ELECTRONIC STRUCTURE OF THE CRYSTALLINE SILICON/n-FOLD SiO2 RING INTERFACE

Using the ab initio local density approach we have studied the electronic structure of the systems consisting of the six-, four- and three-fold planar SiO 2 rings placed upon the surface of the silicon cluster. The interaction of the six- and four-fold rings with the silicon surface changes the electronic structure of the silica particle very weakly and the surface insulator band gap of 7–8 eV remains in their densities of states. The electronic structure of the three-fold planar ring undergoes a significant reconstruction. Its surface band gap is 3.7 eV instead of 7.6 eV for the free particle case. Two groups of the interfacial states were found inside the silicon semiconductor band gap.

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CHANGES INDUCED IN THE SURFACE ELECTRONIC STRUCTURE OF Be(0001) AFTER Si ADSORPTION

Surface Review and Letters ◽

10.1142/s0218625x02002907 ◽

2002 ◽

Vol 09 (02) ◽

pp. 687-691

Author(s):

L. I. JOHANSSON ◽

C. VIROJANADARA ◽

T. BALASUBRAMANIAN

Keyword(s):

Electronic Structure ◽

Band Structure ◽

Band Gap ◽

Electronic Properties ◽

Surface State ◽

Core Level ◽

Clean Surface ◽

Core Level Spectrum ◽

Surface Band ◽

Surface Electronic Structure

A study of effects induced in the Be 1s core level spectrum and in the surface band structure after Si adsorption on Be(0001) is reported. The changes in the Be 1s spectrum are quite dramatic. The number of resolvable surface components and the magnitude of the shifts do decrease and the relative intensities of the shifted components are drastically different compared to the clean surface. The surface band structure is also strongly affected after Si adsorption and annealing. At [Formula: see text] the surface state is found to move down from 2.8 to 4.1 eV. The band also splits at around 0.5 Å-1 along both the [Formula: see text] and [Formula: see text] directions. At [Formula: see text] and beyond [Formula: see text] only one surface state is observed in the band gap instead of the two for the clean surface. Our findings indicate that a fairly small amount of Si in the outer atomic layers strongly modifies the electronic properties of these layers.

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First Principle Investigation of Electronic, Transport, and Bulk Properties of Zinc-Blende Magnesium Sulfide

Electronics ◽

10.3390/electronics9111791 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1791

Author(s):

Uttam Bhandari ◽

Blaise Awola Ayirizia ◽

Yuriy Malozovsky ◽

Lashounda Franklin ◽

Diola Bagayoko

Keyword(s):

Band Gap ◽

Lattice Constant ◽

Density Functional ◽

Local Density ◽

Computational Method ◽

Physical Content ◽

Conduction Bands ◽

Zinc Blende ◽

Densities Of States ◽

Magnesium Sulfide

We have studied electronic, structural, and transport properties of zinc-blende magnesium sulfide (zb-MgS). We employed a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO) method. Our computational method is able to reach the ground state of a material, as dictated by the second theorem of density functional theory (DFT). Consequently, our findings have the physical content of DFT and agree with available, corresponding experimental ones. The calculated band gap of zb-MgS, a direct gap equal to 4.43 eV, obtained at the experimental lattice constant of 5.620 Å, completely agrees with the experimental band gap of 4.45 ± 0.2 eV. We also report total (DOS) and partial (pDOS) densities of states, electron and hole effective masses, the equilibrium lattice constant, and the bulk modulus. The calculated pDOS also agree with the experiment for the description of the states at the top and the bottom of the valence and conduction bands, respectively.

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Electronic structure and total energy of diamond/BeO interfaces

Journal of Materials Research ◽

10.1557/jmr.1992.0696 ◽

1992 ◽

Vol 7 (3) ◽

pp. 696-705 ◽

Cited By ~ 21

Author(s):

Walter R.L. Lambrecht ◽

Benjamin Segall

Keyword(s):

Electronic Structure ◽

Total Energy ◽

Band Gap ◽

Lattice Mismatch ◽

Interface Energy ◽

Adhesion Energy ◽

Misfit Dislocations ◽

Densities Of States ◽

Representative Model ◽

Experimental Values

Electronic structure calculations are used to study the bonding at diamond/BeO interfaces. The {110} interface between zinc blende BeO and diamond is used as a representative model for general reconstructed interfaces characterized by an equal amount of Be–C and O–C bonds. The interface energy is calculated to be 2 J/m2 and combined with the estimated free surface energies to obtain an estimate of the adhesion energy. It is found to be close to the adhesion of BeO to itself, but somewhat lower than that of diamond to itself. The effects of the 7% lattice mismatch on the total energy and the band structure for a biaxially strained pseudomorphic diamond film are investigated. The effect of misfit dislocations, expected to occur for thicker films, on the adhesion energy is estimated to be lower than 10%. The bulk properties, such as equilibrium lattice constant, bulk modulus, cohesive energy, and band gap of BeO are shown to be in good agreement with experimental values and previous calculations. The valence-band offset is calculated to be 3.9 eV and found to take up most of the large band gap discontinuity. The nature of the bonding is discussed in terms of the local densities of states near the interface. The interface localized features are identified in terms of Be–C and O–C bonding and antibonding states.

