BST interdigital capacitors with high tunability on MgO substrate

In this paper, Au/Ba-0.6(0.4)3(Sr)TiO (BST) fierroelectric thin-film interdigital capacitors on MgO substrate are presented. The interdigital capacitors with a 50-mm gap and different doped materials of BST thin film are characterized. Tunability rates of 11.2% and 28% are obtained for the undoped BST thin film and the Mn-doped (3 mol %) BST thin film, respectively, at 3.5 GHz with a bias voltage of 20 V. Furthermore, the loss tangent of the BST thin film is found to be approximately 0.0158 and it decreases with Mn doping. Mn-doped (3 mol %) BST film is suggested to be an effective candidate for high-performance tunable device applications. 2005 Wiley Periodicals, Inc.