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

Here, we present the theory of the conductivity of a pn junction (pnJ) in agraphene channel, placed on aferroelectric substrate, caused by theferroelectricdomain wall for the case of the arbitrary current regime: fromballistic to diffusive one. We calculated the ratio of the pnJ conductions for opposite polarities of voltages, applied to source and drainelectrodes of the channel,G+total/G−total, as a function ofgraphene channel lengthL, electron mean free path λ, andferroelectric substratepermittivityε33f. We have demonstrated that the small values ofG+total/G−total (0.1 and smaller), which correspond to the efficientgraphene pnJ based rectifier, can be obtained for theferroelectrics with highε33f≫100 and for the ratios ofL/λ ∼ 1 or smaller. However, forferroelectrics with extremely highε33f(relaxor or PbZrxTi1 −xO3 with the composition x near the morphotropic phase boundary x  = 0.52), the ratioG+total/G−total can be essentially smaller than unity for the case of a pronounced diffusive regime of current as well. This makes theferroelectric substrates with highpermittivity excellent candidates for the fabrication of new generation of rectifiers based on thegraphene pnJ. Thetemperature effect on theG+total/G−total ratio was studied within the Landau-Ginzburg-Devonshire approach. We have demonstrated that the rectifying properties of thegraphene pnJ become better in the vicinity ofCurie temperature. However, for thetemperatures higher than theCurie te...

Source: Journal of Applied Physics - December 2, 2016 Category: Physics Authors: Maksym V. Strikha and Anna N. Morozovska Source Type: research