Abstract

We report the growth of a GaN layer on a (101¯0) m-plane ScAlMgO4 (SAM) substrate. The GaN layer demonstrated (101¯3) preference growth orientation. The anisotropy of the crystalline quality was distinctly observed through an X-ray rocking curve (XRC) taken across the sample surface over various azimuths across the orthogonal directions [0001] and [12¯10] of the SAM substrate. Notably, the crystalline quality exhibited gradual degradation as the substrate was rotated around its surface normal away from the c-direction [0001] of the SAM substrate toward the a-direction [112¯0]. This degradation of the GaN layer was quantified by an increase in the XRC full width at half maxima for the (101¯3) XRC: starting from 1210 arcsec at 0° azimuth, deteriorating to its lowest crystallinity at 1512 arcsec at 60° azimuth, before a slight improvement to 1481 arcsec at 90°
azimuth, followed by a symmetrical repetition of this pattern. Additionally, basal stacking faults in the (101¯3)-oriented GaN were observed along the [0001] direction using scanning transmission electron microscopy. Moreover, the selected area electron diffraction analysis was utilized to confirm the (101¯3) growth orientation that was found to be consistent with the X-ray diffraction result. The c-direction of the (101¯3)-oriented GaN layer was determined and it exhibited a metal face through integrated differential phase contrast imaging.