Impact of Localization on the Optical Properties of InGaN-Based Red Light-Emitting Diodes Grown on a Silicon Substrate

The electroluminescence (EL) and photoluminescence (PL) of InGaN-based red light-emitting diodes (LEDs) grown on a silicon substrate have been investigated over a wide range of temperatures. At cryogenic temperatures, carrier localization in shallow potential energy minima limits radiative recombination and reduces the external quantum efficiency (EQE) of InGaN-based red LEDs, and thermal hopping of carriers from the shallow potential minima to the potential energy valley contributes to alleviation of carrier leakage from localization. The EL properties of InGaN-based red LEDs can be significantly affected by localization-induced recombination in the QW adjacent to the p-GaN layer. Since the significant differences between EL and PL on the temperature dependence of quantum efficiency, the EL internal quantum efficiency (IQE) of InGaN-based red LEDs cannot be adequately determined by the traditional temperature-dependent PL method, in which the IQE is assumed to be unity at the lowest measured temperature.