scholarly journals Наноструктуры AlN и GaN: аналитические оценки характеристик электронного спектра

2020 ◽  
Vol 62 (6) ◽  
pp. 955
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Silicon Carbide ◽  
Band Gap ◽  
Carbon Nanostructures ◽  
Numerical Results ◽  
Effective Masses ◽  
Linear Chains ◽  
Analytical Expressions ◽  
Zigzag Type

For AlN and GaN infinite flat sheets, free and decorated nanoribbons with the zigzag-type edges and linear chains the analytical expressions for the band-gap widths, characteristic velocities and effective masses are obtained. Numerical results are compared with the values of the corresponding characteristics calculated within the same models for the silicon carbide and carbon nanostructures. The role of substrate is also briefly discussed.

Carbon nanostructures grown on 3D silicon carbide foams: Role of intermediate silica layer and metal growth

2014 ◽  
Vol 258 ◽  
pp. 110-118 ◽  
Author(s):  
Saheed A. Ganiyu ◽  
Oki Muraza ◽  
Abbas S. Hakeem ◽  
Khalid Alhooshani ◽  
Muataz A. Atieh
Keyword(s):  
Silicon Carbide ◽  
Carbon Nanostructures ◽  
Silica Layer

scholarly journals Diverse Role of Silicon Carbide in the Domain of Nanomaterials

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
T. Sahu ◽  
B. Ghosh ◽  
S. K. Pradhan ◽  
T. Ganguly
Keyword(s):  
Silicon Carbide ◽  
Optical Properties ◽  
Band Gap ◽  
High Performance ◽  
Theoretical Work ◽  
Optical Devices ◽  
Unique Property ◽  
Promising Material ◽  
Indirect Band Gap

Silicon carbide (SiC) is a promising material due to its unique property to adopt different crystalline polytypes which monitor the band gap and the electronic and optical properties. Despite being an indirect band gap semiconductor, SiC is used in several high-performance electronic and optical devices. SiC has been long recognized as one of the best biocompatible materials, especially in cardiovascular and blood-contacting implants and biomedical devices. In this paper, diverse role of SiC in its nanostructured form has been discussed. It is felt that further experimental and theoretical work would help to better understanding of the various properties of these nanostructures in order to realize their full potentials.

scholarly journals Низкоразмерные структуры карбида кремния: аналитические оценки характеристик электронного спектра

2020 ◽  
Vol 54 (5) ◽  
pp. 446
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Silicon Carbide ◽  
Electronic Structure ◽  
Function Method ◽  
Tight Binding ◽  
Band Gaps ◽  
Tight Binding Approximation ◽  
One Dimensional ◽  
Dielectric Substrates ◽  
Effective Masses ◽  
Analytical Expressions

Abstract Using the Green’s function method within the tight-binding approximation, the electronic structure of an infinite silicon-carbide sheet, and nanoribbons and one-dimensional chains cut from it, is considered. Analytical expressions for band gaps, electron effective masses and characteristic velocities are derived. The effect of metal and dielectric substrates on the band characteristics is discussed.

scholarly journals Role of Bi3+ ions on structural, optical, photoluminescence and electrical performance of Cd0.9-xZn0.1BixS QDs

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
A. Krishnamoorthy ◽  
P. Sakthivel ◽  
I. Devadoss ◽  
V. M. Anitha Rajathi
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Optical Transmittance ◽  
Electrical Performance ◽  
Chemical Route ◽  
Red Emission ◽  
The Mean ◽  
Cubic Structure ◽  
Cyclic Voltammetry Analysis

AbstractIn this work, the Cd0.9-xZn0.1BixS QDs with different compositions of Bi3+ ions (0 ≤ x ≤ 0.05) were synthesized using a facile chemical route. The prepared QDs were characterized for analyzing the structural, morphological, elemental, optical, band gap, photoluminescence and electrochemical properties. XRD results confirmed that the Cd0.9-xZn0.1BixS QDs have a cubic structure. The mean crystallite size was increased from ~ 2 to ~ 5 nm for the increase of Bi3+ ions concentration. The optical transmittance behavior was decreased with increasing Bi3+ ions. The scanning electron microscope images showed that the prepared QDs possessed agglomerated morphology and the EDAX confirmed the presence of doped elements as per stoichiometry ratio. The optical band gap was slightly blue-shifted for initial substitution (Bi3+  = 1%) of Bi3+ ions and red-shifted for further increase of Bi3+ compositions. The optical band gap was ranged between 3.76 and 4.0 eV. High intense red emission was received for Bi3+ (1%) doped Zn:CdS QDs. The red emission peaks were shifted to a higher wavelength side due to the addition of Bi3+ ions. The PL emission on UV-region was raised for Bi3+ (1%) and it was diminished. Further, a violet (422 nm) and blue (460 nm) emission were received for Bi3+ ions doping. The cyclic voltammetry analysis showed that Bi3+ (0%) possessed better electrical properties than other compositions of Bi3+ ions.

