scholarly journals THE EFFECT OF STRAIN ON THE EXCITON SPECTRUM OF GERMANIUM

1965 ◽  
Vol 43 (1) ◽  
pp. 12-27 ◽  
Author(s):  
A. M. Glass
Keyword(s):  
Optical Absorption ◽  
Band Structure ◽  
Effective Mass ◽  
Absorption Edge ◽  
Energy Gap ◽  
Applied Strain ◽  
Binding Energies ◽  
Direct Transition ◽  
Mass Approximation ◽  
Exciton Spectrum

The intensity of optical absorption, near the absorption edge in germanium, is examined as a function of strain applied to the lattice at 90 °K. The results are interpreted in terms of the change of the band structure of the lattice with applied strain. The absorption edge in unstrained germanium shows a single sharp peak due to direct-transition exciton formation at k = 0, whereas the edge in the strained specimens shows two exciton peaks. The peak positions vary linearly with both compressional and tensional strain up to the maximum strains applied (0.1% deformation). The exciton binding energies in the strained germanium lattice, calculated within the effective mass approximation, are approximately equal and independent of the magnitude of the strain. The separation of the peaks gives for the shear deformation potentials the values |b| = (2.7 ± 0.3) eV/unit (100) shear and |d| = (4.7 ± 0.5) eV/unit (111) shear. The positions of the peaks give the shift of the energy gap as −(10.3 ± 1) eV/unit dilation.Lattice imperfections are found to have no effect on the interpretation of the results.

OPTICAL INTERSUBBAND TRANSITIONS AND BINDING ENERGIES OF DONOR IMPURITIES IN Ga1-xInxNyAs1-y/GaAs/Al0.3Ga0.7As QUANTUM WELL UNDER THE ELECTRIC FIELD

2012 ◽  
Vol 26 (06) ◽  
pp. 1250013 ◽  
Author(s):  
F. UNGAN ◽  
U. YESILGUL ◽  
E. KASAPOGLU ◽  
H. SARI ◽  
I. SOKMEN
Keyword(s):  
Binding Energy ◽  
Optical Absorption ◽  
Electric Field ◽  
Quantum Well ◽  
Applied Electric Field ◽  
Shallow Donor ◽  
Binding Energies ◽  
Intersubband Transitions ◽  
Mass Approximation ◽  
Intersubband Optical Absorption

The effects of nitrogen and indium mole concentration on the intersubband optical absorption for (1–2) transition and the binding energy of the shallow-donor impurities in a Ga 1-x In x N y As 1-y/ GaAs / Al 0.3 Ga 0.7 As quantum well under the electric field is theoretically calculated within the framework of the effective-mass approximation. Results are obtained for several concentrations of nitrogen and indium, and the applied electric field. The numerical results show that the intersubband transitions and the impurity binding energy strongly depend on the nitrogen and indium concentrations.

BARRIER THICKNESS DEPENDENCE OF OPTICAL ABSORPTION OF EXCITONS IN GaAs COUPLED QUANTUM WIRE

2004 ◽  
Vol 11 (01) ◽  
pp. 49-55 ◽  
Author(s):  
E. KASAPOGLU ◽  
M. GUNES ◽  
H. SARI ◽  
I. SÖKMEN
Keyword(s):  
Binding Energy ◽  
Optical Absorption ◽  
Quantum Wire ◽  
Variational Approach ◽  
Quantum Wires ◽  
Binding Energies ◽  
Barrier Thickness ◽  
Mass Approximation ◽  
Quantum Well Wires ◽  
Coupled Quantum Well

We have calculated the binding energy of excitons, and the interband optical absorption in rectangular coupled quantum-well wires of GaAs surrounded by Ga 1-x Al x As in effective-mass approximation, using the variational approach. Results obtained show that the exciton binding energies and optical absorption depend on the sizes of the wire and barrier thickness. To the best of our knowledge the exciton binding energy and interband optical absorption in the rectangular coupled quantum wires have not been clarified yet.

Donor States in Spherical GaAs-Ga1-xAlxAs Quantum Dots

1997 ◽  
Vol 11 (15) ◽  
pp. 673-679 ◽  
Author(s):  
Ecaterina C. Niculescu ◽  
Ana Niculescu
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Effective Mass ◽  
Coulomb Potential ◽  
Adjustable Parameter ◽  
Binding Energies ◽  
Central Cell ◽  
Shallow Donors ◽  
Mass Approximation ◽  
Donor States

The effect of the central cell correction on the binding energies of shallow donors in a spherical GaAs-Ga 1-x Al x As quantum dot is studied. The effective-mass approximation within a variational scheme is adopted and central cell corrections are calculated by using a Coulomb potential modified with an adjustable parameter. For small values of the radius of the dot large corrections are obtained for the shallow donors studied.

