scholarly journals Superluminescence in Green Emission GaInN/GaN Quantum Well Structures under Pulsed Laser Excitation

2007 ◽  
Vol 1040 ◽  
Author(s):  
Jayantha Senawiratne ◽  
Stephanie Tomasulo ◽  
Theeradetch Detchprohm ◽  
Mingwei Zhu ◽  
Yufeng Li ◽  
...  
Keyword(s):  
Quantum Well ◽  
Green Emission ◽  
Blue Shift ◽  
Pump Intensity ◽  
Optical Investigation ◽  
Quantum Well Structures ◽  
Bulk Gan ◽  
Piezoelectric Field ◽  
Grown Structure ◽  
Internal Absorption

AbstractWe report nonlinear optical investigation of green emission GaInN/GaN multi-quantum structures grown along c- and m-axes on sapphire and bulk GaN substrates, respectively. Under intense pulsed photo excitation, we observed strong superluminescence near the lasing condition in c-plane grown quantum well structures with full width at half maximum of 6 nm. The superluminescence couples out of the edge of the sample in a mode pattern consistent with gain in a high mode of the waveguide. The wavelength of the superluminescence is 474 nm. The threshold intensity of superluminescence was found to be 156 kW/cm2. Increasing pump intensity leads to a strong photoluminescence blueshift as large as 380 meV in samples grown along the c-axis on sapphire substrate, while under the same excitation conditions, the blue shift for the m-axis grown structure on bulk GaN substrate is less than 10 meV. The large emission blueshift is hereby attributed to the internal piezoelectric field in the c-axis grown structure. We observe a gain value of 20 cm-1 together with internal absorption losses of 2.3 – 6.0 cm-1 for the superluminescent samples.

scholarly journals Electric Field Distribution in strained p-i-n GaN/InGaN multiple quantum well structures.

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
A.N. Cartwright ◽  
Paul M. Sweeney ◽  
Thomas Prunty ◽  
David P. Bour ◽  
Michael Kneissl
Keyword(s):  
Quantum Well ◽  
Electric Field Distribution ◽  
Theoretical Calculations ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Piezoelectric Field ◽  
Piezoelectric Fields ◽  
Time Resolved Photoluminescence

The presence of piezoelectric fields within p-i-n GaN/InGaN multiple quantum well structures is discussed. Time integrated and time-resolved photoluminescence measurements and theoretical calculations of the effect of these fields is presented. Furthermore, a description of how these fields influence the carrier dynamics and a discussion of how the piezoelectric field effects the design of GaN/InGaN devices is presented.

Characterization and Griwth of Oicanic Multiple Qanm Well Structures

1990 ◽  
Vol 198 ◽  
Author(s):  
F.F. So ◽  
S.R. Forrest ◽  
Y.Q. Shi ◽  
W.H. Steier
Keyword(s):  
Quantum Well ◽  
Layer Thickness ◽  
Organic Semiconductors ◽  
Multiple Quantum Well ◽  
Energy Shift ◽  
Blue Shift ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Singlet Exciton ◽  
Molecular Beam Deposition

ABSTRACTMultiple quantum well structures consisting of alternating layers of two crystalline organic semiconductors, namely, 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) and 3,4,7,8 naphthalenetetracarboxylic dianhydride (NTCDA), have been grown by organic molecular beam deposition. The layer thickness was varied from 10 to 200 Å. Birefringence measurements indicate that there is a strong structural ordering in all PrCDA layers, although the PrCDA and NTCDA crystal structures are incommensurate. From optical absorption measurements, it is found there is a blue shift in the lowest energy PICDA singlet exciton line with decreasing layer thickness. A model based on exciton quantum confinement is proposed to explain the energy shift. We have measured the low temperature photoluminescence spectra of organic quantum well structures, and found a slight red shift in the spectra with decreasing well width. These results are also discussed.

scholarly journals Исследование напряжeнности внутренних электрических полей в активной области светодиодных структур на основе InGaN/GaN с разным числом квантовых ям методом спектроскопии электропропускания

