INVESTIGATION OF STRUCTURAL, OPTICAL, AND DIELECTRIC PROPERTIES OF PVA-KI FOR TEMPERATURE SENSOR APPLICATIONS

2019 ◽  
Vol 26 (09) ◽  
pp. 1950054
Author(s):  
T. A. HANAFY ◽  
I. T. ZEDAN ◽  
A. E. BEKHEET
Keyword(s):  
Dielectric Constant ◽  
Temperature Sensor ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Measurements ◽  
Index Formula ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Sensor Applications ◽  
Loss Index

Polyvinyl alcohol (PVA) films doped with potassium iodide (KI) have been prepared by casting from their aqueous solutions. The structure of the doped samples was investigated using Fourier transform infrared spectroscopy. The addition of KI to PVA structure leads to form crosslinking as well as the increase of the amorphous ratio within the investigated sample. The optical measurements were recorded at room temperature in the range of 200–2500[Formula: see text]nm. It was found that the optical energy gap of the investigated sample increases with increasing KI ratio. The effect of the addition increment of KI on the optical parameters of PVA has been investigated. Dielectric spectra of PVA doped with KI were studied in the temperature and the frequency ranges of 303–373[Formula: see text]K and 100[Formula: see text]Hz–5[Formula: see text]MHz, respectively. The behavior of dielectric constant ([Formula: see text]) and dielectric loss index ([Formula: see text]) of PVA sample doped with KI exhibits good linearity with temperature. The obtained results suggest strongly the applicability of these materials in the temperature sensor applications.

scholarly journals Effect of Pb percentage on optical parameters of PbxCd1-xSe thin films

2019 ◽  
Vol 14 (29) ◽  
pp. 1-7
Author(s):  
Farah Q. Kamil
Keyword(s):  
Thin Films ◽  
Thermal Evaporation ◽  
Energy Gap ◽  
Optical Measurements ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Glass Substrates

PbxCd1-xSe compound with different Pb percentage (i.e. X=0,0.025, 0.050, 0.075, and 0.1) were prepared successfully. Thin filmswere deposited by thermal evaporation on glass substrates at filmthickness (126) nm. The optical measurements indicated thatPbxCd1-xSe films have direct optical energy gap. The value of theenergy gap decreases with the increase of Pb content from 1.78 eV to1.49 eV.

DEPENDENCE OF THE OPTICAL AND ELECTRICAL PROPERTIES OF CHEMICALLY ANNEALED VACUUM-DEPOSITED a-Si:H FILMS ON THE DEPOSITION RATE

2012 ◽  
Vol 27 (02) ◽  
pp. 1350015
Author(s):  
AHMED M. EL-NAGGAR
Keyword(s):  
Activation Energy ◽  
Electrical Properties ◽  
Deposition Rate ◽  
Room Temperature ◽  
Energy Gap ◽  
Dark Conductivity ◽  
Optical Parameters ◽  
Optical And Electrical Properties ◽  
Optical Energy Gap ◽  
Optical Energy

The influence of the deposition rate of chemically annealed vacuum-deposited a-Si : H films on its optical and electrical properties was studied. The optical parameters were studied using spectrophotometric measurements of the film transmittance in the wavelength range 200–3000 nm. It was found that with increasing the silicon deposition rate from 0.09 to 0.23 nm/s, the refractive index, n, decreases from 3.78 to 3.45 at 1.5 μm, and the optical energy gap, Eg, decreases from 1.74 to 1.66 eV, while the Urbach parameter, ΔE, increases from 77 to 99 meV. The dark conductivity was measured at temperatures descending from 480 to 170 K. It was found that the room temperature dark conductivity values decreased from 1.11 × 10-6 (Ω⋅ cm )-1 to 2.08 × 10-10 (Ω⋅ cm )-1 with increasing the deposition rate from 0.09 to 0.23 nm/s respectively, while the activation energy Ea increased from 0.53 to 0.84 eV with increasing deposition rate. As a result, a good quality a-Si : H film with optical energy gap of 1.74 eV, Urbach parameter of 77 meV, dark conductivity of 1.11 × 10-6 (Ω⋅ cm )-1, and activation energy of 0.53 eV was successfully prepared at a low deposition rate of 0.09 nm/s.

