Development of tunable film bulk acoustic wave resonator (FBAR) utilizing BiFeO3-BaTiO3 multiferroics
Examensarbete för masterexamen
This thesis aims at improving the performance of novel (1-x)BiFeO3-xBaTiO3 multiferroic based tunable film bulk acoustic resonator (FBAR) up to the desired level of practical applications by optimizing material compositions and film growth conditions. FBARs are currently widely used in advanced wireless communication systems like mobile phones and global positioning systems for their low energy consumption and high performance features. For applications in agile microwave systems a novel microwave component - a tunable FBAR is recently introduced and being developed. Unlike traditional fixed frequency devices, the resonance frequencies of tunable FBARs can be adjusted with applied DC bias electric field by utilizing the field enhanced piezoelectric effect in the multiferroic thin films. In this project, the (1-x)BiFeO3-xBaTiO3 thin films are grown by Pulsed Laser Deposition (PLD) method. An Agilent N5230 A vector network analyzer and ground-signal-ground (GSG) microprobes are used to measure the microwave performance of test structures in the frequency range 1-10 GHz. Modified Butterworth-Van Dyke (mBVD) model is applied to extract the FBAR equivalent circuit parameters. The recently developed model of DC bias induced piezoelectric effect in paraelectric phase ferroelectrics is applied to analyze the performance of the tunable FBARs. Several compositions have been studied and characterized, in which the composition of 0.67BiFeO3-0.33BaTiO3-0.003Mn reveals the highest tunability of series resonance frequency 4.4% and electromechanical coupling coefficient 11.3%, with the quality factor of 145 at 3.40 GHz resonance frequency. These parameters are the highest among reported so far for the tunable FBAR.
Halvledarfysik , Kommunikationssystem , Keramteknik , Materialvetenskap , Nanovetenskap och nanoteknik , Semiconductor physics , Communication Systems , Ceramics , Materials Science , Nanoscience & Nanotechnology