Ta2O5/SiO2 insulating acoustic mirrors for AlN-based X-band BAW resonators

This work describes the performance of AlN-based bulk acoustic wave resonators built on top of insulating acoustic reflectors and operating at around 8 GHz. The acoustic reflectors are composed of alternate layers of amorphous Ta2O5and SiO2 deposited at room temperature by pulsed-DC reactive sputtering in Ar/O2 atmospheres. SiO2 layers have a porous structure that provides a low acoustic impedance of only 9.5 MRayl. Ta2O5 films exhibit an acoustic impedance of around 39.5 MRayl that was assessed by the picoseconds acoustic technique These values allow to design acoustic mirrors with transmission coefficients in the centre of the band lower than -40 dB (99.998 % of reflectance) with only seven layers. The resonators were fabricated by depositing a very thin AlN film onto an iridium bottom electrode 180 nm-thick and by using Ir or Mo layers as top electrode. Resonators with effective electromechanical coupling factors of 5.7% and quality factors at the antiresonant frequency around 600 are achieved.

Proyecto de las labores que deben emprenderse en la mina de galena "El Principio" del término de La Carolina (Jaén) adquirida por la Compañía Vascongada de Minería, para llegar a una producción anual de 180.000 toneladas de mineral preparados para la venta

Proyecto de las labores que deben emprenderse en la mina de galena "El Principio" del término de La Carolina (Jaén) adquirida por la Compañía Vascongada de Minería, para llegar a una producción anual de 180.000 toneladas de mineral preparados para la venta