Modeling the transient optical parameters in laser-excited band gap materials

2016 ◽  
Vol 56 (1) ◽  
pp. 011015 ◽  
Author(s):  
Anika Rämer ◽  
Lasse Haahr-Lillevang ◽  
Baerbel Rethfeld ◽  
Peter Balling
Keyword(s):  
Band Gap ◽  
Optical Parameters ◽  
Excited Band

scholarly journals Flexible Methyl Cellulose/Polyaniline/Silver Composite Films with Enhanced Linear and Nonlinear Optical Properties

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1225
Author(s):  
Ali Atta ◽  
Mostufa M. Abdelhamied ◽  
Ahmed M. Abdelreheem ◽  
Mohamed R. Berber
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Nonlinear Optical ◽  
Composite Films ◽  
Methyl Cellulose ◽  
Carbon Cluster ◽  
Nonlinear Susceptibility ◽  
Optical Parameters ◽  
Flexible Polymer

In order to potentiate implementations in optical energy applications, flexible polymer composite films comprising methyl cellulose (MC), polyaniline (PANI) and silver nanoparticles (AgNPs) were successfully fabricated through a cast preparation method. The composite structure of the fabricated film was confirmed by X-ray diffraction and infrared spectroscopy, indicating a successful incorporation of AgNPs into the MC/PANI blend. The scanning electron microscope (SEM) images have indicated a homogenous loading and dispersion of AgNPs into the MC/PANI blend. The optical parameters such as band gap (Eg), absorption edge (Ed), number of carbon cluster (N) and Urbach energy (Eu) of pure MC polymer, MC/PANI blend and MC/PANI/Ag films were determined using the UV optical absorbance. The effects of AgNPs and PANI on MC polymer linear optical (LO) and nonlinear optical (NLO) parameters including reflection extinction coefficient, refractive index, dielectric constant, nonlinear refractive index, and nonlinear susceptibility are studied. The results showed a decrease in the band gap of MC/PANI/AgNPs compared to the pure MC film. Meanwhile, the estimated carbon cluster number enhanced with the incorporation of the AgNPs. The inclusion of AgNPs and PANI has enhanced the optical properties of the MC polymer, providing a new composite suitable for energy conversion systems, solar cells, biosensors, and nonlinear optical applications.

scholarly journals Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1316
Author(s):  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Hewa O. Ghareeb ◽  
Elham M. A. Dannoun ◽  
Sarkawt A. Hussen ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Metal Complex ◽  
Band Gap ◽  
Optical Band Gap ◽  
Complex Dielectric Constant ◽  
Poly Vinyl Alcohol ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
Casting Technique

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

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.

scholarly journals Steps Toward the Band Gap Identification in Polystyrene Based Solid Polymer Nanocomposites Integrated with Tin Titanate Nanoparticles

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2320 ◽  
Author(s):  
Ahang M. Hussein ◽  
Elham M. A. Dannoun ◽  
Shujahadeen B. Aziz ◽  
Mohamad A. Brza ◽  
Rebar T. Abdulwahid ◽  
...  
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
Polymer Nanocomposites ◽  
Absorption Edge ◽  
Optical Band Gap ◽  
Solid Polymer ◽  
Optical Parameters ◽  
Optical Dielectric Constant ◽  
Solution Cast ◽  
Optical Dielectric

In the current study, the film fabrication of polystyrene (PS) based polymer nanocomposites (NCs) with tuned refractive index and absorption edge was carried out using the solution cast method. X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) light characterization techniques were performed. The structural and optical properties of the prepared films were specified. The hump of PS decreased significantly when SnTiO3 nanoparticles (NPs) were introduced. Sharp and high intense peaks of SnTiO3 NPs at a high filler ratio were observed. The crystalline size was determined for SnTiO3 NPs from the sharp crystalline peaks using Debye-Scherrer’s equation and was found to be 25.179 nm, which is close enough to that described by the supplier. Several optical parameters, such as absorption coefficient (α), refractive index (n), and optical dielectric properties, were investigated. The absorption spectra were tuned with increasing SnTiO3NPs. Upon the addition of the NPs to the PS host polymer, the absorption edge undergoes shifting to lesser photon energy sides. The optical dielectric constant (ε′) was correlated to the refractive index. The study of the optical band gap was conducted in detail using both Tauc’s model and the optical dielectric loss (ε″) parameter. The results showed that the ε″ parameter is noteworthy to be measured in the optical band gap study of materials.

EVALUATING OPTICAL PARAMETERS FROM ELECTRONIC STRUCTURE AND CRYSTAL STRUCTURE FOR BINARY (ANB8-N) AND TERNARY $({\rm A}^N {\rm B}^{2 + N}{\rm C}^{7 - N}_2)$ TETRAHEDRAL SEMICONDUCTORS

2010 ◽  
Vol 24 (24) ◽  
pp. 2511-2524 ◽  
Author(s):  
AJAY SINGH VERMA ◽  
SHEETAL SHARMA ◽  
V. K. JINDAL
Keyword(s):  
Crystal Structure ◽  
Refractive Index ◽  
Electronic Structure ◽  
Band Gap ◽  
Nearest Neighbor ◽  
Optical Parameters ◽  
Neighbor Distance ◽  
Nearest Neighbor Distance ◽  
Tetrahedral Semiconductors ◽  
Straight Lines

