Fabrication and Characteristic of a Double Piezoelectric Layer Acceleration Sensor Based on Li-Doped ZnO Thin Film

In this paper, a double piezoelectric layer acceleration sensor based on Li-doped ZnO (LZO) thin film is presented. It is constituted by Pt/LZO/Pt/LZO/Pt/Ti functional layers and a Si cantilever beam with a proof mass. The LZO thin films were prepared by radio frequency (RF) magnetron sputtering. The composition, chemical structure, surface morphology, and thickness of the LZO thin film were analyzed. In order to study the effect of double piezoelectric layers on the sensitivity of the acceleration sensor, we designed two structural models (single and double piezoelectric layers) and fabricated them by using micro-electro-mechanical system (MEMS) technology. The test results show that the resonance frequency of the acceleration sensor was 1363 Hz. The sensitivity of the double piezoelectric layer was 33.1 mV/g, which is higher than the 26.1 mV/g of single piezoelectric layer sensitivity, both at a resonance frequency of 1363 Hz.