Physical properties of (Ba,Sr)TiO/sub 3/ thin films used for integrated capacitors in microwave applications

Recently, there has been significant interest in use of (Ba, Sr)TiO/sub 3/ (BST) thin films for tunable high frequency (RF and microwave) components. In this paper we discuss the electrical properties of BST thin films gown by metalorganic chemical vapor deposition (MOCVD) as a function of DC bias and frequency at low frequency ( 50%) over the entire frequency range, making them suitable for these microwave applications. The effect of titanium content, thickness and Pt roughness on dielectric losses and tunability are discussed. Implications for microwave devices are discussed as well. Finally, we report the fabrication of a BST thin film device using a 3-layer mask set to measure electrical properties at RF/microwave frequencies.