Fig. 2

A high-resolution z-stack imaging sequence through MOCVD epitaxial layers grown on an am-GaN substrate. Images (a–e) are taken with focal depth increments of 2.5 μm through the epitaxial layers to the top of the bulk am-GaN substrate while (f–j) are taken every 25 μm within the bulk am-GaN substrate. Approximate scan locations are shown in k).