Problems of superradiant lasing in magnetized quantum wells: two-color regime, inhomogeneous broadening, and VCSEL scheme

2001 ◽  
Author(s):  
A. A. Belyanin ◽  
V. V. Kocharovsky ◽  
Vl. V. Kocharovsky ◽  
D. S. Pestov
Keyword(s):  
Quantum Wells ◽  
Inhomogeneous Broadening

Exciton–Light Coupling in Quantum Wells in the Presence of Inhomogeneous Broadening

1997 ◽  
Vol 164 (1) ◽  
pp. 189-192 ◽  
Author(s):  
A. V. Kavokin ◽  
M. R. Vladimirova ◽  
L. C. Andreani ◽  
G. Panzarini ◽  
J. J. Baumberg
Keyword(s):  
Quantum Wells ◽  
Inhomogeneous Broadening ◽  
Light Coupling

Four-wave mixing and terahertz emission from three-level systems in quantum wells: Effects of inhomogeneous broadening

1994 ◽  
Vol 50 (16) ◽  
pp. 11915-11923 ◽  
Author(s):  
Xuejun Zhu ◽  
Mark S. Hybertsen ◽  
P. B. Littlewood ◽  
Martin C. Nuss
Keyword(s):  
Quantum Wells ◽  
Four Wave Mixing ◽  
Inhomogeneous Broadening ◽  
Wave Mixing ◽  
Terahertz Emission

Optical Gain Spectra in InGaN/GaN Quantum Wells with the Compositional Fluctuations

1998 ◽  
Vol 537 ◽  
Author(s):  
Takeshi Uenoyama
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Optical Gain ◽  
Inhomogeneous Broadening ◽  
Localized States ◽  
Quantum Well Structures ◽  
Potential Fluctuation ◽  
Quantum Disk ◽  
Gain Spectra

The compositional fluctuations of the In content were found in InGaN/GaN quantum wells and it caused the localized states by the potential fluctuation. We have evaluated the optical gain of GaN based quantum well structures with localized states. The localized states are treated as the subband states of the quantum disk-like dots in the well. It was found that the inhomogeneous broadening played an important role in the optical gain and that it should be reduced to use the benefit of the localized states for laser oscillations.

scholarly journals Effect of Inhomogeneous Broadening in Ultraviolet III-Nitride Light-Emitting Diodes

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7890
Author(s):  
Friedhard Römer ◽  
Martin Guttmann ◽  
Tim Wernicke ◽  
Michael Kneissl ◽  
Bernd Witzigmann
Keyword(s):  
Active Region ◽  
Quantum Wells ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Inhomogeneous Broadening ◽  
Aluminium Content ◽  
Hole Density ◽  
Free Hole ◽  
Light Emitting ◽  
The Impact

In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still in progress. The polarisation in the anisotropic wurtzite lattice and the low free hole density in p-doped III-nitride compounds with high aluminium content make the design for high efficiency a critical step. The growth kinetics of the rather thin active quantum wells in III-nitride LEDs makes them prone to inhomogeneous broadening (IHB). Physical modelling of the active region of III-nitride LEDs supports the optimisation by revealing the opaque active region physics. In this work, we analyse the impact of the IHB on the luminescence and carrier transport III-nitride LEDs with multi-quantum well (MQW) active regions by numerical simulations comparing them to experimental results. The IHB is modelled with a statistical model that enables efficient and deterministic simulations. We analyse how the lumped electronic characteristics including the quantum efficiency and the diode ideality factor are related to the IHB and discuss how they can be used in the optimisation process.

Electron/hole energy shifts in narrow GaAs/AlAs quantum wells: Inhomogeneous broadening due to half‐monolayer well‐width fluctuations

1990 ◽  
Vol 57 (14) ◽  
pp. 1404-1406 ◽  
Author(s):  
W. S. Fu ◽  
G. R. Olbright ◽  
A. Owyoung ◽  
J. F. Klem ◽  
R. M. Biefeld ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Inhomogeneous Broadening ◽  
Electron Hole ◽  
Hole Energy

Effect of inhomogeneous broadening on optical properties of excitons in quantum wells

1998 ◽  
Vol 57 (8) ◽  
pp. 4670-4680 ◽  
Author(s):  
Lucio Claudio Andreani ◽  
Giovanna Panzarini ◽  
Alexey V. Kavokin ◽  
Maria R. Vladimirova
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Inhomogeneous Broadening

