Optical properties of the massive Vanadium dioxide

2015 ◽  
Vol 8 (3) ◽  
pp. 2222-2230
Author(s):  
Abderrahim Benchaib ◽  
Abdesselam Mdaa ◽  
Izeddine Zorkani ◽  
Anouar Jorio
Keyword(s):  
Optical Properties ◽  
Variational Method ◽  
Band Gap ◽  
Effective Mass ◽  
Dielectric Function ◽  
Vanadium Dioxide ◽  
Normal Incidence ◽  
Index Of Refraction ◽  
The Real

 We can easily extract the optical properties from a material starting from its permittivity complexes ԑ; . The real part of this dielectric function clearly takes its place in the Colombian interaction of an exciton. We are interested in exciton 1S in the case of the massive vanadium dioxide. We will solve Schrödinger’s equation for this exciton by variational method and we obtain  according to energy E of the same exciton. We make a simulation by means of the Maple software of   and of the index of refraction n according to energy E of the exciton 1S, around and far from the band gap of this material while being based on the approximation of the effective mass. We will extract the reflectivity R and transmittivity T of the massive vanadium dioxide for the normal incidence of the incidental photons by considering a slightly absorbent semiconductor state. 

Optical properties of the Vanadium dioxide

2015 ◽  
Vol 8 (2) ◽  
pp. 2148-2155 ◽  
Author(s):  
Abderrahim Benchaib ◽  
Abdesselam Mdaa ◽  
Izeddine Zorkani ◽  
Anouar Jorio
Keyword(s):  
Energy Efficiency ◽  
Optical Properties ◽  
Critical Temperature ◽  
Thin Layer ◽  
Dielectric Function ◽  
Vanadium Dioxide ◽  
Ultra Violet ◽  
Index Of Refraction ◽  
Practical Utility ◽  
Infra Red

The vanadium dioxide is a material thermo chromium which sees its optical properties changing at the time of the transition from the phase of semiconductor state ↔ metal, at a critical temperature of 68°C. The study of the optical properties of a thin layer of VO₂ thickness 82 nm, such as the dielectric function, the index of refraction, the coefficient ofextinction, the absorption’s coefficient, the reflectivity, the transmittivity, in the photonic spectrum of energy ω located inthe interval: 0.001242 ≤ ω (ev) ≤ 6, enables us to control well its practical utility in various applications, like the intelligentpanes, the photovoltaic, paintings for increasing energy efficiency in buildings, detectors of infra-red (I.R) or ultra-violet(U.V). We will make simulations with Maple and compare our results with those of the literature

Optical properties of a thin layer of the Vanadium dioxide at the metal state

2015 ◽  
Vol 9 (1) ◽  
pp. 2303-2310
Author(s):  
Abderrahim Benchaib ◽  
Abdesselam Mdaa ◽  
Izeddine Zorkani ◽  
Anouar Jorio
Keyword(s):  
Optical Properties ◽  
Thin Layer ◽  
Vanadium Dioxide ◽  
Ultra Violet ◽  
Index Of Refraction ◽  
Cost Of Energy ◽  
Infra Red ◽  
Metal State ◽  
The Cost ◽  
Reversible Phase

The vanadium dioxide VO₂ currently became very motivating for the nanotechnologies’ researchers. It makes party of the intelligent materials because these optical properties abruptly change semiconductor state with metal at a critical  temperature θ = 68°C. This transition from reversible phase is carried out from a monoclinical structure characterizing its semiconductor state at low temperature towards the metal state of this material which becomes tétragonal rutile for  θ ˃ 68°C ; it is done during a few nanoseconds. Several studies were made on this material in a massive state and a thin layer. We will simulate by Maple the constant optics of a thin layer of VO₂ thickness z = 82 nm for the metal state according to the energy ω of the incidental photons in the energy interval: 0.001242 ≤ ω(ev) ≤ 6, from the infra-red (I.R) to the ultra-violet (U.V) so as to be able to control the various technological nano applications, like the detectors I.R or the U.V,  the intelligent windows to  increase  the energy efficiency in the buildings in order to save the cost of energy consumption by electric air-conditioning and the paintings containing nano crystals of this material. The constant optics, which we will simulate, is: the index of refraction, the reflectivity, the transmittivity, the coefficient of extinction, the dielectric functions ԑ₁ real part and  ԑ₂  imaginary part of the permittivity complexes ԑ of this material and the coefficient absorption. 

