Visible-light photoresponse of AlN-based film bulk acoustic wave resonator

Abstract

Visible-light photoresponse of an AlN-based film bulk acoustic wave resonator (FBAR) is demonstrated. It is found that the FBAR exhibits a resonant frequency downshift under purple light illumination and the magnitude of the frequency downshift increases as the power density increases within the range of 5–40 mW/cm2. A resonant frequency downshift of 1313 KHz is observed under 40 mW/cm2 illumination, corresponding to a minimum detection power of 6.09 nW. A sub-bandgap photoresponse of the AlN thin film is proposed to explain this phenomenon.