Size-dependent light output, spectral shift, and self-heating of 400 nm InGaN light-emitting diodes

2010 ◽  
Vol 107 (1) ◽  
pp. 013103 ◽  
Author(s):  
Zheng Gong ◽  
Shirong Jin ◽  
Yujie Chen ◽  
Jonathan McKendry ◽  
David Massoubre ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Output ◽  
Spectral Shift ◽  
Light Emitting ◽  
Size Dependent ◽  
Self Heating

scholarly journals Size-Dependent Quantum Efficiency of Flip-Chip Light-Emitting Diodes at High Current Injection Conditions

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 88
Author(s):  
Xingfei Zhang ◽  
Yan Li ◽  
Zhicong Li ◽  
Zhenlin Miao ◽  
Meng Liang ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Current Density ◽  
Flip Chip ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Current Injection ◽  
High Current ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Size Dependent

Versatile applications call for InGaN-based light-emitting diodes (LEDs) to operate at ultra-high current densities with high quantum efficiency. In this work, we investigated the size-dependent effects of the electrical and optical performance of LEDs as increasing the current density up to 100 A/cm2, which demonstrated that mini-strip flip-chip LEDs were superior option to achieve better performance. In detail, at a current density of 100 A/cm2, the light output power density of these mini-strip LEDs was improved by about 6.1 W/cm2, leading to an improvement in the wall-plug efficiency by 4.23%, while the operating temperature was reduced by 11.3 °C, as compared with the large-sized LEDs. This could be attributed to the increase in the sidewall light extraction, alleviated current crowding effect, and improved heat dissipation. This work suggests an array of mini-strip LEDs would provide an option in achieving higher luminescent efficiency at ultrahigh current injection conditions for various applications.

Micro-Raman Spectroscopy: Self-Heating Effects In Deep UV Light Emitting Diodes

2002 ◽  
Vol 743 ◽  
Author(s):  
A. Sarua ◽  
M. Kuball ◽  
M. J. Uren ◽  
A. Chitnis ◽  
J. P. Zhang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Heat Dissipation ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Self Heating ◽  
Micro Raman Spectroscopy ◽  
Heating Effects ◽  
Heat Sinking

ABSTRACTUltraviolet light emitting diodes (LED) based on GaN and its ternary alloy AlGaN are key devices for applications such as solid state white lighting and chemical sensing. Ultraviolet LEDs are prone to self-heating effects, i.e., temperature rises during operation, contributing significantly to the commonly observed saturation of light output power at relatively low input currents. Rather little, however, is known about the actual device temperature of an operating ultraviolet LED. Using micro-Raman spectroscopy temperature measurements were performed as a function of input current on 325nm-Al0.18Ga0.82N/Al0.12Ga0.88N multiple quantum wells LEDs grown on sapphire substrates, flip-chip mounted on SiC for heat-sinking. Temperature maps were recorded over the active device area. Temperature rises of about 65 °C were measured at input currents as low as 50mA (at 8V) for 200 μm x 200 μm size LEDs despite flipchip mounting the devices. Temperature rises at the device edges were found to be higher than in the device center, due to combined heat sinking and current crowding effects. Finite difference heat dissipation simulations were performed and compared to the experimental results.

Characterization of the Interdependence Between the Light Output and Self-Heating of Gallium Nitride Light-Emitting Diodes

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Bikramjit Chatterjee ◽  
James Spencer Lundh ◽  
Daniel Shoemaker ◽  
Tae Kyoung Kim ◽  
Hoyeon Kim ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Material System ◽  
Optical Performance ◽  
Characterization Methods ◽  
Light Emitting ◽  
Self Heating ◽  
Near Ultraviolet ◽  
Environment Temperature

Abstract With the advent of gallium nitride (GaN) as an enabling material system for the solid-state lighting industry, high-power and high-brightness light-emitting diodes (LEDs) with wavelengths ranging from near ultraviolet to blue are being manufactured as part of a tremendously large and ever-increasing market. However, device self-heating and the environment temperature significantly deteriorate the LED's optical performance. Hence, it is important to accurately quantify the LED's temperature and correlate its impact on optical performance. In this work, three different characterization methods and thermal simulation were used to measure and calculate the temperature rise of an InGaN/GaN LED, as a result of self-heating. Nanoparticle-assisted Raman thermometry was used to measure the LED mesa surface temperature. A transient Raman thermometry technique was utilized to investigate the transient thermal response of the LED. It was found that under a 300 mW input power condition, self-heating is negligible for an input current pulse width of 1 ms or less. The temperature measured using nanoparticle-assisted Raman thermometry was compared with data obtained by using the forward voltage method (FVM) and infrared (IR) thermal microscopy. The IR and Raman measurement results were in close agreement whereas the data obtained from the widely accepted FVM underestimated the LED temperature by 5–10%. It was also observed that an increase in environment temperature from 25 °C to 100 °C would degrade the LED optical power output by 12%.

