NOISE CHARACTERISTICS AND RELIABILITY OF LIGHT EMITTING DIODES BASED ON NITRIDES

2007 ◽  
Vol 07 (03) ◽  
pp. L367-L378 ◽  
Author(s):  
SANDRA PRALGAUSKAITĖ ◽  
VILIUS PALENSKIS ◽  
JONAS MATUKAS ◽  
JUOZAS PETRULIS ◽  
GENADIJUS KURILČIK
Keyword(s):  
Light Emitting Diodes ◽  
Forward Bias ◽  
Reverse Current ◽  
Correlation Factor ◽  
Device Fabrication ◽  
Electrical Noise ◽  
Device Structure ◽  
Light Emitting ◽  
Noise Characteristics ◽  
Terminal Voltage

Optical and electrical noises and correlation factor between optical and electrical fluctuations of nitride-based light emitting diodes (LEDs) have been investigated under forward bias. Their electrical, optical and noise characteristics were compared with ones of LEDs of other materials. LED noise characteristic changes during aging have been measured, too. It is found that optical and electrical noise spectra under forward bias for more reliable LEDs distinguish by lower l/f type fluctuations and Lorentzian type noise at higher frequencies. LEDs with intensive 1/f noise demonstrate shorter lifetime. It is shown that reason of LED degradation is related with defects presence in device structure. These defects can be formed during device fabrication or appear during operation. An analysis of LED current-voltage and electrical noise characteristics under forward and reverse bias has shown that LEDs with intensive 1/f electrical noise, large reverse current (low reverse breakdown voltage) and larger terminal voltage under forward bias distinguish by short lifetime.

scholarly journals Copper Indium Disulfide Quantum Dot Light Emitting Diodes for Display and Lighting Technologies

2019 ◽  
Vol 20 (3) ◽  
Author(s):  
Stefano Barba
Keyword(s):  
Reaction Time ◽  
Quantum Dot ◽  
Large Scale ◽  
Light Emitting Diodes ◽  
Device Fabrication ◽  
Device Structure ◽  
Light Emitting ◽  
High Performing ◽  
Copper Indium Disulfide ◽  
Copper Indium

While significant advances in the development of quantum dot light emitting diodes (QLEDs) have been reported, these devices are primarily based on cadmium chalcogenide quantum dot (QD) materials. Both environmental and health concerns arise due to the toxicity of cadmium and consequently, alternative less toxic QDs must be developed for large scale QLED applications such as display and solid state lighting technologies.  In this work, copper indium disulfide (CIS) was investigated as an alternative QD material for QLED applications. Through experimentation with material synthesis and device fabrication, this project aimed to develop high performing CIS QLEDs. Several synthetic approaches were experimented with and it was determined that the injection of shorter chain 1-octanethoil as sulfur precursor with extensive shell reaction time resulted in highly luminescent QDs.  Single color QLEDs were fabricated based on typical device structure, using highly luminescent synthesized CIS QDs as the emissive layer in multilayer devices. Varying the shell reaction time of QDs in order to vary shell thickness resulted in significant differences in device performance. Using thicker shell QDs, high performing devices were obtained with the best performing QLEDs displaying a high peak current efficiency of 14.7 cd/A and high external quantum efficiency of 5.2%.

Reliability investigation of light-emitting diodes via low frequency noise characteristics

2015 ◽  
Vol 55 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Sandra Pralgauskaitė ◽  
Vilius Palenskis ◽  
Jonas Matukas ◽  
Justinas Glemža ◽  
Grigorij Muliuk ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Light Emitting ◽  
Noise Characteristics

Recent advances in flexible organic light-emitting diodes

2016 ◽  
Vol 4 (39) ◽  
pp. 9116-9142 ◽  
Author(s):  
Rui-Peng Xu ◽  
Yan-Qing Li ◽  
Jian-Xin Tang
Keyword(s):  
Light Emitting Diodes ◽  
Device Fabrication ◽  
Organic Light Emitting Diodes ◽  
Light Extraction ◽  
Light Emitting ◽  
Organic Light ◽  
Recent Advances ◽  
Transparent Conductive Electrodes ◽  
Encapsulation Methods

This review summarizes the recent achievements in flexible OLEDs involving transparent conductive electrodes, device fabrication, light extraction technologies, as well as encapsulation methods.

Reliability and Performance of Pseudomorphic Ultraviolet Light Emitting Diodes on Bulk Aluminum Nitride Substrates

2009 ◽  
Vol 1202 ◽  
Author(s):  
Shawn R. Gibb ◽  
James R. Grandusky ◽  
Yongjie Cui ◽  
Mark C. Mendrick ◽  
Leo J. Schowalter
Keyword(s):  
Dislocation Density ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Device Structure ◽  
Light Emitting ◽  
Bulk Crystal Growth ◽  
Low Dislocation Density ◽  
Piezoelectric Effects ◽  
And Performance ◽  
Pseudomorphic Growth

AbstractLow dislocation density epitaxial layers of AlxGa1-xN can be grown pseudomorphically on c-face AlN substrates prepared from high quality, bulk crystals. Here, we will report on initial characterization results from deep ultraviolet (UV) light emitting diodes (LEDs) which have been fabricated and packaged from these structures. As reported previously, pseudomorphic growth and atomically smooth surfaces can be achieved for a full LED device structure with an emission wavelength between 250 nm and 280 nm.A benefit of pseudomorphic growth is the ability to run the devices at high input powers and current densities. The high aluminum content AlxGa1-xN (x∼70%) epitaxial layer can be doped n-type to obtain sheet resistances < 200 Ohms/sq/μm due to the low dislocation density. Bulk crystal growth allows for the ability to fabricate substrates of both polar and non-polar orientations. Non-polar substrates are of particular interest for nitride growth because they eliminate electric field due to spontaneous polarization and piezoelectric effects which limit device performance. Initial studies of epitaxial growth on non-polar substrates will also be presented.

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