ON THE OPTICAL CHARACTERISTICS OF CdS THIN FILMS DEPOSITED BY QUASI-CLOSED VOLUME TECHNIQUE

2004 ◽  
Vol 18 (09) ◽  
pp. 1287-1297 ◽  
Author(s):  
MIHAELA RUSU ◽  
IULIA SALAORU ◽  
M. E. POPA ◽  
G. I. RUSU
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Absorption Spectra ◽  
Energy Gap ◽  
Index Of Refraction ◽  
Closed Volume ◽  
Optical Energy Gap ◽  
Cds Thin Films

Cadmium sulfide (CdS) thin films (d=0.15–1.15 μ m ) were deposited onto glass substrates by the quasi-closed volume technique under vacuum. The investigations shown that the films are polycrystalline and have a hexagonal structure. It was experimentally established that the films with stable structure can be obtained if they are submitted to a heat treatment, consisting of several succesive heating/cooling cycles within a given temperature range (ΔT=300–600 K ), the temperature dependence of the electrical conductivity becomes reversible. For heat-treated samples, the values of thermal activation energy calculated from the temperature dependence of the electrical conductivity, ranged between 2.30–2.45 eV. The spectral dependences of the transmission and absorption coefficients were studied in the range 500–1400 nm. The influence of heat treatment on the shape of the absorption spectra and dispersion index of refraction is studied for samples with different thickness. Optical energy gap, calculated from the absorption spectra was in the range 2.30–2.5 eV.

scholarly journals Studies on Surface Morphology and Electrical Conductivity of PS Thin Films in Presence of Divalent Complexes

2019 ◽  
Vol 16 (3) ◽  
pp. 0588 ◽  
Author(s):  
Al-Taa'y Et al.
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Refractive Index ◽  
Surface Morphology ◽  
Structural Modification ◽  
Energy Gap ◽  
Three Dimensional ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Energy Gaps

       Optical properties and surface morphology of pure and doped Polystyrene films with different divalent metals of Zn, Cu and Sn and one concentration percentage have been studied. Measurements of UV-Vis spectrophotometer and AFM spectroscopy were determined. The absorbance, transmittance and reflectance spectrums were used to study different optical parameters such as absorption coefficient, refractive index, extinction coefficient and energy gap in the wavelengths rang 200-800nm. These parameters have increased in the presence of the metals. The change in the calculated values of energy gaps with doping metals content has been investigated in terms of PS matrix structural modification. The value of optical energy gap was found decreasing from 4.5eV of pure PS to reach 4.45, 4.38 and 4.32eV for Zn, Cu and Sn respectively. Measurement by AFM spectroscopy was done for two and three dimensional topographic images. From figures, the data of roughness average were 7.29, 7.31, 3.37 and 6.73nm for samples (Blank, Zn, Cu and Sn) respectively.

Heat Treatment at Different Temperatures and its Effect on the Optical Properties of Pure PMMA and PMMA-Coumarin

2021 ◽  
Vol 900 ◽  
pp. 42-47
Author(s):  
J.N. Zainab ◽  
Kareem Ali Jasim ◽  
Farah Jawad Kadhum ◽  
Auday H. Shaban
Keyword(s):  
Heat Treatment ◽  
Absorption Coefficient ◽  
Absorption Spectra ◽  
Optical Constant ◽  
Optical Constants ◽  
Energy Gap ◽  
Pmma Film ◽  
Pure Pmma ◽  
Optical Energy Gap ◽  
Different Temperatures

The effect of thermal treatment on optical constants of pure PMMA and with addition (15 and 35) ml of coumarin at different temperatures (100, 110 and 120) C0 for 1 hour were investigated. Cast method used to prepares films of pure PMMA and PMMA with (15 and 35) of coumarin. UV/VIS spectrometer technique used to measure the absorption spectra for these films. The optical constant (absorption spectra and absorption coefficient) don’t changes after applied temperatures in pure PMMA film but the optical constant (absorption spectra and absorption coefficient) in PMMA with (15 and 35) ml of coumarin increased with applied temperatures. The optical energy gap of pure PMMA and PMMA with (15 and 35) ml of coumarin slightly decreased after applied temperature up to 1200 C.

Effects of Indium on the Properties of N-Type CdS Thin Films Deposited by Spray Pyrolysis

1986 ◽  
Vol 77 ◽  
Author(s):  
Y. T. Kim ◽  
S. C. Park ◽  
S. K. Chung
Keyword(s):  
Thin Films ◽  
Doping Level ◽  
Thermal Activation ◽  
Energy Gap ◽  
Indium Content ◽  
Optical Energy Gap ◽  
Electrical And Optical Properties ◽  
Free Carriers ◽  
Order Of Magnitude ◽  
Cds Thin Films

ABSTRACTEffects of the doping level of indium impurity on electrical and optical properties of the CdS thin films, prepared with solution-sprayed method have been studied. The density of free carriers can be raised to an order of magnitude higher than that of non-doped case by increasing doping level of indium up to 0.01mole-% while indium doping does not significantly change the mobility from its value in non-doped samples. The optical energy gap is decreased with increasing indium content while the thermal activation energy remains unchanged. The experimental results are discussed in terms of the self compensation and radiative recombination phenomena.

