Milad Zolfagharloo Koohi

Temperature dependent characteristics of intrinsically switchable ferroelectric composite FBARs

This paper presents temperature dependent characteristics of intrinsically switchable ferroelectric composite FBARs. Ba0.5Sr0.5TiO3 and Si are used to form a composite FBAR. Measurement results show that both series and parallel resonance frequencies decrease with the temperature. The temperature coefficient of frequency is approximately -35 ppm/°C. The variation of quality factor and electromechanical coupling coefficient is less than 6.5% and 6.2% above 20 V bias.

Lateral-wave spurious-modes elimination in switchable ferroelectric BST-on-Si composite FBARs

This paper provides experimental results for elimination of lateral-wave spurious modes observed in switchable ferroelectric BST-on-Si composite FBARs using a frame design technique. This approach is used in piezoelectric FBAR design, however here it is applied for the first time to design intrinsically switchable ferroelectric BST acoustic resonators. The BST-on-Si composite FBAR presented here is a structure with the dispersion type-I characteristic, which requires a raised frame to eliminate any higher-order lateral-wave spurious modes. Based on 2-D Multiphysics simulations, FBARs with and without a frame are designed, verifying the utility of using a frame to improve device performance. Both FBARs are fabricated and measured, and then their performance is compared. Measurement results validate the effectiveness of a frame in the design of switchable BST FBARs, allowing for device performance improvement.