 Abstract piezoelectric MEMS can be used as sensors, actuators, energy harvesters, accelerometers, and communication modules. Aluminum nitride ALN is an attractive piezoelectric material due to its ability to be integrated into semiconductor circuitry. Microelectromechanical resonators with ALN sandwiched between n-type silicon assai and top metal electrodes with or without a silicon oxide layer were designed and fabricated. The effect of the oxide layer was found to be up to a fourfold increase in quality factor, Q, which was consistent from very high frequency VHF to super high frequency SHF. This effect was demonstrated using thin plate bulk acoustic wave modes from 70 to 80 MHz using the second contour mode and first width extensional mode and from 9.5 to 10.5 GHz using high overtone thickness modes. To explore potential applications of ALN-transduced Q-enhanced MEMS devices in harsh environments, measurements from minus 200°C to plus 200°C were performed. The Q enhancement was found to be persistent across. This article was authored by David D. Lines and Henke Shandrahalam. We are article.tv, links in the description below.