Polycrystalline κ-Ga₂O₃ on Si(100) substrates with GZO buffer layers

Kappa-phase gallium oxide (κ-Ga₂O₃) is an emerging piezoelectric semiconductor with potential applications in radio-frequency devices. However, heteroepitaxial growth of κ-Ga₂O₃ on silicon substrates remains challenging owing to large lattice mismatch and interfacial oxidation. This study demonstrates the growth of polycrystalline κ-Ga₂O₃ thin films deposited by mist chemical vapor deposition (mist CVD) on Si(100) substrates using Ga-doped ZnO (GZO) buffer layers. Structural characterization via X-ray diffraction, scanning electron microscopy, and transmission electron microscopy reveals that κ-Ga₂O₃ films exhibit a c-axis oriented polycrystalline structure with random in-plane orientations, which yields isotropic properties that are advantageous for device applications. A ZnGa₂O₄ intermediate layer is identified at the κ-Ga₂O₃/GZO interface, which plays a critical role in phase stabilization. These findings indicate that polycrystalline κ-Ga₂O₃ on Si substrates represents a promising platform for piezoelectric semiconductor devices.