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Density of states calculations for Ni-Al Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165082 ◽

1996 ◽

Vol 54 ◽

pp. 524-525 ◽

Cited By ~ 1

Author(s):

Jose R. Alvarez ◽

Peter Rez

Keyword(s):

Electronic Structure ◽

Angular Momentum ◽

Energy Loss ◽

Density Of States ◽

Local Density ◽

Plane Waves ◽

Al Alloys ◽

Wave Functions ◽

Band Theory ◽

Densities Of States

Impurities at grain boundaries can have dramatic effects on the ductility or embrittlement of metals and metallic alloys. The mechanism for these effects is controversial, but it is believed that charge redistribution induced by the impurity atoms is responsible. Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) can be used to measure changes in unoccupied densities of states (DOS) when a small nanometer sized probe is moved across a grain boundary. To interpret the energy loss fine structure band theory is needed to relate the observations, which represent an angular momentum resolved density of states at a particular atomic site, to the local electronic structure in the material.We compare the Linearized Augmented Plane Wave (LAPW) and layered Korringa-Kohn-Rostoker (LKKR) methods for calculating densities of states relevant for energy loss in Ni-Al alloys. Both methods can give the angular momentum resolved densities of states at a particular site and both use the Local Density Approximation (LDA). The LAPW method allows ab initio electronic structure calculations of materials by introducing atomic spheres where the basis wave functions are approximated by solutions of a radial potential; for the interstitial region between the atoms the basis wave functions are approximated by plane waves.

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Calculation of the Electronic Structure of Silicon Nanocrystals

MRS Proceedings ◽

10.1557/proc-358-25 ◽

1994 ◽

Vol 358 ◽

Cited By ~ 2

Author(s):

Nicola A. Hill ◽

K. Birgitta Whaley

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Cluster Size ◽

Silicon Nanocrystals ◽

Tight Binding ◽

Time Dependent ◽

Surface Relaxation ◽

Tight Binding Approximation ◽

Si Nanocrystals ◽

Densities Of States

ABSTRACTThe densities of states for Si nanocrystals with diameters between 15 and 35 Å are calculated using a time-dependent algorithm within the tight-binding approximation [1]. The calculated effects of surface termination and surface relaxation on the electronic properties of Si are shown. The variation in band-gap with cluster size is calculated for clusters up to 60 Å in diameter.

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Electronic Structure Studies of Impurities In Fe.

Microscopy and Microanalysis ◽

10.1017/s1431927600010187 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 659-660

Author(s):

Jose R. Alvarez ◽

Peter Rez

Keyword(s):

Mechanical Properties ◽

Electronic Structure ◽

Density Functional ◽

Local Density ◽

Functional Theory ◽

Edge Structure ◽

Densities Of States ◽

Crystalline System ◽

Electron Energy Loss ◽

Linearized Augmented Plane Wave

Small concentrations of impurities can dramatically change mechanical properties of metals and alloys since they modify bonding and cohesion at grain boundaries. In particular, impurities like B, C, P and S have received considerable attention for their effect on the mechanical properties of Fe. It is known that B and C behave as cohesive enhancers, whereas P and S tend to embrittle iron. Ab initio electronic structure calculations for supercell models of Fe crystals with B, C, P and S impurities have been performed to understand how these impurities modify the electronic states on surrounding atoms The calculations give the charge density distribution, localized densities of states (LDOS) and the total energy of the system. The angular momentum resolved LDOS, when multiplied by slowly varying matrix elements, can be directly related to the experimentally measured electron energy loss near edge structure.The calculations have been performed using two different methods. One is the Linearized Augmented Plane Wave (LAPW) method, in which the Kohn-Sham equations of density functional theory are self-consistently solved within the Local Density Approximation (LDA) to obtain energies and charge distributions of a crystalline system.