Energy Spectra of CdS/Cd1-xZnx S Nano Dot Under The Influence of Magnetic Field

2014 ◽  
Vol 4 (1) ◽  
pp. 460-466
Author(s):  
P. Elangovan ◽  
M. Balakumari ◽  
A. Milton Franklin Benial
Keyword(s):  
Magnetic Field ◽  
Effective Mass ◽  
Applied Magnetic Field ◽  
Theoretical Study ◽  
Shallow Donor ◽  
Binding Energies ◽  
Energy Spectra ◽  
Mass Approximation ◽  
Zn Concentration ◽  
Frame Work

We present a theoretical study on shallow donor binding energies of CdS/ CdZnS nano dot as a strength of  applied magnetic field along Z direction for various Zn concentration. Calculations are carried out by using the technique of variational ansatz within the frame work of effective mass approximation. Our results show that the binding energies are drastically affected by the dot radius, the strength of magnetic field and concentrations.

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.

Dependence on well widths of total optical absorption coefficient of asymmetric triple GaAlAs/GaAs and GaInAs/GaAs quantum wells

2019 ◽  
Vol 33 (17) ◽  
pp. 1950175 ◽  
Author(s):  
O. Ozturk ◽  
E. Ozturk ◽  
S. Elagoz
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Quantum Wells ◽  
Effective Mass ◽  
Energy Gap ◽  
Energy Levels ◽  
Great Influence ◽  
Optical Absorption Coefficient ◽  
Optical Modulators

Herein, the total optical absorption coefficient (TOAC) and the electronic characteristics of asymmetric triple Ga[Formula: see text]Al[Formula: see text]As/GaAs (A model) and Ga[Formula: see text]In[Formula: see text]As/GaAs (B model) quantum wells (QWs) have been examined related to the well widths (WWs). For TOAC, we first varied all WWs equally, and then we kept a WW constant and changed the other two WWs. The wavefunctions (WFs), the subband energies and the probability densities of asymmetric triple quantum wells (ATQW) with different QW shapes under effective mass approach were determined by the solution of Schrödinger equation. According to the results obtained, the major diversities of A and B models are the effective mass and the energy gap. The potential depth and the energy levels (ELs) of A model are continuously smaller than of B model. We see that WWs have a great influence on TOAC and the electronic features of ATQW. The inter-subband absorption spectrum designates blue/red shifts, when the energy spacing varies with WWs. These characteristics draw a convenient attention for the purpose of adjustable semiconductor devices. Hence, the alteration of this absorption spectrum, which could be fit for many optical modulators and infra-red optical device applications, may be efficiently realized by changing WWs. Highlights Energy spacing varies by increasing WWs. Due to the shape of the wells, the influence of each WW is quite different from the others. TOAC varies with rising WWs. The absorption spectrum illustrates red or blue shifts depending on WWs.

Carrier Concentrations in Degenerate Semiconductors Having Band Gap Narrowing

2008 ◽  
Vol 63 (3-4) ◽  
pp. 193-198 ◽  
Author(s):  
Atanu Das ◽  
Arif Khan
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Effective Mass ◽  
Density Of States ◽  
Electrical Transport ◽  
Effective Mass Approximation ◽  
Degenerate Semiconductors ◽  
Mass Approximation ◽  
Heavily Doped ◽  
Band Gap Narrowing

The density-of-states effective mass approximation and the conduction-band effective mass approximation are employed to formulate carrier concentrations and the diffusivity-mobility relationship (DMR) for heavily doped n-semiconductors exhibiting band gap narrowing. These are very suitable for the investigation of electrical transport also in heavily doped p-semiconductors. Numerical calculations indicate that the DMR depends on a host of parameters including the temperature, carrier degeneracy, and the non-parabolicity of the band structure.

OPTICAL ABSORPTION EDGE INVESTIGATIONS IN Sn2P2S6 AND SnP2S6 CRYSTALS

2000 ◽  
Vol 6 (0) ◽  
pp. 32-39
Author(s):  
І. П. Студеняк ◽  
В. В. Митровцій ◽  
Д. Ш. Ковач ◽  
О. А. Микайло ◽  
М. І. Гурзан ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Edge ◽  
Optical Absorption Edge
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