Controlling oxide surface dipole and reactivity with intrinsic nonstoichiometric epitaxial reconstructions

Abstract

The composition and reconstruction of oxide surfaces can be deterministically controlled via ambient conditions. We demonstrate that such intrinsic alterations can have a crucial effect on the surface dipole and reactivity, even for surfaces with the same crystallographic plane. The surface dipole potential drops of ${\mathrm{BaTiO}}_{3},\phantom{\rule{0.16em}{0ex}}{\mathrm{SrTiO}}_{3},\phantom{\rule{0.16em}{0ex}}{\mathrm{LaFeO}}_{3}$, and ${\mathrm{TiO}}_{2}$ surfaces with various reconstructions and compositions are shown to vary by as much as 5 V, leading to significant variation of the band edge positions at these surfaces. These variations are shown to correlate with the calculated oxygen binding energy, demonstrating how oxide surface reactivity can be substantially manipulated using environmental changes.