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New Insights into the Nature of the Band Gap of CuGeO3 Nanoparticles: Synthesis, Electronic Structure, and Optical and Photocatalytic Properties

10.26434/chemrxiv.8362409.v1 ◽

2019 ◽

Author(s):

Victor Y. Suzuki ◽

Luís Henrique Cardozo Amorin ◽

Natália H. de Paula ◽

Anderson R. Albuquerque ◽

Julio Ricardo Sambrano ◽

...

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Material Design ◽

Photocatalytic Properties ◽

Critical Parameters ◽

Synthetic Approach ◽

Microwave Assisted ◽

Theoretical Approaches ◽

Nanoparticles Synthesis ◽

First Time

We report, for the first time, new insights into the nature of the band gap of <a>CuGeO3 </a>(CGO) nanocrystals synthesized from a microwave-assisted hydrothermal method in the presence of citrate. To the best of our knowledge, this synthetic approach has the shortest reaction time and it works at the lowest temperatures reported in the literature for the preparation of these materials. The influence of the surfactant on the structural, electronic, optical, and photocatalytic properties of CGO nanocrystals is discussed by a combination of experimental and theoretical approaches, and that results elucidates the nature of the band gap of synthetized CGO nanocrystals. We believe that this particular strategy is one of the most critical parameters for the development of innovative applications and that result could shed some light on the emerging material design with entirely new properties.

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Improving the ZT of SnTe using electronic structure engineering: unusual behavior of Bi dopant in the presence of Pb as a co-dopant

Materials Advances ◽

10.1039/d1ma00696g ◽

2021 ◽

Vol 2 (19) ◽

pp. 6267-6271 ◽

Cited By ~ 3

Author(s):

U. Sandhya Shenoy ◽

D. Krishna Bhat

Keyword(s):

Electronic Structure ◽

Synergistic Effect ◽

Band Gap ◽

Resonance Level ◽

Unusual Behavior ◽

Level Increase ◽

Structure Engineering

Extraordinary tuning of electronic structure of SnTe by Bi in the presence of Pb as a co-adjuvant dopant. Synergistic effect of resonance level, increase in the band gap, valence and conduction sub-bands convergence leads to enhanced TE performance.

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Band-Gap Solitons in Nonlinear Photonic Crystal Waveguides and Their Application for Functional All-Optical Logic Gating

Photonics ◽

10.3390/photonics8070250 ◽

2021 ◽

Vol 8 (7) ◽

pp. 250

Author(s):

Vakhtang Jandieri ◽

Ramaz Khomeriki ◽

Tornike Onoprishvili ◽

Daniel Erni ◽

Levan Chotorlishvili ◽

...

Keyword(s):

Photonic Crystal ◽

Band Gap ◽

Crystalline Silicon ◽

Logic Gates ◽

Photonic Crystal Waveguides ◽

Optical Logic ◽

Logical Operation ◽

Pulse Envelope ◽

Gap Soliton ◽

All Optical

This review paper summarizes our previous findings regarding propagation characteristics of band-gap temporal solitons in photonic crystal waveguides with Kerr-type nonlinearity and a realization of functional and easily scalable all-optical NOT, AND and NAND logic gates. The proposed structure consists of a planar air-hole type photonic crystal in crystalline silicon as the nonlinear background material. A main advantage of proposing the gap-soliton as a signal carrier is that, by operating in the true time-domain, the temporal soliton maintains a stable pulse envelope during each logical operation. Hence, multiple concatenated all-optical logic gates can be easily realized paving the way to multiple-input ultrafast full-optical digital signal processing. In the suggested setup, due to the gap-soliton features, there is no need to amplify the output signal after each operation which can be directly used as a new input signal for another logical operation. The efficiency of the proposed logic gates as well as their scalability is validated using our original rigorous theoretical formalism confirmed by full-wave computational electromagnetics.

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Electronic structure engineering of tin telluride through co-doping of bismuth and indium for high performance thermoelectrics: a synergistic effect leading to a record high room temperature ZT in tin telluride

Journal of Materials Chemistry C ◽

10.1039/c9tc01184f ◽

2019 ◽

Vol 7 (16) ◽

pp. 4817-4821 ◽

Cited By ~ 19

Author(s):

U. Sandhya Shenoy ◽

D. Krishna Bhat

Keyword(s):

Electronic Structure ◽

Synergistic Effect ◽

Band Gap ◽

High Performance ◽

Room Temperature ◽

Band Offset ◽

Valence Band Offset ◽

Co Doping ◽

Tin Telluride ◽

Structure Engineering

Resonance states due to Bi and In co-doping, band gap enlargement, and a reduced valence-band offset in SnTe lead to a record high room-temperature ZT.

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