Recombination of Localized Excitons in InGaN Single- and Multiquantum-Well Structures

1996 ◽  
Vol 449 ◽  
Author(s):  
S. Chichibu ◽  
T. Azuhata ◽  
T. Sota ◽  
S. Nakamura
Keyword(s):  
Quantum Well ◽  
Stark Effect ◽  
Molar Fraction ◽  
Green Light ◽  
Localized States ◽  
Single Quantum Well ◽  
Light Emitting ◽  
Transmission Electron ◽  
Localized Excitons ◽  
Multiquantum Well

ABSTRACTSpontaneous emission mechanisms of InGaN single quantum well (SQW) blue and green light emitting diodes (LEDs) and multiquantum well (MQW) laser diode (LD) structures were investigated. Their static electroluminescence (EL) peak was assigned to the recombination of excitons localized at certain potential minima in the quantum well (QW). The transmission electron micrographs (TEM) indicated fluctuation of In molar fraction in the QWs. The blueshift of the EL peak caused by the increase of the driving current was explained by combined effects of the quantum-confinement Stark effect and band filling of the localized states by excitons.

Localized Excitons in InGaN

1997 ◽  
Vol 482 ◽  
Author(s):  
S. ChichiBu ◽  
T. Deguchi ◽  
T. Sota ◽  
K. Wada ◽  
S. Nakamura
Keyword(s):  
Quantum Well ◽  
Stark Effect ◽  
Driving Forces ◽  
Multiple Quantum Well ◽  
Molar Fraction ◽  
Three Dimensional ◽  
Multiple Quantum ◽  
Single Quantum Well ◽  
Potential Fluctuation ◽  
Localized Excitons

AbstractEmission mechanisms of the device-quality quantum well (QW) structure and bulk three dimensional (3D) InGaN materials grown on sapphire substrates without any epitaxial lateral overgrown GaN (ELOG) base layers were investigated. The InxGx1−xN layers showed various degree of spatial potential (bandgap) fluctuation, which is probably due to a compositional inhomogeneity or monolayer thickness fluctuation produced by some kinetic driving forces initiated by the threading dislocations (TDs) or growth steps during the growth. The degree of fluctuation changed remarkably around nominal InN molar fraction x=0.2, which changes to nearly 8–10 % for the strained InxGa1−xN. This potential fluctuation induces energy tail states both in QW and 3D InGaN, showing a large Stokes-like shift combined with the red shift due to quantum confined Stark effect (QCSE) induced by the piezoelectric field. The spontaneous emission from undoped InGaN single quantum well (SQW) light-emitting diodes (LED's), undoped 3D double heterostructure (DH) LED's, and multiple quantum well (MQW) laser diode (LD) wafers was assigned as being due to the recombination of excitons localized at the potential minima, whose area was determined by cathodoluminescence (CL) mapping to vary from less than 60 nm to 300 nm in lateral size in the case of QW's. The lasing mechanisms of the cw In0.15Gao.85N MQW LD's having small potential fluctuation, whose bandgap broadenings are less than about 50 meV, can be described by the well-known electron-hole-plasma (EIHP) picture with Coulomb enhancement. The inhomogenous MQW LD's are considered to lase by EHP in segmented QW's or Q-disks. It is desirable to use entire QW planes with small potential inhomogeneity as gain media for higher performance LD operation.

Single-quantum well InGaN green light emitting diode degradation under high electrical stress

1999 ◽  
Vol 39 (8) ◽  
pp. 1219-1227 ◽  
Author(s):  
Daniel L. Barton ◽  
Marek Osinski ◽  
Piotr Perlin ◽  
Petr G. Eliseev ◽  
Jinhyun Lee
Keyword(s):  
Quantum Well ◽  
Light Emitting Diode ◽  
Green Light ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting ◽  
Electrical Stress

Current-modulated electroluminescence spectroscopy and its application to InGaN single-quantum-well blue and green light-emitting diodes

2001 ◽  
Vol 79 (8) ◽  
pp. 1100-1102 ◽  
Author(s):  
Takashi Azuhata ◽  
Takefumi Homma ◽  
Yoshikazu Ishikawa ◽  
Shigefusa F. Chichibu ◽  
Takayuki Sota ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting

Degradation of Single-Quantum Well InGaN Green Light Emitting Diodes Under High Electrical Stress

