STUDIES ON STRUCTURAL, SURFACE MORPHOLOGICAL, OPTICAL, LUMINESCENCE AND UV PHOTODETECTION PROPERTIES OF SOL–GEL Mg-DOPED ZnO THIN FILMS

2019 ◽  
Vol 26 (03) ◽  
pp. 1850167 ◽  
Author(s):  
A. MAHROUG ◽  
B. MARI ◽  
M. MOLLAR ◽  
I. BOUDJADAR ◽  
L. GUERBOUS ◽  
...  
Keyword(s):  
Thin Films ◽  
Doping Concentration ◽  
Sol Gel ◽  
Visible Region ◽  
Wurtzite Structure ◽  
Visible Range ◽  
Bandgap Energy ◽  
Mg Doping ◽  
Uv Emission ◽  
Morphological Studies

Undoped and magnesium-doped zinc oxide thin films were prepared by the sol–gel method. Results from X-ray diffraction indicated that the films exhibited a hexagonal wurtzite structure and were highly oriented along the [Formula: see text]-axis. The intensity of the (002) diffraction peak increased with increasing the Mg doping concentration. Also, Mg doping inhibited the growth of crystallite size which decreased from 46[Formula: see text]nm to 38[Formula: see text]nm with doping concentration. Morphological studies by atomic force microscopy (AFM) indicated the uniform thin film growth and the decreasing of grain size and surface roughness with Mg doping. Optical analysis showed that the average transmittance of all films was above 90% in the visible range and Mg doping has significantly enhanced the bandgap energy of ZnO. Two Raman modes assigned to [Formula: see text] and [Formula: see text] for the ZnO wurtzite structure were observed for all films. UV emission peak and three defect emission peaks in the visible region were observed by photoluminescence measurements at room temperature. The intensity ratio of UV emission to the visible emission increased with the Mg concentration. Photocurrent measurements revealed that all films presented the photoresponses with [Formula: see text]-type semiconducting behavior and their generated photocurrents were reduced by Mg doping. The prepared thin films of high quality with improved properties by Mg doping could be proposed to workers in the field of optoelectronic devices for using them as a strong candidate.

scholarly journals Boron-doped TiO2 (B-TiO2) Thin Films Grown Using Sol-Gel Spin Coating Method

2018 ◽  
pp. 1-17
Author(s):  
D. O. Samson ◽  
A. D. A. Buba
Keyword(s):  
Thin Films ◽  
Wavelength Range ◽  
Doping Concentration ◽  
Sol Gel ◽  
Visible Region ◽  
Boron Doping ◽  
Pure Tio2 ◽  
Visible Range ◽  
Ultraviolet Region ◽  
Tio2 Thin Films

In this study, the effect of modifying boron doping concentration on the optical properties, electrical properties and microstructural images of TiO2 thin films was investigated by the sol-gel technique by grinding TiO2 powder with a boron compound at a wavelength range of 250 nm to 850 nm. The SEM micro-images revealed the homogenous, continuous and nanocrystalline surface morphology: 10% is the tolerable amount of boron doping concentration into the TiO2 for achieving sphere-like nanostructures materials with low agglomeration. The XRD spectra of the B-TiO2 films showed anatase peaks of greater intensities when compared to the pure TiO2 film. All the films illustrate extinction coefficient in the visible region of solar spectra corresponding to the low absorption, and absorption peaks established in the ultraviolet region near 330nm with the optical transmittance varied from over 52 - 96% in the UV-Vis wavelength range. Diffuse reflectance absorption spectra analysis indicated that the incorporation of B into TiO2 material results in a substantial red shift and the absorption extends significantly into the visible range. The optical band gap energy values of the thin films were found to be 3.38, 3.35, 3.28, 3.26, and 3.36eV. This showed a low probability of raising the electron across the mobility gap with the photon energy in the visible region. The refractive index values varied between 1.891 and 1.922 depending on the percentage content of boron. Moreover, the imaginary part of the dielectric constant increase slowly, whereas the real part increases sharply and the optical conductivity was found to increase with the increase in boron addition.  

Doping and Annealing Effects on the Optical Bandgap of the Nickel Doped Copper Oxide Thin Films

2021 ◽  
Vol 16 (2) ◽  
pp. 243-248
Author(s):  
Fatmah S. Bahabri ◽  
Alaa Y. Mahmoud ◽  
Wafa A. Alghameeti
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Doping Concentration ◽  
Cupric Oxide ◽  
Optical Bandgap ◽  
Visible Range ◽  
Bandgap Energy ◽  
Direct Bandgap ◽  
Annealing Temperatures ◽  
Annealing Effects

In this work, we study the optical properties of the Nickel doped cupric oxide Ni-CuO thin films with Ni various doping concentrations (0, 20, 30, 50, 70, and 80%), at two different annealing temperatures; 200 and 400 °C. The absorbance and optical bandgap for the films are calculated and compared. We find that all films exhibit clear peaks in the visible range, with the increase in the absorptivity via increasing both annealing and Ni concentration. We also find that the annealing affects the shape of the absorbance peaks to be narrowed and blue shifted. Investigation on the direct bandgap energy shows that all films exhibit large direct gap; ranging from 3.87 to 4.01 eV. For non-annealed films, direct bandgap increases with increasing the Ni concentration, while for the annealed samples, the direct bandgap generally decreases by annealing, and with increasing the doping concentration. For the indirect bandgap analysis, the calculated values of the bandgap are ranging from 0.62 to 1.96 eV. We find that for non-annealed films, the indirect bandgap increases with increasing the doping concentration, while after annealing, the bandgap decreases with increasing the doping concentration for the annealing at 200 and 400 °C, with more decreasing in the gap at 400 °C.

