Low-impedance Thin-film Aln-on-diamond Lateral-extensional Resonators

Abstract

The focus of this thesis is the design and fabrication of thin-film piezoelectric-on-diamond resonators to have very low insertion loss values. Ultrananocrystalline films with different Young's modulus were used as the substrate for these resonators in order to extend the resonance frequency beyond the limits achievable with silicon. This work is dedicated to investigate different techniques to improve the resonator performance. Effect of the lateral geometries as well as the support configurations on the insertion loss and the quality factor of the resonator were studied. The multi-tethered designs with lengths equal to odd multiples of half-wavelength and support length of (2n+1) λ⁄4 exhibit an improved performance. A thin-film piezoelectric-on-diamond resonator is reported with a record low insertion loss of 2.6 dB at 888 MHz and f.Q product of 2.72*1012 while maintaining a very small footprint (205m x 209m). The TCF of this resonator is measured to be -9.6 ppm/C which is much lower than the devices fabricated on silicon. Also, this TPoD device can withstand input powers up to +22dBm, which is higher than the devices fabricated on silicon reported till the date.