scholarly journals Токовый шум и падение эффективности светодиодов при туннелировании носителей из квантовой ямы InGaN/GaN с участием дефектов

2019 ◽  
Vol 53 (1) ◽  
pp. 104
Author(s):  
Н.И. Бочкарева ◽  
А.М. Иванов ◽  
А.В. Клочков ◽  
Ю.Г. Шретер
Keyword(s):  
Space Charge ◽  
Quantum Wells ◽  
Quantum Efficiency ◽  
Space Charge Region ◽  
Noise Level ◽  
Efficiency Droop ◽  
Experimental Frequency ◽  
Light Emitting ◽  
Thermally Activated ◽  
Electric Field Direction

AbstractThe current dependences of the spectral noise density and quantum efficiency in green and blue light-emitting diodes with InGaN/GaN quantum wells (QWs) are measured. It is shown that the noise level greatly increases at high currents at which there is a quantum efficiency droop. The mechanism by which the current noise is formed is associated with hopping transport via the deep states of color centers in GaN across the n barrier of an InGaN/GaN QW. The source of the noise is the hopping resistance of the space-charge region, which limits the current of thermally activated electrons into the QW. The efficiency droop and the increase in noise level are attributed to a change in the electric-field direction near the QW at high injection levels and to an increase in the tunneling leakage of holes from the QW. It is shown that the experimental frequency-related noise spectra having the shape of a Lorentzian spectrum at the working currents are related to the frequency of hopping between deep centers near the InGaN/GaN QW and to Maxwell relaxation in the space-charge region.

Application Of The Sah-noyce-shockley Recombination Mechanism To The Model Of The Voltagecurrent Relationship Of Led Structures With Quantum Wells

2020 ◽  
pp. 31-38
Author(s):  
Fedor I. Manyakhin ◽  
Arthur B. Vattana ◽  
Lyudmila O. Mokretsova
Keyword(s):  
Space Charge ◽  
Quantum Wells ◽  
Bias Voltage ◽  
Space Charge Region ◽  
Mathematic Model ◽  
Continuous Series ◽  
Recombination Mechanism ◽  
Light Emitting ◽  
Proposed Model ◽  
Relationship Of

The Sah-Noyce-Shockley (SNS) space charge region recombination theory is applied to build the mathematic model of the voltage-current relationships (VCR) of light emitting diodes with quantum wells. Unlike the mathematic model of VCR, for SNS in the proposed model, non-uniformity of recombination centres distribution over the space charge region and dependence of their mean concentration on voltage are assumed as well as the fact that the nonideality factor of forward current dependence on bias voltage may have a continuous series of values from 1 to 5 and is defined by the dependence on bias voltage of both saturation current and exponent of the VCR mathematical model.

scholarly journals Dependence of aging on inhomogeneities in InGaN/AlGaN/GaN light-emitting diodes

2000 ◽  
Vol 5 (S1) ◽  
pp. 668-674
Author(s):  
V.E. Kudryashov ◽  
S.S. Mamakin ◽  
A.N. Turkin ◽  
A.E. Yunovich ◽  
A.N. Kovalev ◽  
...  
Keyword(s):  
Space Charge ◽  
Quantum Efficiency ◽  
Space Charge Region ◽  
Radiation Intensity ◽  
Light Emitting Diodes ◽  
Reverse Current ◽  
Spectral Parameters ◽  
Light Emitting ◽  
Potential Fluctuations ◽  
Normal Currents

Changes of properties of green LEDs based on InxGa1−xN/AlyGa1−y/GaN heterostructures were studied during 150÷200 hours at currents J = 30÷ 80 MA The radiation intensity at low currents (0.1÷1 mA) is quite sensitive to such an aging, it falls down 10÷100 times. Quantum efficiency and spectral parameters at normal currents (J ≈ 10 mA) change non-monotonically during aging, some degradation is observed after 168 hours. The degradation is observed also after a short (< 1 min) period of reverse current. These phenomena are discussed in terms of under threshold defect’s formation and their migration in the space charge region of p-n-heterojunction. Potential fluctuations in the space charge region are quite sensitive to this process.

