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/cm2 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 (∼2.3 V) turn-on voltage.