High-Resolution Spectroscopy of Individual Quantum Dots in Wells

MRS Bulletin ◽  
1998 ◽  
Vol 23 (2) ◽  
pp. 44-48 ◽  
Author(s):  
Daniel Gammon
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Inhomogeneous Broadening ◽  
Spectral Lines ◽  
Laser Spot ◽  
High Resolution Spectroscopy ◽  
Semiconductor Quantum Dot ◽  
Interface Fluctuations ◽  
Series Of Experiments ◽  
Nanostructure Systems

Currently spectroscopists are studying many semiconductor quantum-dot (QD) systems in great detail because of their scientific and technological importance. However as in all nanostructure systems in which significant confinement energies exist, size fluctuations lead to inhomogeneous broadening of the spectral lines. This blurring of the spectra severely reduces the amount of information obtainable from spectroscopy. The finding has initiated an effort to isolate optically and study spectroscopically individual QDs. Studies involving individual QDs in most QD systems have been published. Here the results of a series of experiments are reviewed on GaAs QDs defined by interface fluctuations in narrow GaAs quantum wells. These experiments demonstrate the elegance and potential of single-QD spectroscopy.An example of single-QD photoluminescence (PL) spectroscopy appears in Figure 1. The spectra shown were obtained at a temperature of 6 K by successively reducing the size of the laser spot on a GaAs quantum-well sample through the use of small apertures in a metal mask. The bottom trace is a PL spectrum obtained with a macroscopic laser spot diameter of 25μm. The spectrum shows two broad peaks corresponding to the recombination of excitons in parts of the quantum well that are either 10 or 11 monolayers wide (2.8 or 3.1 nm). The spectrum is strongly inhomogeneously broadened as shown most directly by a reduction in the aperture size. The relatively broad lines break up into a decreasing number of extraordinarily narrow PL spikes as the aperture is reduced to submicroscopic dimensions. These PL spikes arise from excitons localized in individual QD potentials. Remarkably the linewidth decreases from several meV in the ensemble-averaged spectrum (25-μm aperture) to 10s of μeV in the single QD spectra, corresponding to an effective improvement in resolution of two orders in magnitude. By probing individual QDs, it becomes possible to resolve directly a number of phenomena that previously were hidden in the inhomogeneous linewidth.

Emission Mechanisms in UV Emitting GaN/AlN Multiple Quantum Well Structures

2003 ◽  
Vol 798 ◽  
Author(s):  
Madalina Furis ◽  
Alexander N. Cartwright ◽  
Hong Wu ◽  
William J. Schaff
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Temperature Dependence ◽  
Multiple Quantum Well ◽  
Activation Energies ◽  
Inhomogeneous Broadening ◽  
Binding Energies ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Donor And Acceptor

ABSTRACTThe need for efficient UV emitting semiconductor sources has prompted the study of a number of heterostructures of III-N materials. In this work, the temperature dependence of the photoluminescence (PL) properties of UV-emitting GaN/AlN multiple quantum well (MQW) heterostructures were investigated in detail. In all samples studied, the structure consisted of 20 GaN quantum wells, with well widths varying between 7 and 15 Å, clad by 6nm AlN barriers, grown on top of a thick AlN buffer that was deposited on sapphire by molecular beam epitaxy. The observed energy corresponding to the peak of the emission spectrum is in agreement with a model that includes the strong confinement present in these structures and the existence of the large built-in piezoelectric field and spontaneous polarization present inside the wells. The observed emission varies from 3.5 eV (15 Å well) to 4.4 eV (7 Å well). Two activation energies associated with the photoluminescence quenching are extracted from the temperature dependence of the time-integrated PL intensity. These activation energies are consistent with donor and acceptor binding energies and the PL is dominated by recombination involving carriers localized on donor and/or acceptor states.Moreover, the temperature dependence of the full width at half-maximum (FWHM) of the PL feature indicates that inhomogeneous broadening dominates the spectrum at all temperatures. For the 15 and 13 Å wells, we estimate that the electron-phonon interaction is responsible for less than 30% of the broadening at room temperature. This broadening is negligible in the 9 Å wells over the entire temperature range studied. Well width fluctuations are primarily responsible for the inhomogeneous broadening, estimated to be of the order of 250meV for one monolayer fluctuation in well width.

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