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Warrington, United Kingdom

Rigutti L.,CNRS Material Physics Group | Mancini L.,CNRS Material Physics Group | Hernandez-Maldonado D.,CNRS Material Physics Group | Hernandez-Maldonado D.,SuperSTEM STFC Daresbury Laboratories | And 7 more authors.
Journal of Applied Physics | Year: 2016

The ternary semiconductor alloy Al0.25Ga0.75N has been analyzed by means of correlated photoluminescence spectroscopy and atom probe tomography (APT). We find that the composition measured by APT is strongly dependent on the surface electric field, leading to erroneous measurements of the alloy composition at high field, due to the different evaporation behaviors of Al and Ga atoms. After showing how a biased measurement of the alloy content leads to inaccurate predictions on the optical properties of the material, we develop a correction procedure which yields consistent transition and localization energies for the alloy photoluminescence. © 2016 AIP Publishing LLC. Source


Mancini L.,CNRS Material Physics Group | Hernandez-Maldonado D.,CNRS Material Physics Group | Hernandez-Maldonado D.,SuperSTEM STFC Daresbury Laboratories | Lefebvre W.,CNRS Material Physics Group | And 7 more authors.
Applied Physics Letters | Year: 2016

The optical properties of m-plane InGaN/GaN quantum wells grown on microwire sidewalls were investigated carrying out a correlative scanning transmission electron microscopy (STEM), atom probe tomography (APT), and micro-photoluminescence study applied on single nanoscale field-emission tips obtained by a focused ion beam annular milling. Instead of assuming simple rectangular composition profiles, yielding misleading predictions for the optical transition energies, we can thus take into account actual compositional distributions and the presence of stacking faults (SFs). SFs were shown to be responsible for a lowering of the recombination energies of the order of 0.1 eV with respect to those expected for defect-free quantum wells (QWs). Such energy reduction allows establishing a good correspondence between the transition energies observed by optical spectroscopy and those calculated on the basis of the QWs In measured composition and distribution assessed by STEM structural analysis and APT chemical mapping. © 2016 AIP Publishing LLC. Source

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