scholarly journals Investigating the Effect of Piezoelectric Polarization on GaN-Based LEDs with Different Prestrain Layer by Temperature-Dependent Electroluminescence

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
C. K. Wang ◽  
Y. Z. Chiou ◽  
T. H. Chiang ◽  
T. K. Lin
Keyword(s):  
Active Region ◽  
Quantum Wells ◽  
Blue Shift ◽  
Polarization Field ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Simple Method ◽  
Light Emitting ◽  
Piezoelectric Polarization ◽  
Transition Position

The effect of piezoelectric polarization on GaN-based light emitting diodes (LEDs) with different kinds of prestrain layers between the multiple quantum wells (MQWs) and n-GaN layer is studied and demonstrated. Compared with the conventional LED, more than 10% enhancement in the output power of the LED with prestrain layer can be attributed to the reduction of polarization field within MQWs region. In this study, we reported a simple method to provide useful comparison of polarization fields within active region in GaN-based LEDs by using temperature-dependent electroluminescence (EL) measurement. The results pointed out that the polarization field of conventional LED was stronger than that of the others due to larger variation of the wavelength transition position (i.e., blue-shift change to red-shift) from 300 to 350 K, and thus the larger polarization field must be effectively screened by injecting more carriers into the MQWs region.

Temperature Dependence of the Linewidth and Peak Position of the Intersubband Infrared Absorption in GaAs/Al0.3Ga0.7As Quantum Wells

1990 ◽  
Vol 216 ◽  
Author(s):  
M. O. Manasreh ◽  
C. E. Stutz ◽  
K. R. Evans ◽  
F. Szmulowicz ◽  
D. W. Fischer
Keyword(s):  
Quantum Wells ◽  
Infrared Absorption ◽  
Dopant Concentration ◽  
Blue Shift ◽  
Peak Position ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Optical Phonon Mode ◽  
Weakly Coupled ◽  
Absorption Technique

ABSTRACTThe linewidth and peak position (vo) of the intersubband transition (IT) in GaAs/Al0.3Ga0.7As multiple quantum wells are studied as a function of temperature using the infrared absorption technique. We find that electrons in the GaAs well are weakly coupled to the GaAs normal optical phonon mode. The total integrated area of IT absorption is found to be approximately constant in the samples that were doped in the well but temperature dependent in the samples that were doped in the barrier. We also find that vo increases as the temperature decreases. This blue shift is found to increase as the dopant concentration is increased. We calculated the absorption spectrum in a nonparabolic-anisotropic envelope function approximation including temperature dependent effective masses, nonparbolicity, conduction band offsets, the Fermi level, and lineshape broadening. Our results indicate that a large manybody correction, in particular an exchange interaction (Eexch) for the ground state, is necessary to account for the observed blue shift as the dopant concentration increases.

Temperature-dependent Carrier Leakage in InGaN/GaN Multiple Quantum Wells Light-emitting Diodes

2017 ◽  
Vol 38 (1) ◽  
pp. 63-69
Author(s):  
刘诗涛 LIU Shi-tao ◽  
王立 WANG Li ◽  
伍菲菲 WU Fei-fei ◽  
杨祺 YANY Qi ◽  
何沅丹 HE Yuan-dan ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diodes ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Light Emitting

A Role of the Built-in Piezoelectric Field in InGaN/AlGaN/GaN Multiple Quantum Wells in the Electroferlectance Experiments

2007 ◽  
Vol 1040 ◽  
Author(s):  
Pavel Bokov ◽  
Lev Avakyants ◽  
Mansur Badgutdinov ◽  
Anatoly Chervyakov ◽  
Stanislav Shirokov ◽  
...  
Keyword(s):  
Electric Field ◽  
Quantum Wells ◽  
Reverse Bias ◽  
Flip Chip ◽  
Blue Shift ◽  
Multiple Quantum ◽  
Reverse Bias Voltage ◽  
Light Emitting ◽  
Piezoelectric Field

AbstractThe influence of built in piezoelectric field in the light-emitting diodes based on InGaN/AlGaN/GaN heterostructures on the electroreflectance spectra have been studied. The structures were grown by MOCVD technology and «flip-chip» mounted. Light was emitted or reflected through sapphire substrate. The built in electric field in the structure was modulated by pulses of reverse bias from -6 to +1 V applied to the contacts of diode. Observed blue shift of spectral line from InGaN/GaN multiply quantum wells region with the increasing reverse bias voltage has been explained as the result of lowering of the electric field in the quantum well.

scholarly journals Enhanced Optoelectronic Performance of Yellow Light-Emitting Diodes Grown on InGaN/GaN Pre-Well Structure

