Modeling of a ZnO single crystal bulk-acoustic-wave X-ray detector

Piezoelectric semiconductor based bulk acoustic wave resonators have been demonstrated to be applicable in the field of Infrared, UV, and X-ray detections in recent years. Analytical equations are needed to model their responses. In this work, the conductivity dependent performance of the bulk acoustic wave resonator with the ohmic electrodes was modeled by coupling the piezoelectric constructive relations with the charge-current continuity equation in the piezoelectric semiconductor, which can be utilized to calculate the responses of a ZnO single crystal bulk-acoustic-wave X-ray detector. Under X-ray irradiation, the conductivity of the piezoelectric-semiconductor is increased due to the photoelectric effect, which can decrease the wave velocity, and reduce the resonant frequency as a result. The model derived in this work can also be applicable to other bulk-acoustic-wave resonator based optical sensors with ohmic electrodes.