TUNABLE (BA, SR)TIO{sub}3 INTERDIGITAL CAPACITOR ONTO SI WAFER FOR RECONFIGURABLE RADIO

摘要

In this article, the potential feasibility of integrating BST films into Si wafer by adopting tunable interdigital capacitor (IDC) with TiO{sub}2 thin film buffer layer is suggested. TiO{sub}2 as buffer layer is grown onto Si substrate by atomic layer deposition and the coplanar IDC on Ba{sub}xSr{sub}(1-x)TiO{sub}3(500 nm)/TiO{sub}2(50 nm)/high resistivity Si (HR-Si) is fabricated. BST interdigital tunable capacitors integrated on HR-Si substrate with high tunability and low loss tangent are characterized for their microwave performances. BST/HR-Si and BST/TiO{sub}2/HR-Si IDCs show much enhanced tunability values of 31% and 40%, respectively as compared to the value of 21% obtained with BST film on MgO single crystal substrate at the bias of 5 kV/cm. BST/TiO{sub}2/HR-Si structure shows much improved figure of merit of 504.4 as compared to 418.53 and 101.68 of BST/MgO and BST/HR-Si structure, respectively.