Deposition and characterization of low-loss epitaxial non-linear dielectric thin films for microwave devices

Oxide ferroelectric thin films fur frequency-tunable microwave devices, in which the dielectric constant of the non-linear dielectric is varied by app lication of electric fields, have been deposited using PLD. We have fabrica ted single phase epitaxial Ba0.6Sr0.4TiO3 and KTaO3 thin film capacitors fo r applications at 300K acid 77K, respectively. Single phase KTaO3 films wer e obtained only with excess potassium source in the target along with KTaO3 ; perovskite phase. The films have been characterized for structure and mor phology by X-ray diffraction and AFM. The dielectric properties were measur ed in the low frequency range from 100 kHz to 10 MHz, using interdigitated capacitors. Low loss tangents (0.002 at 300K) were observed fur highly orie nted Ba0.6Sr0.4TiO3 films. The importance of low losses for various devices is discussed and the dielectric constants, loss tangents and tunability of these films are reported in this gaper.