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Epitaxial growth of complex oxides on large-area wafers, such as sapphire and silicon, represents a key step toward scalable oxide device production. Solid phase epitaxy allows the synthesis of γ-Al2O3 on α-Al2O3 and provides a template with a matched lattice constant and appropriate cubic symmetry for subsequent heteroepitaxial growth of perovskite complex oxides. Nb-doped SrTiO3 thin films were deposited epitaxially on (111)-oriented γ-Al2O3 intermediate layers on (0001) c-axis-oriented sapphire α-Al2O3 crystals using pulsed laser deposition. The Nb:SrTiO3 thin films with a thickness of 53 nm, grown at 700 °C on γ-Al2O3, reached fully relaxed lattice parameters and were epitaxially oriented with respect to the substrate. Nb:SrTiO3 layers deposited using identical deposition conditions directly on α-Al2O3, without the γ-Al2O3 intermediate layer, were polycrystalline. The sheet conductivity of Nb:SrTiO3 grown on γ-Al2O3/α-Al2O3 is more than ten times higher than that of Nb:SrTiO3 grown directly on α-Al2O3 without the γ-Al2O3 layer. The results point to new directions for the integration of (111)-oriented pseudocubic perovskite complex oxides and the integration of epitaxial complex oxides over larger areas using α-Al2O3 single-crystal substrates.