Micromachined ultrasound transducer using multiple piezoelectric materials

A transducer comprising:

• a substrate having an opening formed therethrough;
• first and second piezoelectric layers made of corresponding different first and second piezoelectric materials, wherein one of the first and second piezoelectric material is optimized for transmitter mode operation and another of the first and second piezoelectric materials is optimized for receiver mode operation;
• and
• three or more electrodes, implemented in two or more conductive electrode layers, wherein the first piezoelectric layer is formed directly on the substrate over the opening, wherein the first piezoelectric layer is sandwiched between a first pair of electrodes of the three or more electrodes and wherein the second piezoelectric layer is sandwiched between a second pair of electrodes of the three or more electrodes, wherein the first and second pairs of electrodes contain no more than one electrode of the three or more electrodes that is common to both the first pair and the second pair.