Morphology investigation of MOVPE homoepitaxial (001) β-Ga2O3 growth on on-axis and 6° off-axis substrates

The morphology of the (001) β-Ga ₂ O ₃ homoepitaxially grown film on on-axis and 6° off-axis toward [1̅00] substrates by metalorganic vapor phase epitaxy (MOVPE) were investigated by adjusting Ga supersaturation via molecular flow rate O ₂ /Ga-ratio. The growth conditions were guided by the step-flow growth model previously established for (100) β-Ga ₂ O ₃ film growth with a 4° off-axis miscut toward [001̅]. The intentional miscut in (001) β-Ga ₂ O ₃ substrate was found to facilitate the groovy morphologies, but may not preclude the (4̅01) twins, while increasing Ga supersaturation leads to groovy morphologies for the grown film on off-axis (001) substrates and islands formation for grown film on on-axis (001) substrates at 800 °C; however, only the multi-step arrays have been obtained in the grown film on on-axis (001) substrates at 700 °C with the same Ga-supersaturation ranges, indicating an island suppression. An anisotropic kinetic growth model was introduced to explain the observed groove directions. These morphologies may be partially attributed to the (100) twin plane.