scholarly journals Influence of Film Thickness and Heat Treatment on the Physical Properties of Mn Doped Sb2Se3 Nanocrystalline Thin Films

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
I. K. El Zawawi ◽  
Manal A. Mahdy ◽  
E. A. El-Sayad
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Film Thickness ◽  
Energy Gap ◽  
Blue Shift ◽  
Amorphous Structure ◽  
Treatment Temperature ◽  
Optical Energy Gap ◽  
Heat Treated ◽  
Nanocrystalline Thin Films

Nanocrystalline thin films of Sb37.07Mn1.95Se60.98 with different thickness (7, 20, 40, and 80 nm) were successfully prepared via inert gas condensation technique. As-deposited films showed amorphous structure by grazing incident in-plane X-ray diffraction (GIIXD) technique. All films of different thicknesses were heat treated at 433 K for 90 min. The GIIXD pattern of annealed films showed nanocrystalline orthorhombic structure. The effect of thickness of annealed films on the structure and optical properties was studied. Calculated particle sizes are 20.67 and 24.15 for 40 and 80 nm thickness of heat treated film. High resolution transmission electron microscope HRTEM images and their diffraction patterns proved that 40 nm film thickness annealed at different temperature has nanocrystalline nature with observed (high) crystallinity that increases with annealing temperature. Blue shift of optical energy gap was observed from 1.68 to 2 eV with decreasing film thickness from 80 to 7 nm. Film thickness of 40 nm was exposed to different heat treated temperatures from 353 to 473 K to detect its effect on structure and optical and electrical properties. Blue shift from 1.73 to 1.9 eV was observed in its optical band gap due to direct transition as heat treatment temperature decreasing from 473 to 353 K. Electrical conductivity was studied for different heat treated films of thickness 40 nm, and intrinsic conduction mechanism is dominant. The activation energy Ea was affected by heat treatment process.

scholarly journals Optical Investigations of CdSe1-x Tex Thin Films

2011 ◽  
Vol 8 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Energy Gap ◽  
Fundamental Absorption Edge ◽  
Low Pressure ◽  
Direct Transition ◽  
Optical Energy Gap ◽  
Thermal Evaporation Method ◽  
Glass Substrates ◽  
Heat Treated

The alloys of CdSe1-xTex compound have been prepared from their elements successfully with high purity (99.9999%) which mixed stoichiometry ratio (x=0.0, 0.25, 0.5, 0.75 and 1.0) of (Cd, Se and Te) elements. Films of CdSe1-xTex alloys for different values of composition with thickness(0.5?m) have been prepared by thermal evaporation method at cleaned glass substrates which heated at (473K) under very low pressure (4×10-5mbar) at rate of deposition (3A?/s), after that thin films have been heat treated under low pressure (10-2mbar) at (523K) for two hours. The optical studies revealed that the absorption coefficient (?) is fairly high. It is found that the electronic transitions in the fundamental absorption edge tend to be allowed direct transition. It was also found that the optical energy gap vary non-linearly with composition (x) and have a minimum value at x=0.5 and increases after heat treatment. It is found that the optical constants vary non-linearly with composition, and the behavior inverse at x=0.5, and affected by heat treatment. The behavior of ?1 is similar to the behavior of n, while the behavior of ?2 is similar to the behavior of k.

scholarly journals Study Influence of Substrate Temperature on Optical Properties of CdS Thin Films Prepared by Chemical Spray pyrolysis

2019 ◽  
Vol 32 (1) ◽  
pp. 6 ◽  
Author(s):  
Karrar Mahdi Saleh
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Substrate Temperature ◽  
Spray Pyrolysis ◽  
Energy Gap ◽  
Nitrate Solution ◽  
Chemical Spray Pyrolysis ◽  
Optical Energy Gap ◽  
Chemical Spray ◽  
Cds Thin Films

This study aims to prepare Cadmium Sulphide (CdS) thin films using thermal Chemical Spray Pyrolysis (CSP) on glass of different temperatures substrate from cadmium nitrate solution. Constant thickness was (430 ± 20 nm) and the effect of substrate temperature on the optical properties of prepared thin films. Optical properties have been studied from transmittance and absorbance spectral within wavelengths range (360 - 900 nm). The results show that all the prepared films have a direct electron transitions and optical energy gap between (2.31-2.44 eV). They also show that the transmittance and optical energy gap of films prepared from nitrate solution increase with increasing of substrate temperature, then transmittance start downward with the continued increase in temperature (400, 450) oC.

Temperature Dependence of Optical Energy Gap of Gallium Selenide

2001 ◽  
Vol 8 (3-4) ◽  
pp. 251-259 ◽  
Author(s):  
M. Kepinska ◽  
M. Nowak ◽  
Z. Kovalyuk ◽  
R. Murri
Keyword(s):  
Temperature Dependence ◽  
Energy Gap ◽  
Gallium Selenide ◽  
Optical Energy Gap ◽  
Optical Energy
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