Electronic Theory of Gettering and Passivation of Impurities in Semiconductors

1992 ◽  
Vol 262 ◽  
Author(s):  
K. Masuda-Jindo
Keyword(s):  
Tight Binding ◽  
Lattice Defects ◽  
Recursion Method ◽  
Impurity Atoms ◽  
Metal Impurities ◽  
Electronic Theory ◽  
Simple Physical Interpretation ◽  
Systematic Understanding ◽  
Gap States ◽  
Light Impurities

ABSTRACTWe calculate the interaction (segregation) energies Egegr between the extended lattice defects (dislocations and grain boundaries) and impurity atoms in semiconductors by using a microscopic electronic theory. In particular, we use the tight-binding recursion method coupled to the generalized zeros-and poles method and investigate the interaction between the extended lattice defects and various kinds of the impurity atoms in semiconductors (Si). For the systematic understanding of the impurity gettering, we consider a wide variety of impurities, both sp-valence and transition metal impurities, Ti, V, Cr, Mn, Fe, Co, Ni and Cu. We will show that the variation of the gap states plays an important role in determining the interaction energy Esegr between the impurity atom and the extended lattice defects- We also discuss the passivation of the extended lattice defects by interstitial light impurities like hydrogen in Si crystal, we present a simple physical interpretation of the impurity gettering and passivation in semiconductors.

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.

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.

Metal Contacts on a-GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
T. U. Kampen ◽  
W. Mönch
Keyword(s):  
Tight Binding ◽  
Image Force ◽  
Schottky Contacts ◽  
Metal Contacts ◽  
Zero Bias ◽  
Barrier Heights ◽  
Current Voltage ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Gap States

The Schottky barrier heights of silver and lead contacts on n-type GaN (0001) epilayers were determined from current-voltage characteristics. The zero-bias barrier heights and the ideality factors were found to be linearly correlated. Similar observations were previously reported for metal contacts on Si (111) and GaAs (110) surfaces. The barrier heights of ideal Schottky contacts are characterized by image force lowering of the barrier only. This gives an ideality factor of 1.01. From our data we obtain barrier heights of 0.82 eV and 0.73eV for ideal Ag and Pb contacts on GaN, respectively. The metal-induced gap states (MIGS) model predicts the barrier heights of ideal Schottky contacts on a given semiconductor to be linearly correlated with the electronegativities of the metals. The two important parameters of this MIGS-and-electronegativity model are the charge neutrality level (CNL) of the MIGS and a slope parameter. The CNL may be calculated from the dielectric band gap and using the empirical tight-binding method. The slope parameters are given by the optical dielectric constant of the respective semiconductor. The predictions of the MIGS model for metal/GaN contacts are confirmed by the results presented here and by barrier heights previously reported by others for Au, Ti, Pt, and Pd contacts on GaN.

scholarly journals The t2g – eg band splitting of atoms on a rough surface

2015 ◽  
Vol 39 (1) ◽  
pp. 37-43
Author(s):  
Ain Ul Huda ◽  
Taskeya Haider ◽  
Supriya Saha ◽  
Mesbahuddin Ahmed
Keyword(s):  
Molecular Beam Epitaxy ◽  
Rough Surface ◽  
Density Of States ◽  
Molecular Beam ◽  
Tight Binding ◽  
Orbital Method ◽  
Recursion Method ◽  
Academy Of Sciences ◽  
Ag Substrate ◽  
Deposition Techniques

Any deposition techniques lead to the production of rough surfaces. Some researchers proposed a pair of coupled continuum equations, which models the molecular beam epitaxy. This model was used to generate a rough surface of Fe, which is deposited on a Ag substrate. Then use of recursion method of Haydock with the parameter of tight binding linearized muffin tin orbital method of Anderson revealed that the t2g and eg bands are nondegenerate at bulk and [100] plane but near the rough surface, the degeneracy is broken and splitting of density of states depends on the curvature of the surface.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 37-43, 2015

Electronic modes in carbon nanotubes with single and double impurity sites

2017 ◽  
Vol 31 (29) ◽  
pp. 1750220
Author(s):  
P. G. Komorowski ◽  
M. G. Cottam
Keyword(s):  
Carbon Nanotubes ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Longitudinal Axis ◽  
Binding Model ◽  
Substitutional Impurity ◽  
Impurity Atoms ◽  
Spatial Configurations ◽  
Impurity Sites ◽  
Walled Carbon Nanotubes

A theoretical study of isolated and doubly-clustered impurities is presented for the electronic excitations in a carbon nanotube lattice. Using a matrix operator formalism and a tight-binding model where the interactions between atoms take place via nearest-neighbor hopping, the properties of the excitations are deduced. A geometry consisting of long, single-walled carbon nanotubes is assumed with the defects introduced in the form of substitutional impurity atoms, giving rise to the localized electronic modes of the nanotube as well as the propagating modes of the pure (host) material. The impurities are assumed to be in a low concentration, having the form of either a single, isolated defect or a small cluster of two defects close together. A tridiagonal matrix technique is employed within a Green’s function formalism to obtain the properties of the discrete modes of the system, including their frequencies and localization. The numerical examples show a dependence on the nanotube diameters and on the relative spatial configurations of the impurities. The results contrast with the previous studies of line impurities since there is no translational symmetry along the longitudinal axis of the nanotubes in the present case.

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