Wafer-scale heteroepitaxy of Sn-alloyed <b>ε</b> -Ga2O3 on sapphire via low-pressure mist-CVD

The industrial deployment of metastable ε-Ga2O3 on sapphire is currently impeded by intrinsic crystallographic incompatibility and the difficulty of achieving macroscopic homogeneity via solution-based growth techniques. Here, we present a Sn-mediated lattice engineering approach to resolve these limitations using a scalable low-pressure mist-chemical vapor deposition system. Beyond its conventional role as a dopant, we demonstrate that heavy Sn alloying effectively modulates the cation sublattice, promoting the randomization within the Pna21 rotational domains and reducing the overall symmetry of the orthorhombic framework. This symmetry regulation significantly mitigates the lattice misfit with the substrate, reducing the (004) x-ray rocking curve full-width at half-maximum to 0.045° (162 arc sec). Transmission electron microscope investigations indicate a rapid lattice recovery mechanism, where initial interfacial disorder is effectively suppressed within a few nanometers. Furthermore, we demonstrated highly consistent wafer-level growth, realizing a thickness deviation of merely ∼2 nm across a 2-in. wafer for a ∼60 nm thick epitaxial film. This work identifies Sn-alloyed ε-Ga2O3 as a versatile and high-fidelity template, offering a simplified single-source route for the scalable manufacturing of next-generation power electronics.