Theoretical Study of Native Defect Coiplexes in GaAs

1985 ◽  
Vol 46 ◽  
Author(s):  
P.J. Lin-Chng ◽  
Yuan Li
Keyword(s):  
Theoretical Study ◽  
Tight Binding ◽  
Lattice Relaxation ◽  
Antisite Defect ◽  
Interaction Matrix ◽  
Native Defect ◽  
Matrix Elements ◽  
Recursion Method ◽  
Defect Complexes ◽  
Realistic Interaction

AbstractA theoretical study of native defect complexes in GaAs is reported here. These calculations are based on tight-binding Hamiltonians and employ a large cluster recursion method to obtain the changes of local densities of states. A new description of the tight-binding matrix elements developed by us is used to take into account the lattice relaxation and to provide the interaction matrix elements between the antisite defect and its neigiitors. We have examined the complexes GaAsVGa, (VGa)2, VGaAsGaVGa, VGaAsGaVGa, AsGaVAs and VAsAsGaVAs. The results indicate that the use of realistic interaction between the antisite atom and its neighloors is essential to obtain an accurate result for the midgap state of the isolated antisite and that the GaAsVGa,AsGaVAs, (VGa)2 may be responsible for the A,D hole traps and the electron trap C as proposed recently by Zou et al. using a thermochemical model. Both VGaAsGaVGa and VGaAsGaVAs are found to produce states in the gap. It is not possible to exclude either of them as a candidate for the EL2 state. A detailed analysis of the states induced by the defect complexes is made.

ENERGY GAP DEPENDENCE ON ANION CONCENTRATION FOR GaxIn1-xAsyP1-y QUATERNARY ALLOY BY RECURSION METHOD

2004 ◽  
Vol 18 (18) ◽  
pp. 955-962
Author(s):  
MUSA EL-HASAN ◽  
REZEK ESTATIEH
Keyword(s):  
Density Of States ◽  
Energy Gap ◽  
Local Density ◽  
Tight Binding ◽  
Quaternary Alloy ◽  
Average Density ◽  
Local Density Of States ◽  
Recursion Method ◽  
Orbital Decomposition ◽  
Lattice Matched

Three terminators have been tested, square root terminator, quadreture terminator and linear terminator, it was found that the linear terminator is the best, so it was used in calculating local density of states (LDOS) and it's orbital decomposition, alloy average density of states, and energy gap for different anion concentrations for InP lattice matched alloy. The results were compared with our previous calculations of (LDOS), and results from other methods. Energy gap was compared with experimental measurements. A five orbital sp3s* per atom model was used in the tight-binding representation of the Hamiltonian.

Tight Binding Modeling of Properties Related to Field Emission from Nanodiamond Clusters

2000 ◽  
Vol 621 ◽  
Author(s):  
Denis A. Areshkin ◽  
Olga A. Shenderova ◽  
Victor V. Zhirnov ◽  
Alexander F. Pal ◽  
John J. Hren ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Field Emission ◽  
Density Of States ◽  
Electron Affinity ◽  
Potential Distribution ◽  
Tight Binding ◽  
Matrix Elements ◽  
Energy States ◽  
Bulk Diamond ◽  
Modeling Of Properties

ABSTRACTThe electronic structure of nanodiamond clusters containing between 34 and 913 carbon atoms was calculated using a tight-binding Hamiltonian. All clusters had shapes represented by an octahedron with (111) facets with the top and the bottom vertices truncated to introduce (100) surfaces. The tight-binding Hamiltonian consisted of environment-dependent matrix elements, and C-H parameters fit to reproduce energy states of the cyclic C6 and methane. The calculations predict a density of states similar to bulk diamond for clusters with radii greater than ∼2.5nm, and insignificant differences in the potential distribution between the clusters and bulk diamond for radii greater than ∼1nm. Hydrogen passivated nanodiamond clusters are estimated to have an electron affinity of approximately -1.8 eV.

scholarly journals Терагерцовая спектроскопия магнитоэлектрика HoAl-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=-

2022 ◽  
Vol 130 (1) ◽  
pp. 59
Author(s):  
А.М. Кузьменко ◽  
В.Ю. Иванов ◽  
А.Ю. Тихановский ◽  
А.Г. Пименов ◽  
А.М. Шуваев ◽  
...  
Keyword(s):  
Crystal Field ◽  
Excited States ◽  
Ground State ◽  
Theoretical Study ◽  
Low Frequency ◽  
Local Symmetry ◽  
Matrix Elements ◽  
The Matrix ◽  
Excitation Conditions ◽  
Ground Multiplet

Experimental and theoretical study of submillimeter (terahertz) spectroscopic and magnetic properties of the rare-earth aluminum borate HoAl3(BO3)4 were performed at temperatures 3–300 K. In the transmittance spectra a number of resonance lines were detected at frequencies 2–35 cm–1 for different radiation polarizations. These modes were identified as transitions between the lower levels of the ground multiplet of the Ho3+ ion split by the crystal field, including both transitions from the ground state to the excited ones and transitions between the excited states. The established excitation conditions of the observed modes and the simulation of the spectra made it possible to separate the magnetic and electric dipole transitions and to determine the energies of the corresponding states, their symmetry, and the matrix elements of the transitions. Low-frequency lines that do not fit into the established picture of the electron states of Ho3+ were also found; these lines, apparently, correspond to the ions with the distorted by defects local symmetry of the crystal field.