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3231
Author(s):  
Xiaoyu Zhao ◽  
Zehong Wan ◽  
Liyan Gong ◽  
Guoyi Tao ◽  
Shengjun Zhou
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Fold Increase ◽  
Blue Shift ◽  
Underlying Mechanism ◽  
Localized States ◽  
Multiple Quantum ◽  
Light Emitting

InGaN-based long-wavelength light-emitting diodes (LEDs) are indispensable components for the next-generation solid-state lighting industry. In this work, we introduce additional InGaN/GaN pre-wells in LED structure and investigate the influence on optoelectronic properties of yellow (~575 nm) LEDs. It is found that yellow LED with pre-wells exhibits a smaller blue shift, and a 2.2-fold increase in light output power and stronger photoluminescence (PL) intensity compared to yellow LED without pre-wells. The underlying mechanism is revealed by using Raman spectra, temperature-dependent PL, and X-ray diffraction. Benefiting from the pre-well structure, in-plane compressive stress is reduced, which effectively suppresses the quantum confined stark effect. Furthermore, the increased quantum efficiency is also related to deeper localized states with reduced non-radiative centers forming in multiple quantum wells grown on pre-wells. Our work demonstrates a comprehensive understanding of a pre-well structure for obtaining efficient LEDs towards long wavelengths.

PROPOSAL OF NOVEL STRUCTURE LIGHT EMITTING DEVICES CONSISTING OF InN/GaN MQWs WITH ULTRATHIN InN WELLS IN GaN MATRIX

2008 ◽  
Vol 18 (04) ◽  
pp. 993-1003 ◽  
Author(s):  
AKIHIKO YOSHIKAWA ◽  
SONG-BEK CHE
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Blue Shift ◽  
Growth Conditions ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Quantum Confined Stark Effect ◽  
Novel Structure ◽  
Structure Light

Novel structure light emitting diodes (LEDs) made of InN / GaN multiple quantum wells (MQWs) are proposed and demonstrated. The MQWs consisted of very fine and narrow 1 monolayer (ML)-thick InN wells embedded in GaN matrix, which were successfully fabricated by radio-frequency molecular beam epitaxy. The thickness of InN wells can be fractional ML and/or two MLs depending on the growth conditions, resulting in different wavelength light emissions from deep violet to blue. Epitaxy processes for the MQWs fabrication are very unique on the basis of the self-ordering and coherent growth mode for atomically flat ~1 ML InN well deposition on GaN template. It is shown that the epitaxy temperature for 1 ML InN wells can be much higher than the highest epitaxy temperature of thick InN layer due to the effects of GaN matrix. Bright electroluminescence (EL) emission is observed at 418 nm at room temperature in LEDs fabricated by the MQWs. Further it is confirmed that the quantum confined Stark effect (QCSE) in InN wells is remarkably reduced due to the effects with using ultimately thin InN wells as active layers, resulting an extremely small blue shift in the EL peak wavelengths for two orders different injection current levels.

scholarly journals Высокоэффективные (EQE=37.5%) инфракрасные (850 нм) светодиоды с брэгговским и зеркальным отражателями

2021 ◽  
Vol 55 (12) ◽  
pp. 1218
Author(s):  
А.В. Малевская ◽  
Н.А. Калюжный ◽  
С.А. Минтаиров ◽  
Р.А. Салий ◽  
Д.А. Малевский ◽  
...  
Keyword(s):  
Active Region ◽  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Current Densities ◽  
Hydride Epitaxy

Developed and investigated are IR (850nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostructures grown by the MOC-hydride epitaxy technique with multiple quantum wells in the active region and with a double optical reflector consisted of a multilayer Al0.9Ga0.1As/Al0.1Ga0.9As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency (EQE) of 37.5% at current densities greater than 10A/cm2 have been fabricated.

scholarly journals III-Nitride Multi-Quantum-Well Light Emitting Structures with Selective Carrier Injection

2019 ◽  
Vol 9 (18) ◽  
pp. 3872
Author(s):  
Hussein S. El-Ghoroury ◽  
Mikhail V. Kisin ◽  
Chih-Li Chuang
Keyword(s):  
Active Region ◽  
Quantum Well ◽  
Quantum Wells ◽  
Light Emitting Diode ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Carrier Injection ◽  
Light Emitting ◽  
Efficient Control ◽  
Multi Quantum Well

Incorporation into the multi-layered active region of a semiconductor light-emitting structure specially designed intermediate carrier blocking layers (IBLs) allows efficient control over the carrier injection distribution across the structure’s active region to match the application-driven device injection characteristics. This approach has been successfully applied to control the color characteristics of monolithic multi-color light-emitting diodes (LEDs). We further exemplify the method’s versatility by demonstrating the IBL design of III-nitride multiple-quantum-well (MQW) light-emitting diode with active quantum wells uniformly populated at LED operational current.

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