Optical properties of amorphous hydrogenated carbon films: A spectroscopic ellipsometry study

1987 ◽  
Vol 2 (5) ◽  
pp. 645-647 ◽  
Author(s):  
Shuhan Lin ◽  
Shuguang Chen
Keyword(s):  
Optical Properties ◽  
Spectroscopic Ellipsometry ◽  
Carbon Films ◽  
Index Of Refraction ◽  
The Real ◽  
Complex Index ◽  
Tentative Explanation ◽  
Amorphous Hydrogenated Carbon ◽  
Ellipsometry Data ◽  
Complex Index Of Refraction

Optical properties of plasma-deposited amorphous hydrogenated carbon films were studied by spectroscopic ellipsometry. From the ellipsometry data, the real and imaginary parts, n and k, of the complex index of refraction of the film have been deduced for photon energies between 2.0 and 4.0 eV for as-grown as well as for thermally annealed films. Here n and k showed considerable variation with subsequent annealing, even under 400°C. A tentative explanation of the results is proposed.

OPTICAL PROPERTIES OF BORO-GERMANATE GLASS SYSTEMS

2007 ◽  
Vol 21 (15) ◽  
pp. 955-963
Author(s):  
M. Y. NADEEM ◽  
I. M. AWAN ◽  
M. F. WASIQ
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Absorption Edge ◽  
Optical Band Gap ◽  
Glass Composition ◽  
Index Of Refraction ◽  
Germanate Glass ◽  
Optical Absorbance ◽  
Three Samples ◽  
Compositional Series

Three samples of boro-germanate glass system ( GeO 2– B 2 O 3) were prepared by cooling the melt from 1473°K in the compositional series containing 40, 35 and 30 mol% B 2 O 3. For these glasses the optical absorbance, % transmission, optical band gap, relative permittivity (ε r ), index of refraction (n) and index of dispersion (Abbe No., V d ) have been determined. The position of the absorption edge and hence the optical band gap (E opt ) was found to depend on glass composition. The absorption edge was attributed to indirect transitions. The values of E opt and n d were observed to decrease with increasing B 2 O 3 content while ε r and V d increased with increasing B 2 O 3 content.

Mechanical, Electronic and Optical Properties of Two Phases of NbB4: First-Principles Calculations

2018 ◽  
Vol 73 (5) ◽  
pp. 453-460 ◽  
Author(s):  
Ruike Yang ◽  
Shaowei Ma ◽  
Qun Wei ◽  
Dongyun Zhang
Keyword(s):  
Optical Properties ◽  
Transition Metal ◽  
Band Gap ◽  
The Novel ◽  
Electronic And Optical Properties ◽  
The Real ◽  
Hard Materials ◽  
Metal Borides ◽  
Two Phases ◽  
Hardness Values

AbstractAs transition metal borides have been successfully synthesised, the study of the combination of transition metal and boron is another effective way to investigate the properties of boride. We have predicted the novel phase Amm2-NbB4. Using the Cambridge Serial Total Energy Package (CASTEP) code, we further researched on the mechanical, electronic and optical properties of C2/c- and Amm2-NbB4. It is found that both the phases of NbB4 are dynamically and mechanically stable at 0 and 100 GPa. Their Vickers hardness values are both 34 GPa, which indicate that they are hard materials. The band gap of C2/c-NbB4 is 0.145 eV, which indicates that it is a semiconductor (or metalloid) at 0 GPa. For the Amm2-NbB4, the band structure without band gap indicates it is a metal at 0 GPa. The optical properties of these two structures are similar. At 0 eV, the real part of dielectric function is 28.8 for C2/c-NbB4, and the real part value for Amm2-NbB4 is 43. We hope our work will provide some help to the experimental work about the technology of the material.

Optical Properties of Carbon thin films Containing Nanoparticles

1997 ◽  
Vol 498 ◽  
Author(s):  
M. Chhowalla ◽  
A. I. Munindradasa ◽  
K. G. Lim ◽  
G. A. J. Amaratunga ◽  
C. J. Kiely
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Amorphous Carbon ◽  
Carbon Nanoparticles ◽  
Optical Band Gap ◽  
Amorphous Matrix ◽  
Index Of Refraction ◽  
Tetrahedral Amorphous Carbon ◽  
Optical Gap

ABSTRACTThe incorporation of carbon nanoparticles in the forms of nanotubes and bucky onions have shown to improve the mechanical properties of amorphous carbon (a-C) thin films. In this paper we report on the change in the optical properties of a-C films containg nanoparticles. The optical band gap, index of refraction and extinction coefficient are studied. The optical band gap in highly tetrahedral amorphous carbon (ta-C) is found to be around 2 eV. It decreases almost linearly with the sp2 fraction. It is theorized that the clustering of the sp2 sites leads to a reduction in the band gap. In this paper, we study the influence of large sp2 clusters in forms of graphitic nanoparticles on the optical of ta-C. We find that the optical gap remains around 1.8 eV even with the large inclusions of clustered nanoparticles. Furthermore, the gap remains close to 1.8 eV even when the sp2 fraction in the amorphous matrix is increased. The index of refraction however is found to decrease with the sp2 fraction indicating a reduction in density.

