Structural And Electronic Properties of GaN/AL Interfaces

1997 ◽  
Vol 482 ◽  
Author(s):  
S. Picozzi ◽  
A. Continenza ◽  
S. Massidda ◽  
A. J. Freeman
Keyword(s):  
Electronic Properties ◽  
Ohmic Contacts ◽  
Local Density ◽  
Full Potential ◽  
Junction Region ◽  
Augmented Plane Wave ◽  
Structural And Electronic Properties ◽  
Transitivity Rule ◽  
Gap States ◽  
Linearized Augmented Plane Wave

AbstractThe structural and electronic properties of the GaN/Al interface are determined from first principles local density full potential linearized augmented plane wave (FLAPW) calculations. The charge distribution of the gap states as a function of the distance from the interface shows that the gap states induced into the semiconductor by the presence of Al are strongly localized in the junction region. Furthermore, we find that Al does not provide good ohmic contacts on the clean nitrides considered, in contrast with experimental results on chemically treated GaN, but in agreement with recent measurements on the clean surface[1]. We also study some auxiliary systems (all grown on a GaN substrate), i.e. the Al/AlN interface, the GaN/AlN heterojunction and the GaN/Al with an AlN intralayer (GaN-AlN/Al). The transitivity rule for the GaN/Al, AlN/Al and GaN/AlN interfaces is fairly well satisfied and small differences must be ascribed to differences in the interface morphology. Finally, we find that the AIN intralayer does not significantly affect the p-type Schottky barrier height of the GaN/Al interface.

CORRELATION BETWEEN LOCAL OXYGEN DISORDER AND ELECTRONIC PROPERTIES IN SUPERCONDUCTING RESR2CU3O6+X(RE = Y, YB)

2003 ◽  
Vol 17 (04n06) ◽  
pp. 873-878 ◽  
Author(s):  
A. PRODI ◽  
A. GAUZZI ◽  
E. GILIOLI ◽  
F. LICCI ◽  
M. MAREZIO ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Local Density ◽  
Full Potential ◽  
Orthorhombic Distortion ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Structural And Electronic Properties ◽  
Large Elastic Strain ◽  
Linearized Augmented Plane Wave ◽  
Local Oxygen

This work aims at understanding the large reduction of superconducting critical temperature Tc observed in YSr 2 Cu 3 0 6+x as compared to its YBa 2 Cu 3 O 6+x counterpart (ΔTc = -30 K ). We report on a combined study of structural and electronic properties of RESr 2 Cu 3 O 6+x(RE = Y, Yb) polycrystalline samples. Neutron diffraction data and Cu NQR spectra show that, contrary to REBa 2 Cu 3 O 6+x RESr 2 Cu 3 O 6+x is locally tetragonal and no CuO chains are formed. This arises from the random occupancy of oxygen along the a- or b- direction in the basal planes. Ab-initio calculations of the electronic structure using the full-potential linearized-augmented-plane-wave method (FLAPW) in the local density approximation (LDA) suggest that the CuO chains are not formed because of the large elastic strain associated with the orthorhombic distortion produced by the chain formation. In addition, by using a [Formula: see text] supercell simulating the absence of chains, we find that oxygen disorder greatly alters the band structure near the Fermi level. Our analysis indicates that this alteration leads to a reduction of hole transfer from the CuO chains to the CuO 2 planes, which accounts for the reduction of Tc experimentally observed.

Ab initio studies of the structural, electronic, and optical properties of quaternary BxAlyGa1–x–yN compounds

2016 ◽  
Vol 71 (2) ◽  
pp. 125-134 ◽  
Author(s):  
M’hamed Larbi ◽  
Rabah Riane ◽  
Samir F. Matar ◽  
Ahmed Abdiche ◽  
Mustapha Djermouni ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Local Density ◽  
Lattice Parameter ◽  
Band Gaps ◽  
Full Potential ◽  
Generalized Gradient ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Structural And Electronic Properties ◽  
Linearized Augmented Plane Wave

AbstractOriginal first-principles calculations were performed to study the structural and electronic properties of quaternary BxAlyGa1–x–yN compounds, using the non-relativistic full-potential linearized augmented plane wave method as employed in the Wien2k code. For the exchange-correlation potential, local density approximation and generalized gradient approximation have been used to calculate theoretical lattice parameters, bulk modulus, and their pressure derivatives. Non-linear variation with compositions x and y of the lattice parameter, bulk modulus, and direct and indirect band gaps have been found. The calculated bowing of the fundamental band gaps is in good agreement with the available experimental and theoretical values.

Structural and Electronic Properties of Narrow Gap Zincblende and Chalcopyrite Compounds

1990 ◽  
Vol 193 ◽  
Author(s):  
T.M. de Pascale ◽  
F. Meloni ◽  
M. Serra ◽  
S. Massidda ◽  
A. Continenza ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Full Potential ◽  
Narrow Gap ◽  
Augmented Plane Wave ◽  
Bulk Semiconductors ◽  
Structural And Electronic Properties ◽  
Indium Compounds ◽  
Linearized Augmented Plane Wave ◽  
Ternary Semiconductors

ABSTRACTIndium compounds and corresponding epitaxially grown superlattices have provided good single crystals suitable for accurate experimental measurements and have added new interest to the study of the constituent bulk semiconductors and the II-IV-V2 chalcopyrite crystal phases. This paper reports results of structural and electronic properties of narrow gap binary and ternary semiconductors determined selfconsistently from first principles using both the full potential linearized augmented plane wave (FLAPW) and norm-conserving pseudopotentials (PP) total-energy methods.

scholarly journals Study of Structural and Electronic Properties of Fluoride Perovskite KCaF3 using FP-LAPW Method