Electronic Structure of Epitaxial SiO2/Si(100) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
T. Motooka
Keyword(s):  
Tight Binding ◽  
Interface States ◽  
Photoelectron Spectra ◽  
Band Spectrum ◽  
Binding Model ◽  
Initial Oxidation ◽  
Recursion Method ◽  
Densities Of States ◽  
Local Densities ◽  
Gap States

ABSTRACTThe local densities of states (LDOS) of epitaxial SiO, layers on Si(100) surfaces have been calculated using the recursion method combined with the Harrison's universal tight-binding model. The interface states associated with strained epitaxial layers of β-cristobalite (√2×√2)R45° and tridymite (1010)<0001> || Si(100)<011> were examined. In the β-cristobalite layer, gap states due to the surface Si dangling bonds appeared while they were eliminated by H termination. In the tridymite layer, the interface states primarily composed of the surface Si back bonds appeared near the Si conduction band minimum. Comparing the calculated DOS with photoelectron spectra for initial oxidation processes of clean Si(100), it was found that the valence band spectrum from the initial oxide formed at ∼300°C resembled that of the β-cristobalite layer.

scholarly journals Experimental and theoretical study of lattice relaxation around refractory atoms in nickel

2008 ◽  
Vol 56 (17) ◽  
pp. 4601-4607 ◽  
Author(s):  
V. Koteski ◽  
H.-E. Mahnke ◽  
J. Belošević-Čavor ◽  
B. Cekić ◽  
G. Schumacher
Keyword(s):  
Theoretical Study ◽  
Lattice Relaxation

scholarly journals Theoretical Study of InAlN/GaN High Electron Mobility Transistor (HEMT) with a Polarization-Graded AlGaN Back-Barrier Layer

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 885 ◽  
Author(s):  
Yan Gu ◽  
Dongmei Chang ◽  
Haiyan Sun ◽  
Jicong Zhao ◽  
Guofeng Yang ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Theoretical Study ◽  
Lattice Relaxation ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
Two Dimensional ◽  
Drift Diffusion ◽  
High Electron Mobility ◽  
Al Content ◽  
Dimensional Electron Gas

An inserted novel polarization-graded AlGaN back barrier structure is designed to enhance performances of In0.17Al0.83N/GaN high electron mobility transistor (HEMT), which is investigated by the two-dimensional drift-diffusion simulations. The results indicate that carrier confinement of the graded AlGaN back-barrier HEMT is significantly improved due to the conduction band discontinuity of about 0.46 eV at interface of GaN/AlGaN heterojunction. Meanwhile, the two-dimensional electron gas (2DEG) concentration of parasitic electron channel can be reduced by a gradient Al composition that leads to the complete lattice relaxation without piezoelectric polarization, which is compared with the conventional Al0.1Ga0.9N back-barrier HEMT. Furthermore, compared to the conventional back-barrier HEMT with a fixed Al-content, a higher transconductance, a higher current and a better radio-frequency performance can be created by a graded AlGaN back barrier.

SYMMETRY AND ELECTRO-OPTICAL PROPERTIES OF NANOTUBES

2002 ◽  
Vol 01 (03n04) ◽  
pp. 313-325 ◽  
Author(s):  
M. DAMNJANOVIĆ ◽  
I. MILOŠEVIĆ ◽  
T. VUKOVIĆ ◽  
B. NIKOLIĆ ◽  
E. DOBARDŽIĆ
Keyword(s):  
Carbon Nanotubes ◽  
Optical Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Optical Characteristics ◽  
Optical Transitions ◽  
Matrix Elements ◽  
Selection Rules ◽  
Single Wall Carbon ◽  
Quantum Numbers

The symmetry of single-wall carbon and inorganic tubes is reviewed. For the carbon nanotubes it is used to get the full set of quantum numbers, in the efficient precision (combined density functional and tight-binding methods) calculation of electronic bands and their complete assignation, to obtain the selection rules for optical transitions and the momenta matrix elements for the Bloch eigen-states. The optical characteristics are thoroughly found, and discussed.

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