High quality GaN films on miscut (1 1 1) diamond substrates through non-c orientation suppression

The GaN films are grown on 4° miscut to (1 1 0) and (1 0 0) orientation (1 1 1) diamond substrates by metal organic chemical vapor deposition respectively. The ordinary (1 1 1) diamond substrate is used as reference. The morphology and crystal quality of the three GaN films are characterized by atomic force microscope, scanning electron microscope, Raman spectra, photoluminescence, and X-ray diffraction (XRD). The GaN epilayer on miscut to (1 1 0) orientation (1 1 1) diamond presents a superior quality with smooth surface, clear A1(LO) peak of Raman shift and XRD rocking curve with full width half maximum of 1357 arcsec, which is a remarkable result reported. Through the analysis, we found that when GaN grows on miscut to (1 1 0) orientation (1 1 1) diamond substrates, non-c orientation grain would be greatly suppressed so that c orientation buffers easier to grow laterally and merge into thin films. The non-c orientation suppression process greatly improves the quality of GaN film on (1 1 1) diamond.