Crystal orientation of GaN layers on (10 1 0) m ‐plane sapphire

Based on the atomic arrangement of the $(10{\bar {1}}0)$ m ‐plane sapphire surface, we have developed a model for the initial nucleation process of gallium‐nitride (GaN). This model describes why $(11{\bar {2}}2)$ and $(10{\bar {1}}{\bar {3}})$ are the preferred orientations of GaN on the $(10{\bar {1}}0)$ sapphire. The experimental results from high‐resolution X‐ray diffraction measurements, like the crystallographic relations and the twinning of the $(1{\bar {1}}0{\bar {3}})$ orientation are explained by the model too. Our model also predicts that $(11{\bar {2}}2)$ thin films are metal‐polar and $(1{\bar {1}}0{\bar {3}})$ thin films are nitrogen‐polar.