INFRARED CHARACTERIZATION OF SRTIO3 THIN-FILMS USING ATTENUATED TOTALREFLECTANCE

Attenuated Total Reflectance was used to measure phonon vibration freq uencies over the range 425-800 cm(-1) of SrTiO3 thin films deposited e ither directly on LaAlO3, or on YBCO-coated LaAlO3 single crystal subs trates. In the s-polarized spectra, the transverse optic Ti-O stretchi ng vibration shifted to lower frequencies as the film thickness increa sed, which was attributed to damping caused by the generation of lower frequency phonon modes. The transverse Ti-O stretching vibration was also observed in the p-polarized spectra, but was more heavily damped, which indicates the damping is more pronounced when the electric fiel d has a component perpendicular to the film surface. Damping of the tr ansverse modes was attributed to coupling of these modes to other phon on modes, and may be a source of the high losses at microwave frequenc ies.