Dielectric properties of Mn-doped BST thin films for microwave application

In this letter, we report on the effect of Mn doping on the tunability and dielectric loss of Ba0.6Sr0.4TiO3 thin films at low frequency (100 kHz) and at microwave frequency (3.5 GHz), respectively. Perovskite Ba0.6Sr0.4TiO3 thin films were deposited on Pt/TiO2/SiO2/Si and MgO single crystal substrates by pulsed laser deposition. At an applied electric field of 150 kV/cm, the BST films (0, 1, 3, 5 mol% Mn doped) grown on Pt/TiO2/SiO2/Si substrate showed the tunability value within the range from 46% to 49%. With 3% Mn doped BST thin films, results gave a tunability of 49% and a loss tangent as low as 0.0158 and the highest figure of merit of about 31. The microwave properties of BST films grown on MgO substrate were measured using interdigital capacitors (IDC) structure at 3.5 GHz. 3 mol% Mn doped BST also showed better tunability (27.4%) compared to that (11.6%) of undoped BST film. It is suggested that 3 mol% Mn doped BST film is effective candidate for high performance tunable device applications.