Aging of InGaN/AlGaN/GaN Light-Emitting Diodes

1997 ◽  
Vol 482 ◽  
Author(s):  
A. E. Yunovich ◽  
A. N. Kovalev ◽  
V. E. Kudryashov ◽  
F. Imanyakin ◽  
A. N. Turkin
Keyword(s):  
Light Emitting Diodes ◽  
Single Quantum Well ◽  
Light Emitting ◽  
Second Stage ◽  
Active Layers ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Radiation Activation ◽  
Luminescent Spectra ◽  
Two Stages

AbstractChanges in luminescent spectra, current-voltage, and capacitance-voltage characteristics were studied versus time of working at forward currents for light-emitting diodes based on InGaN/AlGaN/GaN heterostructures. The samples of blue and green LEDs with a single quantum well InGaN active layers were studied during 102-2.103 hours at currents 30–80 mA. An increase in efficiency at the first stage and a decrease one at the second stage were detected. The main changes were detected at low currents in blue diodes for tunnel components of current and radiation. Activation of acceptors Mg because of residual H atoms are going out of complexes Mg-H and creation of donor type defects are proposed as models for two stages. A model of injection stimulated (non-thermal) underthreshold creation of defects can explain the results.

Electrical Measurement of Recombination Lifetime in Blue Light Emitting Diodes

2004 ◽  
Vol 829 ◽  
Author(s):  
M. A. Awaah ◽  
R. Nana ◽  
K. Das
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Deep Level ◽  
Electrical Measurement ◽  
High Concentration ◽  
Recombination Lifetime ◽  
Light Emitting ◽  
Radiative Processes ◽  
Current Voltage ◽  
Capacitance Voltage

ABSTRACTA recombination lifetime of approximately 25 ns was extracted from measured reverse recovery storage times in AlGaN/GaN/AlGaN double heterojunction blue light emitting diodes. This experimentally determined lifetime is expected to arise from a combination of radiative and non-radiative processes occurring in the diodes. The non-radiative processes are likely to be due the presence of a high concentration deep-states as identified from the current-voltage and capacitance-voltage measurements. Current-voltage characteristics of these diodes were highly non-ideal as indicated by high values of the ideality factor ranging from 3.0 – 7.0. Logarithmic plots of the forward characteristics indicated a space-charge-limited-current (SCLC) conduction in presence of a high density of “deep-level states” in the active region of the diodes. An analysis of these characteristics yielded an approximate density of these deep-level states as 2 × 1017/cm3. The density of deep-states extracted from capacitance-voltage measurements were in good agreement with that obtained from current-voltage measurements.

Electrical Characterization of Blue Light Emitting Diodes as a Function of Temperature

2005 ◽  
Vol 892 ◽  
Author(s):  
Murthy Madhu ◽  
Alphonse Marie Kamto Tegueu ◽  
Michael Awaah ◽  
Dake Wang ◽  
Minseo Park ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Electrical Characterization ◽  
Leakage Currents ◽  
Light Emitting ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Double Heterojunction ◽  
Increasing Temperature ◽  
Recombination Lifetimes

AbstractBlue light emitting diodes (LEDs) based on an AlGaN/GaN/AlGaN double heterojunction structure were electrically characterized as a function of temperature. Current-voltage (I-V), capacitance-voltage (C-V) and reverse recovery storage time measurements were conducted at temperatures in the range between -8° and 75° C. Capacitance-voltage measurements as a function frequency (20 Hz – 1 MHz) and electroluminescence study at room temperature were also performed. It was observed that the diode turn-on voltage decreased with increasing temperature, however, reverse leakage currents monitored at -1, -5 and -10 V showed only a slight increase with increasing temperature. The concentration of deep states and their position in the bandgap, as extracted from logarithmic plots of the forward characteristics, were not influenced by the measurement temperature. Recombination lifetimes, as obtained from experimentally determined reverse recovery storage times, remained constant over the range of temperature considered. A higher value of diode capacitance was observed at low measurement frequencies (20 Hz – 1 kHz), gradually dropping to a lower value over a frequency range between (1 kHz – 100 kHz) and remained constant from 100 kHz to 1 MHz. A loss peak centered about 10 kHz was observed in the corresponding plot of gm/ω as a function of frequency, f. The position of the peak in the gm/ω - frequency (f) plot and dC/dω(for f in the range 1 kHz – 100 kHz ), yielded a concentration of deep-states of approximately 2.2 × 1015/cm3, located at 0.39 eV above the valence bandedge.

