The performance enhancement of the hydrophone based on the piezoelectric gate of field effect transistor for low frequency application

A hydrophone based on the transduction using the electric field of piezoelectric ceramic directly applied on the gate of field effect transistor was proposed, and the feasibility was shown in the year of 2010. Although the feasibility was proved with proper working condition, the fabricated device had some problems on the stability, noise, and sensitivity. The electric field generated from the piezoelectric ceramic in thickness mode, which receives the acoustic pressure from the pressure amplifying head mass structure, modulates the channel current of field effect transistor. The parametric analysis for the transduction was done for the performance enhancement. To realize stable and highly sensitive modulation, the field effect transistor was designed and fabricated with improved gate insulation layer. The passivation for the field effect transistor was also performed to protect the device from external factors and reduce the noise. The sensitivity evaluation setup using the free field calibration method was modified for more accurate measurement. The evaluation results for the improved device are to be presented. [Research supported by MRCnd.]