Reflectivity study of hexagonal GaN films grown on GaAs: surface roughness, interface layer, and refractive index

Comprehensive reflectivity investigations were performed on hexagonal GaN films grown by molecular beam epitaxy on GaAs substrates in the energy range of 1.4 to 3.8 eV at room temperature. Findings indicate that the reflectivity is strongly affected by a surface roughness. Also, the optical data indicate the development of an interface layer between the film and the substrate which is in agreement with findings from transmission electron microscopy studies.