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

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

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.

Study the Effect of Junction Temperature on the Peak Wavelength in GaN-Based High-Power Green Light Emitting Diodes

2011 ◽  
Vol 399-401 ◽  
pp. 1034-1038
Author(s):  
Rong Rong Zhuang ◽  
Ping Cai ◽  
Jiang Li Huang
Keyword(s):  
High Power ◽  
Temperature Rise ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Red Shift ◽  
Junction Temperature ◽  
Spectral Peak ◽  
Peak Wavelength ◽  
Drive Current ◽  
Light Emitting

The junction temperature of GaN-based high-power green light emitting diodes is measured using the temperature coefficients of the diode forward voltage, from changes in temperature and changes in drive current to measure the LED junction temperature and the corresponding spectral, Respectively. Experiments show that, junction temperature due to environmental temperature increased, and the red shift of the spectral peak wavelength. When low temperature or less then the rated current range, the drive current increased in junction temperature rise due to the spectral peak wavelength blue shift . When the current is increased in the range of close to or greater than the rated current, leading to the junction temperature rise will cause spectral red shift . The peak wavelengths’ shift degree of 0.0579nm / k, 0.0751 nm / k and-0.1974nm / k, -0.0915 nm / k are calculated in both cases. The phenomenon is due to the LED junction temperature increases lead to band gap shrinkage, and the result of the role of spontaneous polarization and piezoelectric polarization in Ⅲ-nitride semiconductor 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

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

Red-shift of vanadate band-gap by cation substitution for application in phosphor-converted white light-emitting diodes

2014 ◽  
Vol 104 (18) ◽  
pp. 181904 ◽  
Author(s):  
XianTao Wei ◽  
Jun Wen ◽  
Shuo Li ◽  
Shan Huang ◽  
Jun Cheng ◽  
...  
Keyword(s):  
Band Gap ◽  
White Light ◽  
Light Emitting Diodes ◽  
Red Shift ◽  
Cation Substitution ◽  
Light Emitting ◽  
White Light Emitting Diodes

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

InGaN/GaN multi-quantum-well planar metal-semiconductor-metal light-emitting diodes

2008 ◽  
Vol 44 (6) ◽  
pp. 441 ◽  
Author(s):  
C. Miao ◽  
H. Lu ◽  
X.Z. Du ◽  
Y. Li ◽  
R. Zhang ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Metal Semiconductor Metal ◽  
Multi Quantum Well

Radiative Recombination Efficiency of InGaN-Based Light-Emitting Diodes Evaluated at Various Temperatures and Injection Currents

2007 ◽  
Vol 46 (No. 25) ◽  
pp. L627-L629 ◽  
Author(s):  
Hisashi Masui ◽  
Hitoshi Sato ◽  
Hirokuni Asamizu ◽  
Mathew C. Schmidt ◽  
Natalie N. Fellows ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Recombination Efficiency ◽  
Injection Currents
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