Low Critical Concentration of Metal–Insulator Transition of Vanadium Doped Amorphous Boron

2011 ◽  
Vol 80 (2) ◽  
pp. 024709 ◽  
Author(s):  
Kenji Tanabe ◽  
Kohei Soga ◽  
Shizuka Hosoi ◽  
Kazuaki Osumi ◽  
Hideshi Yamaguchi ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Insulator Transition ◽  
Amorphous Boron ◽  
Metal Insulator Transition ◽  
Metal Insulator

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

2005 ◽  
Vol 04 (01) ◽  
pp. 45-53 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Hydrostatic Pressure ◽  
Quantum Well ◽  
Ionization Energy ◽  
Critical Concentration ◽  
Shallow Donor ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Mass Approximation ◽  
The One

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.

scholarly journals Metal-insulator transition and the character of the hole impurity bands in ferromagnetic GaMnAs disordered dilute magnetic semiconductor

2008 ◽  
Vol 1118 ◽  
Author(s):  
R. da Silva Neves ◽  
A. Ferreira da Silva ◽  
R. Kishore
Keyword(s):  
Dilute Magnetic Semiconductor ◽  
Critical Concentration ◽  
Mean Field ◽  
Magnetic Semiconductor ◽  
Impurity Band ◽  
Insulator Transition ◽  
Ferromagnetic Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
The Mean

ABSTRACTThe study of ferromagnetic transition of Ga1-xMnxAs dilute magnetic semiconductor (DMS) is much of interest mainly due to the potential application in spintronic devices. Based on the mean field approach we present the average contribution of the hole spins by considering the holes in an impurity band (IB) and the critical concentration for the metal-insulator transition (MIT) in this semiconductor. In order to calculate the mean configuration of spins of impurities Mn+2 we use a formalism proposed for a spatial disordered system. The results for the metallic densities around the MIT transition are compared to experimental results and other theoretical findings.

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

2009 ◽  
Vol 23 (09) ◽  
pp. 1229-1242 ◽  
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.

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

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.

Fermi-surface reconstruction close to a pressure-induced metal-insulator transition

2004 ◽  
Vol 114 ◽  
pp. 277-281 ◽  
Author(s):  
J. Wosnitza ◽  
J. Hagel ◽  
O. Stockert ◽  
C. Pfleiderer ◽  
J. A. Schlueter ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Surface Reconstruction ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Fermi Surface Reconstruction
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