Current injection efficiency induced efficiency-droop in InGaN quantum well light-emitting diodes

• Published in: Solid-state electronics Vol. 54; no. 10; pp. 1119 - 1124
• Main Authors: Zhao, Hongping, Liu, Guangyu, Arif, Ronald A., Tansu, Nelson
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2010
• Subjects: Barriers; Current density; Current injection; Density; Efficiency-droop; III-Nitride; Indium gallium nitrides; InGaN QWs; Light-emitting diodes; Quantum efficiency; Reduction; InGaN QWs; Light-emitting diodes; III-Nitride; Efficiency-droop
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2010.05.019

Current injection efficiency and its impact on efficiency-droop in InGaN single quantum well (QW) based light-emitting diodes (LEDs) are investigated. The analysis is based on current continuity relation for drift and diffusion carrier transport across the QW-barrier system. A self-consistent 6-band k · p method is used to calculate the band structure for InGaN QW. The analysis indicates that the internal quantum efficiency in the conventional 24-Å In 0.28Ga 0.72N–GaN QW structure reaches its peak at low injection current density and reduces gradually with further increase in current due to the large carrier thermionic emission. Structures combining 24-Å In 0.28Ga 0.72N QW with 15-Å Al 0.1Ga 0.9N barriers show slight reduction in quenching of the injection efficiency as current density increases. The use of 15-Å Al 0.83In 0.17N barriers shows significant reduction in efficiency-droop (10% reduction of the internal quantum efficiency at current density of 620 A/cm 2). Thus, InGaN QWs employing thin layers of larger bandgap AlInN barriers suppress the efficiency-droop phenomenon significantly.