title: Polarization induced self-doping in epitaxial Pb(Zr0.20Ti0.80)O3 thin films.
abstract: The compensation of the depolarization field in ferroelectric layers requires the presence of a suitable amount of charges able to follow any variation of the ferroelectric polarization. These can be free carriers or charged defects located in the ferroelectric material or free carriers coming from the electrodes. Here we show that a self-doping phenomenon occurs in epitaxial, tetragonal ferroelectric films of Pb(Zr0.2Ti0.8)O3, consisting in generation of point defects (vacancies) acting as donors/acceptors. These are introducing free carriers that partly compensate the depolarization field occurring in the film. It is found that the concentration of the free carriers introduced by self-doping increases with decreasing the thickness of the ferroelectric layer, reaching values of the order of 10(26) m(-3) for 10 nm thick films. One the other hand, microscopic investigations show that, for thicknesses higher than 50 nm, the 2O/(Ti+Zr+Pb) atomic ratio increases with the thickness of the layers. These results suggest that the ratio between the oxygen and cation vacancies varies with the thickness of the layer in such a way that the net free carrier density is sufficient to efficiently compensate the depolarization field and to preserve the outward direction of the polarization.
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Lucian
authors.initials: L
authors.lastname: Pintilie
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Corneliu
authors.initials: C
authors.lastname: Ghica
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Cristian Mihail
authors.initials: CM
authors.lastname: Teodorescu
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Pintilie
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Cristina
authors.initials: C
authors.lastname: Chirila
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Iuliana
authors.initials: I
authors.lastname: Pasuk
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Lucian
authors.initials: L
authors.lastname: Trupina
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Luminita
authors.initials: L
authors.lastname: Hrib
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Andra Georgia
authors.initials: AG
authors.lastname: Boni
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Georgiana Apostol
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Laura Elena
authors.initials: LE
authors.lastname: Abramiuc
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Raluca
authors.initials: R
authors.lastname: Negrea
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Mariana
authors.initials: M
authors.lastname: Stefan
authors.affiliation: National Institute of Materials Physics, Atomistilor 105 bis, Magurele, 077125, Romania.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ghica