Tunable Interdigitated Capacitances on Ba0.3Sr0.7TiO3 Thin-Film

BaxSr1-xTiO3 thin films were deposited by rf magnetron sputtering on sapphire substrate. A TiOx buffer layer was deposited on sapphire in order to control the (111)-preferred orientation. Specific coplanar waveguides have been fabricated on this structure and used to achieve a microwave characterization of the Ba0.3Sr0.7TiO3 up to 67 GHz. Interdigitated capacitors (IDC) were then realized on 350 nm of BST deposited on sapphire substrate. The capacitive aspect is retained up to 67 GHz. Tunablity of 35% under a low electric field (150 kV/cm) was measured up to 67 GHz.