Electronic Structures of Shallow Acceptors Confined in Si/SiGe Quantum Well Structures

1999 ◽  
Vol 607 ◽  
Author(s):  
Q.X. Zhao ◽  
M. Willander
Keyword(s):  
Quantum Wells ◽  
Energy Levels ◽  
Binding Energies ◽  
Dielectric Constants ◽  
Recent Experimental Data ◽  
Quantum Well Structures ◽  
Barrier Materials ◽  
Boron Doped ◽  
Shallow Acceptors ◽  
Band Mixing

AbstractEnergy levels of the shallow acceptor states have been calculated for center-doped Si/Si1−xGex/Si quantum wells (QWs). The impurity states were calculated using an effective-mass theory that accounts for valence-band mixing as well as the mismatch of band parameters and dielectric constants between well and barrier materials. Acceptor binding energies and splitting between the acceptor 1S3/2(Γ7) and 1S3/2(Γ6) ground states were studied at various Ge concentrations and well widths. The results are discussed in comparison with the recent experimental data from the lateral transport measurements in boron-doped Si/SiGe quantum wells.

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.

Interband transitions dependent on indium concentration in Ga1−xInxAs/GaAs asymmetric triple quantum wells

2018 ◽  
Vol 32 (05) ◽  
pp. 1850052 ◽  
Author(s):  
B. O. Alaydin ◽  
E. Ozturk ◽  
S. Elagoz
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electronic Properties ◽  
Radiative Decay ◽  
Interband Transition ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Quantum Well Structures ◽  
Transition Energies ◽  
Decay Times

In this paper, the optical and electronic properties of asymmetric triple quantum well (ATQW) structures are studied depending on the indium concentrations while quantum well (QW) thicknesses and barrier widths are kept constant. Calculation of electronic properties are done within the framework of the effective mass approximation. The indium concentrations in left quantum well (LQW) and right quantum well (RQW) are varied in order to see the change of energy levels. Then, interband transition energies, wavelengths, oscillator strengths and radiative decay times are determined depending on barrier height. The scope of this study, for the first time in the literature, covers converged interband transition energies for the asymmetric quantum well structures.

Light- and Heavy-Hole Bound Exciton Transitions and Free to Bound Transitions in GaxAl1-xAs/GaAs Quantum Wells

1989 ◽  
Vol 163 ◽  
Author(s):  
Donald C. Reynolds ◽  
K.K. Bajaj
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Free Exciton ◽  
Light Hole ◽  
Binding Energies ◽  
Temperature Dependent ◽  
Neutral Donor ◽  
Free Hole ◽  
Quantum Well Structures ◽  
Exciton Transitions

AbstractExcitons bound to neutral donors in AlxGa1-xAs/GaAs quantum wells were observed by high resolution resonant excitation photoluminescence, and temperature dependent photoluminescence measurements. Changes in the binding energy of excitons are observed when the donors are located in the center of the well, at the edge of the well, or in the center of the barrier. The variations in these binding energies are reported as a function of well size from 75–350Å. The binding energies increased as the well size was reduced to about 100Å, with further reductions in well size they decreased.Light-hole free excitons bound to neutral donors were observed in AlxGa1-xAs/GaAs quantum wells. The transitions were observed, using selective excitation photoluminescence spectroscopy, in the energy region between the light-hole and heavy-hole free exciton transitions where no other intrinsic transitions exist. The neutral donor-bound heavy-hole free-exciton transitions were also observed when the light-hole bound exciton transitions were observed. Quantum well structures which showed no evidence of a heavy-hole donor bound exciton also showed no evidence of a light-hole donor bound exciton.Free to bound transitions, free hole to bound electron, have also been observed in the AlxGa1-xAs/GaAs quantum wells. The diamagnetic shift of these transitions was used to distinguish them from excitonic transitions.

INFLUENCE OF ELECTRIC FIELD ON THE BINDING ENERGY OF HYDROGENIC IMPURITY WITH SPATIALLY DEPENDENT MASS IN NITRIDE PARABOLIC QUANTUM WELLS

2007 ◽  
Vol 21 (05) ◽  
pp. 279-286 ◽  
Author(s):  
FENG-QI ZHAO ◽  
JIAN GONG
Keyword(s):  
Binding Energy ◽  
Electric Field ◽  
Quantum Wells ◽  
Ground State ◽  
Quantum Confinement Effect ◽  
Energy Levels ◽  
Binding Energies ◽  
Hydrogenic Impurity ◽  
Dependent Mass ◽  
Parabolic Quantum Wells

The ground state and binding energies of the hydrogenic impurity in a finite GaN/Al x Ga 1-x N parabolic quantum well (PQW) are investigated by using variational method. The effect of an electric field and spatial dependence effective mass (SDEM) are considered in the calculation. The results indicate that the effect of the SDEM on the energy levels is more obvious in the case of the narrower well width L. The effects decrease with increasing L, and tend to zero. The electric field shifts the energy levels towards lower energies with increasing well width L. Furthermore the ground state binding energy of the hydrogenic impurity in GaN/Al x Ga 1-x N PQWs is larger than that in GaAs/Al x Ga 1-x As PQWs. Therefore, we affirm that there is stronger quantum confinement effect in GaN/Al x Ga 1-x N PQW.

