Time-resolved photoluminescence studies of InGaN/GaN multi-quantum-wells blue and green light-emitting diodes at room temperature

Time-resolved photoluminescence (TRPL) of the blue and green LEDs, which has the same number of quantum-well (QW) pairs and the different etched depths, has been studied at room temperature. The purpose is to analyze the effect of different indium (In) content and defects density on TRPL. The carrier lifetime of radiative recombination and non-radiative for blue LED (In = 0.15) is 625.0 ns and 55.6 ns, and for green ones (In = 0.21), the figure is 363.6 ns and 35.0 ns. The carrier lifetime is reduced along with the increasing of In-component. As the etched depth deepened of blue LED, the non-radiative recombination lifetime tends to infinity. When it comes to low indium content, the PL spectra present a blue shift. With the increasing of indium mole fraction, the blue shift appeared at first, and then a red shift has been observed. And the spectral shift has disappeared, while etching the LEDs. At last, we clarify the results, through the band bending caused by polarization electric field.