Time-resolved electro-luminescence studies of InGaN blue LEDs with chip size variations

In this study, we report carrier dynamics of three InGaN Blue LEDs with three chip sizes by time‐resolved electroluminescence (TREL) measurements. Experiments results show that the sample with the largest chip size has the smallest EL width and longest response time among the three samples. It implies that the current spreading for larger chip size need more time. It is partially attributed to the fact that carrier relaxation into the strongly localized states (high‐indium clusters) need more time. Furthermore, the long decay times are due to the carrier recombination from the deep trapped localization states and/or the high defect density inside the samples. Also, the decay times of the three samples are nearly independent of the chip size and applied voltage. This implies that the sum densities of localization states and defects of the three samples have nearly the same order of magnitude. By reducing the density of the defects, the quantum efficiency of the LEDs can be increased at least by a factor of 10. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)