Weak Dependence of Voltage Amplification in a Semiconductor Channel on Strain State and Thickness of a Multidomain Ferroelectric in a Bilayer Gate

Ferroelectric/dielectric layered stacks are of special interest as gate oxides in the pursuit of designing low-power transistors, where the electrostatics of such stacks are thought to provide a means to allow for voltage amplification in the semiconductor channel. Strain and thickness dependence of the response of such a gate stack in relation to voltage amplification in a semiconductor channel becomes important to identify, which is what we study in this work using a thermodynamic approach. For a ferroelectric multidomain state as the stable phase in the stack, our findings show that a limited magnitude of voltage amplification appears to be feasible. Voltage amplification at the semiconductor surface is computed to hardly exceed 1.2 in thick bilayers (40 nm) for strains stabilizing the multidomain state and attains even less than this value for the thinner stacks.