scholarly journals The optical properties of a- (GeS2)100-xGax thin films

2019 ◽  
Vol 11 (21) ◽  
pp. 28-36
Author(s):  
Bushra A. Hasan
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Constants ◽  
Optical Band Gap ◽  
Bulk Material ◽  
Localized States ◽  
Optical Parameters ◽  
Evaporation Technique ◽  
Opposite Manner ◽  
Average Bond

Thin films whose compositions can be expressed by (GeS2)100-xGax (x=0, 6,12,18) formula were obtained by thermal evaporation technique  of bulk material at a base pressure of ~10-5 torr. Optical transmission spectra of the films were taken in the range of 300-1100 nm then the optical band gap, tail width of localized states,  refractive index, extinction coefficient were calculated. The optical constants were found to increase at low concentration of Ga (0 to12%) while they decreases with further addition of Ga. The optical band gap was found to change in opposite manner to that of optical constants. The variation in the optical parameters are explained in terms of average bond energy of the system.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

scholarly journals Effect of thickness on the optical properties of Gaas thin films

2013 ◽  
Vol 37 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Chitra Das ◽  
Jahanara Begum ◽  
Tahmina Begum ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Band Gap ◽  
Optical Band Gap ◽  
Visible Region ◽  
Solar Spectrum ◽  
Band Gap Energy ◽  
Optical Parameters ◽  
Gap Energy

Effect of thickness on the optical and electrical properties of gallium arsenide (GaAs) thin films were studied. The films of different thicknesses were prepared by vacuum evaporation method (~10-4 Pa) on glass substrates at a substrate temperature of 323 K. The film thickness was measured in situ by a frequency shift of quartz crystal. The thicknesses were 250, 300 and 500 nm. Absorption spectrum of this thin film had been recorded using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300 - 2500 nm. The values of some important optical parameters of the studied films (absorption coefficient, optical band gap energy and refractive index; extinction co-efficient and real and imaginary parts of dielectric constant) were determined using these spectra. Transmittance peak was observed in the visible region of the solar spectrum. Here transmittance showed better result when thicknesses were being increased. The optical band gap energy was decreased by the increase of thickness. The refractive index increased by increasing thickness while extinction co-efficient and real and imaginary part of dielectric constant decreased. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15684 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 83-91, 2013

Effect of MWCNT addition on the optical band gap of PVA/CS transient biocomposites

2021 ◽  
pp. 002199832110370
Author(s):  
Ömer Bahadır Mergen
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Band Gap ◽  
Optical Band Gap ◽  
Rapid Development ◽  
Measurement Techniques ◽  
Resistivity Measurement ◽  
Optical Parameters ◽  
Optical And Electrical Properties ◽  
Biocomposite Films

In recent years, as a result of increasing environmental concerns, biodegradable materials have gained great attention. With the rapid development of electronic technology, the importance of innovation and development of low-cost, sustainable, transient bioelectronics materials is increasing. In this research, the preparation of Poly(Vinyl Alcohol) (PVA), Chitosan (CS), and Multi-Walled Carbon nanotube (MWCNT) biocomposite films have been described. The solution mixing, ultrasonic mixing, and spin coating techniques were used to prepare the PVA/CS/MWCNT biocomposite thin films. UV–Vis absorption spectroscopy and two-point probe resistivity measurement techniques were used to study the optical and electrical properties of the biocomposite thin films. Optical band gap energies ( Eg) of PVA/CS/MWCNT biocomposites were obtained using the Tauc and Absorbance Spectrum Fitting (ASF) methods. Results obtained with both methods were found to be exactly the same. Experimental results have shown that with increasing MWCNT concentration, electrical conductivity (σ) increases from 1.75x10−16 S to 2.94x10−3 S, and Eg decreases significantly. At the same time, the fundamental optical parameters such as band tail (Urbach) energy ( Eu), refractive index ( n), absorption ( α), and extinction ( k) coefficient of the PVA/CS/MWCNT biocomposites were investigated in the UV-VIS range. The improvement observed in the optical and electrical properties of PVA/CS/MWCNT biocomposite films shows that these composites could be used as bioelectronics materials.

Investigative Study of Optical Parameters of Se80.5Bi1.5Te18-yAgy Thin Films

2012 ◽  
Vol 710 ◽  
pp. 739-744 ◽  
Author(s):  
Anup Kumar ◽  
Pawan Heera ◽  
P. B Baraman ◽  
Raman Sharma
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Integrated Circuits ◽  
Band Gap ◽  
Communication Systems ◽  
Optical Band Gap ◽  
Optical Parameters ◽  
Optical Integrated Circuits ◽  
Increase With Increase ◽  
Good Transparency

The optical constants, like absorption coefficient (α), optical band gap (Eg) and refractive index (n), in Se80.5Bi1.5Te18-yAgy (y= 0, 1.0 and1.5) thin films are calculated using well known Swanepoel’s method in the spectral range of 600-2000 nm. The optical band gap has been estimated by using Tauc’s extrapolation method and is found to increase with increase in Ag content. The present results shows that the large value of nonlinear refractive index and good transparency of these thin films will make them a very promising materials for optical integrated circuits in the optical communication systems.

