Doped Ba0.6Sr0.4TiO3 thin films for microwave device applications at room temperature

The dielectric property comparison between laser-ablated Mn-doped and undoped Ba0.6Sr0.4TiO3 (BST) thin films at low frequency (100 kHz) and at microwave frequencies has been demonstrated. The dielectric properties were characterized at low frequency using interdigital capacitors, and at microwave frequencies with coplanar waveguide (CPW) meander-line phase shifters. With 1% Mn-doped BST films, results to date gave a dielectric constant as high as 2100, a tunability of 85% with DC bias field of 88 kV/cm, and a loss tangent without DC bias as low as 0.0033 at 100 kHz and room temperature. At 10 GHz, our best result to date was also obtained with 1% Mn-doped BST film deposited on MgO substrate, which at room temperature possess a dielectric constant of 1820 with a tunability of 56% at 40 kV/cm DC electric field, and a loss tangent of 0.006 at zero bias.