Project title: Improvement of tunability and dielectric loss of (BaxSr1-x)TiO3 thin films for microwave tunable applications

Barium strontium titanate ((BaxSr1-x)TiO3 or (BST) thin films exhibit large dielectric constant, high tunability at microwave frequencies, and favorable growth characteristics and have been extensively investigated in the past decade for potential applications in tunable microwave devices, such as field dependent capacitors, tunable resonators, filters, variable frequency dividers and phase shifters. To satisfy potential microelectronics applications, BST thin films with a high tenability and low dielectric losses are required. However, the realization of these devices has been hampered by high microwave losses, as well as by the reliability issues over operating frequency and temperature ranges. The main objectives of this project are (i) to improve the quality of the BST thin films (especially reducing microwave loss) through precisely controlling the composition and microstructures; and (ii) to gain a better fundamental understanding of composition-processing-microstructure-microwave property relationships of BST thin films. The knowledge gained in this study will be beneficial for the development of high quality BST thin films for microwave tunable applications.

Z K Xu (apzkx@cityu.edu.hk)

Suitable for: M.Phil. or Ph.D.