Thick α-Ga 2 O 3 Layers on Sapphire Substrates Grown by Halide Epitaxy

This work reports on the epitaxial-film growth and characterization of a new wide-gap semiconductor α-Ga 2 O 3 . Layers are deposited by chloride vapor phase epitaxy on sapphire substrates with a basal orientation. The thickness of the layers of the investigated samples is from 0.5 μm to a value of 10 μm, the latter being record-breaking for today. The structural and optical properties of the obtained samples are studied. It is shown that all samples are structurally uniform, single phase, and have an R 3̅ c corundum-like structure similar to that of the sapphire used as the substrate. It is shown that the full-width at half-maximum of the rocking curves for the (0006) reflection of α-Ga 2 O 3 changes with the layer thickness and approaches 240 arcsec for the thickest layers. Both thin and thick layers are transparent in the visible and UV (ultraviolet) spectral range up to an absorption edge at 5.2 eV.