Effect of post-annealing temperature on the dielectric function of solution-processed LaAlO x /Si Films

We report the optical properties of amorphous LaAlOx (LAO) films grown by using the sol-gel process. The dielectric functions e of the LAO films are obtained from 0.7 to 8.6 eV as a function of post-annealing temperature using spectroscopic ellipsometry. The LAO precursor sols were prepared at a molar ratio of La:Al = 1:1, were deposited on p-type Si substrates, and were sintered at 400 °C. Post-annealing was performed for 1 min in N2 by rapid thermal annealing (RTA) at 700, 850, and 1000 °C. The e spectra of the resulting LAO films were obtained from the measured pseudodielectric functions by using multilayer calculations with the Tauc-Lorentz dispersion relation. We found that the values of e for the sol-gel-deposited LAO films depended on the RTA temperature. This dependence provides a fundamental tuning basis for the solution-processed manufacture of LAO devices.