Current crowding effect on the ideality factor and efficiency droop in blue lateral InGaN/GaN light emitting diodes

By examining two types of lateral InGaN/GaN light emitting diodes with different contact patterns, we demonstrate that in the intermediate range of current where the space-charge region dominates in the device performance, the ideality factor (β) increases from 1.9 (current spreading design) up to 2.4 (current crowding design). This modification of β-factor could be erroneously treated as the change of free carrier recombination nature. The current crowding design is also responsible for the local overheating and heavier efficiency droop that occurs at the characteristic current 2.3 times smaller in comparison with the current spreading design.