Evolution of crystal imperfections during current-stress ageing tests of green InGaN light-emitting diodes

Abstract

We perform ageing tests under high current on several green InGaN light-emitting diodes and compare the luminous homogeneities of chip surfaces, shapes of external quantum efficiency (EQE) curves, and electroluminescence spectra during different ageing stages. By curve fittings to the EQE curves, with the ABC and two-level models, we discover that a high injection current density can modify the defect configuration in quantum wells even at room temperature, as high-temperature annealing can. For In-rich devices, the removal of localization centers is another origin of luminous intensity decay in addition to the formation of point defects.