Fabrication and Characterization of a GaN Light-emitting Diode (LED) with a Centered Island Cathode

Abstract

Uniform spreading of injection current in light-emitting diodes (LEDs) is one of the crucial requirements for better device performances. It is reported that non-uniform current spreading leads to low output power, high current crowding, heating, and reliability degradation of the LED device. This paper reports on the effects of different surface and electrode geometries in the LEDs. To increase the output power of LEDs and reduce the series resistance, a rectangular-type LED (RT-LED) with a centered island cathode has been fabricated and investigated by comparison with a conventional LED (CV-LED). The performances of RT-LEDs were prominently enhanced via uniform current spreading and low current crowding. Performances in terms of increased output power and lower forward voltage of simulated RT-LEDs are much superior to those of CV-LEDs. Based on these results, we investigated the correlation between device geometries and optical characteristics through the fabricated CV and RT-LEDs. The measured output power and forward voltage of the RT-LEDs at 100 mA are 64.7% higher and 8% smaller compared with those of the CV-LEDs.

High-Performance Triangular Miniaturized-LEDs for High Current and Power Density Applications

“…Also, Schubert et al and Kang et al previously reported that the self-heating could also be reduced by changing the electrode geometries. 9,20 Through our theoretical calculation, we find that longer effective n-electrode length is beneficial for the higher efficiency, too. Here, the effective n-electrode length is the part of the n-electrode length that allows for effective current spreading from the p-electrode to the n-electrode.…”

Improvement of Light Extraction Efficiency of LED Packages Using an Enhanced Encapsulant Design

“…The EQE of an LED can be expressed as the product of the current injection efficiency (CIE, η inj ), internal quantum efficiency (IQE, η int ), and light extraction efficiency (LEE, η extr ) [3,4]. The LEE of an LED depends strongly on the critical angle θ c for total internal reflection at the interface between the two media, which is determined by Eq.…”