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.

PHOTOCONDUCTIVITY, PHOTOREFLECTANCE AND PHOTOLUMINESCENCE OF GaAs-AlAs MULTIPLE QUANTUM WELLS

1985 ◽  
Vol 56 ◽  
Author(s):  
H. NEFF ◽  
K. J. BACHMANN ◽  
W. D. LAIDIG
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Heavy Hole ◽  
Multiple Quantum Well ◽  
Light Hole ◽  
Multiple Quantum ◽  
Indirect Transition ◽  
Temperature Dependent ◽  
Direct Inter ◽  
Phonon Absorption

AbstractEmploying temperature dependent photoconductivity, photoluminescence and photoreflectivity measurements, we have analyzed a GaAs-AlAs multiple quantum well. The above optical techniques clearly resolve the fundamental inter-subband transitions, including heavy hole-light hole splittings. At T < 60K an anomalously high photoconductivity was discovered below the direct inter-subband transitions and is attributed tentatively to the presence of extrinsic interface states within the bandgap. For T > l00K the fundamental indirect transition was discovered and associated with LO (L) - phonon absorption.

Modulated Reflectance Spectroscopy of CdTe-Cd1−xMnxTe Multiple Quantum Wells and Superlattices Grown by Pulsed Laser Evaporation and Epitaxy

1992 ◽  
Vol 285 ◽  
Author(s):  
D. Labrie ◽  
J.J. Dubowski
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Free Exciton ◽  
Multiple Quantum Well ◽  
Pulsed Laser ◽  
Reflectance Spectroscopy ◽  
Light Hole ◽  
Laser Evaporation ◽  
Multiple Quantum ◽  
Superlattice Structures

ABSTRACTPiezoreflectance and photoreflectance spectroscopies have been used to investigate the electronic properties of CdTe-Cd1-xMnxTe (x − 0.10) multiple quantum well and superlattice structures grown by Pulsed Laser Evaporation and Epitaxy (PLEE). The structures with the CdTe well widths from 54Å to 245Å have been investigated. The spectra exhibit a series of signatures which are attributed to free exciton transitions occuring between the heavy-hole and light-hole bands and the upper electron subbands within the CdTe well layers. The spectra indicate that the PLEE grown structures are of an excellent quality typical of the best currently available material.

Light- and heavy-hole free-exciton transitions in narrowInxGa1−xAs/GaAs quantum wells

1992 ◽  
Vol 45 (19) ◽  
pp. 11156-11160 ◽  
Author(s):  
D. C. Reynolds ◽  
K. R. Evans ◽  
C. E. Stutz ◽  
B. Jogai ◽  
C. R. Wie ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Free Exciton ◽  
Exciton Transitions

Excited quantum states in CdTe–Cd1−x MnxTe multiple quantum wells and superlattices grown by pulsed laser evaporation and epitaxy

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1027-1034 ◽  
Author(s):  
D. Labrie ◽  
X. Wang ◽  
J. J. Dubowski
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Free Exciton ◽  
Pulsed Laser ◽  
Light Hole ◽  
Multiple Quantum Wells ◽  
Laser Evaporation ◽  
Multiple Quantum ◽  
Transition Energies ◽  
Line Positions

The photoreflectance and piezoreflectance spectra of CdTe–Cd0.9Mn0.1 Te multiple quantum wells and superlattices grown by pulsed laser evaporation and epitaxy display series of signatures that are attributed to free exciton transitions occurring between the heavy-hole and light-hole bands, and the upper electron subbands. The signature line positions are in excellent agreement with calculated transition energies obtained from a simple Kronig–Penney model that includes strain effects and the nonparabolicity of the conduction band.

scholarly journals Valence Band Mixing in GaAs/AlGaAs Quantum Wells Adjacent to Self-Assembled InAlAs Antidots

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Takuya Kawazu
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Valence Band ◽  
Energy Barrier ◽  
Heavy Hole ◽  
Electronic States ◽  
Light Hole ◽  
Photoluminescence Excitation ◽  
Band Mixing ◽  
Valence Band Mixing

Optical properties of GaAs/AlGaAs quantum wells (QWs) in the vicinity of InAlAs quantum dots (QDs) were studied and compared with a theoretical model to clarify how the QD strain affects the electronic states in the nearby QW. In0.4Al0.6As QDs are embedded at the top of the QWs; the QD layer acts as a source of strain as well as an energy barrier. Photoluminescence excitation (PLE) measurements showed that the QD formation leads to the increase in the ratio Ie-lh/Ie-hh of the PLE intensities for the light hole (lh) and the heavy hole (hh), indicating the presence of the valence band mixing. We also theoretically calculated the hh-lh mixing in the QW due to the nearby QD strain and evaluated the PLE ratio Ie-lh/Ie-hh.

