Analysis of nonradiative recombination mechanisms and their impacts on the device performance of InGaN/GaN light-emitting diodes

We investigate the nonradiative recombination mechanisms of two conventional InGaN/GaN-based blue light-emitting diodes with different threading dislocation densities (TDDs). The current-voltage, the ideality factor, and the slope of the light-versus-current curve on log scales are analyzed to distinguish the dominant nonradiative recombination mechanisms at room temperature. Through the analysis, we infer the dominant nonradiative recombination mechanisms to be the Shockley-Read-Hall process for the sample with a low TDD (similar to 1 x 10(8)cm(-2)) and the defect-assisted tunneling for the sample with a high TDD (similar to 1 x 10(9)cm(-2)). For more detailed analysis of the nonradiative recombination mechanisms and their impacts on the device performance, we execute the temperature-dependent photovoltage and temperature-dependent electroluminescence efficiency experiments. The sample with a low TDD is found to be more prone to the carrier spill-over at cryogenic temperatures due to the deactivation of point defects, while the sample with a high TDD is more robust to the operation at cryogenic temperatures owing to the relative insensitiveness of the defect-assisted tunneling to temperature. (C) 2015 The Japan Society of Applied Physics