Limits for the graphene on ferroelectric domain wall p-n-junction rectifier for different regimes of current

TL;DR

This paper develops a theoretical model for graphene pn junctions on ferroelectric substrates, analyzing their rectifying behavior across different current regimes and substrate permittivities, highlighting conditions for efficient rectification.

Contribution

The study provides a comprehensive theory of graphene ferroelectric domain wall pn junction conductivity across all current regimes, including effects of temperature and substrate permittivity.

Findings

Small G+/G- ratios indicate efficient rectification.

High permittivity ferroelectrics enhance rectification, especially in diffusive regimes.

Rectification improves near the Curie temperature, vanishing above it.

Abstract

Here we present the theory of the conductivity of pn junction (pnJ) in graphene channel, placed on ferroelectric substrate, caused by ferroelectric domain wall (FDW) for the case of arbitrary current regime: from ballistic to diffusive one. We calculated the ratio of the pnJ conductions for opposite polarities of voltages, applied to source and drain electrodes of the channel,G+/G- as the function of the graphene channel length L, electron mean free path {\lambda} and ferroelectric substrate permittivity. We have demonstrated, that the small values of G+/G-(0.1 and smaller), which correspond to efficient graphene pnJ based rectifier, can be obtained for the ferroelectrics with high and for the ratios of L/{\lambda}~1 or smaller. However, for ferroelectrics with extremely high permittivity(relaxor or PbZrxTi1-xO3 with composition x near the morphotropic phase boundary x=0.52) the ratio G+/G- can be essentially smaller then unity for the case of a pronounced diffusive regime of current as well. This makes the ferroelectric substrates with high permittivity excellent candidates for the fabrication of new generation of rectifiers based on the graphene pnJ. Temperature effect on ratio was studied within Landau-Ginzburg-Devonshire approach. We have demonstrated that rectifying properties of the graphene pnJ become better in the vicinity of Curie temperature. However, for the temperatures higher than Curie temperature the rectifying effect vanishes due to the ferroelectric polarization disappearance.