Internal Quantum Efficiency of Nitride-based Light-Emitting Diodes

The internal quantum efficiency (IQE) of InGaN-based light-emitting diodes has been studied by means of excitation-power-density- and temperature-dependent photoluminescence spectroscopy. The IQE was evaluated at various excitation photon energies using a wavelength-tunable dye laser system. The IQE obtained under selective excitation of InGaN active layers was higher than that obtained under band-to-band excitation of GaN and AlGaN cladding layers. The enhanced value of IQE under selective excitation reflected the intrinsic optical quality of the InGaN active layer itself.