Pyroelectric origin of the carrier density modulation at graphene-ferroelectric interface

TL;DR

This paper investigates how the pyroelectric effect influences carrier density modulation in graphene on ferroelectric substrates under high-frequency conditions, revealing a significant impact on conductivity and interface physics.

Contribution

It introduces a theoretical model showing that pyroelectric effects can significantly alter free carrier density and conductivity at graphene-ferroelectric interfaces at terahertz frequencies.

Findings

Pyroelectric effect creates a temperature gradient in the ferroelectric.

The temperature gradient induces a polarization gradient affecting electric fields.

Carrier density in graphene oscillates due to the pyroelectric-induced electric fields.

Abstract

Using continuous approximation we study the static and high-frequency heat dissipation in multi-layer graphene on a ferroelectric. We demonstrate that the Joule heating effect, caused by a high-frequency ac electric current in graphene, creates a pronounced temperature gradient in a ferroelectric substrate. The pyroelectric effect transforms the gradient into the spontaneous polarization gradient.. Therefore, the high-frequency depolarizing electric field occurs and penetrates in the multi-layer graphene. Free charges in graphene immediately screen the electric field and thus their density oscillates at high-frequency. Performed calculations had proved that the pyroelectric effect can modify essentially the free carrier density at the graphene-ferroelectric interface and consequently the conductivity of multi-layer graphene channel. So, pyroelectric mechanism can be critical for understanding of the complex physical thermal and electrical processes taking place across and along graphene-ferroelectric interfaces at terahertz frequencies.