2020 ◽  
Vol 54 (4) ◽  
pp. 420
Author(s):  
А.Э. Асланян ◽  
Л.П. Авакянц ◽  
А.В. Червяков ◽  
А.Н. Туркин ◽  
С.С. Мирзаи ◽  
...  
Keyword(s):  
Active Region ◽  
Quantum Well ◽  
Quantum Wells ◽  
Electric Fields ◽  
Green Emission ◽  
Spectral Lines ◽  
Interband Transitions ◽  
Barrier Type ◽  
Piezoelectric Field

Abstract The internal electric fields of InGaN/GaN-based green-emission LED heterostructures with various numbers of quantum wells in the active region are investigated by electrotransmission spectroscopy. The frequencies of the observed spectral lines are attributed to possible types of interband transitions. An increase in the number of interband transitions of the “quantum well—quantum barrier” type with an increase in the number of quantum wells is found. This is explained by the nonidentical degree of segregation of In atoms in different GaN barriers layers. The strength of internal electric fields in quantum wells is calculated for various values of the bias of the p – n junction using a series of electrotransmission spectra. It is found that the strength of the internal piezoelectric field decreases from 3.20 to 2.82 MV/cm with an increase in the number of quantum wells.

InGaAs/InGaAsP Quantum-Well Engineering for Multiple Regrowth MOVPE Process

2005 ◽  
Vol 891 ◽  
Author(s):  
Hans-Jeorg Lohe ◽  
Emilio Gini ◽  
Riccardo Scollo ◽  
Franck Robin ◽  
Heinz Jaeckel
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Blue Shift ◽  
Heating Time ◽  
Emission Wavelength ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Monolithically Integrated ◽  
Layer Structures ◽  
Quantum Well Width

ABSTRACTFor the heterogeneous integration of several layer structures for absorber, gain and passive waveguide sections in a monolithically-integrated mode locked laser diode, the bandgap of the absorber section has to be matched to the emission wavelength of the gain section. Because of the use of a multiple regrowth process for optical butt-coupling, the first grown multiple quantum-well gain material undergoes a quantum-well intermixing process, resulting in a blue shift of the emitting optical wavelength. Experimental results show, that the blue shift is dependent on the process details and cannot be investigated by simple thermal cycling of unprocessed quantum well-structures. With the introduction of an effective quantum-well width computed from the emission wavelength we found a linear relationship between the effective quantum well width shrinkage and the cumulated regrowth heating time of 8.3Å/h at a growth temperature of 630°C. Therefore knowing the cumulated regrowth time for a laser fabrication, we could successfully design the initial quantum well thickness that yields the targeted emitting wavelength and excellent matching to the absorber bandedge.

scholarly journals Piezoelectric Field Effect on Optical Properties of GaN/GaInN/AlGaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 628-633 ◽  
Author(s):  
Jin Seo Im ◽  
H. Kollmer ◽  
O. Gfrörer ◽  
J. Off ◽  
F. Scholz ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Field Effect ◽  
Blue Shift ◽  
Asymmetric Structure ◽  
Band Bending ◽  
Time Resolved ◽  
Model Calculations ◽  
Piezoelectric Field ◽  
Strained Quantum Well

We designed and studied two sample groups: first, GaInN/AlGaN/GaN quantum wells with asymmetric barrier structure and secondly, GaInN/GaN quantum wells with asymmetrically doped barriers. Time-resolved measurements on the asymmetric structure reveal an enhanced oscillator strength when the AlGaN barrier is on top of the GaInN quantum well, indicating a better carrier confinement in such a structure. The photoluminescence emission energy of the GaInN/GaN quantum well with doped GaN barriers shifts towards higher energy than that of undoped samples due to screening, but only when the GaN barrier layer below the quantum well is doped. In contrast, the sample where only a GaN cap layer above the quantum well is doped, shows no blue-shift. These results, showing asymmetries in GaInN/GaN quantum wells, provide confirming evidence of the piezoelectric field effect and allow us to determine the sign of the piezoelectric field, which points towards the substrate in a compressively strained quantum well. Furthermore, we performed model calculations of the global band bending and the screening effect, which consistently explain our experimental findings.

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