LAUSR

Abstract We studied the optical and crystal properties of semipolar (11-22) hexagonal epitaxial lateral overgrown (HELO) GaN films with different SiO2 hexagonal pattern widths (6–15 μm). With increasing SiO2 hexagonal pattern width, it was difficult to achieve coalescence and planarization of the semipolar HELO-GaN film. Furthermore, the surface root mean square roughness of the semipolar (11-22) HELO-GaN film increased with the increasing SiO2 hexagonal pattern width. With the increasing SiO2 hexagon pattern width, the full width at half maximum (FWHM) of the X-ray rocking curve (XRC) toward [1-100] decreased from 1474 to 721 arcsec, but the FWHM of XRCs toward [11-2-3] decreased to 9 μm, and then, increased with the SiO2 pattern width (> 12 μm). However, the PL intensity of the semipolar HELO-GaN film increased with the SiO2 hexagonal pattern width. From the findings of this study, we believe that the optical and crystal properties of the semipolar (11-22) HELO-GaN film would be significantly affected by the SiO2 hexagonal pattern width because of the friction between the GaN and SiO2 pattern during the coalescence and planarization step.