InGaN light-emitting diodes: Efficiency-limiting processes at high injection

2013 ◽  
Vol 31 (5) ◽  
pp. 050809 ◽  
Author(s):  
Vitaliy Avrutin ◽  
Shopan din Ahmad Hafiz ◽  
Fan Zhang ◽  
Ümit Özgür ◽  
Hadis Morkoç ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
High Injection

Approaches Towards the Ultimate Luminous Output Power of Light-Emitting Diodes: Bottlenecks and Remedies

2015 ◽  
Author(s):  
Xiaokun Zhang ◽  
Xiao-Dong Xiang ◽  
Yong Xiang
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Thermal Runaway ◽  
Efficiency Droop ◽  
Injection Current ◽  
Light Emitting ◽  
Excessive Heat ◽  
High Injection ◽  
Current Densities ◽  
The Cost

Although light-emitting diodes (LEDs) hold great promises for high-efficiency lighting applications, the cost per lumen still poses a challenge for LEDs to fast penetrate into the markets. Increasing the output power per LED chip reduces the number of chips required for a specific luminous flux, thus reducing the cost of LED luminaires. However, it is well known that the luminous output power of LEDs (Pout) cannot be enhanced simply by increasing the injection current density (Jinj) due to efficiency droop. Extensive efforts have been made towards avoiding efficiency droop at high injection current densities (e.g., Jinj > 50 A/cm2). Gardner et al. reported a double-heterostructure LED with an external quantum efficiency (EQE) of 40% at 200 A/cm2. Xie et al. introduced an electron-blocking layer into the LED devices and the EQE peak occurred at 900 A/cm2 approximately. Nevertheless, the EQE is always lower than 100%, excessive heat will accumulate in LEDs at high current densities and increase the junction temperatures, which will damage the device and limit its luminous output power and lifetime. In this paper, the recombination mechanism in the LED active area is analyzed and an analytic relationship between Pout and Jinj is proposed. The calculated results show that the best Pout currently achieved is far lower than its potential value. The temperature dependence of the Pout-Jinj relationship is also calculated and the thermal state of LEDs at high injection current densities predicted. The results demonstrate that LED luminaires with thermal management based on conventional fin-shaped heat sinks suffer from thermal runaway due to excessive heat accumulation before reaching their ultimate output power. The gap between the existing and predicted Pout is mainly due to thermal runaway of LED devices at high injection current densities, instead of efficiency droop. Therefore, the short-term solution of LED luminous output power enhancement should be better cooling of LED modules, such as jet/spray cooling, heat pipe cooling, or 3D embedded two-phase cooling. Long-term solutions continue to focus on reducing the efficiency droop with improved LED device structures and advanced materials.

scholarly journals Saga of efficiency degradation at high injection in InGaN light emitting diodes

2014 ◽  
Vol 38 ◽  
pp. 269-313 ◽  
Author(s):  
Vitaliy AVRUTIN ◽  
Shopan A. HAFIZ ◽  
Fan ZHANG ◽  
Ümit ÖZGÜR ◽  
Enrico BELLOTTI ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
High Injection

S6-G4: High injection and efficiency droop in GaInN light-emitting diodes

2014 ◽  
Author(s):  
Guan-Bo Lin ◽  
David S. Meyaard ◽  
E. Fred Schubert ◽  
Jaehee Cho ◽  
Jong Kyu Kim ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Efficiency Droop ◽  
Light Emitting ◽  
High Injection

Long-wavelength shift of ZnSSe metal-semiconductor-metal light-emitting diodes with high injection currents

2000 ◽  
Author(s):  
Yan-Kuin Su ◽  
Wen Ray Chen ◽  
Shoou-Jinn Chang ◽  
Fuh-Shyang Juang ◽  
W. H. Lan ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Wavelength Shift ◽  
Light Emitting ◽  
Long Wavelength ◽  
High Injection ◽  
Metal Semiconductor Metal ◽  
Injection Currents

The red shift of ZnSSe metal-semiconductor-metal light emitting diodes with high injection currents

2000 ◽  
Vol 47 (7) ◽  
pp. 1330-1333 ◽  
Author(s):  
Y.K. Su ◽  
W.R. Chen ◽  
S.J. Chang ◽  
F.S. Juang ◽  
W.H. Lan ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Red Shift ◽  
Light Emitting ◽  
High Injection ◽  
Metal Semiconductor Metal ◽  
Injection Currents

Identifying the cause of the efficiency droop in GaInN light-emitting diodes by correlating the onset of high injection with the onset of the efficiency droop

2013 ◽  
Vol 102 (25) ◽  
pp. 251114 ◽  
Author(s):  
David S. Meyaard ◽  
Guan-Bo Lin ◽  
Jaehee Cho ◽  
E. Fred Schubert ◽  
Hyunwook Shim ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Efficiency Droop ◽  
Light Emitting ◽  
High Injection

TiN Enhancement of Output Performance for Light-Emitting Diodes under High Injection Current

2004 ◽  
Vol 43 (2) ◽  
pp. 594-597 ◽  
Author(s):  
Chien-Chih Liu ◽  
Wei-Ting Wang ◽  
Mau-Phon Houng ◽  
Yeong-Her Wang
Keyword(s):  
Light Emitting Diodes ◽  
Injection Current ◽  
Light Emitting ◽  
Output Performance ◽  
High Injection

GaN-Based Light-Emitting Diodes: Efficiency at High Injection Levels

2010 ◽  
Vol 98 (7) ◽  
pp. 1180-1196 ◽  
Author(s):  
Ümit Ozgur ◽  
Huiyong Liu ◽  
Xing Li ◽  
Xianfeng Ni ◽  
Hadis Morkoç
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
High Injection
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