Ferroelectric Domain Walls as Conductive Channels in Ferroelectric Semiconductors

Abstract

We have studied that ferroelectric domain walls act as conductive channels in  ferroelectric semiconductors. The static conductivity of domain walls with different  incline angle with respect to the spontaneous polarization vector was calculated  numerically in the uniaxial ferroelectric semiconductors of n type. The static  conductivity drastically increases at the inclined head to head wall by an order of  magnitude for small incline angles and by three orders of magnitude for the  perpendicular domain wall due to strong accumulation of compensating free  charges. We have presented the polarization structure and transport behavior at the  domain walls in the multiaxial ferroelectrics like BiFeO3 and Pb(Zr,Ti)O3 determined  by the interplay of the strong ferroelectric coupling between polarization  components and inhomogeneous elastic strains along the walls. The impact of the  ferroelectric coupling, proximity and finite size effect on the polarization vector,  potential electric field and carrier redistribution across the thin stripes and  cylindrical nanodynamics was analysed. Flexoelectric coupling is high for  ferroelectric leads to the appearance of polarization components perpendicular to  the wall plane and its strong gradient across the wall and even for unchanged walls.  The carrier accumulation effect by the nominally unchanged domain stripes and  cylindrical walls appears to be significant and increases upto 10-30 times for domain  in Pb(Zr,Ti)O3 for the typical range of flexoelectric coefficients. The charge of  accumulated carrier was determined by the sign of the flexoelectric coefficient. We  found that the carrier accumulation is highest when the wall plane is perpendicular  to the spontaneous polarization direction at wall and it decreases with bound charge  decrease and reaches minimum for the parallel domain wall. The obtained results  were found in good agreement with previous results.