Circuit structures including a FinFET resonant body transistor are disclosed. One circuit structure includes: a plurality of fins over a substrate and a plurality of gate structures over the plurality of fins, the plurality of gate structures comprising at least one voltage sensing gate, and at least two of the plurality of fins comprising multiple pn-junctions disposed on opposing sides of the at least one voltage sensing gate, the multiple pn-junctions being fabricated to operate as driving units; at least one phononic crystal, wherein the at least one phononic crystal is arranged to confine vibrational energy arising from electrically induced mechanical stresses in the fins comprising driving units; and, wherein the electrically induced mechanical stresses modulate carrier mobility in the at least one voltage sensing gate to produce a current extractable by the circuit structure.

A semiconductor structure includes a semiconductor substrate, fins coupled to the semiconductor substrate, FinFETs on the fins, a common gate for the FinFETs, a dielectric layer on the semiconductor substrate, the dielectric layer surrounding a cavity with the semiconductor substrate providing bottom confinement of the acoustic cavity by total internal reflection, and an interconnect structure above the FinFETs, the interconnect structure including phononic crystal(s) to confine acoustic energy in the cavity including the cavity and metal layer(s) sandwiched between two dielectric layers. The semiconductor structure may be realized, during FEOL fabrication of a FinFET, by forming a cavity on a surface of a semiconductor substrate. Then, after fabrication of the FinFET, forming an interconnect structure for the FinFET. During formation of the interconnect structure, materials of the interconnect structure are used to form a phononic crystal to confine the cavity between the phononic crystal and the semiconductor substrate.

An embodiment includes a first nonplanar transistor including a first fin that includes first source and drain nodes, and a first channel between the first source and drain nodes; a second nonplanar transistor including a second fin that includes second source and drain nodes, and a second channel between the second source and drain nodes; a nonplanar gate on the first fin between the first source and drain nodes and on the second fin between the second source and drain nodes; and first insulation included between the gate and the first fin and second insulation between the gate and the second fin; wherein the gate mechanically resonates at a first frequency when at least one of the gate and the first fin is actuated with alternating current (AC) to produce periodic forces on the gate. Other embodiments are described herein.