Proton energy dependence of the light output in gallium nitride light-emitting diodes

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%.

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Investigation of light output performance for gallium nitride-based light-emitting diodes grown on different shapes of patterned sapphire substrate

Materials Science in Semiconductor Processing ◽

10.1016/j.mssp.2015.02.002 ◽

2015 ◽

Vol 33 ◽

pp. 149-153 ◽

Cited By ~ 12

Author(s):

Guofeng Yang ◽

Jianjun Chang ◽

Jianli Zhao ◽

Yuying Tong ◽

Feng Xie ◽

...

Keyword(s):

Gallium Nitride ◽

Sapphire Substrate ◽

Light Emitting Diodes ◽

Light Output ◽

Patterned Sapphire Substrate ◽

Light Emitting ◽

Output Performance ◽

Different Shapes

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

MRS Proceedings ◽

10.1557/proc-764-c5.5 ◽

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.

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

Micromachines ◽

10.3390/mi12040399 ◽

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.

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Numerical Simulation on Electrical-Thermal Properties of Gallium-Nitride-Based Light-Emitting Diodes Embedded in Board

Advances in OptoElectronics ◽

10.1155/2012/495981 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Xing-ming Long ◽

Rui-jin Liao ◽

Jing Zhou

Keyword(s):

Finite Element ◽

Gallium Nitride ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Thermal Characteristics ◽

Junction Temperature ◽

Current Crowding ◽

Total Thermal Resistance ◽

Light Emitting ◽

Packaging Structure

The electrical-thermal characteristics of gallium-nitride- (GaN-) based light-emitting diodes (LED), packaged by chips embedded in board (EIB) technology, were investigated using a multiphysics and multiscale finite element code, COMSOL. Three-dimensional (3D) finite element model for packaging structure has been developed and optimized with forward-voltage-based junction temperatures of a 9-chip EIB sample. The sensitivity analysis of the simulation model has been conducted to estimate the current and temperature distribution changes in EIB LED as the blue LED chip (substrate, indium tin oxide (ITO)), packaging structure (bonding wire and chip numbers), and system condition (injection current) changed. This method proved the reliability of simulated results in advance and useful material parameters. Furthermore, the method suggests that the parameter match on Shockley's equation parameters, Rs, nideal, and Is, is a potential method to reduce the current crowding effect for the EIB LED. Junction temperature decreases by approximately 3 K to 10 K can be achieved by substrate thinning, ITO, and wire bonding. The nonlinear-decreasing characteristics of total thermal resistance that decrease with an increase in chip numbers are likely to improve the thermal performance of EIB LED modules.

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

IEEE Electron Device Letters ◽

10.1109/led.2009.2029985 ◽

2009 ◽

Vol 30 (11) ◽

pp. 1152-1154 ◽

Cited By ~ 16

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

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

Nanomaterials ◽

10.3390/nano9081178 ◽

2019 ◽

Vol 9 (8) ◽

pp. 1178 ◽

Cited By ~ 2

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.

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