Phase tailoring and wafer-scale uniform hetero-epitaxy of metastable-phased corundum α-Ga2O3 on sapphire

•The scale-up epitaxy of high quality α-Ga2O3 on large-sized sapphire substrates is realized in a home-made mist-CVD system with a vertical hot-wall cylinder reactor.•The pure phase α-Ga2O3 single-crystalline epilayers with atomic smooth surface and low dislocation density was achieved through temperature-controlled phase engineering.•Realization of the scale-up epitaxy of high quality α-Ga2O3 on 2-inch sapphire substrates.•Phase tailoring of Ga2O3 epilayers with optimal growth temperature.