Structural and optical properties of PbI2 nanostructures obtained using the thermal evaporation method

2013 ◽  
Vol 91 (10) ◽  
pp. 826-832 ◽  
Author(s):  
Safaa I. Mohammed ◽  
Y. Al-Douri ◽  
U. Hashim ◽  
N.M. Ahmed ◽  
R. Al-Gaashani
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Band Gap ◽  
Energy Band ◽  
Room Temperature ◽  
Crystal Size ◽  
Thermal Evaporation ◽  
Energy Band Gap ◽  
Thermal Evaporation Method ◽  
Evaporation Method

Lead iodide (PbI2) nanostructures were successfully prepared using the thermal evaporation method on a glass substrate at room temperature. The structural properties were analyzed using X-ray diffraction, which revealed that the crystal size increases as thickness increases. Crystal size was calculated to be in the range 27.3–61.08 nm. In addition, the preferred growth orientation was (001) for all samples. The surface morphologies using scanning electron microscopy have shown an increasing of grain size with increasing thickness. Also, optical properties using ultraviolet–visible spectroscopy were researched as a function of thickness. The absorption data have indicated direct transmission with optical energy band gap that varies continuously from 2.35 to 2.40 eV at room temperature. The refractive index and optical dielectric constant were investigated to verify the suitability of the model for electro-optical systems. The low fluctuation in energy band gap indicates that the grain size is quite small. The obtained results are in good agreement with experimental and theoretical data.

scholarly journals Effect of Dopant Concentration on the Structural, Optical and Sensing Properties of (SnO2)1-x(TiO2:CuO)x Sprayed Films

2019 ◽  
Vol 16 (2) ◽  
pp. 0361
Author(s):  
Mahmood Et al.
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Energy Band ◽  
Spray Pyrolysis Technique ◽  
Single Crystal Silicon ◽  
Dielectric Constants ◽  
Energy Band Gap ◽  
Crystal Silicon ◽  
X Ray ◽  
Regular Manner

      Spray pyrolysis technique was subjected to synthesized (SnO2)1-x (TiO2: CuO) x Thin films on different substrates like glass and single crystal silicon using. The structure of the deposited films was studied using x-ray diffraction. A more pronounced diffraction peaks of SnO2 while no peaks of (CuO , TiO2 ) phase appear in the X-ray profiles by increasing of the content of (TiO2 , CuO) in the sprayed films. Mixing concentration (TiO2 , CuO) influences on the size of the crystallites of the SnO2 films ,the size of crystallites of the spray paralyzed oxide films change in regular manner by increasing of (TiO2 , CuO) amount. The effect of mixing concentration on the optical properties of the films was also investigated. The reflectance and transmittance spectra  in the wavelength range (300-1100) nm were employed to determine the optical properties such as energy band gap (Eg) and refractive index (n),  extinction coefficient  (k) , real and imaginary parts of dielectric constants (ε1, ε2) for (SnO2)1-x(TiO2:CuO)x films. The energy band gap omit of which showed reduction from (3.65 to 2.2) eV by reducing of SnO2 amount from (100 to 70) % .The reduction of energy band gap was ascribed to the new tail states introduced in the band gap of tin oxide. The sensitivity of the prepared sensor film was determined resistance difference of the films when exposed to oxidizing gas. The data declared that the mixed SnO2 films have better sensitivity in comparison with unmixed films.

scholarly journals Effects of Temperature on Morphological, Structural and Optical Characteristics of CdTe Films for PV Applications

2020 ◽  
Vol 27 (1) ◽  
pp. 10-16
Author(s):  
M.A. Salawu ◽  
A.B. Alabi ◽  
J.T. Adeleke ◽  
H.T. Sulu ◽  
S.B. Sharafa ◽  
...  
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
Energy Band ◽  
Thermal Evaporation ◽  
Optical Transmittance ◽  
Cdte Film ◽  
Crystal Defects ◽  
Optical Characteristics ◽  
Energy Band Gap ◽  
Cdte Films

Cadmium telluride (CdTe) is a direct band gap semiconductor for direct light-to-electricity conversion. The films are promising photovoltaic materials for CdS/CdTe solar cells because of its energy band gap of 1.5 eV and higher absorption co-efficient (>104cm-1). This work presents the characterization of 1 μm CdTe films for photovoltaic applications. The films were deposited on cleaned glass substrates using thermal evaporation. The effect of annealing temperatures (as deposited, 400°C and 500°C) on morphological, structural and optical characteristics of CdTe films was investigated for an hour and characterized with Scanning Electron Microscope (SEM), Powder X-ray diffraction (PXRD) and UV-Visible spectrophotometer. The results revealed that the reflectance characteristics of CdTe films depend on the wavelength of electromagnetic spectra. The maximum percentage optical transmittance of CdTe films for as-grown, 400°C and 500oC films were 59%, 60% and 58% respectively at 800 nm wavelength. The absorbance decreases with increasing in wavelength and was found to be 1.65, 1.25 and 0.85 % for the as-grown, 400°C and 500oC films respectively. The absorption coefficient exhibits higher values in the shorter wavelength and decreases as the wavelength and temperatures increases and the band gap becomes wider. The SEM analyses showed that the films were homogenous and free from crystal defects. The results revealed that 1 μm CdTe film may be used as absorber layer in CdS/CdTe thin film solar cells. Keywords: CdTe, Glass substrate, Thermal evaporation, Annealing temperature, Energy band gap

scholarly journals Facile Synthesis, Diffused Reflectance Spectroscopy & Fluorescence Studies of Ni0.5-xMg0.5CuxFe2O4 Nanoparticles

2021 ◽  
Author(s):  
Pradeep Chavan
Keyword(s):  
Grain Size ◽  
Band Gap ◽  
Energy Band ◽  
Fluorescence Emission ◽  
Ferrite Nanoparticles ◽  
Energy Band Gap ◽  
Visible Absorption ◽  
Structural Formation ◽  
Fluorescence Studies ◽  
Auto Combustion

Abstract The present study focused on the structural, morphological, optical and fluorescence properties of Ni 0.5-x Mg 0.5 Cu x Fe 2 O 4 (x = 0.0, 0.1, 0.3 and 0.5) nanoparticles synthesized by using auto combustion technique. The structural formation of the ferrite nanoparticles were confirmed by FTIR spectroscopic study. From FTIR spectra of the synthesized ferrite nanoparticles, metal ions are situated in two different sub lattices i.e. tetrahedral (A-site) and octahedral (B-site) in ferrites. The surface morphology and grain size of Cu substituted Ni-Mg ferrite nanoparticles were estimated from the micrographs of atomic force microscopy (AFM); the maximum grain size 54.69 nm was obtained. Spectra of UV-Visible absorption of the synthesized ferrite nanoparticles were carried-out by using UV-Vis spectrophotometry; the maximum absorption was observed at 418 nm. The energy band gap of ferrite nanoparticles has been estimated using UV-Vis absorption spectra; the energy band gap 3.50 eV was obtained. From the fluorescence emission spectroscopy of synthesized ferrite nanoparticles, the ferrite samples emit red colour in the region of 680 nm.

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