Effects of Current Spreading in GaN-based Light-emitting Diodes Using ITO Spreading Pad

Abstract

Abstract-In conventional LEDs, a mesa-structure is usually used and it causes the current to be overcrowded in a specific region. We propose a novel structure of GaN-based LED to overcome this problem. In order to distribute the current in an active region, a spreading pad is inserted at the p-type region in the GaN based LED device. The inserted spreading pad helps the current flow because it is more conductive than the p-type GaN layer. By performing electrical and optical simulations, the effects of the spreading pad insertion are confirmed. The results of electrical simulation show that the current spreads more uniformly and more radiative recombination is produced as well. Moreover, from the optical simulation, it is revealed that the ITO is less absorptive material than p-GaN if the condition of specific wavelength sources is satisfied. Considering all of the results, we can conclude that the luminescent power is enhanced by the spreading pad.

Coupled thermo–electrical analysis of highly scaled GaN micro-LEDs with meshed hybrid conductors

“…However, many structural, physical, and thermo-electrical hurdles remain to be addressed before GaN-based micro-LED displays can become an effective solution. First, the lighting efficiency of highly scaled GaN microstructures is severely limited by current crowding and constrained current spreading [12][13][14][15]. Many previous studies have reported a drastic lowering of internal quantum efficiency as the GaN device scales below 50 µm pitch [16][17][18].…”