Heteroepitaxial growth of thickα-Ga2O3film on sapphire (0001) by MIST-CVD technique

The 8 μ m thick single-crystalline α -Ga 2 O 3 epilayers have been heteroepitaxially grown on sapphire (0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-half-maximum (FWHM) of rocking curves for the (0006) and (10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 10 6 and 1.63 × 10 9 cm −2 , respectively, indicative of high single crystallinity. The out-of-plane and in-plane epitaxial relationships are [0001] α -Ga 2 O 3 //[0001] α -Al 2 O 3 and [11-20] α -Ga 2 O 3 //[11-20] α -Al 2 O 3 , respectively. The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α -Ga 2 O 3 epilayer. The achieved high quality α -Ga 2 O 3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.