Refined Characterization Up to Millimeter Waves of Ferroelectric KTN Thin Film for Efficient Integrated Tunable Devices

A KTa0.65Nb0.35O3 thin film has been deposited by Pulsed Laser Deposition on MgO substrate. By means of specific metallization patterns, such as CPW transmission lines and interdigitated capacitors, a broad-band characterization of devices is performed from 40 MHz up to 67 GHz with the superposition of static E-field to polarize the ferroelectric KTN film. Next, the complex permittivity of the 400nm KTN thin film is deduced from these HF measurements using a refined extraction procedure. Results show a distributed relaxation on all the frequency range, ruled by a Cole-Davidson model. Results on tunability of the capacitance devices are promising and reach a value of 64% under a static E-field of 400 kV/cm.