Heteroepitaxial growth of thick α-Ga2O3 film on sapphire (0001) by MIST-CVD technique

The 8 mu m thick single-crystalline alpha-Ga2O3 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-halfmaximum (FWHM) of rocking curves for the (0006) and (10-14) planes are 0.024 degrees and 0.24 degrees, and the corresponding densities of screw and edge dislocations are 2.24 x 106 and 1.63 x 109 cm(-2), respectively, indicative of high single crystallinity. The out-of-plane and in-plane epitaxial relationships are [0001] alpha-Ga2O3//[0001] alpha-Al2O3 and [11-20] alpha-Ga2O3//[11-20] alpha-Al2O3, 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 alpha-Ga2O3 epilayer. The achieved high quality alpha-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.