GaAs–AlGaAs multiple-quantum-well lasers for monolithic integration with optical modulators

1991 ◽  
Vol 69 (3-4) ◽  
pp. 491-496 ◽  
Author(s):  
F. Chatenoud ◽  
K. M. Dzurko ◽  
M. Dion ◽  
D. Moss ◽  
R. Barber ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Cavity Length ◽  
Multiple Quantum Well ◽  
Monolithic Integration ◽  
Quantum Well Lasers ◽  
Multiple Quantum ◽  
Optical Modulators ◽  
Single Quantum Well ◽  
Quantum Well Structures

Calculations of multiple-quantum-well laser threshold current show that a common minimum current value exists for each number of wells, at an appropriate cavity length. This optimum cavity length decreases rapidly with increasing number of wells, for instance from about 300 to 110 μm for one to three wells. Granded-index separate-confinement heterostructure (GRINSCH) lasers with 1–10 quantum wells, grown by molecular beam epitaxy, show consistently low threshold currents that agree well with theoretical predictions. Lasing is achieved at 160 A cm−2 and 4.6 mA for broad-area and ridge waveguide single-quantum-well devices, respectively. The field-dependent electroabsorption of these devices when operating as wave-guide modulators indicates good modulation properties for one and three quantum-well structures, with on:off ratios above 55 at lasing wavelength. The behavior becomes more complex with increasing number of wells. This systematic study of discrete multiple-quantum-well lasers and modulators demonstrates that GRINSCH structures with 1–3 wells are the most suitable for monolithic integration. Design rules for the laser cavity are also presented for numbers of wells ranging from 1 to 10.

Stimulated Emission from Single- and Multiple-Quantum-Well GaN-AlGaN Separate-Confinement Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
D. A. S. Loeber ◽  
N. G. Anderson ◽  
J. M. Redwing ◽  
J. S. Flynn ◽  
G. M. Smith ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Optical Pumping ◽  
Multiple Quantum Well ◽  
Emission Spectra ◽  
Stimulated Emission ◽  
Emission Characteristics ◽  
Multiple Quantum ◽  
Photoluminescence Properties ◽  
Single Quantum Well

ABSTRACTStimulated emission characteristics are examined for GaN-AlGaN separate-confinement quantum-well heterostructures grown by MOVPE on 4H-SiC substrates. We specifically focus on comparison of structures with different quantum well active region designs. Polarization resolved edge emission spectra and stimulated emission thresholds are obtained under optical pumping using a stripe excitation geometry. Stimulated emission characteristics are studied as a function of the number of quantum wells in the structure, and are correlated with surface photoluminescence properties. We find reduced stimulated emission thresholds and increased surface photoluminescence intensities as the number of quantum wells is reduced, with the best results obtained for a single-quantum-well structure. These results should provide useful information for the design of GaN-based quantum well lasers.

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.

Electron–electron inter-subband scattering in GaAs quantum wells

1996 ◽  
Vol 74 (S1) ◽  
pp. 252-255
Author(s):  
Zhi Zhong Xu ◽  
D. Morris
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electron Scattering ◽  
Multiple Quantum Well ◽  
Golden Rule ◽  
Multiple Quantum ◽  
Hot Electron ◽  
Quantum Well Structures ◽  
Scattering Rate ◽  
Relaxation Channel

The role of electron–electron scattering in the dynamics of inter-subband relaxation in GaAs quantum wells is investigated theoretically. The scattering rate is calculated using the Fermi golden rule, as a function of the carrier densities. The dependence of the inter-subband relaxation time on the quantum-well width is also investigated. Calculations are performed for multiple quantum-well structures with well widths varying from 80 to 240 Å (1 Å = 10−10 m). The hot electron distribution and the subband occupation function are taken into account in these calculations. Results show that the electron–electron scattering rate increases linearly as a function of the carrier densities. A band-filling effect limits the efficiency of this mechanism under high carrier densities (> 1012 cm−2). For thick well (180 Å) structures, this relaxation channel is as efficient as the phonon relaxation channel.

Impact of Layer Number on Flexible High-Voltage Nanostructured Solar Cells

MRS Advances ◽  
2016 ◽  
Vol 1 (14) ◽  
pp. 891-899
Author(s):  
Roger E. Welser ◽  
Ashok K. Sood ◽  
S. Rao Tatavarti ◽  
Andree Wibowo ◽  
David M. Wilt
Keyword(s):  
Solar Cells ◽  
Quantum Well ◽  
Short Circuit ◽  
Multiple Quantum Well ◽  
Open Circuit ◽  
Multiple Quantum ◽  
Single Quantum Well ◽  
Quantum Well Structures ◽  
Layer Number ◽  
The Impact

ABSTRACTNanostructured quantum well and quantum dot solar cells are being widely investigated as a means of extending infrared absorption and enhancing photovoltaic device performance. In this work, we describe the impact of nanostructured layer number on the performance of flexible, highvoltage InGaAs/GaAs quantum well solar cells. Multiple quantum well structures are observed to have a higher short circuit current but a lower open circuit voltage than similar single quantum well structures. Analysis of the underlying dark diode characteristics indicate that these highvoltage structures are limited by radiative recombination at high bias levels. The results of this study suggest that future development efforts should focus on maximizing the current generating capability of a limited number of nanostructured layers and minimizing recombination within the nanostructured absorber.

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