Technique to evaluate the diode ideality factor of light-emitting diodes

A photoluminescence technique has been demonstrated on InGaN/GaN light-emitting diodes (LEDs) to evaluate their diode ideality factors. Selectively excited active regions produce potential differences between two contact terminals in addition to luminescence, from which the rate of recombination and terminal voltage have been related. Obtained ideality factors on commercial LEDs were between 1.1 and 2.4, which were significantly smaller than values determined via current–voltage characteristics. The ideality factor has been discussed from the viewpoint of direct-band-gap light-emitting pn junctions, and the notion that quantum-well structure takes over the role of the recombination plane introduced by the Sah–Noyce–Shockely analysis is proposed.