THE EFFECT OF HYDROSTATIC PRESSURE ON METAL–INSULATOR TRANSITION IN QUANTUM WELL SEMICONDUCTOR SYSTEMS II

Using a variational procedure within the effective mass approximation, the ionization energies of a shallow donor in a quantum well (QW) of GaAs/Ga 1-x Al x As superlattice system under the influence of pressure with the exact dielectric function are obtained. The vanishing of ionization energy initiating Mott transition is observed within the one-electron approximation. The effects of Anderson localization using a simple model, and exchange and correlation in the Hubbard model are included in this model. It is found that the ionization energy (i) increases when well width increases for a given pressure, (ii) decreases and reaches a bulk value for a larger well width, (iii) increases with increasing external hydrostatic pressure for a given QW thickness, and (iv) the critical concentration at which the metal–insulator transition (MIT) occurs is increased when pressure is applied. It also is demonstrated that MIT is not possible in a hydrostatic pressure in a quantum well supporting scaling theory of localization. All the calculations have been carried out with finite and infinite barriers and the results are compared with available data in the literature.

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LASER INDUCED METAL INSULATOR TRANSITION THROUGH EXCITON MECHANISM IN QUANTUM WELL SYSTEMS

Modern Physics Letters B ◽

10.1142/s0217984909019223 ◽

2009 ◽

Vol 23 (09) ◽

pp. 1229-1242 ◽

Cited By ~ 1

Author(s):

S. RAJASHABALA ◽

S. S. KANMANI ◽

K. NAVANEETHAKRISHNAN

Keyword(s):

Laser Radiation ◽

Quantum Well ◽

Diamagnetic Susceptibility ◽

Critical Concentration ◽

Binding Energies ◽

Insulator Transition ◽

Metal Insulator Transition ◽

Metal Insulator ◽

Mass Approximation ◽

Exciton Mechanism

Within the effective mass approximation, the binding energies of a Wannier exciton in a GaAs-Ga 1-x Al x As quantum well in an electric field are investigated using a variational method. The binding energiesare obtained upon illlumination by laser radiation. The binding energy decreases as the well size increases when the size of the well is beyond 50 Å. The above behavior is for a quantum well of finite confinement. We have investigated the metal-insulator transition in such a system and report the values of critical concentrations of excitons at which metal-insulator transition occurs for different well dimensions. The calculated diamagnetic susceptibility shows the catastrophic behavior at the critical concentration.

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METAL–INSULATOR TRANSITION IN A QUASI-LOW-DIMENSIONAL SEMICONDUCTOR SYSTEM

International Journal of Modern Physics B ◽

10.1142/s021797920302332x ◽

2003 ◽

Vol 17 (30) ◽

pp. 5725-5735

Author(s):

A. JOHN PETER

Keyword(s):

Hubbard Model ◽

Critical Concentration ◽

Shallow Donor ◽

Insulator Transition ◽

Metal Insulator Transition ◽

Metal Insulator ◽

Mass Approximation ◽

Semiconductor System ◽

Low Dimensional ◽

The Relationship

Metal–Insulator transition using exact quasi dielectric functions is investigated for a shallow donor in an isolated well of GaAs/Ga 1-x Al s As superlattice system within the effective mass approximation. Vanishing of the donor ionization energy as a function of well width and the donor concentration suggests that no transition is possible below a well width of 50 Å supporting the scaling theory of localization. The effects of Anderson localization, exchange and correlation in the Hubbard model are included in a simple way. The relationship between the present model and the Mott criterion in terms of Hubbard model is also brought out. The critical concentration is enhanced when a random distribution of impurities is considered. Results are compared with the existing data available and discussed in the light of existing literature.

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MAGNETIC STUDIES OF METAL–INSULATOR TRANSITION IN A QUANTUM WELL SYSTEM

International Journal of Nanoscience ◽

10.1142/s0219581x08005341 ◽

2008 ◽

Vol 07 (04n05) ◽

pp. 207-213 ◽

Cited By ~ 1

Author(s):

A. JOHN PETER ◽

L. CAROLINE SUGIRTHAM

Keyword(s):

Magnetic Field ◽

Quantum Well ◽

Effective Mass ◽

Diamagnetic Susceptibility ◽

Insulator Transition ◽

Magnetic Studies ◽

Metal Insulator Transition ◽

Metal Insulator ◽

Intense Magnetic Field ◽

Mass Approximation

Metal–insulator transition in doped semiconductors is investigated in the presence of intense magnetic fields. A variational procedure within the effective mass approximation is employed using the Thomas–Fermi screening function and the exact quasi-Q2D Lindhard dielectric function. The Hubbard model results are justified using an effective mass that depends on interimpurity separation. The nonparabolicity of the subband is included using an energy-dependent effective mass. Though an increase of ionization energy with a magnetic field is observed for isolated donor models, the metallization occurs with an intense magnetic field at a higher concentration for a particular well width. The diamagnetic susceptibility of a hydrogenic donor impurity in GaAs / Ga 1 - x Al x As quantum well systems is discovered in the observation of metal–insulator transition. It is shown that the diamagnetic susceptibility diverges for all critical concentrations for a given well width. The large diamagnetic susceptibility (> 6) is observed at the transition. All the calculations are carried out for infinite and finite barriers, and the results are compared with the existing literature.

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