Capacitance–Voltage and Current–Voltage Measurements of Nitride Light-Emitting Diodes

2007 ◽  
Vol 54 (12) ◽  
pp. 3223-3228 ◽  
Author(s):  
N. C. Chen ◽  
W. C. Lien ◽  
Y. S. Wang ◽  
H. H. Liu
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Current Voltage ◽  
Capacitance Voltage

Electrical Characterization of GaN Based Ultraviolet and Blue Light Emitting Diodes

2006 ◽  
Vol 955 ◽  
Author(s):  
Alphonse-Marie Kamto Tegueu ◽  
Okechukwu Akpa ◽  
Arindra Guha ◽  
Kalyankumar Das
Keyword(s):  
Light Emitting Diodes ◽  
Deep Level ◽  
Electrical Characterization ◽  
High Concentration ◽  
Light Emitting ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Double Heterojunction ◽  
Uv Leds

ABSTRACTGallium nitride based ultraviolet (UV) and blue AlGaN/GaN/AlGaN double heterojunction structure light emitting diodes (LEDs) were electrically characterized using current-voltage (I-V) and capacitance-voltage (C-V) measurements as a function of frequency. An analysis of logarithmic plots of the forward I-V characteristics indicated that current in these diodes was proportional to Vx, as opposed to eqV/nkT, where x was observed to be either 1 or 2 at low biases increasing to as high as 40 at higher biases. The dependence of diode forward current on Vx is likely to be due to space charge limited current in the presence of a high concentration of deep level states in the bandgap. The concentration of deep states and their position in the band gap were extracted from these logarithmic plots. For both the blue and the UV LEDs, several closely spaced levels were obtained, located most likely in the range between EV and EV + 0.5 eV with concentrations of the order of 1016/cm3 to 1017/cm3. Capacitance-voltage measurements as a function of frequency (200 Hz - 1 MHz) at room temperature yielded a density of approximately 1 × 1015 cm−3 located at 0.46 eV above the valence band-edge for both the UV and blue LED. Even though the location of these deep states from the I-V and C-V measurements are within the same range, the two orders magnitude difference in the concentration of deep states is not well understood at this point.

Phosphor-free InGaN micro-pyramid white light emitting diodes with multilayer graphene electrode

RSC Advances ◽  
2015 ◽  
Vol 5 (122) ◽  
pp. 100646-100650 ◽  
Author(s):  
Binglei Fu ◽  
Yan Cheng ◽  
Zhao Si ◽  
Tongbo Wei ◽  
Xionghui Zeng ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Multilayer Graphene ◽  
Light Emitting ◽  
Graphene Electrode ◽  
Active Layers ◽  
White Light Emitting Diodes

We reported the combination of micro-pyramid active layers and graphene electrode to realize the phosphor-free InGaN based white light emitting diodes (LEDs).

Effect of deep-level states on current-voltage characteristics and electroluminescence of blue and UV light-emitting diodes

2010 ◽  
Vol 207 (6) ◽  
pp. 1489-1496 ◽  
Author(s):  
R. Nana ◽  
P. Gnanachchelvi ◽  
M. A. Awaah ◽  
M. H. Gowda ◽  
A. M. Kamto ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Deep Level ◽  
Uv Light ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics

Dependence of Electron Overflow on Emission Wavelength and Crystallographic Orientation in Single-Quantum-Well III–Nitride Light-Emitting Diodes

2013 ◽  
Vol 6 (5) ◽  
pp. 052103 ◽  
Author(s):  
Yoshinobu Kawaguchi ◽  
Shih-Chieh Huang ◽  
Robert M. Farrell ◽  
Yuji Zhao ◽  
James S. Speck ◽  
...  
Keyword(s):  
Quantum Well ◽  
Crystallographic Orientation ◽  
Light Emitting Diodes ◽  
Emission Wavelength ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting

scholarly journals Side-chain conjugated polymers for use in the active layers of hybrid semiconducting polymer/quantum dot light emitting diodes

2016 ◽  
Vol 7 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Ana Fokina ◽  
Yeonkyung Lee ◽  
Jun Hyuk Chang ◽  
Lydia Braun ◽  
Wan Ki Bae ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Conjugated Polymers ◽  
Light Emitting Diodes ◽  
Side Chain ◽  
Hybrid Polymer ◽  
Semiconducting Polymer ◽  
Light Emitting ◽  
Active Layers

Three monomers,M1–M3, with modified carbazole cores and styrene functionality were polymerized by RAFT. The polymers were then used in the active layers of hybrid polymer/quantum dot light emitting diodes.

Estimating internal quantum efficiency of light-emitting diodes from current–voltage curves

2019 ◽  
Vol 12 (3) ◽  
pp. 032002 ◽  
Author(s):  
Chenziyi Mi ◽  
Lai Wang ◽  
Jie Jin ◽  
Zhibiao Hao ◽  
Yi Luo ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Light Emitting ◽  
Current Voltage
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