2017 ◽  
pp. 100-103
Author(s):  
K. Neupane ◽  
R. K. Thapa
Keyword(s):  
Electronic Properties ◽  
First Principles Calculation ◽  
Exchange Potential ◽  
Full Potential ◽  
Pressure Derivative ◽  
Augmented Plane Wave ◽  
Exchange Correlation ◽  
Equilibrium Lattice Constant ◽  
Structural And Electronic Properties ◽  
Linearized Augmented Plane Wave

To study the structural and electronic properties of cubical perovskite KCaF3, the first principles calculation within the full potential linearized augmented plane wave (FP-LAPW) method is applied. The exchange correlation effects are included through the GGA exchange potential. The calculated structural properties such as equilibrium lattice constant, the bulk modulus and its pressure derivative are in agreement with the published results of other authors. From our study we have found that the band gap of KCaF3 is 6.4 eV which is the indication of insulating behavior.The Himalayan Physics Vol. 6 & 7, April 2017 (100-103)

FIRST-PRINCIPLE THEORETICAL STUDY ON THE CALCIUM FERRITE-TYPE LiMn2O4

2010 ◽  
Vol 03 (02) ◽  
pp. 93-96 ◽  
Author(s):  
MEILING LI ◽  
YUE ZHANG ◽  
LIN LI
Keyword(s):  
Magnetic Moments ◽  
Mixed Valence ◽  
Calcium Ferrite ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Augmented Plane Wave Method ◽  
Structural And Electronic Properties ◽  
Mixed Valence Compound ◽  
Linearized Augmented Plane Wave

The structural and electronic properties of the calcium ferrite-type LiMn 2 O 4 were studied using the full-potential linearized augmented plane wave method. The results showed that LiMn 2 O 4 was an antiferromagnetic semiconductor from GGA+U calculations, similar to the experimental report of Li 0.92 Mn 2 O 4. The spin magnetic moments and density of states of Mn atoms showed that LiMn 2 O 4 was a mixed-valence compound with Mn 3+ and Mn 4+ cations randomly distributed amongst the octahedral sites.

Structural, Electronic, and Magnetic Properties of Surfaces, Interfaces, and Superlattices

1985 ◽  
Vol 63 ◽  
Author(s):  
Arthur J. Freeman ◽  
C. L. Fu ◽  
T. Oguchi
Keyword(s):  
Total Energy ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Complex Materials ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Local Density Functional Theory ◽  
Flapw Method ◽  
Linearized Augmented Plane Wave

ABSTRACTAdvances in all-electron local density functional theory approaches to complex materials structure and properties made possible by the implementation of new computational/theoretical algorithms on supercomputers are exemplified in our full potential linearized augmented plane wave (FLAPW) method. In this total energy self-consistent approach, high numerical stability and precision (to 10 in the total energy) have been demonstrated in a study of the relaxation and reconstruction of transition metal surfaces. Here we demonstrate the predictive power of this method for describing the structural, magnetic and electronic properties of several systems (surfaces, overlayers, sandwiches, and superlattices).

scholarly journals Thermodynamic properties, electronic and crystallographic structure, and magnetic response of the Sr2HoNbO6 material

2018 ◽  
Vol 42 (164) ◽  
pp. 180
Author(s):  
Críspulo E. Deluque Toro ◽  
Ariday S. Mosquera Polo ◽  
Jorge I. Villa Hernández ◽  
David Arsenio Landínez Téllez ◽  
Jairo Roa-Rojas
Keyword(s):  
Thermodynamic Properties ◽  
Plane Wave ◽  
Local Density Approximation ◽  
Local Density ◽  
Crystallographic Structure ◽  
Magnetic Response ◽  
Full Potential ◽  
Density Approximation ◽  
Augmented Plane Wave ◽  
Linearized Augmented Plane Wave

En el presente trabajo se utilizó el código Wien2k, en el marco de la teoría del funcional de la densidad de Kohn-Sham, aplicando el método de ondas planas aumentadas y linealizadas (full-potential linearized augmented plane wave, FP- LAPW) y adoptando la aproximación de gradiente generalizado (GGA) de Perdew, Burke y Ernzerhof para la energía de intercambio y correlación, así como la aproximación de densidad local (local density approximation, LDA) para el cálculo de la densidad de estados y la estructura de bandas de la perovskita doble Sr2HoNbO6. Para los cálculos se consideró el grupo Fmm (#225), experimentalmente obtenido a partir de mediciones de difracción de rayos X y del método de refinamiento de Rietveld. El parámetro de red experimental fue de 8.018 Å, el cual concuerda en un 99,2 % con las predicciones teóricas efectuadas a partir de la minimización de la energía mediante la ecuación de estado de Murnaghan. A partir de mediciones de susceptibilidad magnética en función de la temperatura y del ajuste con la ley de Curie, se obtuvo el valor del momento magnético efectivo 10,01 μB. Este valor es muy cercano del esperado teóricamente a partir de las reglas de Hund (10,60 μB). La brecha de energía determinada entre las bandas de valencia y de conducción fue de 3,3 eV, lo que revela el carácter aislante de la perovskita compleja Sr2HoNbO6 para la configuración de espín hacia arriba, en tanto que se observó el carácter semiconductor para la polarización de espín hacia abajo, con una brecha de energía de 0,77 eV. Las propiedades termodinámicas se calcularon a partir de la ecuación de estado usando el modelo cuasi-armónico de Debye. Un comportamiento del calor específico, con CV≈CP, se encontró a temperaturas inferiores a T = 500 K, con valores del límite de Dulong-Petit que doblaban los que se han reportado para materiales del tipo de la perovskita. © 2018. Acad. Colomb. Cienc. Ex. Fis. Nat.

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