Exploiting kinetics and thermodynamics to grow phase-pure complex oxides by molecular-beam epitaxy under continuous codeposition

We report the growth of PbTiO3 thin films by molecular-beam epitaxy utilizing continuous codeposition. In addition to the requirements from thermodynamics, whether the resulting film is single-phase PbTiO3 or not at a particular temperature depends strongly on the film growth rate and the incident fluxes of all species, including titanium. We develop a simple theory for the kinetics of lead oxidation on the growing film surface and find that it qualitatively explains the manner in which the adsorption-controlled growth window of PbTiO3 depends on lead flux, oxidant flux, and titanium flux. We successfully apply the kinetic theory to the dependence of the growth of BiFeO3 on oxidant type and surmise that the theory may be generally applicable to the adsorption-controlled growth of complex oxides by MBE.