OPTICAL PROPERTIES OF THERMALLY EVAPORATED METAL-FREE PHTHALOCYANINE (H2Pc) THIN FILMS

2005 ◽  
Vol 19 (27) ◽  
pp. 4057-4071 ◽  
Author(s):  
M. M. EL-NAHASS ◽  
M. M. SALLAM ◽  
H. A. M. ALI
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Film Thickness ◽  
Energy Gap ◽  
Fundamental Absorption Edge ◽  
Absorption Region ◽  
Metal Free ◽  
Polycrystalline Form ◽  
Absorption Measurements

The optical properties of metal-free phtalocyanine ( H 2 Pc ) in thin film form is investigated. X-ray diffractograms of the ( H 2 Pc ) powder show that it has a α-polycrystalline form with a monoclinic structure. The thermal evaporation of ( H 2 Pc ) powder leads to α-polycrystalline films, oriented preferentially to the (001) plane. After annealing at 623 K for two hours, a mixture of α- and β-phases is formed on an amorphous background. The optical properties of ( H 2 Pc ) thin films have been studied using spectrophotometeric measurements of transmittance and reflectance in the range 200–2200 nm for a different film thickness. The refractive index and the absorption index show independence on the film thickness. The refractive index shows anomalous dispersion in the region of the fundamental absorption edge. The absorption measurements show the characteristic splitting of the Q-band and ΔQ is obtained as 0.22 eV. The absorption coefficient in the absorption region reveals indirect transitions. The fundamental and the onset energy gap are determined as 2.74 eV and 1.55 eV, respectively.

scholarly journals Synthesis and characterization of Eu3+ doped TiO2 thin films deposited by spray pyrolysis technique for photocatalytic application

2020 ◽  
Author(s):  
Shereen Alshomar
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Refractive Index ◽  
Optical Properties ◽  
Film Thickness ◽  
Photocatalytic Degradation ◽  
Spray Pyrolysis ◽  
Spray Pyrolysis Technique ◽  
Average Grain Size ◽  
Double Beam

Abstract In this study, nanocrystalline TiO 2 : Eu 3+ thin films are successfully formed by spray pyrolysis technique deposited on glass substrate. Optical, electrical, structure, surface morphology, and photocatalytic degradation of Methylene blue have been examined. The optical properties of the films are analyzed using transmittance and reflectance spectra, which are measured using UV-Vis-NIR double-beam spectrophotometer. Optical properties such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and Urbach energy (E u ) have been calculated as a function of Eu 3+ concentration. Film thickness were evaluated using the refractive index dependence on wavelength . The films thickness were determined as 97.13, 122.62, 123.24, 117.14 and 128.25 nm, respectively, for Eu doped TiO 2 at 0,4, 6, 8 and 10 wt % doping concentration. The band gap values raised from 3.29 to 3.42 eV with increasing the Eu 3+ dopant concentration. The highest electrical conductivity was found to be 3.01x10 -2 (Ω.cm) -1 at high doping level with 10 wt% Eu 3+ . The XRD analysis illustrate the tetragonal crystal structure of films with anatase phase and reduces crystallite size linearly with increasing Eu 3+ concentration. Scanning electron microscopy (SEM) analysis indicated consistent allocation of irregular and spherical shaped grains covering the substrate surface. The average grain size in range of 82.5 – 51.1 nm is observed and films show porous nature. The photocatalytic effect of TiO 2 : Eu 3+ thin films is predicted from the degradation of methylene blue (MB) at room temperature under UV light irradiation. An enhancement in photocatalytic degradation observed by increasing the amount of Eu 3+ due to increase in the e/h pair production and increase of film thickness. These results make TiO 2 : Eu 3+ thin films as attractive candidate for photovoltaic cells and other optoelectronic device applications

EFFECT OF DEPOSITION TEMPERATURE ON THE PROPERTIES OF TIO2 THIN FILMS DEPOSITED BY MOCVD

2016 ◽  
Vol 23 (02) ◽  
pp. 1650001 ◽  
Author(s):  
ZAKI S. KHALIFA
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Deposition Temperature ◽  
Energy Gap ◽  
Organic Chemical ◽  
Tio2 Thin Films ◽  
Optical Energy Gap

Crystal structure, microstructure, and optical properties of TiO2 thin films deposited on quartz substrates by metal-organic chemical vapor deposition (MOCVD) in the temperature range from 250[Formula: see text]C to 450[Formula: see text]C have been studied. The crystal structure, thickness, microstructure, and optical properties have been carried out using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), atomic force microscope (AFM), and UV-visible transmittance spectroscopy, respectively. XRD patterns show that the obtained films are pure anatase. Simultaneously, the crystal size calculated using XRD peaks, and the grain size measured by AFM decrease with the increase in deposition temperature. Moreover, the texture of the films change and roughness decrease with the increase in deposition temperature. The spectrophotometric transmittance spectra have been used to calculate the refractive index, extinction coefficient, dielectric constant, optical energy gap, and porosity of the deposited films. While the refractive index and dielectric constant decrease with the increase of deposition temperature, the porosity shows the opposite.

