The dependence of oxygen vacancy distributions in BiFeO3 films on oxygen pressure and substrate

Abstract

The epitaxial ͑001͒-oriented 250 nm BiFeO 3 /50 nm SrRuO 3 films were deposited on DyScO 3 and SrTiO 3 substrates, respectively. Following the growth, the cooling in lower oxygen pressure results in the creation of oxygen vacancies at the surface of the BiFeO 3 film and the epitaxial strain drives these vacancies to diffuse from the film surface to the film interface. The SrTiO 3 substrate strongly absorbs oxygen vacancies from the BiFeO 3 film while the DyScO 3 substrate does not. Therefore, the depth distribution of oxygen vacancies depends on the oxygen pressure during cooling, the epitaxial strain, and the substrate absorbing oxygen vacancies.

Upward ferroelectric self-poling in (001) oriented PbZr0.2Ti0.8O3 epitaxial films with compressive strain

“…Oxygen vacancies can conjugate at the PZT interface under compressive strain and finally relax strain in theory. [13][14][15][16] Most oxygen vacancies are neutral and do not produce a strong enough upward E in to pole PZT films. In addition to this, the thicker PZT epitaxial films without self-poling trait were annealed at 600…”

Towards reversible control of domain wall conduction in Pb(Zr0.2Ti0.8)O3 thin films

“…The key difference is therefore the overall higher initial population of oxygen vacancies, determined by the choice of substrate. 22 As schematically shown in Fig. 4(b), this higher population of oxygen vacancies in as-grown PZT STO allows the formation of a domain wall conducting channel through the film.…”

“…We note that our previous studies on perovskite ferroelectrics 20,21 showed no significant differences in the structural or the functional properties between films grown on the same substrates by the two different methods, making the choice of substrate the defining parameter in our study. We could therefore compare domain wall transport in samples with very different oxygen vacancy densities and substrate chemical properties 22 but similar high crystalline 23,24 and surface quality.…”

Nanoscale studies of ferroelectric domain walls as pinned elastic interfaces

“…Epitaxial ferroelectric films grown on these two substrates show very different disorder as a result of the superior crystalline quality of Czochralski-grown DyScO 3 , with significantly fewer dislocations than Verneuil-grown SrTiO 3 , and of the high chemical activity of SrTiO 3 substrates during growth, leading to increased densities of oxygen vacancies [148]. Extracting domain growth dynamics from measurements of domain radius as a function of writing time in the films allows qualitatively similar creep motion to be observed in both ultrahigh vacuum and ambient conditions.…”