Optical Investigations of AlGaN on GaN Epitaxial Films

We have investigated Al x Ga l-x N/GaN heterostructures (0 x Ga l-x N films induce additional compressive strain on the underlying GaN film. Compositional inhomogeneities are present, but the fluctuations are too small to be important for carrier localisation. The broadening of the luminescence line width in the alloy can be described by statistical disorder of a random alloy.