The pulse Sn-assisted growth promotes the preparation of high-quality single-crystal ε-Ga2O3 films using MOCVD technology.

The single crystal ε-Ga2O3 thin films were successfully grown on c-plane sapphire substrates using metal-organic chemical vapor deposition (MOCVD). By employing the pulse method to introduce Sn as a growth adjuvant, the issue of phase mixing between β and ε phases, which commonly occurs when high-purity oxygen is used as the oxygen source in MOCVD, was effectively resolved. The physical phase composition, film surface quality and thickness of the epitaxial films of three sets of samples (not Sn, pulse Sn, direct Sn) were characterized using X-ray diffractometer, atomic force microscope and scanning electron microscope. High-quality ε-Ga2O3 single-crystal thin films were obtained under the conditions of Sn-assisted growth using the pulse method, resulting in a 51 % increase in the epitaxial growth rate. Elemental analysis through X-ray photoelectron spectroscopy, combined with Gibbs free energy changes, that insight into the role of elemental Sn in the reaction. Through comparison and analysis, it was found that pulsed Sn is more fully involved in the reaction and plays a more efficient role than the direct Sn. The concentration of elemental Sn in the epitaxial film was analyzed using SIMS tests, from the substrate interface to the surface of the film, the Sn element exhibited a gradual accumulation toward the surface. The microstructures of the different samples were compared by transmission electron microscopy. Additionally, the reason that Sn elements promote the formation of ε-Ga2O3 single crystal was explained from the perspective of structure.