Shockley-Read-Hall recombination and efficiency droop in InGaN/GaN multiple-quantum-well green light-emitting diodes

The influence of Shockley-Read-Hall (SRH) non-radiative recombination on efficiency droop is investigated for two similar InGaN/GaN multiple-quantum-well green light-emitting diodes (LEDs) with quite different luminescence efficiency. The high-efficiency diode exhibits a pronounced efficiency peak followed by a significant droop as injection current increases, while the low-efficiency sample shows a relatively small droop. Combining with the recombination rate equations, our analysis reveals that, in comparison with the high-efficiency sample, in the low-efficiency diode the injected carrier density in InGaN well layers is decreased at high currents due to the strong SRH process, leading to an apparently reduced droop. This may be a possible physical mechanism responsible for the linkage between the low efficiency and the small efficiency droop