Donor impurity in vertically-coupled quantum-dots under hydrostatic pressure and applied electric field

In this work we make a predictive study on the binding energy of the ground state for hydrogenic donor impurity in vertically-coupled quantum-dot structure, considering the combined effects of hydrostatic pressure and in growth-direction applied electric field. The approach uses a variational method...

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Veröffentlicht in:The European physical journal. B, Condensed matter physics Jg. 73; H. 3; S. 309 - 319
Hauptverfasser: Duque, C. M., Barseghyan, M. G., Duque, C. A.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Berlin/Heidelberg Springer-Verlag 01.02.2010
EDP Sciences
Schlagworte:
Complex Systems
Condensed Matter Physics
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Exact sciences and technology
Fluid- and Aerodynamics
Physics
Physics and Astronomy
Quantum dots
Solid State and Materials
Solid State Physics
Binding Energy
Electron Wave Function
Hydrostatic Pressure
Aluminum Concentration
Quantum Well
Defect states
Gallium arsenides
Potential barrier
Pressure effects
Variational methods
Quantum dots
Aluminium Gallium Arsenides Mixed
Effective mass model
Phenomenological model
H-like ions
Impurities
Electric field effects
Binding energy
Hydrostatic pressure
Wave functions
Donor center
ISSN:1434-6028, 1434-6036
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Beschreibung
Zusammenfassung:In this work we make a predictive study on the binding energy of the ground state for hydrogenic donor impurity in vertically-coupled quantum-dot structure, considering the combined effects of hydrostatic pressure and in growth-direction applied electric field. The approach uses a variational method within the effective mass approximation. The low dimensional structure consists of three cylindrical shaped GaAs quantum-dots, grown in the z-direction and separated by Ga 1-x Al x As barriers. In order to include the pressure dependent Γ – X crossover in the barrier material a phenomenological model is followed. The main findings can be summarized as follows: 1) for symmetrical and asymmetrical dimensions of the structures, the binding energy as a function of the impurity position along the growth direction of the heterostructure has a similar behavior to that shown by the non-correlated electron wave function with maxima for the impurity in the well regions and minima for the impurity in the barrier regions, 2) for increasing radius of the system, the binding energy decreases and for R large enough reaches the limit of the binding energy in a coupled quantum well heterostructure, 3) the binding energy increases for higher Aluminum concentration in the barrier regions, 4) depending of the impurity position and of the structural dimensions of the system (well width and barrier thickness) – and because changing the height of the potential barrier makes possible to induce changes in the degree of symmetry of the carrier-wave function –, the electric field and hydrostatic pressure can cause the impurity binding energy increases or decreases, and finally 5) the line-shape of the binding energy curves are mainly given by the line-shape of the Coulomb interaction.
ISSN:1434-6028
1434-6036
DOI:10.1140/epjb/e2009-00433-7