scholarly journals Temperature Dependence of the Optical Band Gap and Optical Parameters of Tetramethyl Ammonium Tetrachlorozincate (TMA)2ZnCl4 single Crystals Around the Normal and Incommensurate Phase Transitions

2015 ◽  
Vol 9 (1) ◽  
pp. 162-172 ◽  
Author(s):  
A. Abu El-Fadl ◽  
A.M. Nashaat
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Transition ◽  
Incommensurate Phase ◽  
Spectral Studies ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Increasing Temperature

Single crystals of tetramethylammonium tetrachlorozincate [N(CH3)4]ZnCl4 abbreviated hereafter as (TMA)2ZnCl4 were grown using the slow evaporation technique at 315 K. The X-ray powder diffraction patterns indicated that [N(CH)]ZnCl belongs to the orthorhombic system with Pmcn symmetry at room temperature. The lattice constants are found to be a= 12.360 Å, b= 15.687 Å and c= 8.985 Å. The values were in good agreement with the values in previous studies. Ultraviolet–visible–near-infrared (UV–Vis–NIR) spectral studies were carried out in the temperature range 276–307 K. This range of temperature involves two phase transition temperatures (Ti=296 K) from normal (parent) to incommensurate phase and (T=279 K) from incommensurate to commensurate-ferroelectric phase. The cut off wavelength was found to be 195.016 nm at room temperature. The optical transmittance increases with increasing temperature, and the cut off shifts to higher wavelengths. Analysis reveals that the type of optical transition is the indirect allowed one. The optical energy gap (Eg) has the value of 5.903 eV at room temperature. The value of optical energy gap (Eg) decreases with increasing temperature. The changes in the values of the cut off wavelength and optical energy gap (Eg) with changing the temperature were found to take different rates at the two phases under study, besides anomalous takes place at Ti and Tc. The absorption coefficient (α) as a function of the incident photon energy shows an exponential behavior near the absorption edge which suggests that the Urbach rule is obeyed and indicated the formation of a band tail. Urbach parameters were calculated at different temperatures and the frequencies of effective phonons and electron–phonon interaction constants were determined for various phases.

scholarly journals Empirical Relation for Electronic and Optical Properties of Binary Tetrahedral Semiconductors

2021 ◽  
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Atomic Number ◽  
Energy Gap ◽  
Empirical Relation ◽  
Average Energy ◽  
Optical Parameters ◽  
Dielectric Analysis ◽  
Average Atomic Number ◽  
Tetrahedral Semiconductors

The concept of ionicity has been developed by Phillips and Van Vechten from the dielectric analysis of the semiconductors and insulators to evaluate various bond parameters of binary tetrahedral (AIIBVI and AIIIBV) semiconductors. In this paper, an advance hypothesis of average atomic number of the elements in a compound has been used to evaluate intrinsic electronic and optical parameters such as ionic gap (Ec), average energy gap (Eg), crystal ionicity (fi) and dielectric constant (ϵ) of binary tetrahedral semiconductors.

scholarly journals The Effect of Substrate Temperature on the Band Transition, Cauchy Dispersion and Urbach Energy of Nanostructure CdO Thin Films

2015 ◽  
Vol 58 ◽  
pp. 83-89
Author(s):  
Muneer H. Jadduaa ◽  
Zainab Ali Harbi ◽  
Nadir F. Habubi
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Urbach Energy ◽  
Energy Gap ◽  
Chemical Spray Pyrolysis ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Substrate Temperature Increase ◽  
Band Transition ◽  
Cdo Thin Films

Thin films of CdO were prepared by chemical spray pyrolysis (CSP) . The effect of different temperature substrate (300,350,400,450 and 500) °C on some optical parameters has been studied . The transmittance and the optical energy gap were increased from (2.503-2.589) eV ,on the contrary of the rest parameters such as refractive index , real and imaginary parts of dielectric constant and Urbach energy which they were decreased as the substrate temperature increase.

scholarly journals Optical and Structural Properties of CdS Quantum Dots Synthesized Using (MW-CBD) Technique

