Cathode effect on current-voltage characteristics of blue light-emitting diodes based on a polyspirofluorene

2008 ◽  
Author(s):  
G. Garcia-Belmonte ◽  
E. M. Barea ◽  
Y. Ayyad-Limonge ◽  
J. M. Montero ◽  
H. J. Bolink ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics

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.

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

Electrical and Optical Characterisation of Homojjunction Gallium Nitride Light Emitting Diodes

1997 ◽  
Vol 482 ◽  
Author(s):  
G M Laws ◽  
J Morgan ◽  
G B Ren ◽  
I Harrison ◽  
E C Larkins ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Full Width Half Maximum ◽  
Light Emitting Diodes ◽  
Deep Level ◽  
Deep Level Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics

AbstractWe report on the fabrication and characterisation gallium nitride light emitting diodes (LEDs) grown by molecular beam epitaxy on (0001) oriented sapphire and (111)B GaAs substrates. The current voltage characteristics of the devices grown on sapphire show turn on voltages of between 4 and 5V with large on-series resistance of 600Ω; for corresponding devices grown on GaAs these parameters are between 6 and 7V and 150 Ω, respectively.Room temperature electroluminescence (EL) spectra from the GaN LEDs ,grown on sapphire substrates, show a dominant emission at 3.2 eV (397nm) with a full width half maximum (FWHM) of 335 meV which is attributed to free electron to acceptor transitions (e, A−Mg). A broad low intensity deep level emission is also observed centred at 2.4 eV (506nm). The peak of the EL from the devices grown on GaAs is at 3.1eV rather than 3.2eV. The differences between the two sets of devices are probably caused by the different device geometry.Preliminary results show that an “annealing” effect caused by electrical stressing resulted in an improvement of the EL spectra. The stressed samples show an increase in the near band edge emission intensity, a 20meV reduction in the FWHM and a significant reduction in the intensity of the deep level emission. The devices have a large 1/f noise contribution which does not appear to change after electrical stressing.

Neodymium-doped GaAs Light-emitting Diodes

1996 ◽  
Vol 422 ◽  
Author(s):  
S. J. Chang
Keyword(s):  
Quantum Efficiency ◽  
Breakdown Voltage ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Minority Carriers

Nd-doped semiconductor light-emitting diodes were fabricated by implanting Nd ions into a GaAs epi-layer. The fabricated GaAs:Nd diodes show good current-voltage characteristics with a typical reverse breakdown voltage between 8 and 12 V By injecting minority carriers into the diodes, Nd3+ related emissions were observed, at 77 K, in the 0.92, 1.11, and 1.3 μm regions. These electroluminescence signals correspond to the transitions from Nd3+4F3/2 state to the Nd3+4I9/2, 4I1/2, and 4I13/2 states, respectively. The measured external quantum efficiency of the GaAs:Nd diodes at 77 K, was 5 × 10−7.

Electrical and Optical Properties of InGaN/AlGaN Double Heterostructure Blue Light-Emitting Diodes

1997 ◽  
Vol 468 ◽  
Author(s):  
K. Yang ◽  
H. T. Shi ◽  
B. Shen ◽  
R. Zhang ◽  
Z. Z. Chen ◽  
...  
Keyword(s):  
Blue Light ◽  
Carrier Transport ◽  
Light Emitting Diodes ◽  
Forward Bias ◽  
Optical Emission ◽  
Emission Peak ◽  
Light Emitting ◽  
Double Heterostructure ◽  
Current Voltage ◽  
Carrier Tunneling

ABSTRACTIn this paper, we studied the electrical and optical characteristics of Nichia double heterostructure blue light-emitting diodes, with In0.06Ga0.94N:Zn, Si active layer, at 77 and 300 K. Measurement of the forward bias current-voltage behavior of the device demonstrates a departure from the Shockley model of p-n diodes, and it is observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunneling. Electroluminescence experiments of the devices were performed. We obtained an emission peak located at 2.80 eV, and a relatively weaker short-wavelength peak of 3.2 eV. A significant blue shifts of the optical emission peak which is consistent with the tunneling character of electrical characteristics was observed. Furthermore, we studied the properties of electroluminescence under various pulsed currents, and a degradation in I-V characteristics and a low resistance ohmic short were observed.

scholarly journals Current–voltage characteristics of dendrimer light-emitting diodes

2010 ◽  
Vol 43 (38) ◽  
pp. 385106 ◽  
Author(s):  
S G Stevenson ◽  
I D W Samuel ◽  
S V Staton ◽  
K A Knights ◽  
P L Burn ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics
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