Abstract
With a wide bandgap of 5.4 eV, α-Ga2O3 is a promising material for high-breakdown power devices and solar-blind photodetectors but is difficult to grow due its metastability. Sapphire, being isostructural to α-Ga2O3, is therefore the substrate of choice to stabilise epitaxial layers of α-Ga2O3. Since each sapphire plane imposes different surface energy and strain conditions on the epitaxial layer, the choice of substrate orientation is critical to the stabilisation of α-phase. In this work, Ga2O3 thin films were deposited simultaneously on (11-20), a-plane, (10-10) m-plane, (0001) c-plane, and (01-12) r-plane sapphire substrates using metal-organic chemical vapour deposition (MOCVD), and XRD analysis was performed to confirm the resultant phase of Ga2O3 on each plane. We found that, under the same conditions, Ga2O3 assumed β phase on c-plane, mixed phase α & β on a-plane and r-plane, and pure α phase on m-plane. These results indicate that m-plane is most conducive to growing phase-pure α-Ga2O3 layers via MOCVD, and could open opportunities for future device manufacturing.