Low-Temperature Operation of Green, Blue and UV InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes

2003 ◽  
Vol 764 ◽  
Author(s):  
X. A. Cao ◽  
S. F. LeBoeuf ◽  
J. L. Garrett ◽  
A. Ebong ◽  
L. B. Rowland ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Localized States ◽  
Multiple Quantum ◽  
Nonradiative Recombination ◽  
Light Emitting ◽  
Temperature Range ◽  
Green Leds

Absract:Temperature-dependent electroluminescence (EL) of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with peak emission energies ranging from 2.3 eV (green) to 3.3 eV (UV) has been studied over a wide temperature range (5-300 K). As the temperature is decreased from 300 K to 150 K, the EL intensity increases in all devices due to reduced nonradiative recombination and improved carrier confinement. However, LED operation at lower temperatures (150-5 K) is a strong function of In ratio in the active layer. For the green LEDs, emission intensity increases monotonically in the whole temperature range, while for the blue and UV LEDs, a remarkable decrease of the light output was observed, accompanied by a large redshift of the peak energy. The discrepancy can be attributed to various amounts of localization states caused by In composition fluctuation in the QW active regions. Based on a rate equation analysis, we find that the densities of the localized states in the green LEDs are more than two orders of magnitude higher than that in the UV LED. The large number of localized states in the green LEDs are crucial to maintain high-efficiency carrier capture at low temperatures.

scholarly journals Improved Performance of GaN-Based Light-Emitting Diodes Grown on Si (111) Substrates with NH3 Growth Interruption

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 399
Author(s):  
Sang-Jo Kim ◽  
Semi Oh ◽  
Kwang-Jae Lee ◽  
Sohyeon Kim ◽  
Kyoung-Kook Kim
Keyword(s):  
Buffer Layer ◽  
Light Emitting Diodes ◽  
Defect Density ◽  
Strain Relaxation ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Growth Interruption ◽  
Aln Buffer

We demonstrate the highly efficient, GaN-based, multiple-quantum-well light-emitting diodes (LEDs) grown on Si (111) substrates embedded with the AlN buffer layer using NH3 growth interruption. Analysis of the materials by the X-ray diffraction omega scan and transmission electron microscopy revealed a remarkable improvement in the crystalline quality of the GaN layer with the AlN buffer layer using NH3 growth interruption. This improvement originated from the decreased dislocation densities and coalescence-related defects of the GaN layer that arose from the increased Al migration time. The photoluminescence peak positions and Raman spectra indicate that the internal tensile strain of the GaN layer is effectively relaxed without generating cracks. The LEDs embedded with an AlN buffer layer using NH3 growth interruption at 300 mA exhibited 40.9% higher light output power than that of the reference LED embedded with the AlN buffer layer without NH3 growth interruption. These high performances are attributed to an increased radiative recombination rate owing to the low defect density and strain relaxation in the GaN epilayer.

Improved Light Output Power of GaN-Based Light-Emitting Diodes Using Double Photonic Quasi-Crystal Patterns

2009 ◽  
Vol 30 (11) ◽  
pp. 1152-1154 ◽  
Author(s):  
Hung-Wen Huang ◽  
Chung-Hsiang Lin ◽  
Zhi-Kai Huang ◽  
Kang-Yuan Lee ◽  
Chang-Chin Yu ◽  
...  
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Output Power ◽  
Light Emitting

scholarly journals High-Power GaN-Based Vertical Light-Emitting Diodes on 4-Inch Silicon Substrate

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1178 ◽  
Author(s):  
Qiang Zhao ◽  
Jiahao Miao ◽  
Shengjun Zhou ◽  
Chengqun Gui ◽  
Bin Tang ◽  
...  
Keyword(s):  
High Power ◽  
Silicon Substrate ◽  
Flip Chip ◽  
Heat Dissipation ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Current Spreading ◽  
Light Emitting ◽  
Fabry Perot ◽  
Lift Off

We demonstrate high-power GaN-based vertical light-emitting diodes (LEDs) (VLEDs) on a 4-inch silicon substrate and flip-chip LEDs on a sapphire substrate. The GaN-based VLEDs were transferred onto the silicon substrate by using the Au–In eutectic bonding technique in combination with the laser lift-off (LLO) process. The silicon substrate with high thermal conductivity can provide a satisfactory path for heat dissipation of VLEDs. The nitrogen polar n-GaN surface was textured by KOH solution, which not only improved light extract efficiency (LEE) but also broke down Fabry–Pérot interference in VLEDs. As a result, a near Lambertian emission pattern was obtained in a VLED. To improve current spreading, the ring-shaped n-electrode was uniformly distributed over the entire VLED. Our combined numerical and experimental results revealed that the VLED exhibited superior heat dissipation and current spreading performance over a flip-chip LED (FCLED). As a result, under 350 mA injection current, the forward voltage of the VLED was 0.36 V lower than that of the FCLED, while the light output power (LOP) of the VLED was 3.7% higher than that of the FCLED. The LOP of the FCLED saturated at 1280 mA, but the light output saturation did not appear in the VLED.

Self-heating effects at high pump currents in deep ultraviolet light-emitting diodes at 324 nm

2002 ◽  
Vol 81 (18) ◽  
pp. 3491-3493 ◽  
Author(s):  
A. Chitnis ◽  
J. Sun ◽  
V. Mandavilli ◽  
R. Pachipulusu ◽  
S. Wu ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Self Heating ◽  
Heating Effects ◽  
High Pump ◽  
Deep Ultraviolet ◽  
Ultraviolet Light Emitting Diodes

scholarly journals Light Extraction Enhancement of InGaN Based Micro Light-Emitting Diodes with Concave-Convex Circular Composite Structure Sidewall

2019 ◽  
Vol 9 (17) ◽  
pp. 3458 ◽  
Author(s):  
Tan ◽  
Zhou ◽  
Hu ◽  
Wang ◽  
Yao
Keyword(s):  
Composite Structure ◽  
Inductively Coupled Plasma ◽  
Total Internal Reflection ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Electrical Characteristics ◽  
Light Emitting ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Output Characteristics

We demonstrate that the concave-convex circular composite structure sidewall prepared by inductively coupled plasma (ICP) etching is an effective approach to increase the light efficiency without deteriorating the electrical characteristics for micro light-emitting diodes (LEDs). The saturated light output power of the device using the concave-convex circular composite structure sidewalls with a radius of 2 μm is 39.75 mW, an improvement of 7.2% compared with that of the device using flat sidewalls. The enhanced light output characteristics are primarily attributed to the increased photon emitting due by decreasing the total internal reflection without losing the active region area.

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