Pressure Dependence of the Quality Factor of Piezoelectrically driven AlN/Si-Microcantilevers

Abstract

In this work, the fabrication process of piezoelectric AlN cantilevers is presented. The cantilevers were electrically characterized in a vacuum chamber offering the possibility to close-loop control the back pressure from atmospheric conditions down to 5x10-3 mbar. The quality factor (Q factor) is an important figure of merit to evaluate the performance of micro-resonators. In particular, two different modes were detected and analyzed. The first bending mode detected at 19.5 kHz has a quality factor of 470 at atmospheric pressure which increases continuously to 985 at 1x10-1 mbar. The corresponding resonant frequency shifted from 19.500 kHz at atmospheric pressure to 19.573 kHz at 5 mbar. Below this pressure level, the resonance frequency stays unaffected within the measurement accuracy. The second bending mode detected at 117.264 kHz exhibits a quality factor of about 570 at atmospheric pressure increasing continuously to 1275 at 1x10-1 mbar. In agreement with the other resonant frequency under investigation the corresponding resonant frequency decreased from 117.264 kHz at atmospheric pressure to 117.630 kHz at 5 mbar.