Microwave Tunable Device based on Thin Ferroelectric Film

The voltage-dependent dielectric permittivity, ¿, of ferroelectrics is widely used for developing electrically tunable microwave components. In this work, a set of planar Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structures based on Na0.5K0.5NbO3, (NKN), ferroelectric film have been fabricated. These devices have been characterized at frequencies from 1 MHz to 50 GHz, and have a 10:1 tuning range at 1 Mhz and 0.1:1 tuning range at microwave frequencies over a 0-40 V bias range. The microwave losses of these capacitors are comparable to those of commercially available semiconductor varactors for frequencies above 10 GHz, and should be useful for tunable microwave circuits at the temperature of 300 K.