Compositional analysis of AlInGaN quaternary layers grown by metalorganic vapour phase epitaxy

Using wavelength dispersive X-ray spectrometers on an Electron Probe Micro-Analyser we have accurately quantified the elemental composition of a series of homogeneous AlInGaN epitaxial layers. The thickness of the quaternary layer (∼100 nm) necessitates the combination of data measured at a number of different electron beam energies and an analytical model based on a layered structure. The samples studied have aluminium fractions in the range 0.03-0.12 and indium fractions in the region of 0.01. Photoluminescence data from the samples are used to plot the dependency of the luminescence energy, linewidth and intensity on the composition. WDX mapping was employed to investigate spatial variations in the elemental compositions and the films were found to be uniform with no evidence for clustering of In or Al on a >100 nm scale.