LOCALIZED WANNIER EXCITON IN DEFECT LAYER EMBEDDED BETWEEN TWO SEMI-INFINITE SUPERLATTICES

2010 ◽  
Vol 24 (18) ◽  
pp. 3501-3511
Author(s):  
MENG-DONG HE ◽  
LING-LING WANG ◽  
WEI-QING HUANG ◽  
BING-SOU ZOU ◽  
KE-QIU CHEN
Keyword(s):  
Binding Energy ◽  
Variational Approach ◽  
Exciton State ◽  
Defect Layer ◽  
Growth Direction ◽  
Exciton Binding Energy ◽  
Two Dimensional ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Peak Value

The characteristics of the localized Wannier exciton in defect layer (GaAs) embedded between two semi-infinite superlattices (GaAs/Al x Ga 1-x As ) are investigated theoretically using a variational approach. It can be clearly seen the exciton changes in character between three- and quasi-two-dimensional states from the variation of exciton binding energy, in-plane radius, and probability in the superlattices (SLs) growth direction. We find that the extensions of exciton in directions both parallel and perpendicular to the interface of SLs almost approach their minimums as the exciton binding energy reaches peak value at a certain defect width. Our results show that the binding energy of the ground exciton state is sensitive to Al concentration x in Al x Ga 1-x As and thicknesses of the constituent layers. The comparison between excitonic behavior in structural defect SLs and single quantum well is made.

CHALLENGES IN APPLICATION OF A MONTE CARLO METHOD TO STUDY AN EXCITON CONFINED IN AlGaAs/GaAs SINGLE QUANTUM WELL

2012 ◽  
Vol 26 (23) ◽  
pp. 1250129
Author(s):  
M. SOLAIMANI ◽  
M. IZADIFARD ◽  
H. ARABSHAHI ◽  
R. SARKARDEI
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Binding Energy ◽  
Quantum Well ◽  
Monte Carlo Sampling ◽  
Exciton Binding Energy ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Cpu Time ◽  
Computational Aspects

In this work, we have studied some computational aspects of a Monte Carlo method applied to an exciton which is confined in an AlGaAs/GaAs single quantum well. The computational pseudo-code and effect of its computational parameters like number of the Monte Carlo sampling points on a physical quantity like exciton binding energy are investigated. Then the CPU time under the change of such computational parameters are calculated. Finally, the exciton binding energy and errors of different methods of approximating the effective two dimensional coulomb potential for these systems are compared.

The Effects on Electric Field and Hydrostatic Pressure on the Doped Properties in a Strained (In,Ga)N-GaN Coupled Quantum Wells

2021 ◽  
Vol 16 (1) ◽  
pp. 97-103
Author(s):  
Xin-Nan Li ◽  
Guang-Xin Wang ◽  
Xiu-Zhi Duan
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Electric Field ◽  
Quantum Wells ◽  
Variational Approach ◽  
Coupled Quantum Wells ◽  
Zinc Blende ◽  
Impurity Interaction ◽  
The Right ◽  
Peak Value

A variational approach is utilized to investigated the electron-impurity interaction in zinc-blende (In,Ga)N-GaN strained coupled quantum wells. The donor imputrity states are studied in consideration of the effects of hydrostatic pressure and external electric field. Our results indicate that the binding energy visibly depends on hydrostatic pressure, strain of coupled quantum wells, and applied electric field. The binding energy demonstrates a peak value with the reduction of the left-well width, and which displays a minimum value with the increment of the middle-barrier width. A decreasing behavior on the binding energy is also demonstrated when the right-well width enhances. Also the binding energy augments constantly with the increasing hydrostatic pressure. Besides, the dependency of the binding energy on variation of impurity position has been analyzed detailedly.

LOCALIZED EXCITONS IN SELF-ASSEMBLED InxGa1-xN QUANTUM DOTS

2005 ◽  
Vol 19 (12) ◽  
pp. 589-598
Author(s):  
XIAN-QI DAI ◽  
FENG-ZHEN HUANG ◽  
JUN-JIE SHI
Keyword(s):  
Quantum Dots ◽  
Binding Energy ◽  
Variational Approach ◽  
Structural Parameters ◽  
Exciton Binding Energy ◽  
Mass Approximation ◽  
Energy Maximum ◽  
Localized Excitons ◽  
The Relationship ◽  
Good Agreement

Within the framework of effective-mass approximation, the exciton states localized in cylindrical InGaN quantum dots (QDs) are investigated using a variational approach. The relationship between the exciton states and structural parameters of QDs with radius R and height L are studied in detail. The numerical results show that the exciton binding energy is sensitive to the ratio of R/L for a QD with a given volume. There is a maximum in the binding energy, where the electrons and holes are the most efficiently confined in the QDs with special structural parameters. The binding energy maximum can be obtained at about L = 1.7 nm for different QD volumes. The exciton binding energy and emission wavelength depend sensitively on structural parameters and the In content in the In x Ga 1-x N active layer. Our calculated emission wavelengths are in good agreement with experimental data.

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