Optical Transitions Involving Excited States in III-nitride LEDs

The radiative transitions in InGaN-based LEDs grown by plasma assisted molecular beam epitaxy were studied. Electroluminescence spectra were collected for the LEDs with 2.6, 6.5, 7.8, 12 and 15nm thick QW in a broad current regime. The evolution of the emission spectra indicates changes in the nature of carrier recombination. Initially, carriers recombine through ground states, then through mixed transition and lastly only through exited states. Additionally, we modeled operation of the LEDs with self-consistent Schrodinger–Poisson simulations and showed that carrier density and differences in the magnitude of screening of the built-in field inside QWs are causing the change in the light emission.