Exciton binding energies in GaAs films on AlxGa1−xAs substrates

2015 ◽  
Vol 29 (30) ◽  
pp. 1550213 ◽  
Author(s):  
Zhenhua Wu ◽  
Lei Chen ◽  
Qiang Tian
Keyword(s):  
Film Thickness ◽  
Significant Influence ◽  
Heavy Hole ◽  
Dimensional Space ◽  
Light Hole ◽  
Binding Energies ◽  
Substrate Thickness ◽  
Dimensional Approach ◽  
Anisotropic System ◽  
Gaas Films

We use the fractional–dimensional approach (FDA) to study exciton binding energies in GaAs films on [Formula: see text] substrates. In this approach, the Schrödinger equation for a given anisotropic system is solved in a noninteger-dimensional space where the interactions are assumed to occur in an isotropic effective environment. The heavy-hole and light-hole exciton binding energies are calculated as functions of the film thickness and substrate thickness. The numerical results show that both the heavy-hole and light-hole exciton binding energies decrease monotonously as the film thickness increases. When the film thickness and the substrate thickness is relatively small, the change of substrate thickness has comparatively remarkable influence on both heavy-hole and light-hole exciton binding energies. As the substrate thickness increases, both the heavy-hole and light-hole exciton binding energies increase gradually. When the film thickness or the substrate thickness is relatively large, the change of substrate thickness has no significant influence on both heavy-hole and light-hole exciton binding energies.

Temperature Dependence of Photoresponse in p-Type GaAs/AlGaAs Multiple Quantum Wells: Theory and Experiment

1999 ◽  
Vol 607 ◽  
Author(s):  
F. Szmulowicz ◽  
A. Shen ◽  
H. C. Liu ◽  
G. J. Brown ◽  
Z. R. Wasilewski ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Temperature Dependence ◽  
Bound States ◽  
Light Hole ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Long Wavelength ◽  
Hole Level ◽  
Polarization Characteristics ◽  
P Type

AbstractThis paper describes a study of the photoresponse of long-wavelength (LWIR) and mid-infrared (MWIR) p-type GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) as a function of temperature and QWIP parameters. Using an 8x8 envelope-function model (EFA), we designed and calculated the optical absorption of several bound-to-continuum (BC) structures, with the optimum designs corresponding to the second light hole level (LH2) coincident with the top of the well. For the temperature-dependent study, one non-optimized LWIR and one optimized MWIR samples were grown by MBE and their photoresponse and absorption characteristics measured to test the theory. The theory shows that the placement of the LH2 resonance at the top of the well for the optimized sample and the presence of light-hole-like quasi-bound states within the heavy-hole continuum for the nonoptimized sample account for their markedly different thermal and polarization characteristics. In particular, the theory predicts that, for the LWIR sample, the LH-like quasi-bound states should lead to an increased Ppolarized photoresponse as a function of temperature. Our temperature dependent photoresponse measurements corroborate most of the theoretical findings with respect to the long-wavelength threshold, shape, and polarization and temperature dependence of the spectra.

Free and Bound Excitons in GaN Epitaxial Films

1996 ◽  
Vol 449 ◽  
Author(s):  
B.K. Meyer
Keyword(s):  
Thermal Activation ◽  
Chemical Nature ◽  
Epitaxial Films ◽  
Binding Energies ◽  
Temperature Dependent ◽  
Neutral Donor ◽  
Exciton Localization ◽  
Sapphire Substrates ◽  
Shallow Donors ◽  
Shallow Impurities

ABSTRACTWe report on photoluminescence experiments on hexagonal GaN epitaxial films grown on 6H-SiC and sapphire substrates by organo-metallic and hydide vapor phase epitaxy. At low temperatures we observe free and neutral donor bound exciton transitions which allow to establish properties of the free excitons and localisation energies of the bound excitons involving different shallow donors. From temperature dependent luminescence experiments thermal activation energies are determined which measure the exciton localization and donor binding energies. The localization energies of the excitons scale with the respective donor binding energies (Haynes rule). The inter-impurity transitions of neutral donors are observed in fourier transform infra-red absorption. Three shallow donors with binding energies of 34.7 meV, 55 meV and 58 meV can be seen. We present evidence for the chemical nature of the shallow impurities.

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