1996 ◽  
Vol 449 ◽  
Author(s):  
Marek Osiński ◽  
Piotr Perlin ◽  
Ptr G Eliseev ◽  
Gungtan Liu ◽  
Daniel L Barton
Keyword(s):  
Quantum Well ◽  
Failure Analysis ◽  
Light Emitting Diodes ◽  
Pulse Length ◽  
Green Light ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Rapid Degradation ◽  
Light Emitting ◽  
Electrical Stress

ABSTRACTWe performed a degradation study of high-brightness Nichia single-quantum well AlGaN/InGaN/GaN green light-emitting diodes (LEDs). The devices were subjected to high current electrical stress with current pulse amplitudes between 1 A and 7 A and voltages between 10 V and 70 V with a pulse length of 100 ns and a repetition rate of 1 kHz. The study showed that when the current amplitude was increased to the 6 A - 7.5 A range, a fast (about 1 s) degradation occurred, with a visible discharge between the p and n-type electrodes. Subsequent failure analysis revealed severe damage to metal contacts which lead to the formation of shorts in the surface plane of diode. For currents smaller than 6 A, a slow degradation was observed as a decrease in optical power and an increase in the reverse current leakage. After between 24 and 100 hours however, a rapid degradation occurred which was similar to the rapid degradation observed at higher currents. Failure analysis results suggest that carbonization of the plastic encapsulation material on the diode surface leads to the discharge which destroys the diode.

Optical and Electrical Characteristics of Single-Quantum-Well InGaN Light-Emitting Diodes

1996 ◽  
Vol 449 ◽  
Author(s):  
Piotr Perlin ◽  
Marek Osiński ◽  
Petr G Eliseev
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Energy Gap ◽  
Green Light ◽  
Temperature Shift ◽  
Blue Shift ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting ◽  
Increasing Temperature

ABSTRACTWe have studied the electroluminescence and photoluminescence of Nichia single-quantum-well Al0.2Ga0.8N/In0.45Ga0.55N/GaN green light-emitting diodes over a broad range of temperatures (15-300 K) and currents (0.2 μA - 2 A). The most striking behavior is an anomalous temperature shift of both photo- and electroluminescence, with the emission peak moving towards higher energies with increasing temperature. This blue shift is opposite to that of the energy gap of the active layer, which practically excludes interband transitions as responsible for the observed optical transitions. We suggest that population effects within the band tails can account for the observed anomaly. We also determined that the current flowing through the p-n junction is dominated by carrier tunneling, the omnipresent effect in the GaN-based optoelectronic devices.

High-Efficiency Single-Quantum-Well Green and Yellow-Green Light-Emitting Diodes on Semipolar (20\bar21) GaN Substrates

2010 ◽  
Vol 3 (12) ◽  
pp. 122102 ◽  
Author(s):  
Shuichiro Yamamoto ◽  
Yuji Zhao ◽  
Chih-Chien Pan ◽  
Roy B. Chung ◽  
Kenji Fujito ◽  
...  
Keyword(s):  
Quantum Well ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting

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.

OPTICAL PROPERTIES OF GaInN/GaN MULTI-QUANTUM WELL STRUCTURE AND LIGHT EMITTING DIODE GROWN BY METALORGANIC CHEMICAL VAPOR PHASE EPITAXY

2007 ◽  
Vol 17 (01) ◽  
pp. 81-84
Author(s):  
J. Senawiratne ◽  
M. Zhu ◽  
W. Zhao ◽  
Y. Xia ◽  
Y. Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Well ◽  
Stark Effect ◽  
Light Emitting Diode ◽  
Chemical Vapor ◽  
Green Emission ◽  
Luminescence Spectroscopy ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Multi Quantum Well

Optical properties of green emission Ga 0.80 In 0.20 N/GaN multi-quantum well and light emitting diode have been investigated by using photoluminescence, cathodoluminescence, electroluminescence, and photoconductivity. The temperature dependent photoluminescence and cathodoluminescence studies show three emission bands including GaInN/GaN quantum well emission centered at 2.38 eV (~ 520 nm). The activation energy of the non-radiative recombination centers was found to be ~ 60 meV. The comparison of photoconductivity with luminescence spectroscopy revealed that optical properties of quantum well layers are strongly affected by the quantum-confined Stark effect.

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