Observation of Electroluminescence From Quantum Wells Far From p-GaN Layer in Nitride-Based Light-Emitting Diodes

We report the observation of electroluminescence from the first to fourth quantum wells (QWs) from the
p
-GaN layer in InGaN/GaN multiple-QW light-emitting diodes (LEDs) with various indium contents (4%-16%) in each QW. The investigated LED sample showed a lower turn-on voltage and ideality factor as well as a reduction of etching pit density compared with the reference sample. Also, the X-ray reciprocal space maps revealed a partial strain relaxation in the active region. The enhanced hole injection efficiency was attributed to the weakening of strain-induced polarization field in the QWs and the good crystalline quality.