Three-dimensional nanoscale structure of novel nitride materials and devices

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The Cambridge Centre for Gallium Nitride is developing a range of photonic devices which exhibit complex three-dimensional structure. These include micro- and nano-cavities for the confinement of light and the exploration of light matter interactions. Furthermore, we are developing nanoporous gallium nitride and incorporating it into a range of photonic architectures.For these photonic device developments to succeed, it is vital that we fully understand the three-dimensional (3D) structure of these materials and devices at the nanoscale, and this represents an exciting and challenging microscopy problem. Structural insights will be incorporated into models of materials and device properties to understand what structural factors enhance or limit the performance of photonic devices and to drive the future development of improved fabrication techniques.The overall aim of the PhD project is to develop and apply microscopy techniques which allow the three-dimensional characterisation of nanostructured semiconductor samples including not only meso-porous semiconductors, but also lithographically defined photonic and electronic micro- and nanostructures, such as photonic crystals. Both electron tomography (in the transmission electron microscope) and slice-and-view imaging (in the focussed ion beam scanning electron microscope) will be explored. Three-dimensional imaging data will be combined with finite element modelling to predict the impact of the observed nanostructure on materials properties and/or device performance.