Simultaneous composition and cathodoluminescence spectral mapping of III-nitride structures

Gallium nitride based structures have been characterised using the novel approach of simultaneous wavelength-dispersive X-ray microanalysis and cathodoluminescence spectral mapping. Details are presented of the instrumentation developed to carry out such measurements. Application of the technique to MOVPE-grown indium gallium nitride epilayers shows microscopic variations in the indium content, which correlate directly with spatially-dependent shifts observed in the peak wavelength of the luminescence spectrum. Regions of higher indium content are shown to emit at lower energy, mirroring equivalent macroscopic observations