Structural Stability and Optical Properties of hexagonal and cubic CdSe Nanocrystals synthesized in MgO

2004 ◽  
Vol 848 ◽  
Author(s):  
S.W.H. Eijt ◽  
van Huis ◽  
P.E. Mijnarends ◽  
B.J. Kooi ◽  
M. Nanu
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Band Gap ◽  
Structural Changes ◽  
Optical Absorption Spectroscopy ◽  
Cdse Nanocrystals ◽  
High Dose ◽  
Electronic Band ◽  
Supersaturated Solid Solutions ◽  
Direct Band

ABSTRACTWe present a study of CdSe nanocrystals synthesized in MgO by precipitation of Cd and Se supersaturated solid solutions, created in MgO single crystals by ion implantation, in the temperature range between 300 °C and 1100 °C. For high-dose ion implantation, optical absorption spectroscopy revealed the presence of the ∼1.8 eV CdSe semiconductor band-edge. Small sized nanocrystals adopt the rocksalt instead of the wurtzite structure because the former fits better in the MgO matrix and results in lower interface energies. A better understanding of these structural changes and optical properties is obtained from ab-initio total energy calculations on wurtzite, zincblende and rocksalt CdSe using the VASP pseudopotential code. The calculated electronic band structures are compared of zincblende CdSe, a direct band-gap semiconductor, and rocksalt CdSe, which has an indirect optical band-gap.

scholarly journals DFT Study on Structural, Electronic and Optical Properties of Ag-Doped SrTiO3 Perovskite for Optoelectronic Applications

2021 ◽  
Author(s):  
Jalil Rehman ◽  
M.Awais Rehman ◽  
Muhammad Bilal Tahir ◽  
Muhammad Usman ◽  
Faisal Iqbal
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Of States ◽  
Density Functional ◽  
Partial Density ◽  
Electronic Band ◽  
Ag Doping ◽  
Direct Band Gap ◽  
Direct Band ◽  
Optoelectronic Applications

This study addresses the first-principles analysis using generalized gradient approximation (GGA), which is pillared on density functional theory (DFT), to find the effects of silver (Ag) doping on SrTiO3 structurally, electronically and optical properties. As Ag doping into SrTiO3, we see a small decrease in the volume of unit cell. Moreover, Ag-doping adds new states in SrTiO3 at Brillouin zone symmetry points, transferring host material’s indirect band gap to a direct band gap. Ag doping in SrTiO3 results in the transfer density of states to smaller energies and increase in interaction among Ag atom and its surrounding atoms. Moreover, at the conduction band, the partial density of states (PDOS) of SrTiO3 changes generally. As a result, we conclude that Ag doping has an effect on the electronic band structure of SrTiO3. SrTiO3 doping with Ag has improved optical properties and its ability of converting to direct band gap results it in a perfect choice for optoelectronic applications.

scholarly journals Structural, Electronic and Optical Properties of InAs Phases: By GGA-PBG and GGA-EV Approximations

2017 ◽  
Vol 41 (3) ◽  
pp. 172-182
Author(s):  
Leila Sohrabi ◽  
Arash Boochani ◽  
S. Ali Sebt ◽  
S. Mohammad Elahi
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Photonic Devices ◽  
Optical Parameters ◽  
Full Potential ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Electronic Band Gap

Structural, electronic and optical properties of InAs are investigated in the zinc-blende (ZB), rock-salt (RS) and wurtzite (WZ) phases using the full potential linearised augmented plane wave method in the framework of density functional theory (DFT). The electronic band gap of the ZB and WZ phases are improved and in good agreement with experiments by GGA-EV approximation. This compound has a direct band gap in the ZB and WZ phases in point at the centre Brillouin zone and in the RS phase the conduction band crosses towards the valence band and has metallic behaviour. Also, the optical parameters such as the real and imaginary parts of epsilon, energy loss, and the refraction and reflection indices of all the phases are calculated and compared. The calculated optical properties of InAs have promising applications such as the design of optoelectronic and photonic devices.

FIRST PRINCIPLE CALCULATION OF ELECTRONIC BAND STRUCTURE AND OPTICAL PROPERTIES OF KIO3

2009 ◽  
Vol 23 (10) ◽  
pp. 2405-2412
Author(s):  
HARUN AKKUS ◽  
BAHATTIN ERDINC
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Functional Methods ◽  
A Value ◽  
Direct Band

The electronic band structure and optical properties of the ferroelectric single crystal KIO 3 have been investigated using the density functional methods. The calculated band structure for KIO 3 evidences that the crystal has a direct band gap with a value of 2.83 eV. The structural optimization has been performed. The real and imaginary parts of dielectric function, energy-loss function for volume and surface, and refractive index are calculated along the crystallographic axes.

