scholarly journals Electron-blocking by the potential barrier originated from the asymmetrical local density of state in the oxide semiconductor

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Hyeon-Jun Lee ◽  
Katsumi Abe ◽  
Jun Seo Kim ◽  
Myoung-Jae Lee
Keyword(s):  
Potential Barrier ◽  
Local Density ◽  
Oxide Semiconductor ◽  
Density Of State

scholarly journals Investigation of quantum transport and local density of states in a graphene strip connected to a square lattice

2021 ◽  
Author(s):  
Elnaz Rostampour
Keyword(s):  
Quantum Transport ◽  
Dirac Point ◽  
Local Density ◽  
Square Lattice ◽  
Density Of State ◽  
Metallic Lead ◽  
Resonant Tunnelling ◽  
Quantum Billiard ◽  
Plasmon Polaritons ◽  
Theoretical Results

Abstract We theoretically express quantum transport at Dirac points via graphene quantum billiard as a non-magnetic material to connect metallic leads. Our results indicate that the quantum billiard of graphene is similar to a resonant tunnelling device. The centerpiece size and the Fermi energy of the graphene quantum billiard play an important role in the resonant tunnelling. In graphene, change of carrier density can affect plasmon polaritons. At the Dirac point, the conductivity of graphene depends on the geometry, so that the conduction of the evanescent modes is close to the theoretical value of 4e2/πh (where Planck's constant and the electron charge are denoted by h and e, respectively.). This transport property can be used to justify chaotic quantum systems and ballistic transistors. Our theoretical results demonstrate that the local density of state of the graphene sheet for EL = ER = 0 is larger than EL = ER = t (where EL (ER) is onsite energy of the left (right) metallic lead) unlike the current obtained from the calculations.

Electronic Structure and Mechanical Properties of Zircaloy-2 and Zircaloy-4: A First Principle Study

2013 ◽  
Author(s):  
Chunhai Lu ◽  
Wenkai Chen ◽  
Min Chen ◽  
Shijun Ni ◽  
Chengjiang Zhang
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Zirconium Alloy ◽  
Local Density ◽  
Partial Density ◽  
Total Density ◽  
First Principle ◽  
Density Of State ◽  
Virtual Crystal Approximation ◽  
Anisotropic Mechanical Properties

The local-density approximation (LDA) coupled with the virtual crystal approximation (VCA) method electronic structure is applied to evaluate elastic constants, bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio mechanic properties of metal zirconium, Zircaloy-2 and Zircaloy-4. The results show that there is no obvious difference in band structure and total density of state (DOS) between metal zirconium and zirconium alloy. However, p and d electron partial density of state (PDOS) presents the slight difference between metal zirconium and zirconium alloy. Zircaloy-2 and Zircaloy-4 present better elastic mechanical properties than metal zirconium. The metal zirconium and zirconium alloy show the anisotropic mechanical properties.

Oxygen Bonding in Bismuth Layered Compounds SrBi2Ta2O9

2007 ◽  
Vol 997 ◽  
Author(s):  
Dong Su ◽  
Nan Jiang ◽  
Jianguo Wen ◽  
Jianshe Liu
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Local Density ◽  
Layered Compounds ◽  
Density Approximation ◽  
Electron Loss ◽  
Density Of State ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Fine Structures ◽  
Z Contrast

AbstractWith the help of the high resolution Z-contrast scanning transmission electron microscopy (STEM), the near edge fine structures of the electron loss spectroscopy (EELS) arises from different layers are investigated in SBT. The EELS spectra are interpreted by comparing with the calculation using linearnized augment plane wave (LAPW) method within the local density approximation (LDA). The oxygen bonding nature in different layers are discussed. In Bi2O2 layer, oxygen 2p state interacted with the Bi 6p state leads to a high t2g state in density of state while in SrTa2O7 layer, oxygen 2p state hybridized with Ta 5d and Sr 5d, which leads a higher eg state than t2g state.

Scanning tunneling spectroscopy of a magnetic adatom on graphene

2014 ◽  
Vol 28 (31) ◽  
pp. 1450225 ◽  
Author(s):  
Yang Gao ◽  
Kai-He Ding
Keyword(s):  
Gate Voltage ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Differential Conductance ◽  
Scanning Tunneling ◽  
Density Of State ◽  
Tunneling Microscopy ◽  
Substitutional Site ◽  
Kondo Resonance

We present a theoretic study on scanning tunneling spectroscopy (STS) of a magnetic adatom on graphene. Three typical configurations of adatoms on graphene are considered explicitly: the adatom is on the top of a carbon atom (TC), in a substitutional site (SC), or above the center of the honeycomb hexagon (HC). Based on the nonequilibrium Green's function method, we derive the local density of state (LDOS) for the adatom and the differential conductance through the scanning tunneling microscopy (STM) device. Our results show that in comparison with the cases of the TC and SC, there exists an anomalous broadening of the local adatom energy level in the HC, which pushes the adatom energy to first cross the Fermi level, leading to the appearance of an antiresonance in the LDOS due to the interference between the Kondo resonance and the broadened adatom level. Correspondingly, the bias dependence of the differential conductance in the HC exhibits a more asymmetric sharp Kondo peak pinned to the gate voltage, and its height still remains significantly large compared to that for the other two cases. Additionally, with decreasing the gate voltage, the Kondo peak in the differential conductance gradually decays, and eventually vanishes in the absence of the gate voltage.

