Biblio
Filters: Keyword is scandium compounds [Clear All Filters]
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2019. On the Coupling Coefficient of ScyAl1-yN-based Piezoelectric Acoustic Resonators. 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC). :1–4.
This work investigates the electromechanical coupling coefficient (kt2) attained by two available piezoelectric acoustic resonator technologies relying on Aluminum Scandium Nitride (ScyAl1-yN) films to operate. In particular, by using a theoretical approach, we extracted the maximum kt2-value attainable, for different scandium-doping concentrations (from 0% to 40%), by Film-Bulk-Acoustic-Resonators (FBARs) and Cross-Sectional-Lamé-Mode Resonators (CLMRs). For the first time, we show how the use of higher scandium doping concentrations can render the kt2 of CLMRs higher (35%) than the one attained by FBARs (28%). Such a unique feature renders CLMRs as ideal candidates to form lithographically defined resonators and filters for next-generation wideband radiofrequency (RF) front-ends.
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2019. Single Crystalline Scandium Aluminum Nitride: An Emerging Material for 5G Acoustic Filters. 2019 IEEE MTT-S International Wireless Symposium (IWS). :1–3.
Emerging next generation wireless communication devices call for high-performance filters that operate at 3-10 GHz frequency range and offer low loss, small form factor, wide bandwidth and steep skirts. Bulk and surface acoustic wave devices have been long used in the RF front-end for filtering applications, however their operation frequencies are mostly below 2.6 GHz band. To scale up the frequency of the filters, the thickness of the piezoelectric material needs to be reduced to sub-micron ranges. One of the challenges of such scaling is maintaining high electromechanical coupling as the film thickness decreases, which in turn, determines the filter bandwidth.Aluminum Nitride (AlN) - popular in today's film bulk acoustic resonators (FBARs) and mostly deposited using sputtering techniques-shows degraded crystal quality and poor electromechanical coupling when the thickness of AlN film is smaller than 1 μm.In this work, we propose using high-quality single-crystalline AlN and Scandium (Sc)-doped AlN epi-layers grown on Si substrates, wherein high crystal quality is maintained for ultra-thin films of only 400 nm thickness. Experimental results verify improved kt2 for 3-10 GHz resonators, with quality factors of the order of 250 and kt2 values of up to 5%based on bulk acoustic wave resonators. The experimental results suggest that single-crystal Sc-AlN is a great material candidate for 5G resonators and filters.