2020 ◽  
pp. 44-52
Author(s):  
Ahmed Ahmed S. Abed ◽  
Sattar J. Kasim ◽  
Abbas F. Abbas
Keyword(s):  
Thin Films ◽  
Quantum Dots ◽  
Room Temperature ◽  
Energy Gap ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Optical Energy Gap ◽  
Glass Substrates ◽  
High Adhesion ◽  
Uv Visible

In the present study, the microwave heating method was used to prepare cadmium sulfide quantum dots CdSQDs films. CdS nanoparticles size average obtained as (7nm). The morphology, structure and composition of prepared CdSQDs were examined using (FE-SEM), (XRD) and (EDX). Optical properties of CdSQDs thin films formed and deposited onto glass substrates have been studied at room temperature using UV/ Visible spectrophotometer within the wavelength of (300-800nm), and Photoluminescence (PL) spectrum. The optical energy gap (Eg) which estimated using Tauc relation was equal (2.6eV). Prepared CdS nanoparticles thin films are free from cracks, pinholes and have high adhesion to substrate.

Optical Detection of Band Gap Variations Due to Ordering in Ga0.47In0.53As on InP

1992 ◽  
Vol 281 ◽  
Author(s):  
D. J. Arent ◽  
K. A. Bertness ◽  
Sarah R. Kurtz ◽  
M. Bode ◽  
J. M. Olson
Keyword(s):  
Band Gap ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Energy Gap ◽  
Growth Conditions ◽  
Band Gap Energy ◽  
Optical Energy Gap ◽  
Lower Growth ◽  
Transmission Electron ◽  
High Resolution Images

ABSTRACTA reduction in the optical energy gap of more than 65 meV has been observed in In0.53Ga0.47 As grown on (100) InP by atmospheric pressure metalorganic vapor phase epitaxy. The band gap energies were deduced from room temperature photocurrent spectroscopic measurements, accounting for differences in composition and strain. Spontaneous CuPt type ordering of In and Ga atoms on the (111) subplanes of the InGaAs2 was confirmed by transmission electron microscopy. Superlattice signatures in the transmission micrographs were observed only for samples with associated reduced band gap energies, and were confirmed by visible double periodicity in high resolution images. In0.53Ga0.47 As was grown under a variety of conditions, some which promoted ordering. In general, lower growth temperatures and moderate (∼4 μ/hr) growth rates promoted a greater degree of ordering and reduction of the band gap energy. The influence of growth conditions on the ordered structure is considered within the context of current theories.

scholarly journals Estimation of optical parameters of silicon single crystals with different orientations

2019 ◽  
Vol 37 (1) ◽  
pp. 65-70
Author(s):  
M.M. El-Nahass ◽  
H.A.M. Ali
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Single Crystals ◽  
Energy Gap ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
High Frequency Dielectric Constant ◽  
Single Oscillator Model ◽  
Indirect Allowed Transition ◽  
Single Oscillator

AbstractOptical properties of Si single crystals with different orientations (1 0 0) and (1 1 1) were investigated using spectrophotometric measurements in a spectral range of 200 nm to 2500 nm. The data of optical absorption revealed an indirect allowed transition with energy gap of 1.1 ± 0.025 eV. An anomalous dispersion in refractive index. The normal dispersion of the refractive index was discussed according to Wemple-DiDomenico single oscillator model. The oscillator energy Eo, dispersion energy Ed, high frequency dielectric constant ∈∞, lattice dielectric constant ∈L and electronic polarizability αe were estimated. The real ∈1 and imaginary ∈2 parts of dielectric constant were also determined.

Optical energy gap variation in GaxIn1−x As alloys

1968 ◽  
Vol 46 (2) ◽  
pp. 157-159 ◽  
Author(s):  
John C. Woolley ◽  
Mathew B. Thomas ◽  
Alan G. Thompson
Keyword(s):  
Thermoelectric Power ◽  
Fermi Energy ◽  
Room Temperature ◽  
Energy Gap ◽  
Empirical Equations ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Good Agreement ◽  
Gap Values

Room-temperature optical energy-gap values have been determined for GaxIn1−x As alloys, and have been corrected, where necessary, for the Burstein effect by finding Fermi energy values from thermoelectric power data. The results show good agreement with the empirical equations given previously for mixed III–V alloys.

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