DC Bias Effects on Optimizing ScAlN Air-Coupled pMUT Performance Parameters

In this work, we demonstrate that the performance of ScAIN pMUTs can be enhanced by adjusting DC bias voltages. DC biases up to 80 V on ScAIN pMUTs contribute to film stress alleviation and enhance pMUT performance. Laser Doppler Vibrometry characterization was performed to evaluate an improvement in displacement transfer according to the DC bias, as well as to investigate the ferroelectric effect of 15% scandium-doped AIN film. As a result, both transmission sensitivity and receive sensitivity are improved by 11 % and 50%, respectively, at 80V bias compared to 0V. Additionally, a 55% enlargement in the -3dB bandwidth (BW) has been achieved.