-based high- dielectric films
E. Cicerrella, J. L. Freeouf, L. F. Edge, D. G. Schlom, T. Heeg, J. Schubert, S. A. Chambers; Optical properties of La-based high- dielectric films. J. Vac. Sci. Technol. A 1 November 2005; 23 (6): 1676–1680. https://doi.org/10.1116/1.2056555
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