Research on Performance of Red Vertical AlGaInP/GaAs Light-Emitting Diodes Influenced by Current Crowding

Abstract

The authors show that the performance of red vertical AlGaInP/GaAs light-emitting diodes is compromised by the current crowding (CC) effect in the moderate-current (space charge region dominates in the device performance) and high-current (series resistance dominates in the equivalent circuit of a device) domains. Depending on the contact pattern, a remarkable part of the performance degradation comes as a result of the electrical power lost on the series resistance ( 17%). CC affects the ideality factor and causes the current spreading length to decrease from 425 m at low currents to 75 m at a current of 250 mA.

Research on Electrical Efficiency Degradation Influenced by Current Crowding in Vertical Blue InGaN-on-SiC Light-Emitting Diodes

“…Importantly, the power losses on R s cannot be neglected at the injection currents even much lower than I r . Such observations coincide well with the results of previous studies performed on vertical AlGaInP [8], AlGaAs [9], and InAsSbP [10] LEDs and demonstrate the critical need for developing a current crowding-free vertical design for highpower LEDs.…”

“…Interestingly, the well-known Shockley equation for an ideal diode clearly describes the I − V curves only in the medium-current domain (3·10 −5 A < I < 2·10 −3 A) while an exponential (injection) model of diode is invalid for the two other domains. This is a similar finding as in [8] and is caused by the fact that in the low-current domain (I < 10 −5 A), the electrical properties of LEDs are affected by the shunt resistance, which is lower than the junction resistance in the equivalent electrical circuit of LEDs, while R s clearly dominates in the high-current domain (I >10 mA).…”

Comparative study of III-phosphide- and III-nitride-based light-emitting diodes: understanding the factors limiting efficiency

“…using photonic crystals, surface plasmons, nanopatterned substrates, and surface texturing [42][43][44]. Furthermore, decreasing the junction temperature and optimizing the electrode structure [45] are likely to be effective.…”