Analysis of High Dose Implanted Silicon by High Depth Resolution Rbs and Spectroscopic Ellipsometry and TEM

1984 ◽  
Vol 35 ◽  
Author(s):  
T. Lohner ◽  
G. Mezey ◽  
M. Fried ◽  
L. GhiţA ◽  
C. Ghiţa ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Spectroscopic Ellipsometry ◽  
Composite Structures ◽  
Depth Resolution ◽  
High Dose ◽  
Detailed Characterization ◽  
High Depth ◽  
Qualitative Picture

ABSTRACTOne of the applications of high dose ion implantation is to form surface alloys or compound layers. The detailed characterization of such composite structures is of great importance. This paper tries to answer the question: how can we outline, at least, a qualitative picture from the optical properties measured by ellipsometry of high dose Al and Sb implanted silicon. Attempts are done to separate the effect of implanted impurities from the dominant disorder contribution to the measured optical properties. As the ellipsometry does not provide information enough to decide the applicability of optical models therefore methods sensitive to the structure (channeling and TEM) were applied too.

Structural Analysis of Silicon Doped by Plasma Source Ion Implantation

1993 ◽  
Vol 316 ◽  
Author(s):  
R.J. Matyi ◽  
D.L. Chapek ◽  
J.R. Conrad ◽  
S.B. Felch
Keyword(s):  
Ion Implantation ◽  
Diffuse Scattering ◽  
Structural Changes ◽  
Plasma Source ◽  
Perfect Crystal ◽  
Crystal Defects ◽  
High Dose ◽  
X Ray ◽  
Doped Silicon ◽  
Plasma Source Ion Implantation

ABSTRACTWe have used high resolution x-ray diffraction to analyze the structural changes that accompany boron doping of silicon by BF3 plasma source ion implantation (PSII). Triple crystal diffraction analysis of as-implanted PSII doped silicon showed little excess x-ray diffuse scattering, even when analyzed using the asymmetric (113) reflection for increased surface sensitivity. This result suggests that PSΠ is capable of providing high dose implantation with low damage. Annealing of the PSII-doped silicon showed the development of a compressive surface layer, indicated by enhanced x-ray scattering directed perpendicular to the surface. Virtually all of the scattering from the annealed samples was concentrated in the so-called “surface streak” which arises due to dynamical diffraction from the perfect crystal Si structure. Little if any diffuse scattering due to kinematic scattering from crystal defects was detected. These observations indicate that plasma source doping can be used to achieve both a shallow implant depth and an extremely uniform incorporation of boron into the silicon lattice.

scholarly journals Stimulated Emission and Optical Properties of Solid Solutions of Cu(In,Ga)Se2 Direct Band Gap Semiconductors

2018 ◽  
Vol 85 (2) ◽  
pp. 267-273
Author(s):  
I. E. Svitsiankou ◽  
V. N. Pavlovskii ◽  
E. V. Lutsenko ◽  
G. P. Yablonskii ◽  
A. V. Mudryi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Solid Solutions ◽  
Stimulated Emission ◽  
Direct Band Gap ◽  
Direct Band

scholarly journals Indirect-to-direct band gap transition and optical properties of metal alloys of Cs2Te1−xTixI6: a theoretical study

RSC Advances ◽  
2020 ◽  
Vol 10 (60) ◽  
pp. 36734-36740
Author(s):  
Diwen Liu ◽  
Wenying Zha ◽  
Rusheng Yuan ◽  
Benyong Lou ◽  
Rongjian Sa
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Theoretical Study ◽  
Metal Alloys ◽  
Double Perovskites ◽  
Direct Band Gap ◽  
Photovoltaic Applications ◽  
Direct Band

In recent years, double perovskites have attracted considerable attention as potential candidates for photovoltaic applications.

First-principles investigation of the structural, elastic, electronic, and optical properties of semiconducting AgBr1–xIx (0 ≤ x ≤ 1) ternary alloys in rock-salt and zinc blende structures

2020 ◽  
Vol 98 (9) ◽  
pp. 834-848
Author(s):  
H. Rekab-Djabri ◽  
Mohamed Drief ◽  
Manal M. Abdus Salam ◽  
Salah Daoud ◽  
F. El Haj Hassan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Rock Salt ◽  
Density Functional ◽  
Local Density ◽  
Ternary Alloys ◽  
Full Potential ◽  
Zinc Blende ◽  
Lmto Method ◽  
Direct Band

In this work, first principle calculations of the structural, electronic, elastic, and optical properties of novel AgBr1–xIx ternary alloys in rock-salt (B1) and zinc-blende (B3) structures are presented. The calculations were performed using the full-potential linear muffin-tin orbital (FP-LMTO) method within the framework of the density functional theory (DFT). The exchange and correlation potentials were treated according to the local density approximation (LDA). The lattice constants for the B1 and B3 phases versus iodide concentration (x) were found to deviate slightly from the linear relationship of Vegard’s law. The calculated electronic properties showed that AgBr1–xIx alloys in the B3 structure have a direct band gap (Γ – Γ) for all concentrations of x, which means that they can be used in long-wavelength optoelectronic applications, while in the B1 structure they have an indirect (Γ – R) band gap. The elastic constants Cij, shear modulus G, Young’s modulus E, Poisson’s ratio ν, index of ductility B/G, sound velocities vt, vl, and vm, and Debye temperature θD were also reported and analyzed. By incorporating the basic optical properties, we discussed the dielectric function, refractive index, optical reflectivity, absorption coefficient, and optical conductivity in terms of incident photon energy up to 13.5 eV. The present results were found to be in good agreement with the available experimental and other theoretical results.

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