Within this paper, we summarize some of the degradation mechanism that still affect GaN-based optoelectronic devices. The most common source of the degradation is the creation of lattice defects, which lower the optical efficiency due to their role as non-radiative recombination centers, as proven in the case of UV-B LEDs. The local generation of defects is not the only possibility, with diffusion of impurities (possibly hydrogen from the p-side) being shown to be the limiting factor in the case of green laser diodes. Under extreme bias conditions, such as the EOS events, the robustness of the current carriers and spreading structures is critical, as shown by failure of bonding wires, metal lines and vias in white LEDs. In every optoelectronic device photons themselves possess an energy at least equal to the bandgap, and can be an additional source of degradation that cannot be eliminated.
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