Nontrivial temperature behavior of the carrier concentration in graphene on ferroelectric substrate with domain walls

This work explores a nontrivial temperature behavior of the carriers concentration, which governs the conductance of the graphene channel on ferroelectric substrate with domain walls that is a basic element for field effect transistors of new generation. We revealed the transition from a single to double antiferroelectric-like hysteresis loop of the concentration voltage dependence that happens with the temperature increase and then exist in a wide temperature range (350-500) K. We have shown that the double loops of polarization and concentration can have irregular shape that remains irregular as long as the computation takes place, and the voltage position of the different features (jumps, secondary maxima, etc) changes from one period to another, leading to the impression of quasi-chaotic behavior. It appeared that these effects originate from the nonlinear screening of ferroelectric polarization by graphene carriers, as well as it is conditioned by the temperature evolution of the domain structure kinetics in ferroelectric substrate. The nonlinearity rules the voltage behavior of polarization screening by graphene 2D-layer and at the same time induces the motion of separated domain walls accompanied by the motion of p-n junction along the graphene channel. Since the domain walls structure, period and kinetics can be controlled by changing the temperature, we concluded that the considered nano-structures based on graphene-on-ferroelectric are promising for the fabrication of new generation of modulators based on the graphene p-n junctions. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.