Fully funded thesis at CEA. We are looking for a motivated candidate with a strong background in solid state physics. A visit of the lab and the discussion of the project to adapt to the candidate’s interest is possible. The project is in collaboration with international labs where scientific stays might be arranged during the thesis. Summary : Light Emitting Diodes (LEDs) made of nitride materials are universally used for energy-efficient lighting. They however suffer from a drastic drop in efficiency at high current densities and high indium concentrations (for green or red emission), which are obstacles to extending their use. The thesis aims at identifying the role of defects and spatial heterogeneities on loss processes with respect to radiative recombination. The main experimental technique is low energy electron microscopy.