The trade-off between tuning ratio and quality factor of BaxSr1-xTiO3 MIM capacitors on alumina substrates

Abstract

Barium strontium titanate with different compositions is deposited using wet-chemical processing on a glass planarization layer, on top of alumina substrates. Three samples were fabricated with BaxSr1-xTiO3 (BST) with the barium content x varying between 0.8 and 1. The poly-crystalline films are 530 ± 12 nm thick. The optimization in terms of permittivity and quality factor is explored for barium strontium titanate on alumina substrates. The trade-off between the permittivity and quality factor (at 1 GHz) is investigated. Our results show that wet-chemical processing on glass-planarized alumina results in a quality factor between 21–27 at 1 GHz and a tuning ratio from 1.8 to 2.0 at an electric field of 0.4 MV/cm