Optimized tight‐binding valence bands and heterojunction offsets in strained III‐V semiconductors

1991 ◽  
Vol 70 (8) ◽  
pp. 4342-4356 ◽  
Author(s):  
Neal G. Anderson ◽  
Sean D. Jones
Keyword(s):  
Tight Binding ◽  
Valence Bands

ELEMENTARY EXCITATIONS AND OPTICAL ABSORPTION IN A POLYACENE CHAIN

2003 ◽  
Vol 17 (10) ◽  
pp. 2023-2034 ◽  
Author(s):  
Z. AN ◽  
C. Q. WU
Keyword(s):  
Optical Absorption ◽  
Tight Binding ◽  
Electronic States ◽  
Open Boundary ◽  
Aromatic Rings ◽  
Open Boundary Condition ◽  
Elementary Excitations ◽  
Strongly Coupled ◽  
Valence Bands ◽  
Doubly Charged

Within a tight-binding Su–Schrieffer–Heeger model, the elementary excitations and optical absorption of a polyacene chain are investigated. The polyacene chain composed of a number of aromatic rings is considered as two strongly coupled polyacetylene chains with an open boundary condition. First of all we found an interchain-coupled neutral soliton in a pristine chain as a consequence of odd-number sites in each chain. There are two localized electronic states accompanying the soliton and appearing in the conduction and valence bands, respectively. Moreover, an injected electron or hole will induce a polaron-like deformation mixed with the interchain soliton, while two extra electrons or holes will result in three separate solitons, among which one is doubly charged and other two are neutral. The optical absorption due to these elementary excitations are obtained.

Tight-Binding Model for Zn3As2 Valence Bands

1992 ◽  
Vol 173 (2) ◽  
pp. K25-K28 ◽  
Author(s):  
K. Sierański ◽  
Szatkowski
Keyword(s):  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model ◽  
Valence Bands

Electronic Theory of Mn - Alloyed Diluted Magnetic Semiconductors

1986 ◽  
Vol 89 ◽  
Author(s):  
H. Ehrenreich ◽  
K. C. Hass ◽  
B. E. Larson ◽  
N. F. Johnson
Keyword(s):  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Tight Binding ◽  
Magnetic Interactions ◽  
Potential Approximation ◽  
Exchange Constants ◽  
Density Band ◽  
Level Model ◽  
Diluted Magnetic ◽  
Valence Bands

AbstractRecent calculations of the electronic structure and magnetic interactions in Mn - alloyed II-VI diluted magnetic semiconductors (DMS) are summarized. Detailed band structure results are obtained using an empirical tight-binding, coherent potential approximation approach with input from experiment and local spin density band calculations. The dominant magnetic interactions in these systems result from hybridization between spin-split Mn d states and sp valence bands. Superexchange between Mn moments is well described by a simple three-level model which yields accurate Mn - Mn exchange constants for a variety of II-VI DMS as well as the rocksalt insulators MnO and α-MnS.

Tight-binding model for Zn3P2 valence bands

1993 ◽  
Vol 88 (8) ◽  
pp. 663-666 ◽  
Author(s):  
K. Sierański ◽  
J. Szatkowski
Keyword(s):  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model ◽  
Valence Bands

Multiscale Modeling of a Quantum Dot Heterostructure

2011 ◽  
Vol 1370 ◽  
Author(s):  
P. Sengupta ◽  
S. Lee ◽  
S. Steiger ◽  
H. Ryu ◽  
G. Klimeck
Keyword(s):  
Optical Transition ◽  
Tight Binding ◽  
Integrated Approach ◽  
Multiscale Approach ◽  
Multiscale Simulations ◽  
Numerical Accuracy ◽  
Structure Description ◽  
Valence Bands ◽  
Proper Splitting ◽  
Computational Resources

