Crystal Orientation of GaN Nanostructures Grown on Al₂O₃and Si(111) with a Zr Buffer Layer

We studied the crystallographic orientation of GaN nanostructures grown on Si(111) and Al 2 O 3 substrates. We evaluated Zr metal as a novel alternative to conventional buffer layers such as AlN and ZnO. One-dimensional structures (nanorods and nanoneedles) were grown by hydride vapor phase epitaxy at 650 and 600 °C, and investigated using field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis. FE-SEM images showed that the GaN nanorods had a uniform diameter along the growth direction. XRD results indicated that the nanostructures had a hexagonal crystal structure, and pole figure measurements revealed that GaN nanostructures grown on the Si(111) substrate had a stronger c -axis crystallographic orientation than those grown on the Al 2 O 3 substrate.