First-principles calculations of surfactant-assisted growth of polar CaO(111) oxide film: The case of water-based surfactant

Abstract

Surfactant-assisted growth of polar CaO(111) oxide film in the presence of water-based surfactant is studied by first-principles calculations both from thermodynamic and kinetic point of view. We show that the water molecules not only supply a surfactant by depositing hydrogen on the surface throughout the growth process, but also supply oxygen atoms as an elemental constituent in the film growth with rather small energy barriers, i.e. water oxygen atoms are easily inserted in top surface layer of the growth film during wet oxidation process. Adding the water surfactants to conventional synthesis techniques leads to the continuous presence of hydrogen atoms in surface region during the growth process, which efficiently quenches polarity and dynamically stabilizes the growth of polar surface, and thus facilitates the growth of defect-free CaO(111) films with arbitrary thickness.2

Mesoscopic organization of cobalt thin films on clean and oxygen-saturated Fe(001) surfaces

“…(3) Allowing the growth of thin oxide films characterized by a polar termination, otherwise unstable because of the presence of a diverging electrostatic dipole [32,33]. (4) Extending the stability regime of epitaxy-stabilized metastable structures [34][35][36].…”

Screening mechanisms at polar oxide heterointerfaces

“…Furthermore, as it is clear that bulk oxides with polar surfaces must be charge compensated (at least on the macroscopic level) and growth on such a surface can propagate the polar discontinuity to another location (see, e.g. [23][24][25]), the nature of surface and interface screening can change dynamically and adapt based on the current reservoir of available charge either inside the heterostructures or near the surface from the ambient. The effects can be dramatic and lead to secondary phase formation: for example, Lazarov et al [26] observed the polarity-induced nucleation of metallic inclusions within an oxide film grown on MgO(1 1 1).…”

“…the redistribution of electronic defects [1-3, 41, 42], ionic defects [43][44][45][46], or both [4,5,47,48]) or external (e.g. the development of rough surfaces during growth [49], or the adsorption of compensating layers or foreign species, which can eliminate dynamic surface roughening [23][24][25]50]) to minimize the total electrostatic energy of the system. Regardless, much of the issues are similar, and the ability to manipulate the screening charges dynamically is of particular interest to all these communities.…”

“…Figure25. Schematic band diagram of the interface between a polar film and a nonpolar substrate along the normal direction z, at three different times.…”