Tined gate to control threshold voltage in a device formed of materials having piezoelectric properties

Abstract

Roughly described, a field effect transistor has a first piezoelectric layer supporting a channel, a second piezoelectric layer over the first piezoelectric layer, a dielectric layer having a plurality of dielectric segments separated by a plurality of gaps, the dielectric layer over the second piezoelectric layer, and a gate having a main body and a plurality of tines. The main body of the gate covers at least one dielectric segment of the plurality of dielectric segments and at least two gaps of the plurality of gaps. The plurality of tines have proximal ends connected to the main body of the gate, middle portions projecting through the plurality of gaps, and distal ends separated from the first piezoelectric layer by at least the second piezoelectric layer. The dielectric layer exerts stress, creating a piezoelectric charge in the first piezoelectric layer, changing the threshold voltage of the transistor.