Optical Investigations of In2Se2.7Sb0.3 Thin Films Prepared by Thermal Evaporation Technique

2019 ◽  
Vol 969 ◽  
pp. 355-360 ◽  
Author(s):  
Piyush Patel ◽  
Vimal Patel ◽  
Sandip Vyas ◽  
Jaydev Patel ◽  
Himanshu Pavagadhi
Keyword(s):  
Thin Films ◽  
Optical Constants ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Radiation Detectors ◽  
Thermal Evaporation Technique ◽  
Clean Glass Substrate ◽  
Amorphous Nature ◽  
Evaporation Technique

The III-VI compound semiconductors are important for the fabrication of ionizing radiation detectors, solid-state electrodes, and photosensitive heterostructures, solar cell as well as ionic batteries. In this paper, In2Se2.7Sb0.3 thin films have been grown by thermal evaporation technique onto a with chemically clean glass substrate. Amorphous nature of the films has been discovered by UV-VIS spectrophotometer. The analysis by absorption spectra within the spectral range 200nm -900 nm has been used for the optical characterization of thin films. From these data the optical constants (absorption coefficient (α), refractive index (η), extinction coefficient (k)) and optical band gap (Eg) are studied. The results were discussed, and reported in detail.

scholarly journals Conductivity and Density of States of New Polyphenylquinoline

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 934 ◽  
Author(s):  
Shamil R. Saitov ◽  
Dmitriy V. Amasev ◽  
Alexey R. Tameev ◽  
Vladimir V. Malov ◽  
Marine G. Tedoradze ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Density Of States ◽  
Optical Band Gap ◽  
Dark Conductivity ◽  
Localized States ◽  
Energy Distance ◽  
Temperature Dependences

Electrical, photoelectrical, and optical properties of thin films of a new heat-resistant polyphenylquinoline synthesized using facile methods were investigated. An analysis of the obtained temperature dependences of the dark conductivity and photoconductivity indicates the hopping mechanism of conductivity over localized states arranging at the energy distance of 0.8 eV from the Fermi level located inside the band gap of the investigated material. The optical band gap of the studied material was estimated from an analysis of the spectral dependences of the photoconductivity and absorption coefficient before (1.8–1.9 eV) and after (2.0–2.2 eV) annealing at temperatures exceeding 100 °C. The Gaussian character of the distribution of the localized states of density inside the band gap near the edges of the bands was established. A mechanism of changes in the optical band gap of the investigating polymer under its annealing is proposed.

Optical band gap and dispersion of optical constants of Cu-Ga-S thin films

Optik ◽  
2019 ◽  
Vol 186 ◽  
pp. 147-154 ◽  
Author(s):  
M. Isik ◽  
H.H. Gullu ◽  
E. Coskun ◽  
N.M. Gasanly
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Constants ◽  
Optical Band Gap

STRUCTURAL PARAMETERS AND OPTICAL CONSTANTS OF CdS NANOCRYSTALLINE THIN FILMS

NANO ◽  
2011 ◽  
Vol 06 (03) ◽  
pp. 251-258 ◽  
Author(s):  
B. VISWANATHAN ◽  
J. DHARMARAJA ◽  
J. BALAMURUGAN
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Band Gap ◽  
Crystallite Size ◽  
Optical Conductivity ◽  
Optical Constants ◽  
Optical Band Gap ◽  
Structural Parameters ◽  
Stoichiometric Composition ◽  
Bath Temperature

Optical constants of cadmium sulfide (CdS) thin films were determined in the spectral range of 400–1200 nm from optical absorption and transmittance measurements for different bath temperatures. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) were the techniques used to determine the crystallite structure and morphology of the films. EDX images showed that a sample had a stoichiometric composition. The crystallite size and microstrain were calculated using the Williamson–Hall method. The optical band gap values of the films varied from 2.35 eV to 2.5 eV, depending on the bath temperature. Optical study was performed to calculate the refractive index (n), extinction coefficient (k), optical conductivity (σ), dielectric constant (real and imaginary), and optical band gap using transmission spectra. It has been observed that the conductivity of the synthesized films has a close relationship with the size of the crystallites. The optical conductivity and the crystallite size increase at a temperature of up to 70°C and then start decreasing when the temperature is still increased due to the change in phase from hexagonal to cubic in nature. Moreover, we observed that beyond this temperature the XRD peak shifts toward the nanoregion. The values of microstructure parameters change drastically, whereas the trend of optical constants remains the same.

scholarly journals Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated Thin Films

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Pankaj Sharma ◽  
S. C. Katyal
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Band Gap ◽  
Density Of States ◽  
Spectral Range ◽  
Transmission Spectrum ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Thermal Evaporation Technique ◽  
Evaporation Technique

The present paper reports the effect of Ge addition on the optical band gap and refractive index of thin films. Thin films of and were prepared by thermal evaporation technique at base pressure  Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to . The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.

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