EFFECTIVE MASSES FOR DONOR BINDING ENERGIES IN QUANTUM WELL SYSTEMS

2006 ◽  
Vol 20 (24) ◽  
pp. 1529-1541 ◽  
Author(s):  
S. RAJASHABALA ◽  
K. NAVANEETHAKRISHNAN
Keyword(s):  
Quantum Well ◽  
Effective Mass ◽  
Binding Energies ◽  
Bohr Radius ◽  
Mass Variation ◽  
Effective Masses ◽  
Approximate Form ◽  
Finite Barrier ◽  
Infinite Barrier ◽  
Barrier Model

The donor ionization energies in a quantum well and quantum dot with finite and infinite barriers are estimated for different well dimensions. Using the effective mass (EM) approximation, calculations are presented with constant effective mass and position dependent effective masses that are different for finite and infinite cases. Our results reduce to an approximate form used by X. H. Qi et al., Phys. Rev. B58 (1998) 10578 in the finite barrier model and that of L. E. Oliveira and L. M. Falicov, Phys. Rev. B34 (1986) 8676 in the infinite barrier case. Results are presented by taking the GaAs quantum well as an example. The use of constant effective mass of 0.067m0 is justified for well dimensions ≥a* where a* is an effective Bohr radius which is about 100 Å. While Qi et al. found a maximum of 22% variation in the binding energies due to mass variation, we obtained nearly 100% variation when mass variations are included correctly.

POSITION DEPENDENT EFFECTIVE MASSES FOR DONOR BINDING ENERGIES IN QUANTUM CONFINED SYSTEMS IN AN ELECTRIC FIELD

2010 ◽  
Vol 09 (01n02) ◽  
pp. 83-91 ◽  
Author(s):  
S. RAJASHABALA ◽  
KANNAN RAMAN
Keyword(s):  
Electric Field ◽  
Effective Mass ◽  
Binding Energies ◽  
Bohr Radius ◽  
Ionization Energies ◽  
Effective Masses ◽  
Hydrogenic Donor ◽  
Finite Barrier ◽  
Dependent Mass ◽  
Position Dependent Mass

In our earlier works, the effective mass theory (EMT) was critically examined for a hydrogenic donor in a quantum well (QW) and in a quantum dot (QD) after introducing position dependent effective masses (PDEMs). Our results showed that the use of constant effective mass was justified for all well dimensions a*, the effective Bohr radius which is 100 Å in GaAs. Here the validity of EMT in the presence of an electric field is examined. The electric field dependent donor ionization energies in both the systems with finite and infinite barriers for different well dimensions have been calculated. It is shown that the electric field affects donor binding energies appreciably, the variation being larger in the case of finite barrier systems when PDEM is used. The donor polarizability has also been estimated in both the systems and the results are compared with other works in the literature. The use of EMT is justified if constant effective mass is used in general, even though large variation in the ionization energies occur in the finite barrier cases when position dependent mass is included correctly.

EFFECT OF DIELECTRIC SCREENING ON THE DIAMAGNETIC SUSCEPTIBILITY OF A DONOR IN LOW DIMENSIONAL SEMICONDUCTING SYSTEMS

2009 ◽  
Vol 23 (08) ◽  
pp. 2069-2075
Author(s):  
P. NITHIANANTHI ◽  
P. VICKRAMAN ◽  
K. JAYAKUMAR
Keyword(s):  
Quantum Dot ◽  
Variational Method ◽  
Quantum Well ◽  
Effective Mass ◽  
Diamagnetic Susceptibility ◽  
Quantum Well Wire ◽  
Dielectric Screening ◽  
Low Dimensional ◽  
Infinite Barrier ◽  
Barrier Model

The effect of spatial dielectric screening on the diamagnetic susceptibility (χ dia ) of a donor in Low Dimensional Semiconducting Systems like Quantum Well, Quantum Well Wire and Quantum Dot in the infinite barrier model has been computed and investigated within the effective mass theory using variational method. We observe that the effect of spatial dielectric screening on χ dia decreases with decrease of dimensionality of the system.