Intrinsic Electronic Structures and Optical Anisotropy of α- and β-Phase Copper Phthalocyanine Molecular Crystals

2017 ◽  
Vol 864 ◽  
pp. 133-141
Author(s):  
Xue Yan Wang ◽  
Jian Bang Zheng ◽  
Xiao Jiang Li ◽  
Chong De Cao
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Organic Semiconductors ◽  
Dielectric Function ◽  
Electronic Structures ◽  
Optical Anisotropy ◽  
Density Functional ◽  
Copper Phthalocyanine ◽  
Molecular Crystals ◽  
Β Phase

Electronic structures and optical anisotropy of α- and β-phase copper phthalocyanine (CuPc) molecular crystals have been systemically investigated by first-principles calculations based on Density Functional Theory (DFT). Both crystals were shown to be small gap organic semiconductors with relatively flat and dispersionless bands. The α-CuPc was a direct band gap semiconductor, whereas the β-CuPc was an indirect band gap semiconductor. The analysis of Partial Density of States (PDOS) showed that the top of valance band was mainly contributed by N 2p and C 2p states; the bottom of the conduction band was mainly contributed by N 2p, C 2p and Cu 3d states. The interband optical properties, such as the complex dielectric function, absorption coefficient and complex refractive index, showed a high degree of anisotropy that can be traced to the unique structures of these molecular crystals. The calculated dielectric function for α-CuPc in the low energy region was consistent with the experiment results proposed in the literature. These calculations provided particular interpretations on electronic structure and optical properties of α- and β-CuPc organic semiconductors that were critical to optoelectronics, which would promote the applications of these materials in semiconductor optoelectronic devices.

Microspectroscopy Using a Solid Immersion Lens

2001 ◽  
Vol 7 (S2) ◽  
pp. 148-149
Author(s):  
C.D. Poweleit ◽  
J Menéndez
Keyword(s):  
Spatial Resolution ◽  
Focal Plane ◽  
Numerical Aperture ◽  
Normal Incidence ◽  
Spot Size ◽  
Index Of Refraction ◽  
Objective Lens ◽  
Improvement Factor ◽  
Oil Immersion ◽  
Long Time

Oil immersion lenses have been used in optical microscopy for a long time. The light’s wavelength is decreased by the oil’s index of refraction n and this reduces the minimum spot size. Additionally, the oil medium allows a larger collection angle, thereby increasing the numerical aperture. The SIL is based on the same principle, but offers more flexibility because the higher index material is solid. in particular, SILs can be deployed in cryogenic environments. Using a hemispherical glass the spatial resolution is improved by a factor n with respect to the resolution obtained with the microscope’s objective lens alone. The improvement factor is equal to n2 for truncated spheres.As shown in Fig. 1, the hemisphere SIL is in contact with the sample and does not affect the position of the focal plane. The focused rays from the objective strike the lens at normal incidence, so that no refraction takes place.

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Deposition time dependent study of structural and optical properties of PbS thin films grown by CBD method

2020 ◽  
Vol 13 ◽  
Author(s):  
Minakshi Chaudhary ◽  
Yogesh Hase ◽  
Ashwini Punde ◽  
Pratibha Shinde ◽  
Ashish Waghmare ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Deposition Time ◽  
Secondary Growth ◽  
Cost Effective ◽  
Xrd Analysis ◽  
Structural Morphology ◽  
Glass Substrates ◽  
Cbd Method

: Thin films of PbS were prepared onto glass substrates by using a simple and cost effective CBD method. Influence of deposition time on structural, morphology and optical properties have been investigated systematically. The XRD analysis revealed that PbS films are polycrystalline with preferred orientation in (200) direction. Enhancement in crystallinity and PbS crystallite size has been observed with increase in deposition time. Formation of single phase PbS thin films has been further confirmed by Raman spectroscopy. The surface morphology analysis revealed the formation of prismatic and pebble-like PbS particles and with increase in deposition time these PbS particles are separated from each other without secondary growth. The data obtained from the EDX spectra shows the formation of high-quality but slightly sulfur rich PbS thin films over the entire range of deposition time studied. All films show increase in absorption with increase in deposition time and a strong absorption in the visible and sub-band gap regime of NIR range of the spectrum with red shift in band edge. The optical band gap shows decreasing trend, as deposition time increases but it is higher than the band gap of bulk PbS.

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