Inhomogeneous incorporation of In and Al in molecular beam epitaxial AlInGaN films

Plasma-induced molecular beam epitaxial AlInGaN heterostructures have been characterized by spatial resolved cathodoluminescence and x-ray energy disp ersive microanalysis. Competitive incorporation of Al and In has been obser ved, with the formation of In-rich regions, showing enhanced luminescence a round surface pinholes. These island-like In-rich regions are favored by gr owth at lower temperature due to the higher incorporation of indium into th e alloy. The elastic strain relaxation associated to pinhole formation indu ces preferential local indium incorporation. The diffusion of carriers to t hese areas with reduced band gap enhances the luminescence emission of the quaternary film. The width and intensity of the luminescence appear to be s ensitive to the mismatch between the quaternary film and the GaN layer belo w. (C) 2001 American Institute of Physics.