III-nitride light-emitting diodes (LEDs) are key devices for next-generation solid-state lighting and micro-LED displays. Achieving efficient emission at long wavelengths, particularly in the red spectral range, remains a major challenge. Using a novel experimental approach (STLM) that combines optical spectroscopy with the spatial resolution of scanning tunneling microscopy, we recently revealed how the inclusion of so-called V-defects can result in improved LED efficiencies. Unfortunately, V-defects form naturally at threading dislocations and are therefore randomly distributed, limiting the control that can be achieved over the resulting device architecture. In the framework of a multi-partner, ANR-funded project, we propose a new approach based on III-nitride LEDs grown on intentionally macro-structured substrates. We propose an internship (then funded PhD) project in which the candidate will have the responsibility of performing STLM measurements on macro-structured LEDs fabricated by our colleagues as part of a fully-funded ANR project. The principal objective of the work will be to establish a fundamental understanding of charge injection, transport and recombination in these operational, macro-structured LEDs.