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.

Influence of Defects on Current Transport in GaN/InGaN Multiple Quantum Well Light-Emitting Diodes

2002 ◽  
Vol 722 ◽  
Author(s):  
X. A. Cao ◽  
E. B. Stokes ◽  
S. F. LeBoeuf ◽  
P. M. Sandvik ◽  
J. Kretchmer ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Deep Level ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Tunneling Current ◽  
Chemical Vapor ◽  
Multiple Quantum ◽  
Nonradiative Recombination ◽  
Current Transport ◽  
Light Emitting

AbstractWe have studied the electrical and optical characteristics GaN/InGaN based light-emitting diodes (LEDs) grown on sapphire using metalorganic chemical vapor deposition (MOCVD). Strong correlation has been found between material quality and the mechanism of current transport through the wide-bandgap p-n junction. Tunneling behavior dominates throughout all injection regimes in the devices with high-density defects in the space-charge region, which act as deep-level carrier traps. The approximately current-squared dependence of light output at low currents indicates dominant nonradiative recombination in the active region. However, in a high quality LED diode, tunneling current is only a major contributor at low forward biases. At moderate biases, temperature dependent diffusion-recombination current has been identified as I0 exp(qV/1.6kT). In these devices, nonradiative recombination centers are saturated at current densities as low as 1.4×10-2 A/cm2.

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.

High-Bright InGaN Multiple-Quantum-Well Blue Light-Emitting Diodes on Si (111) Using AlN/GaN Multilayers with a Thin AlN/AlGaN Buffer Layer

2003 ◽  
Vol 42 (Part 2, No. 3A) ◽  
pp. L226-L228 ◽  
Author(s):  
Baijun Zhang ◽  
Takashi Egawa ◽  
Hiroyasu Ishikawa ◽  
Yang Liu ◽  
Takashi Jimbo
Keyword(s):  
Quantum Well ◽  
Buffer Layer ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Algan Buffer
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