ABSTRACTA multiscale approach was adopted for the calculation of confined states in self-assembled semiconductor quantum dots (QDs). While results close to experimental data have been obtained with a combination of atomistic strain and tight-binding (TB) electronic structure description for the confined quantum states in the QD, the TB calculation requires substantial computational resources. To alleviate this problem an integrated approach was adopted to compute the energy states from a continuum 8-band k.p Hamiltonian under the influence of an atomistic strain field. Such multiscale simulations yield a roughly six-fold faster simulation. Atomic-resolution strain is added to the k.p Hamiltonian through interpolation onto a coarser continuum grid. Sufficient numerical accuracy is obtained by the multiscale approach. Optical transition wavelengths are within 7% of the corresponding TB results with a proper splitting of p-type sub-bands. The systematically lower emission wavelengths in k.p are attributable to an underestimation of the coupling between the conduction and valence bands.

SPIN SPLITTING PROPERTIES IN GaSb Γ AND L/X-VALLEYS

2011 ◽  
Vol 25 (15) ◽  
pp. 2039-2045 ◽  
Author(s):  
W. WANG ◽  
M. H. ZHANG
Keyword(s):  
Nearest Neighbor ◽  
Spin Dynamics ◽  
Tight Binding ◽  
Spin Splitting ◽  
Interaction Coefficients ◽  
Binding Model ◽  
Small Band ◽  
Splitting Energy ◽  
Valence Bands ◽  
Explicit Electron

The band structures of GaSb in the Γ-valley as well as L/X-valley are excellently reproduced with sp3d5s* nearest-neighbor tight-binding model. The electron spin splitting energy and the spin–orbit interaction coefficients in the Γ, L and X multi-valleys are calculated. In the Γ-valley, the results obtained are in good agreement with experimental report. We then further extend our calculations to the GaSb L- and X-valleys. We also present the results of the top three valence bands in the Γ-valley. Due to the small band offset and large difference of the density of states between Γ- and L-valleys, it is shown that even at zero electric field, there is still an explicit electron population in the L-valley. These results are important to the realization of spintronic device and the investigation of spin dynamics far away from equilibrium.

The electronic properties of tetrahedral intermetallic compounds IV. The determination of valence bands by a method of linear combination of bond orbitals

1962 ◽  
Vol 270 (1342) ◽  
pp. 397-410 ◽  
Keyword(s):  
Linear Combination ◽  
Atomic Orbital ◽  
Tight Binding ◽  
Covalent Bond ◽  
Tight Binding Approximation ◽  
Plane Wave Method ◽  
Zinc Blende ◽  
Valence Bands ◽  
Experimental Values ◽  
Type Crystal

The linear combination of bond orbitals (l.c.b.o.) method is used to calculate the valence bands of the tetrahedral crystals BN, AlP, GaAs, InSb, CdTe, C (diamond), Si, Ge and grey tin. The l.c.b.o. method, which is mathematically similar to the atomic orbital tight-binding approximation, is described for the zinc-blende form of boron nitride. It is assumed that two adjacent atoms B and N are joined by a partly covalent bond. An electron in such a bond is represented by the localized σ-type bond orbital Ψ = N -1/2 (Φ N +λΦ B ) The periodicity of the crystal is taken into account by forming Bloch functions from these bond orbitals. A fourthorder secular determinant is obtained. This determinant is resolved for the (100) and (111) directions of the Brillouin zone; but for more general points in k-space it is only solved under more restrictive conditions. In the present general discussion, overlap integrals are neglected. The valence bands of a purely covalent diamond-type crystal are easily obtained from those of a partly covalent zinc-blende type crystal by replacing the two different kinds of atom by one common type. Where possible the valence bands obtained with the l.c.b.o. method are compared with the results of other calculations, and with experimental values, though at present none of the widths of the valence bands of these crystals is known accurately. But our forms of the valence bands in the (100) and (111) directions are found to agree well with results previously obtained by the orthogonalized plane wave method. For all the solids studied the maximum of the valence band is at k = (0, 0, 0) and is of p -character, being triply degenerate.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

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