EFFECT OF HYDROSTATIC PRESSURE ON THE BINDING ENERGIES OF EXCITONS IN QUANTUM WELLS

2007 ◽  
Vol 21 (16) ◽  
pp. 2735-2747 ◽  
Author(s):  
G. J. ZHAO ◽  
X. X. LIANG ◽  
S. L. BAN
Keyword(s):  
Dielectric Constant ◽  
Hydrostatic Pressure ◽  
Quantum Wells ◽  
Pressure Effect ◽  
Binding Energies ◽  
Band Offset ◽  
Conduction Band Offset ◽  
Effective Masses ◽  
Finite Barrier ◽  
Effect Of Hydrostatic Pressure

The binding energies of excitons in finite barrier quantum wells under hydrostatic pressure are calculated by a variational method. The influences of hydrostatic pressure on the effective masses of the electron and hole, the dielectric constant, and the conduction band offset between the well and barriers are taken into account in the calculation. The numerical results for the GaAs/Al x Ga 1-x As and GaN/Al x Ga 1-x N quantum wells are given respectively. It is shown that the exciton binding energy increases linearly with the pressure and the pressure effect on arsenide quantum wells is more obvious than that on nitride ones. The exciton binding energies monotonically increase with increasing barrier height, which is related to the Al concentration of the barriers and the influence of the pressure.

Electronic Structure of Si/InAs Composite Channels

2007 ◽  
Vol 995 ◽  
Author(s):  
Marta Prada ◽  
Neerav Kharche ◽  
Gerhard Klimeck
Keyword(s):  
Electronic Structure ◽  
Quantum Well ◽  
Effective Mass ◽  
Tight Binding ◽  
Localized States ◽  
Equivalent Thickness ◽  
Binding Model ◽  
Direct Bandgap ◽  
Effective Masses ◽  
Composite Channels

AbstractElectronic structure calculations on composite channels, consisting of indium arsenide grown on the technologically relevant (001), (011) and (112)-orientated silicon surfaces are reported. The calculations are performed with NEMO 3-D, where atoms are represented explicitly in the sp3d5s* tight-binding model. The Valence Force Field (VFF) method is employed to minimize the strain. NEMO 3-D enables the calculation of localized states in the quantum well (QW) and their dispersion in the quantum well plane. From this dispersion, the bandgap, its direct or indirect in character, and the associated effective masses of the valence and conduction band can be determined. Such composite bandstructure calculations are demonstrated here for the first time. The numerical results presented here can then be included in empirical device models to estimate device performance. Pure InAs QWs create a direct bandgap material, with a relatively small gap and effective masses of about one order of magnitude smaller than for pure Si QW of equivalent thickness. Si, on the other hand, has a larger bandgap, superior thermal and mechanical properties, and a heavily invested industry. Thus heteroepitaxy of both components is expected to yield a highly optimized overall system. For samples grown along the (001) direction, Si is a direct bandgap material, and deposition of an InAs 3nm layer reduces substantially the hole effective mass and slightly the electronic mass, decreasing the magnitude of the gap. Along the (011) and (112)-growth direction, Si QWs are indirect bandgap material, and deposition of a few InAs layers suffies to make the new material a direct-bandgap heterostructure, decreasing significantly the electronic effective mass. (011) and (112) are the experimentally most relevant growth directions since they prevent heterointerface dipoles.

On the scaling of exciton and impurity binding energies and the virial theorem in semiconductor quantum wells and quantum-well wires

2001 ◽  
Vol 692 ◽  
Author(s):  
M. de Leyva-Dios ◽  
L. E. Oliveira
Keyword(s):  
Wave Function ◽  
Quantum Well ◽  
Quantum Wells ◽  
Virial Theorem ◽  
Dimensional Space ◽  
Shallow Donor ◽  
Binding Energies ◽  
Bohr Radius ◽  
Semiconductor Quantum Wells ◽  
Quantum Well Wires

AbstractWe have used the variational and fractional-dimensional space approaches in a study of the virial theorem value and scaling of the shallow-donor binding energies versus donor Bohr radiusin GaAs-(Ga,Al)As semiconductor quantum wells and quantum-well wires. A comparison is made with previous results with respect to exciton states. In the case the donor ground-state wave function may be approximated by a D-dimensional hydrogenic wave function, the virial theorem value equals 2 and the scaling rule for the donor binding energy versus quantum-sized Bohr radius is hyperbolic, both for quantum wells and wires. In contrast, calculations within the variational scheme show that the scaling of the donor binding energies with quantum-sized Bohr radius is in general nonhyperbolic and that the virial theorem value is nonconstant.

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.

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