Quantum-confined Stark effects in the m-plane In_0.15Ga _0.85N/GaN multiple quantum well blue light-emitting diode fabricated on low defect density freestanding GaN substrate

Quantum-confined Stark effects (QCSEs) in a polarization-free m -plane In0.15 Ga0.85 NGaN multiple quantum well (MQW) blue light-emitting diode fabricated on the low defect density (DD) freestanding GaN substrate were investigated. The electroluminescence (EL) peak at 2.74 eV little shifted to the higher energy with the increase in current because of the absence of the polarization fields. The effective radiative lifetime increased and the nonradiative lifetime decreased with the increase in the junction field, and the results were quantitatively explained in terms of field-induced QCSE including tunneling escape of holes from the MQW. As a result of the use of the low DD substrate, the equivalent internal quantum efficiency, which was approximated as the spectrally integrated EL intensity at 300 K divided by that at 150 K, of 43% was achieved.