Hole transport due to shallow acceptors along boron doped SiGe quantum wells

2000 ◽  
Vol 380 (1-2) ◽  
pp. 218-220 ◽  
Author(s):  
I.V Altukhov ◽  
M.S Kagan ◽  
V.P Sinis ◽  
S.G Thomas ◽  
K.L Wang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Hole Transport ◽  
Boron Doped ◽  
Shallow Acceptors ◽  
Sige Quantum Wells

OMVPE Growth of GalnAs/InP Quantum Well Structures

1987 ◽  
Vol 102 ◽  
Author(s):  
G. B. Stringfellow
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Quantum Wells ◽  
Vapor Phase ◽  
Atmospheric Pressure ◽  
Growth Conditions ◽  
Binding Energies ◽  
Optimum Conditions ◽  
Quantum Well Structures ◽  
Maximum Value

ABSTRACTInP/GalnAs/InP quantum well structures have been grown using atmospheric pressure organometallic vapor phase epitaxy (AP-OMVPE). The optimum conditions for growth of extremely abrupt interfaces were studied. The optimum orientation was exactly (100). The growth had to be interrupted for 40 seconds at the first interface and 2 minutes at the 2nd interface to obtain the most abrupt interfaces. The narrowest photoluminescence half widths were obtained at the lowest values (31) of V/III ratio in the input vapor phase. These growth conditions allow the growth of wells as thin as <10Å with photoluminescence (PL) spectra consisting of doublets or triplets. The extremely narrow peaks correspond to regions of the quantum well differing in thickness by a single monolayer. The energy separations of the neighboring peaks are found to increase with decreasing well width until, at a thickness of approximately 12 Å, the separation begins to decrease rapidly with decreasing well width. The exciton binding energies in the quantum wells have also been measured using thermally modulated PL. The binding energy is found to increase with decreasing well width until a maximum value of approximately 17 meV is measured for a nominal well width of approximately 13 Å. For thinner wells the exciton binding energy is found to decrease with decreasing well width.

INTERFACIAL PROPERTY OF THE PSEUDOMORPHIC InGaAs/AlGaAs MULTIPLE QUANTUM WELLS

2001 ◽  
Vol 08 (05) ◽  
pp. 537-540
Author(s):  
D. H. ZHANG
Keyword(s):  
Quantum Wells ◽  
Energy Levels ◽  
Interface Roughness ◽  
Multiple Quantum Wells ◽  
Interfacial Property ◽  
Multiple Quantum ◽  
X Ray Diffraction ◽  
Quantum Well Structures ◽  
X Ray ◽  
P Type

The effects of Be doping in the wells of the p-type pseudomorphic InGaAs/AlGaAs multiple quantum wells were characterized using photoluminescence and X-ray diffraction techniques. It is found that high doping in the wells causes shift of energy levels and deteriorates the well–barrier interfaces of the quantum well structures. The shift of the energy levels is mainly due to the band gap shrinkage while the interface roughness can be explained by interstitial doping.

Effects of Giant Optical Anisotropy in R-plane GaN/AlGaN Quantum Wells by Valence Band Mixing

PIERS Online ◽  
2006 ◽  
Vol 2 (6) ◽  
pp. 562-566 ◽  
Author(s):  
Chun-Nan Chen ◽  
Kao-Feng Yarn ◽  
Win Jet Luo ◽  
Jih-Chen Chiang ◽  
Ikai Lo ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Valence Band ◽  
Optical Anisotropy ◽  
Band Mixing ◽  
Valence Band Mixing

scholarly journals A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Mohd. Muddassir ◽  
Abdullah Alarifi ◽  
Mohd. Afzal
Keyword(s):  
Density Functional ◽  
Weak Interactions ◽  
Energy Levels ◽  
Hirshfeld Surface ◽  
Binding Energies ◽  
Orbital Energy ◽  
Aminosalicylic Acid ◽  
Full Characterization

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.

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