scholarly journals Effect of thickness on the optical properties of ZnO thin films prepared by pulsed laser deposition technique (PLD)

2019 ◽  
Vol 15 (32) ◽  
pp. 114-121
Author(s):  
Maysar A. Salim
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Optical Properties ◽  
Film Thickness ◽  
Energy Gap ◽  
Transparent Conducting Oxide ◽  
Zno Thin Films ◽  
Zno Films ◽  
Zno Thin Film ◽  
Optical Energy Gap

Zinc Oxide (ZnO) thin films of different thickness were preparedon ultrasonically cleaned corning glass substrate, by pulsed laserdeposition technique (PLD) at room temperature. Since mostapplication of ZnO thin film are certainly related to its opticalproperties, so the optical properties of ZnO thin film in thewavelength range (300-1100) nm were studied, it was observed thatall ZnO films have high transmittance (˃ 80 %) in the wavelengthregion (400-1100) nm and it increase as the film thickness increase,using the optical transmittance to calculate optical energy gap (Egopt)show that (Egopt) of a direct allowed transition and its value nearlyconstant (~ 3.2 eV) for all film thickness (150, 180, 210, and 240)nm, so Zn0 thin films were used as a transparent conducting oxide(TCO) in various optoelectronic application such as a window in athin film solar cells.

scholarly journals Constructing Spray Pyrolysis System for the Preparation of Thin Films and Study the Optical Properties of PbO Films

2015 ◽  
Vol 53 ◽  
pp. 146-153
Author(s):  
Nahida B. Hasan ◽  
Mohammed Ahmed Mohammed
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Spray Pyrolysis ◽  
Lead Oxide ◽  
Energy Gap ◽  
Absorbance Spectrum ◽  
Optical Energy Gap ◽  
Direct Energy ◽  
Direct Energy Gap

In this paper, the design of spray pyrolysis system to prepare thin films of various materials system. The study showed that films prepared with good characteristics. films were prepared from lead oxide PbO this way. The study of the optical properties of these films and through recording the absorbance spectrum and transmittance spectrum of films prepared in the wavelength range (300-1100) nm . Optical constant for thin films prepared such as absorption coefficient, the extinction coefficient , the refractive index and the optical energy gap was calculated as well. films prepared found that it has a direct energy gap value 3.1eV.

scholarly journals Structural and optical properties of TiO2:NiO nanoparticles thin films prepare by chemical spray pyrolysis

2021 ◽  
Vol 19 (49) ◽  
pp. 22-31
Author(s):  
Wasan A. Al-Taa'y ◽  
Bushra A. Hasan
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Spray Pyrolysis ◽  
Extinction Coefficient ◽  
Energy Gap ◽  
Anatase Phase ◽  
Chemical Spray Pyrolysis ◽  
Chemical Spray ◽  
Structure Properties

The properties of structural and optical of pure and doped nano titanium dioxide (TiO2) films, prepared using chemical spray pyrolysis (CPS) technique, with different nanosize nickel oxide (NiO) concentrations in the range (3-9)wt% have been studied. X-Ray diffraction (XRD) technique where using to analysis the structure properties of the prepared thin films. The results revealed that the structure properties of TiO2 have polycrystalline structure with anatase phase. The parameters, energy gap, extinction coefficient, refractive index, real and imaginary parts were studied using absorbance and transmittance measurements from a computerized ultraviolet visible spectrophotometer (Shimadzu UV-1601 PC) in the wavelengths range (300-800)nm. Optical properties of TiO2 affected by the adding of NiO impurity where the transmittance increased as NiO concentration increased but with more adding the transmittance returned to decrease again. It was found the extinction coefficient, refractive index, real and imaginary parts values decreased with increasing doping percentage up to 7% and then increases occur one more again at 9%. Energy gap values increased after doping with NiO where the values lies in the range was 3.31 to 3.51 eV .

scholarly journals "The Effects of Additive TiO2 Nanoparticles on the Optical properties of DCM Doped with PVC Thin Films "

2018 ◽  
Vol 5 (1) ◽  
pp. 27-35
Author(s):  
Shymaa K. Hussian ◽  
Thill A. Kadhum Al-musaw ◽  
Shatha Raheem Helal Al himidi
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Tio2 Nanoparticles ◽  
Electronic Transition ◽  
Transition Energy ◽  
Energy Gap ◽  
Sol Gel ◽  
Titania Nanoparticles ◽  
Absorption Region ◽  
Electronic Transition Energy

"In this work thin films containing laser dye (DCM) doped with (PVC) were prepared using casting method. Titania (TiO2) nanoparticles also were synthesized using sol-gel technique. Different titania nanoparticle densities (0.882×1020, 1.765×1020, 2.648×1020 and 3.530×1020 cm-3) were co-doping with dye doped polymer to study the effect of this addition on the optical properties and electronic transition energy gaps in cases of both direct and indirect transitions, Absorbance spectra were measured using Spectrophotometer. Absorption and extinction coefficients as well as the refractive indices have been obtained the spectra of absorbance at the strong absorption region. It was observed from results that the allowed direct electronic transitions energy gap was decreasing from 2.22 to 2.175e.V with the increasing of titania nanoparticles density and the allowed indirect electronic transition energy gap decreasing from 2.19 to 2.13e.V.

