Green InGaN/GaN based LEDs: high luminance and blue shift

Abstract : We report in this paper electro-optical results on InGaN/GaN based green micro light-emitting diodes (µLEDs). Current-light-voltage measurements reveal that the external quantum efficiency (EQE) behavior versus charge injection does not follow the ABC model prediction. Light-emission homogeneity investigation, carried out by photoluminescence mapping, shows that the Quantum Confinement Starck Effect (QCSE) is less significant at the edges of µLEDs. Electroluminescence shows a subsequent color green-to-blue deviation at high carrier injection levels. The extracted spectra at different current injection levels tend to show the appearance of discrete wavelength emissions. These observations may enhance the hypothesis that higher-energy excited-levels in InGaN quantum wells may also contribute to the blue shift, solely attributed to QCSE lessening under intense electric field magnitudes. We hereby present first results dealing with green µLEDs electro-optical performances with regards to their size.