Characterization of (Ba0.5Sr0.5)TiO3 thin films for ku-band phase shifters

The microstructural properties of (Ba 0.5 Sr 0.5 )TiO 3 (BSTO) thin films (300, 700, and 1400 nm thick) deposited on LaAlO 3 (LAO) substrates were characterized using high-resolution x-ray diffractometery. Film crystallinity was the parameter that most directly influenced tunability, and we observed that a) the crystalline quality was highest in the thinnest film and progressively degraded with increasing film thickness; and b) strain at the film/substrate interface was completely relieved via dislocation formation. Paraelectric films such as BSTO offer an attractive means of incorporating low-cost phase shifter circuitry into beam-steerable reflectarray antennas.