Fabrication and optical characterization of thin film composites for coplanar phase shifters

Oxide composites of barium strontium titanium oxide (BSTO) have been fabricated in thin film form by the pulsed laser deposition (PLA) method. The amount of the oxide additive in the BSTO matrix was varied from 1 wt% to 60 wt%. The thin films were deposited on single crystal sapphire substrates. The intent of this work is to study the effect of the oxide additive on the crystal structure of BSTO and compare it to its bulk ceramic counterpart. Glancing angle X-ray diffraction (GAXRD), Fourier transform Raman spectroscopy (FT-Raman), and Fourier transform Infrared spectroscopy (FT-IR) were utilized in this work. Since the bulk ceramics of these composites of BSTO have already been implemented in low loss electronic scanning antennas, it is necessary to characterize the material in its thin film form for applications at higher microwave frequencies (>35 GHz).