The effect of Bragg reflectors on the electromechanical performance of parallel-plate ferroelectric capacitors

Parallel-plate capacitors based on ferroelectric thin films are considered as high density capacitors and varactors. Due to the small thickness of the ferroelectric films, typically less than 1.0 mu m, high electric fields are generated even at relatively low voltages inducing piezoelectric effect associated with electrostriction. This induced piezoelectric effect has negative impact on ferroelectric capacitors since it causes extra loss (electroacoustic transformation of microwave energy). In this work the use of Bragg reflectors between the substrate and ferroelectric film is proposed as a possible way of suppression of the enhanced losses associated with the piezoelectric activity of the ferroelectric film.