Microwave tunable ferroelectric capacitors with enhanced power handling capability based on the silicon carbide substrate

摘要

The tunable planar capacitors based on the BST film deposited onto the silicon carbide (SiC) substrate are presented. Thin BST films on SiC substrates were obtained by RF magnetron sputtering of a ceramic target with Ba0.4Sr0.6TiO3 composition. X-ray diffraction has shown a well-formed perovskite structure with (100) growth texture. The capacitance of planar BST capacitors was estimated as 0.5 pF (that corresponds to BST film permittivity about ε ≅ 500), the dielectric losses as 0.02 and the tunability at the 60 V/μm as n ≅ 1.7. Microwave investigation at the elevated MW signal up to 3 var of the reactive power on the capacitor had demonstrated that the power handling capability of the FE tunable capacitors on the SiC substrate is limited rather by the electric non-linearity than the overheating.