Electrical transport throughPb(Zr,Ti)O3p-nandp-pheterostructures modulated by bound charges at a ferroelectric surface: Ferroelectricp-ndiode

Current through ${\mathrm{}(\mathrm{P}\mathrm{b},\mathrm{L}\mathrm{a})\mathrm{}(\mathrm{Z}\mathrm{r},\mathrm{T}\mathrm{i})\mathrm{O}}_3$ ferroelectrics on perovskite semiconductors is found to exhibit diode characteristics of which polarity is universally determined by the carrier conduction-type semiconductors. A persisting highly reproducible resistance modulation by a dc voltage, which has a short retention, is observed and is ascribed to a band bending of the ferroelectric by the formation of charged traps. This interpretation is consistent with a large relaxation current observed at a low voltage. On the other hand, a reproducible resistance modulation by a pulse voltage, which has a long retention, is observed in metal/${\mathrm{}(\mathrm{P}\mathrm{b},\mathrm{L}\mathrm{a})\mathrm{}(\mathrm{Z}\mathrm{r},\mathrm{T}\mathrm{i})\mathrm{O}}_3/{\mathrm{SrTiO}}_3:\mathrm{Nb}$ but not in metal/${\mathrm{}(\mathrm{P}\mathrm{b},\mathrm{L}\mathrm{a})\mathrm{}(\mathrm{Z}\mathrm{r},\mathrm{T}\mathrm{i})\mathrm{O}}_3/{\mathrm{}(\mathrm{L}\mathrm{a},\mathrm{S}\mathrm{r})\mathrm{}}_2{\mathrm{CuO}}_4$ and is attributed to a possible band bending due to the spontaneous polarization $\mathrm{}\left(P\right)\mathrm{}$ switching. The observed current voltage $\mathrm{}\left(\mathrm{IV}\right)\mathrm{}$ characteristics, the polarity dependence, the relaxation, and the modulation are explicable, if we assume a $p-n$ or a $p-p$ junction at the ferroelectric semiconductor interface (p: hole conduction type, n: electron conduction type). The analysis suggests that an intrinsically inhomogeneous P $\left(\nabla P\right)$ near the ferroelectric/metal interface is likely very weak or existing in a very thin layer, when a reaction of the metal with the ferroelectric is eliminated. Additionally, the various aspects of transport through ferroelectrics are explained as a transport in the carrier depleted region.