High temperature diffusion enabled epitaxy of the Ti-O system

High temperatures promote kinetic processes which can drive crystal synthesis towards ideal thermodynamic conditions, thereby realizing samples of superior quality. While employing very high temperatures in thin-film epitaxy is becoming increasingly accessible through laser-based heating methods, demonstrations of such utility are still emerging. Here we realize a novel self-limited growth mode in the Ti-O system by relying on thermally activated diffusion of oxygen from oxide substrates. High growth temperatures exceeding 1,000 °C maximize the oxygen diffusion effect, enabling the titanium oxide epitaxy even without supplying oxidants into the growth chamber. In this diffusion-controlled growth regime, the oxidation state of the grown film depends primarily on temperature rather than background oxygen pressure. This leads to a diffusion-controlled growth window for single-phase films with superior crystallinity to conventional approaches as evidenced by structural and electrical measurements. The method is potentially of wide use in the growth of transition metal oxides, opening up new opportunities for ultra-high purity epitaxial platforms based on d-orbital systems.