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.

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.

Fractal dimension method for exciton in cylindrical GaAs/AlxGa1−xAs core-shell-cap nanowires

2017 ◽  
Vol 31 (28) ◽  
pp. 1750209 ◽  
Author(s):  
Hui Sun ◽  
Zhenhua Wu ◽  
Qiang Tian
Keyword(s):  
Fractal Dimension ◽  
Binding Energy ◽  
Heavy Hole ◽  
Light Hole ◽  
Binding Energies ◽  
Exciton Binding Energy ◽  
Aluminum Concentration ◽  
Core Shell ◽  
Core Radius ◽  
Shell Width

By use of the fractal dimension method, the binding energies of heavy-hole exciton and light-hole exciton in cylindrical GaAs/Al[Formula: see text]Ga[Formula: see text]As core-shell-cap nanowire are explored. In this study, the exciton is confined in GaAs shell of the GaAs/Al[Formula: see text]Ga[Formula: see text]As core-shell-cap nanowire for a given aluminum concentration of [Formula: see text][Formula: see text]=[Formula: see text]0.3. The numerical results of heavy-hole exciton binding energy, light-hole exciton binding energy and fractal dimension parameter are worked out as functions of shell width and core radius. It has been shown by the calculated results that heavy-hole exciton binding energy and light-hole exciton binding energy firstly increase and then decrease as the shell width increases. When the core radius increases, both the heavy-hole exciton binding energy and light-hole exciton binding energy increase gradually. Exciton problems in GaAs shell of the cylindrical GaAs/Al[Formula: see text]Ga[Formula: see text]As core-shell-cap nanowire are solved in a simple manner to avoid complex and lengthy calculations by using the fractal dimension method.

Simultaneous effects of pressure and temperature on excitons in Pöschl–Teller quantum well

2017 ◽  
Vol 31 (08) ◽  
pp. 1750050 ◽  
Author(s):  
A. Anitha ◽  
M. Arulmozhi
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Effective Mass ◽  
Heavy Hole ◽  
Light Hole ◽  
Binding Energies ◽  
Exciton Binding Energy ◽  
Effective Mass Approximation ◽  
Mass Approximation ◽  
Asymmetric Configuration

Binding energies of the heavy hole and light hole exciton in a quantum well with Pöschl–Teller (PT) potential composed of GaAs have been studied variationally within effective mass approximation. The effects of pressure and temperature on exciton binding energy are analyzed individually and also simultaneously for symmetric and asymmetric configuration of the well. The results show that exciton binding energy (i) decreases as the well width increases, (ii) increases with pressure and (iii) decreases with temperature. Simultaneous effects of these perturbations lead to more binding of the exciton. The results are compared with the existing literature.

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.

scholarly journals Excitonic States and Related Optical Susceptibility in InN/AlN Quantum Well Under the Effects of the Well Size and Impurity Position

2021 ◽  
Vol 4 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Fathallah Jabouti ◽  
Haddou El Ghazi ◽  
Redouane En-nadir ◽  
Izeddine Zorkani ◽  
Anouar Jorio
Keyword(s):  
Quantum Well ◽  
Heavy Hole ◽  
Binding Energies ◽  
Exciton Transition ◽  
Impurity Position ◽  
Optical Susceptibility ◽  
Peak Energy ◽  
Eigen Values ◽  
Excitonic States ◽  
Photoluminescence Peak

Based on the finite difference method, linear optical susceptibility, photoluminescence peak and binding energies of three first states of an exciton trapped by a positive charge donor-impurity ( ) confined in InN/AlN quantum well are investigated in terms of well size and impurity position. The electron, heavy hole free and bound excitons allowed eigen-values and corresponding eigen-functions are obtained numerically by solving one-dimensional time-independent Schrödinger equation. Within the parabolic band and effective mass approximations, the calculations are made considering the coupling of the electron in the n-th conduction subband and the heavy hole in the m-th valence subband under the impacts of the well size and impurity position. The obtained results show clearly that the energy, binding energy and photoluminescence peak energy show a decreasing behavior according to well size for both free and bound cases. Moreover, the optical susceptibility associated to exciton transition is strongly red-shift (blue-shifted) with enhancing the well size (impurity position).

scholarly journals Annihilation Radii for Dislocations Intercepting a Free Surface with Application to Heteroepitaxial Thin Film Growth

1998 ◽  
Vol 535 ◽  
Author(s):  
M. Chang ◽  
S.K. Mathis ◽  
G.E. Beltz ◽  
C.M. Landis
Keyword(s):  
Free Surface ◽  
Film Thickness ◽  
Film Growth ◽  
Interaction Force ◽  
Critical Issue ◽  
Dislocation Motion ◽  
Threading Dislocations ◽  
Fusion Reactions ◽  
Gaas Films ◽  
Preliminary Experimental Data

AbstractOne critical issue in heteroepitaxial, lattice mismatched growth is the inevitable appearance of threading dislocations which reside in the relaxing film and degrade its semiconducting properties. It has been shown in previous work that threading dislocations interact with each other through a series of annihilation and fusion reactions to decrease their density as the film thickness increases and follow a 1/h decay, where h is the film thickness. A characteristic reaction radius is associated with these interactions. In previous simulations, the reaction radius was taken to be a constant value estimated using a simple approximation based on infinite, parallel dislocation lines. Here, a continuum-based elasticity approach is taken to more accurately quantify the reaction radius by comparing the Peach-Koehler force of one dislocation acting on another at a free surface with the lattice resistance to dislocation motion. The presence of the free surface gives rise to a moderate reduction of the interaction force. Results are compared with preliminary experimental data for GaAs films grown on InP.

scholarly journals Probing the light hole/heavy hole switching with correlated magneto-optical spectroscopy and chemical analysis on a single quantum dot

2019 ◽  
Vol 30 (17) ◽  
pp. 175301
Author(s):  
A Artioli ◽  
P Rueda-Fonseca ◽  
K Moratis ◽  
J F Motte ◽  
F Donatini ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Quantum Dot ◽  
Optical Spectroscopy ◽  
Heavy Hole ◽  
Light Hole ◽  
Single Quantum ◽  
Single Quantum Dot

Theoretical Analysis on Resistance-Temperature Characteristic of Ni/HCl-PANI Composites

2014 ◽  
Vol 852 ◽  
pp. 142-146 ◽  
Author(s):  
Sui Yu Qiu ◽  
Zhi Wei Yang ◽  
Hong Qiu
Keyword(s):  
Transition Temperature ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Temperature Characteristic ◽  
Substrate Thickness ◽  
Upper Limit ◽  
Metallic Conduction ◽  
Conduction Behavior ◽  
Doped Polyaniline ◽  
Semiconducting Behavior

Ni/HCl-PANI composites were formed by depositing Ni films on HCl-doped polyaniline (HCl-PANI) substrates. A simple parallel resistor model is used to analyze the resistance-temperature (R-T) characteristic of the composite within 30-300 K. The theoretical analysis reveals that the composite exhibits a metal-semiconductor transition within a certain thickness of the Ni film or the HCl-PANI substrate. The composite shows a semiconducting behavior at temperatures over the transition temperature and a metallic conduction behavior at temperatures below the transition temperature. The transition temperature increases with increasing Ni film thickness whereas it decreases with increasing HCl-PANI substrate thickness. When the Ni film thickness exceeds its upper limit or the HCl-PANI substrate thickness is below its lower limit, the composite only shows the metallic R-T characteristic. When the HCl-PANI substrate thickness exceeds its upper limit, the composite only exhibits the semicoducting R-T characteristic.

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