In this paper, we present new empirical relations to evaluate opto-electronic properties such as refractive index (n), band gap (Eg) and optical electronegativity (Δχ) in terms of electronic structure of atoms (i.e. valence electrons) and crystal structure of materials (i.e. nearest-neighbor distance, d) for zinc blende ( A II B VI and A III B V ) and chalcopyrites ([Formula: see text] and [Formula: see text]) structured solids. The refractive index (n), band gap (Eg) and optical electronegativity (Δχ) of these solids exhibit a linear relationship when plotted against the nearest-neighbor distance d (Å), but fall on different straight lines according to the product of the valence electron of the compounds. We have applied the proposed relation on these solids and found a better agreement with the experimental data as compared to the values evaluated by earlier researchers.

scholarly journals From Green Remediation to Polymer Hybrid Fabrication with Improved Optical Band Gaps

2019 ◽  
Vol 20 (16) ◽  
pp. 3910 ◽  
Author(s):  
M. A. Brza ◽  
Shujahadeen B. Aziz ◽  
H. Anuar ◽  
Muataz Hazza F. Al Hazza
Keyword(s):  
Heavy Metals ◽  
Metal Complexes ◽  
Band Gap ◽  
Optical Band Gap ◽  
Black Tea ◽  
Band Gaps ◽  
Poly Vinyl Alcohol ◽  
Optical Parameters ◽  
Structure Property ◽  
Host Matrix

The present work proposed a novel approach for transferring high-risk heavy metals tometal complexes via green chemistry remediation. The method of remediation of heavy metals developed in the present work is a great challenge for global environmental sciences and engineering because it is a totally environmentally friendly procedure in which black tea extract solution is used. The FTIR study indicates that black tea contains enough functional groups (OH and NH), polyphenols and conjugated double bonds. The synthesis of copper complex was confirmed by the UV-vis, XRD and FTIR spectroscopic studies. The XRD and FTIR analysis reveals the formation of complexation between Cu metal complexes and Poly (Vinyl Alcohol) (PVA) host matrix. The study of optical parameters indicates that PVA-based hybrids exhibit a small optical band gap, which is close to inorganic-based materials. It was noted that the absorption edge shifted to lower photon energy. When Cu metal complexes were added to PVA polymer, the refractive index was significantly tuned. The band gap shifts from 6.2 eV to 1.4 eV for PVA incorporated with 45 mL of Cu metal complexes. The nature of the electronic transition in hybrid materials was examined based on the Taucs model, while a close inspection of the optical dielectric loss was also performed in order to estimate the optical band gap. The obtained band gaps of the present work reveal that polymer hybrids with sufficient film-forming capability could be useful to overcome the drawbacks associated with conjugated polymers. Based on the XRD results and band gap values, the structure-property relationships were discussed in detail.

scholarly journals Study of structural, electrical, and optical properties of nickel-doped tin selenide crystals

2016 ◽  
Vol 94 (2) ◽  
pp. 212-217 ◽  
Author(s):  
G.K. Solanki ◽  
I.L. Chauhan ◽  
K.D. Patel
Keyword(s):  
Band Gap ◽  
Near Infrared ◽  
Visible Region ◽  
Hall Effect Measurement ◽  
Spectroscopic Technique ◽  
Optical Parameters ◽  
X Rays ◽  
X Ray Diffraction ◽  
Tin Selenide ◽  
Power Measurements

Nickel-doped tin selenide crystals can be grown using the direct vapour transport technique. This paper includes structural, electrical, and optical characterizations of SnSeNi0.2 crystals done by X-ray diffraction (XRD), energy-dispersive analysis of X-rays (EDAX), surface microstructure topography, Hall effect measurement carried out to determine type of material, Seebeck coefficient and calculation of power factor has been carried out from the data of thermoelectric power measurements and the ultraviolet–visible (UV-Vis) spectroscopic technique, respectively. The optical absorption spectrum was obtained in an UV-Vis–near-infrared (NIR) spectrometer in the range of 200–2500 nm. The UV-Vis spectroscopic technique has been used to calculate band gap, and the value of the band gap was found to be 0.84 eV in the visible region. Calculation of various optical parameters has been carried out.

Temperature Dependence of Optical Properties and Minority Carrier Diffusion Length in a-SiGe:H,F

1987 ◽  
Vol 95 ◽  
Author(s):  
R. Schwarz ◽  
K. Dietrich ◽  
S. Goedecker ◽  
J. Kolodzey ◽  
D. Slobodin ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Band Gap ◽  
Temperature Coefficient ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Index Of Refraction ◽  
Complex Dielectric Constant ◽  
Optical Parameters ◽  
Minority Carrier Diffusion Length ◽  
Carrier Diffusion

AbstractWe report the temperature dependence of several optical parameters of thin films of hydrogenated and fluorinated amorphous silicon alloys (a-SiGe:H,F) between 5 and 95 °C. The absorption coefficient near the optical band gap Eg increases with temperature. From this increase we calculate a temperature coefficient for Eg of −4.5×10−4 eV/K, which is essentially independent of band gap The concomittant change of index of refraction n was determined in the near infrared region from the interference pattern in the reflection spectra. The temperature coefficient dn/n/dT is 0.9×10−4 K−1 for un-alloyed a-Si:H,F and increases with increasing Ge atomic fraction. The changes of Eg and n with temperature are consistent with a simple quantummechanical description of the complex dielectric constant. We also report the temperature dependence of the minority carrier diffusion length in a-SiGe:H,F.

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