Dependence of Aging on Inhomogeneities in InGaN/AlGaN/GaN Light-Emitting Diodes

1999 ◽  
Vol 595 ◽  
Author(s):  
V.E. Kudryashov ◽  
S.S. Mamakin ◽  
A.N. Turkin ◽  
A.E. Yunovich ◽  
A.N. Kovalev ◽  
...  
Keyword(s):  
Space Charge ◽  
Quantum Efficiency ◽  
Space Charge Region ◽  
Radiation Intensity ◽  
Light Emitting Diodes ◽  
Reverse Current ◽  
Spectral Parameters ◽  
Light Emitting ◽  
Potential Fluctuations ◽  
Normal Currents

AbstractChanges of properties of green LEDs based on InxGa1-xN/AlyGa1-y/GaN heterostructures were studied during 150÷200 hours at currents J = 30÷80 mA. The radiation intensity at low currents (0.1÷1 mA) is quite sensitive to such an aging, it falls down 10÷100 times. Quantum efficiency and spectral parameters at normal currents (J ≈ 10 mA) change non-monotonically during aging, some degradation is observed after 168 hours. The degradation is observed also after a short (< 1 min) period of reverse current. These phenomena are discussed in terms of under threshold defect's formation and their migration in the space charge region of p-n-heterojunction. Potential fluctuations in the space charge region are quite sensitive to this process.

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

High-efficiency near-UV light-emitting diodes on Si substrates with InGaN/GaN/AlGaN/GaN multiple quantum wells

2020 ◽  
Vol 8 (3) ◽  
pp. 883-888 ◽  
Author(s):  
Yuan Li ◽  
Zhiheng Xing ◽  
Yulin Zheng ◽  
Xin Tang ◽  
Wentong Xie ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Multiple Quantum ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Si Substrates

High quantum efficiency LEDs with InGaN/GaN/AlGaN/GaN MQWs have been demonstrated. The proposed GaN interlayer barrier can not only increase the concentration and the spatial overlap of carriers, but also improve the quality of the MQWs.

The Emission Properties of Light Emitting Diodes using InGaN/AlGaN/GaN Multiple Quantum Wells

1998 ◽  
Vol 3 ◽  
Author(s):  
A. E. Yunovich ◽  
V. E. Kudryashov ◽  
A. N. Turkin ◽  
A. Kovalev ◽  
F. Manyakhin
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Multiple Quantum Wells ◽  
Luminescence Spectra ◽  
Multiple Quantum ◽  
Tunnel Current ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Low Probability

Luminescence spectra of Light Emitting Diodes (LEDs) with Multiple Quantum Wells (MQWs) were studied at currents J = 0.15 μA - 150 mA. A high quantum efficiency at low J is caused by a low probability of the tunnel current J (which is maximum at Jm ≈ 0.5-1.0 mA). J(V) curves were measured in the range J= 10−12-10−1 A; at J > 10−3A they may be approximated by a sum of four parts: V= φk+ mkT·[ln(J/J0)+(J/J1)0.5] + J·Rs. The part V ~ (J/J1)0.5is the evidence of a double-injection into i-layers near MQWs. Their presence is confirmed by capacitance measurements. An overflow of carriers through the MQW causes a lower quantum efficiency at high J. A model of a 2D-density of states with exponential tails fits the spectra. The value of T in the active layer was estimated. A new band was detected at high J; it can be caused by non-uniformity of In content in MQWs.

Erratum: “Spatially resolved study of quantum efficiency droop in InGaN light-emitting diodes,” [Appl. Phys. Lett. 101, 252103 (2012)]

2013 ◽  
Vol 103 (11) ◽  
pp. 119902 ◽  
Author(s):  
Yue Lin ◽  
Yong Zhang ◽  
Zhiqiang Liu ◽  
Liqin Su ◽  
Jihong Zhang ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Efficiency Droop ◽  
Light Emitting ◽  
Spatially Resolved

Over 20% external quantum efficiency in red thermally activated delayed fluorescence organic light-emitting diodes using a reverse intersystem crossing activating host

2018 ◽  
Vol 6 (20) ◽  
pp. 5363-5368 ◽  
Author(s):  
Ji Han Kim ◽  
Dong Ryun Lee ◽  
Si Hyun Han ◽  
Jun Yeob Lee
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light

Highly efficient red thermally activated delayed fluorescence organic light-emitting diodes were developed using a reverse intersystem crossing activating host derived from phenylcarbazole and pyridofuropyridine.

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