Advanced electron backscatter diffraction applied to the characterisation of nanostructured nitride materials

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The advanced scanning electron microscopy (SEM) technique of electron backscatter diffraction (EBSD) provides information on the structural properties of materials rapidly and non-destructively with a spatial resolution of tens of nanometers. In particular, the interpretation of the acquired EBSD patterns allows crystallographic orientation, crystal structure and strain distribution across a sample to be mapped. Such information is derived from EBSD patterns acquired for each point on a map. An EBSD pattern comprises overlapping Kikuchi bands which are projections of the planes of the crystal under investigation. Presently commercial software mainly exploits the position of these bands to determine crystallographic information. The application of the EBSD technique could be significantly expanded if subtle changes in the intensity of the Kikuchi bands are exploited. This may be achieved by comparing experimental EBSD patterns with many-beam dynamical simulated patterns. To date, in collaboration with colleagues at Bruker Nano, we have demonstrated that it is possible to map anti-phase domains in GaP and have determined the polarity of GaN nanorods. This project will expand on this work to enable for example the orientation, crystal structure and polarity of arrays of nanorods to be mapped. It will also develop and explore the application of new direct electron detectors and next generation simulation software to investigate structural defects in nanostructured nitride materials.