Impurity charge compensation in graphene by a polarized ferroelectric polymer and its effect on charge transport near the Dirac point

Charge transport near the Dirac point (DP) was investigated in graphene using ferroelectric (FE) gating in the temperature range of 300 < T < 350 K. We observed that the conductivity (sigma) near the DP had a positive temperature gradient that switched to a negative temperature gradient with increasing temperature. The switch to a negative temperature gradient shifted to higher temperatures and gradually weakened upon moving away from the DP. Impurity charge compensation via polarization of the FE together with a temperature-dependent graphene-impurity charge separation was proposed as being responsible for the non-monotonicity in sigma(T). A self-consistent theory for graphene transport with impurity charge scattering and phonon scattering was used to analyze the results. Non-monotonic charge transport was also observed in the temperature dependence of the residual conductivity (sigma(r)). Theoretical analysis of both sigma and sigma(r) revealed a temperature independent contribution of similar to 1.16 sigma(2)/h that is probably inherent to pristine graphene. (C) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Automated summary

The study investigated charge transport near the Dirac point in graphene using ferroelectric gating, finding non-monotonic conductivity near the point. Theoretical analysis suggested that impurity charge compensation and temperature-dependent charge separation may be responsible for this phenomenon.