Comparison of blue and green InGaN/GaN multiple-quantum-well light-emitting diodes grown by metalorganic vapor phase epitaxy

InGaN/GaN multiple-quantum-well (MQW) blue and green-light-emitting diodes (LEDs) were grown on sapphire substrates using metalorganic vapor phase epitaxy. High-resolution transmission microscopy shows that a much larger density of stacking faults exist in the quantum-well region of the blue LEDs than in the green LEDs. In the green LEDs, the blueshift in the electroluminescence (EL) emission energy at larger driving currents is more prominent than in the blue LEDs, which is explained by different strength of quantum confined Stark effect as a result of different piezoelectric field intensity by different scales of strain relaxation in the blue and green MQWs. The steady broadening of the EL emission energy linewidth on the higher energy side with the increase of the driving current was observed in both blue and green LEDs, which is attributed to the band filling effect. (c) 2005 American Institute of Physics.