scholarly journals Impact of Thickness on the Optical Properties of Selenium Thin Films

2021 ◽  
Vol 25 ◽  
Author(s):  
Shiva Udachan ◽  
Narasimha Ayachit ◽  
Lingappa Udachan ◽  
Raghunanda Halembre
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Film Thickness ◽  
Band Gap ◽  
Optical Density ◽  
Energy Gap ◽  
Band Gap Energy ◽  
Primary Objective ◽  
Gap Energy ◽  
The Impact

Objectives: The primary objective of this investigation is to make a systematic study on the impact of thickness on optical properties, such as energy gap, absorption coefficient, optical density etc., for selenium thin films. Understanding of the band gap energy and its influence on film thickness is of utmost importance in acquiring the intended electrical characterization of semiconducting films. Materials and methods: Ultra-purity selenium (99.99 %) was deposited on glass substrates. During deposition, the glass substrate with its holder were rotated with constant speed to have a smooth coating. Results and discussions: The XRD findings indicate that selenium is amorphous in nature. The optical band gap energy is found to be decreasing form (2.3 to 2eV) with the rise of film thickness in interval (200 to 1000 nm). The band gap energy obeys inverse square law with respect to thickness. Conclusion: We have properly grown thin films of Se below the De Broglie wavelength limit by thermal evaporation in vacuum. The optical density varies directly with film thickness. The absorption coefficients were in the interval (0.5 to 4) × 107m-1. The AFM results confirmed that the Se nano-size increases with the increase in thickness. Both the grain boundaries and sub-grain regions are clearly visible in the SEM micrographs

scholarly journals Effect of Manganese Contain on the Optical Properties of CuO Thin Films

2016 ◽  
Vol 65 ◽  
pp. 37-42
Author(s):  
Wasmaa Abdulsattar Jabbar
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Copper Oxide ◽  
Extinction Coefficient ◽  
Energy Gap ◽  
Chemical Spray Pyrolysis ◽  
Chemical Spray ◽  
Uv Visible

Copper oxide prepared with various contains of Manganese by chemical spray pyrolysis. Some optical properties are studied from recording the absorption spectra via UV-Visible spectrophotometer in the range of 460-900 nm. The absorbance increased with increasing Mn-contain in the CuO thin films, and the absorption coefficient. Extinction coefficient and refractive index are decreased with increasing Mn-contain in the CuO thin films, also the energy gap shifted from 2 eV to 1.91 eV after 4%Mn additive.

scholarly journals Influence of annealing temperature on the structural and optical properties of As30Te70 thin films

2017 ◽  
Vol 35 (2) ◽  
pp. 335-345 ◽  
Author(s):  
A.M. Abd-Elnaiem ◽  
M. Mohamed ◽  
R.M. Hassan ◽  
A.A. Abu-Sehly ◽  
M.A. Abdel-Rahim ◽  
...  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Glass Transition ◽  
Extinction Coefficient ◽  
Chalcogenide Glasses ◽  
Annealing Temperature ◽  
Energy Gap ◽  
Optical Parameters ◽  
Optical Energy Gap

Abstract Chalcogenide glasses have attracted much attention largely due to their interesting physical and chemical properties. Though few published articles exist on the As-Te system, little is known about the optical properties of eutectic or near eutectic composition of As-Te system upon heat treatment. Therefore, this paper reports the effects of annealing temperature on the structural and optical parameters of As30Te70 thin films. The bulk and thin films of 150 nm thick As30Te70 chalcogenide glasses were prepared by melt-quenching and thermal evaporation techniques, respectively. The glass transition and crystallization reactions of the bulk samples were investigated using differential scanning calorimetry (DSC). The influence of annealing temperature on the transformation of the crystal structure was studied by X-ray diffraction (XRD), while the surface morphology of the annealed samples was examined using scanning electron microscope (SEM). The optical band gap, refractive index and extinction coefficient were also calculated. The DSC scans showed that the melting temperature remains constant at 636.56 K. In addition, other characteristic temperatures such as the glass transition temperature, the onset crystallization temperature, and the crystallization peak temperature increase with increasing the heating rate. The crystalline phases for the as-prepared and annealed films consist of orthorhombic As, hexagonal Te, and monoclinic As2Te3 phases. Furthermore, the average crystallite size, strain, and dislocation density depend on the annealing temperature. The optical absorption results revealed that the investigated films have a direct transition, and their optical energy gap decreases from 1.82 eV to 1.49 eV as the annealing temperature increases up to 433 K. However, the refractive index, extinction coefficient, dielectric constant and the ratio of free carrier concentration to its effective mass, increase with increasing the annealing temperature.

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