Yellow-green InGaN-based light emitting diodes with emission peak wavelength red shifts under low injection current

We investigate the optical and electrical properties of the yellow-green InGaN-based light-emitting diode (LED) with a InGaN/GaN short-period superlattice and width-modulation quantum wells as the strain-accommodative layer. It is found that the peak wavelength shifts from 568.4 nm at 20 mA to 584.8 nm at 100 mA. The peak intensity of EL spectra doubles when the driving current increases from 20 to 60 mA and decreases to 1.7 times at a driving current of 100 mA. These results are attributed to the state-filling effect and the quantum confined Stark effect (QCSE) of the InGaN/GaN active region are effectively inhibited by inserting the strain-accommodative structure proposed in this work. The bandgap renormalization effect remarkably dominates the EL properties and the heat effect occurs at a driving current over 60 mA.