Microelectromechanical systems (MEMS)-based capacitive micromachined ultrasonic transducer (CMUT) follows the reciprocity principle in the same way as piezoelectric transducers and has proven to be a good alternative to conventional piezoelectric transducers in many aspects such as sensitivity, transduction efficiency and bandwidth. CMUT transducers like piezoelectric transducers operate on resonance frequency to get possible ultrasound output, and high sensitivity in reception. The performance of the CMUT is highly affected by material properties of the membrane and hence constitutes an important parameter to analyze resonance frequency, pull in voltage, capacitance and deflection of the membrane. In this paper, CMUT of circular membrane geometry has been discussed with three different membrane materials – silicon, silicon nitride and polysilicon. Important parameters like resonance frequency, pull in voltage, deflection and capacitance have been calculated with all the three materials and results have been compared. The CMUT is subjected to hydrostatic pressure and electrostatic forces simultaneously and behavior has been studied. The analytical results inferred for the deflection and the pull in voltage can suffice as useful in lieu of expensive ANSYS simulations. Keywords: Collapse voltage, membrane materials, piezoelectric, ultrasonic transducer
