Luminescence properties of InGaN-based dual-wavelength light-emitting diodes with different quantum-well arrangements

Optimized dual-wavelength InGaN-based vertical light-emitting diode (LEDs) structures were investigated by numerical simulations. The results show that different quantum-well arrangements in the active region play an important role in obtaining dual-wavelength emission. It is a better way to obtain the dual-wavelength with uniform intensity by arranging quantum wells (QW) with low indium content near the p-side and the QW with high indium near the n-side. This is because the QWs with lower indium near the p-side layer have higher hole-injection efficiency. On the other hand, arranging QW with high indium content near the p-side leads to poor hole-injection efficiency due to the high polarization fields. The physical and optical mechanisms of these phenomena were explained by the intensity of electrostatic fields, energy-band diagrams, and carrier-concentration distribution in the active region of LEDs.