INFRARED OPTICAL-PROPERTIES OF PEROVSKITE SUBSTRATES FOR HIGH-TC SUPERCONDUCTING FILMS

Perovskite-like compounds like LaAlO3, LaGaO3, and NdGaO3 have been recently proposed as substrates for high-T(c) superconducting films with optimum mechanical and dielectric properties. Measurements of room temperature and 25 K reflectance have been performed from 100 to 20 000 cm-1 in these compounds. The complex dielectric functions epsilon approximately, as well as phonon mode parameters, have been obtained by a best fitting procedure in terms of Lorentzian oscillators. The use of these compounds in the study of the optical properties of thin films is discussed.