Suppression of electron overflow and efficiency droop in N-polar GaN green light emitting diodes

In this letter, we experimentally demonstrate direct correlation between efficiency droop and carrier overflow in InGaN/GaN green light emitting diodes (LEDs). Further, we demonstrate flat external quantum efficiency curve up to 400 A/cm(2) in a plasma assisted molecular beam epitaxy grown N-polar double quantum well LED without electron blocking layers. This is achieved by exploring the superior properties of reverse polarization field of N-face polarity, such as effective carrier injection and higher potential barriers against carrier overflow mechanism. The LEDs were found to operate with a low (similar to 2.3 V) turn-on voltage. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3694967]