Understanding the Enhancement Mechanism of ZnO Nanorod-based Piezoelectric Devices through Surface Engineering

ZnO is a typical piezoelectric semiconductor, and enhancing the piezoelectric output of ZnO-based devices is essential for their efficient applications. Surface engineering is an effective strategy to improve the piezoelectric output of ZnO-based devices, but its unclear regulation mechanism leads to a lack of reasonable guidance for device design. In this work, the regulation effect of the barrier layer in ZnO-based piezoelectric devices is systematically investigated from the carrier perspective through surface engineering, resulting in a significant improvement (nearly 10-fold) in the output performance of piezoelectric devices. The regulation mechanism of the ZnO-Cu₂O p-n heterojunction devices on piezoelectric output is revealed in terms of built-in electric field, depletion layer width, and junction capacitance. These findings facilitate further insight into the enhancement mechanism of the piezoelectric output of ZnO-based devices and provide reasonable ideas for efficient device design.