Dependence of Particle Number on Density of States of an Aluminum Nanocluster

2010 ◽  
Vol 3 (2) ◽  
pp. 88-94
Author(s):  
Natalya V. Tikhovskaya ◽  
Klimentiy N. Yugay
Keyword(s):  
Oxygen Atom ◽  
Hubbard Model ◽  
Density Of States ◽  
Lattice Site ◽  
Particle Number ◽  
Local Density ◽  
Aluminum Atom ◽  
Density Of State

On basis of the Hubbard model density of states of the 2D square nanosystem by size of N × N aluminum atoms with N = 3÷30, and also density of states of the 2D aluminum square nanocluster, where one of the aluminum atom is changed by oxygen atom, is calculated. It is shown that the local density of state depends on the total number of atoms in the cluster, and also on the location of atom in a lattice and the atom sort in a lattice site.

A Comparison of Quantum Correction Models for Nanoscale MOS Structures under Inversion Conditions

2005 ◽  
Vol 480-481 ◽  
pp. 603-610 ◽  
Author(s):  
Yiming Li
Keyword(s):  
Quantum Correction ◽  
Semiconductor Device ◽  
Local Density ◽  
Inversion Layer ◽  
Oxide Semiconductor ◽  
Concentration Peak ◽  
Inversion Charge ◽  
Charge Concentration ◽  
Classical Transport ◽  
Model Features

Quantum correction model features the correction of the inversion layer charge on different classical transport models in semiconductor device simulation. This approach has successfully been of great interest in the recent years. Considering a metal-oxide-semiconductor (MOS) structure in this paper, the Hänsch, the modified local density approximation (MLDA), the density-gradient (DG), the effective potential (EP), and our models are investigated computationally and compared systematically with the result of the Schrödinger-Poisson (SP) model. In terms of the accuracy for (1) the position of the charge concentration peak, (2) the maximum of the charge concentration, (3)the total inversion charge sheet density, and (4) the average inversion charge depth, these well-established models are examined simultaneously. The DG model requires the solution of a boundary value problem, the EP model overestimates the position of the charge concentration peak and the maximum of the charge concentration, our explicit model demonstrates good accuracy among models.

Structure Stability and Electronic Structure of Semiconducting Rhenium Silicide with Doping

2007 ◽  
Vol 26-28 ◽  
pp. 1029-1032 ◽  
Author(s):  
An Ning Qiu ◽  
Lan Ting Zhang ◽  
Jian Sheng Wu
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Local Density ◽  
Structure Stability ◽  
Full Potential ◽  
Density Of State ◽  
Al Doping ◽  
Augmented Plane Wave ◽  
Semiconductor Behavior ◽  
Linearized Augmented Plane Wave

Full-potential linearized augmented plane-wave (FP-LAPW) method within the local density approximation plus self-interaction correction (LDA+USIC) has been applied to study the structure stability and electronic structure of ReSi1.75 and its doped systems with Al and Mo. Structural relaxation results show that the vacancy prefers to occupy the Si3 and Si4 site in the lattice with little ordering. For doping systems, Al prefers to substitute for Si at the Si3 site and Mo prefers to substitute for Re at the Re1 site. ReSi1.75 shows narrow gap semiconductor behavior with an indirect gap of 0.12 eV and a direct gap of 0.36 eV. Al doping compound remains semiconductor while Mo doping compound has a tendency to change into semimetals or metals. The Fermi level of doped systems moves into the valence band resulting in an increase of density of state at the Fermi level. It will enhance the thermoelectric properties and agrees well with the experiment results.

First Principles Study on Structural and Electronic Properties of PZT and PSnZT Using Density Functional Theory

2016 ◽  
Vol 846 ◽  
pp. 734-739 ◽  
Author(s):  
N.H. Hussin ◽  
Mohamad Fariz Mohamad Taib ◽  
F.W. Badrudin ◽  
N.A. Johari ◽  
Nunshaimah Salleh ◽  
...  
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Geometry Optimization ◽  
Lone Pair ◽  
Lattice Parameter ◽  
Density Of State ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Indirect Band Gap

The geometry optimization of the tetragonal supercell 1x1x2 (P4mm, 99 space group) of PZT and PSnZT were calculated using different exchange correlation functional such as Local Density Approximate (LDA-CAPZ) and Generalized Gradient Approximation (GGA-PBE & GGA-PBEsol).The calculation using functional GGA-PBEsol exhibits the most accurate values of lattice parameter and volume of structure relative to the experiment results with typical error of approximately 1% underestimate (only for PZT-as reference materials). The electronic band structure and density of state (DOS) were also studied in order to understand the electron density and hybrization between cation and anion in the compound. The density of state studies indicated existing of hybridizations among anion O 2p, cation Pb 6s/Sn 5s (special lone pair) and the Ti 3d/Zr 4d states of PZT and PSnZT compound. An indirect band gap was respectively obtained for both cubic PZT and PSnZT at the F-G and Q-G point with 3.154 eV and 2.571 eV.

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