Role of Electronic Excitations in Ion Collisions with Carbon Nanostructures

2007 ◽  
Vol 99 (1) ◽  
Author(s):  
Arkady V. Krasheninnikov ◽  
Yoshiyuki Miyamoto ◽  
David Tománek
Keyword(s):  
Carbon Nanostructures ◽  
Electronic Excitations ◽  
Ion Collisions

Role of Surface Band Gap Widening in Cu(In, Ga)(Se, S)2 Thin-Films for the Photovoltaic Performance of ZnO/CdS/Cu(In, Ga)(Se, S)2 Heterojunction Solar Cells

2003 ◽  
Vol 763 ◽  
Author(s):  
U. Rau ◽  
M. Turcu
Keyword(s):  
Thin Films ◽  
Surface Layer ◽  
Solar Cells ◽  
Fermi Level ◽  
Band Gap ◽  
Photovoltaic Performance ◽  
Heterojunction Solar Cells ◽  
Fermi Level Pinning ◽  
Device Efficiency

AbstractNumerical simulations are used to investigate the role of the Cu-poor surface defect layer on Cu(In, Ga)Se2 thin-films for the photovoltaic performance of ZnO/CdS/Cu(In, Ga)Se2 heterojunction solar cells. We model the surface layer either as a material which is n-type doped, or as a material which is type-inverted due to Fermi-level pinning by donor-like defects at the interface with CdS. We further assume a band gap widening of this layer with respect to the Cu(In, Ga)Se2 bulk. This feature turns out to represent the key quality of the Cu(In, Ga)Se2 surface as it prevents recombination at the absorber/CdS buffer interface. Whether the type inversion results from n-type doping or from Fermi-level pinning is only of minor importance as long as the surface layer does not imply a too large number of excess defects in its bulk or at its interface with the normal absorber. With increasing number of those defects an n-type layer proofs to be less sensitive to material deterioration when compared to the type-inversion by Fermi-level pinning. For wide gap chalcopyrite solar cells the internal valence band offset between the surface layer and the chalcopyrite appears equally vital for the device efficiency. However, the unfavorable band-offsets of the ZnO/CdS/Cu(In, Ga)Se2 heterojunction limit the device efficiency because of the deterioration of the fill factor.

scholarly journals Appearance of efficient luminescence energy transfer in doped orthovanadate nanocrystals

2017 ◽  
Vol 50 (3) ◽  
pp. 787-794 ◽  
Author(s):  
Swati Bishnoi ◽  
G. Swati ◽  
Paramjeet Singh ◽  
V. V. Jaiswal ◽  
Mukesh K. Sahu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Band Gap ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
Synthesis Mechanism ◽  
Enhanced Photoluminescence ◽  
Nir Absorption ◽  
Decay Parameters

This paper reports the detailed synthesis mechanism and the structural, morphological and optical characterization of ultraviolet (∼311 nm) excitable samarium doped gadolinium yttrium orthovanadate, (Gd,Y)VO4:Sm3+, nanocrystals. X-ray diffraction and Rietveld refinement studies confirmed that the synthesized samples crystallize in a tetragonal structure withI41/amdspace group. The enhanced photoluminescence intensity of (Gd,Y)VO4:Sm3+compared with the existing YVO4:Sm3+phosphor clearly indicates the significant role of Gd3+ions. This has been attributed to the sensitization of the6PJenergy level of Gd3+ions by energy transfer from orthovanadate (VO43−) ions and subsequent energy trapping by Sm3+ions. The energy transfer from VO43−to Sm3+viaGd3+ions as intermediates and concentration quenching of Gd3+luminescence are discussed in detail. The optical band gap of the as-prepared nanocrystals has been estimated using UV–vis–NIR absorption spectroscopy, which reveals a slightly higher band gap (3.75 eV) for YVO4as compared to GdYVO4(3.50 eV). Furthermore, confocal microcopy, decay parameters and Commission Internationale de l'Eclairage chromatic coordinates have supplemented these studies, which established the suitability of these nanophosphors for achieving spectral conversion in silicon solar cells.

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