New evidence for electron leakage in GaN-LEDs
Using a novel experimental technique, Korean scientists provide new insight into the efficiency loss (droop) in GaN-based light emitting diodes (LEDs). This droop phenomenon puzzles countless researchers around the world for more than a decade. The scientists employed scanning thermal microscopy to measure the temperature profile across the epi-layers of an operating GaN-LED. Featuring nanoscale resolution, the measurement shows a hot spot which moves from the active layers towards the p-doped side of the LED with rising current, accompanied by increasing efficiency droop. The authors conclude that electron leakage into the p-doped side becomes the main cause of the droop at high current, while Auger recombination inside the active layers dominates only at low current.
 E. Jung et al., Applied Physics Letters 106, 041114 (2015).