A low-energy electron diffraction (LEED) Patterson function (PF) with multiple incident angles is used to obtain three-dimensional interatomic information of hexagonal GaN(0001) grown on a $6H-\mathrm{SiC}\mathrm{}\left(0001\right)-\sqrt{3}\times \sqrt{3}$ surface. A Ga-Ga atomic pair between the Ga adlayer and the terminating Ga layer is observed in the LEED PF. This provides direct experimental evidence to support the structural model proposed by first-principles calculations. The LEED PF also shows that the GaN film has a hexagonal structure and the surface has single-bilayer steps.

• Received 18 September 2002

DOI:https://doi.org/10.1103/PhysRevB.67.125409