Simultaneous composition mapping and hyperspectral cathodoluminescence imaging of InGaN epilayers

Gallium nitride based structures have been characterised using the novel approach of simultaneous wavelength-dispersive X-ray microanalysis and cathodoluminescence spectral mapping (or hyperspectral imaging). 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 and with decreased intensity, mirroring equivalent macroscopic observations.