Synthesis, Characterization and Hall Effect Measurements of Nanocrystalline ZnO Thin Films

2012 ◽  
Vol 510-511 ◽  
pp. 186-193 ◽  
Author(s):  
Ashari Maqsood ◽  
M. Islam ◽  
M. Ikram ◽  
S. Salam ◽  
S. Ameer
Keyword(s):  
Thin Films ◽  
Hall Effect ◽  
Sol Gel ◽  
Visible Region ◽  
Zno Thin Films ◽  
Zno Films ◽  
Morphological Studies ◽  
Hall Effect Measurements ◽  
Scherrer Formula

ZnO thin films were prepared by sol-gel method. Prepared thin films were then characterized by SEM, XRD, EDX and Hall effect measurements. SEM confirmed the morphological studies of ZnO thin films. Crystallite size is calculated using the Scherrer formula. Crystallite and grain sizes are obtained through XRD and SEM. EDS analysis confirms mass percentage of ZnO deposited. Decreasing trend of magneto resistance with temperature is observed. The optical transmission spectra of the solgel deposited ZnO thin films showed high transmittance (>70%) in the visible region and indicates that the transmittance of ZnO films gradually decreased as the thickness increased. Decreasing trend of resistivity and sheet resistance with thickness are also observed. The IV characterization of ZnO thin films under influence of UV and dark conditions are reported. The dc electrical resistivity data follow the hoping model.

Regulations of aging time on optical properties of nano-crystalline ZnO thin films fabricated by sol–gel method

2017 ◽  
Vol 10 (03) ◽  
pp. 1750024
Author(s):  
Jitao Li ◽  
Dingyu Yang ◽  
Xinghua Zhu ◽  
Hui Sun ◽  
Xiuying Gao ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Aging Time ◽  
Sol Gel ◽  
Visible Region ◽  
Zno Thin Films ◽  
Visible Range ◽  
Gel Method ◽  
Sol Gel Method ◽  
Nano Crystalline

Nano-crystalline Zinc oxide (ZnO) thin films on glass substrates have been fabricated by sol–gel method for different aging times. The thermal curve of the dried gel was examined and it was found that evaporation of solvent and the decomposition of the organics have completed before 250[Formula: see text]C. X-ray diffraction patterns and Atomic Force Microscope images of samples only have a small difference of microstructure. The transmittance spectra revealed high transmittance in visible region. The optical band gap of the samples remined stable (3.28[Formula: see text]eV). Also, the Urbach energy was calculated to explain the defect concentration. The Photoluminescence spectra in ultraviolet and visible regions were studied, and the decreased intensity of peaks at 387[Formula: see text]nm and the increased emissions in visible range were found. The results showed that excessive aging time can cause degeneration of optical properties of thin films.

scholarly journals Effect of Solvents and Stabilizer Molar Ratio on the Growth Orientation of Sol-Gel-Derived ZnO Thin Films

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
R. Bekkari ◽  
B. Jaber ◽  
H. Labrim ◽  
M. Ouafi ◽  
N. Zayyoun ◽  
...  
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Visible Region ◽  
Zno Thin Films ◽  
Molar Ratio ◽  
Bandgap Energy ◽  
Growth Orientation ◽  
Effect Of Solvents ◽  
Average Grain Size ◽  
Crystalline Growth

This work targets to control the growth orientation of sol-gel-derived ZnO thin films in order to allow different modes of excitation (longitudinal and transverse) when targeted to be used in piezoelectric applications. For that, the effect of solvents and stabilizer molar ratio on the structural and optical characteristics of the obtained films is investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometry. The XRD results show clearly that the synthesized films exhibit hexagonal wurtzite structure without any secondary phases and that the crystallite average size, estimated by the Scherrer formula, is ranged between 13 and 30 nm. The main finding of this work is to show that the control of the crystalline growth orientation is possible simply by varying the solvent nature and/or the stabilizer molar ratio. These later parameters are therefore considered as key factors when seeking to develop the ZnO-based transducers. Actually, the ZnO thin films synthesized with propanol as solvent are oriented only along the c-axis; meanwhile, when using the isopropanol or ethanol, other preferential orientations appear. Additionally, the effect of MEA molar ratio (r) has been studied on the propanol-derived films (the unfavorable case). It has been found that this parameter has a direct effect on the crystalline growth orientation of these films and that a new preferential orientation (100) appears at low r. On the other hand, SEM images show the formation of homogeneous nanocrystalline thin films with an average grain size ranged between 19 and 35 nm. Moreover, the ZnO thin films exhibit a high transparency in the visible region, and the measured transmittance is ranged from 85 to 97%. However, the change of ZnO film orientation has no significant effect on the direct bandgap energy which is closed to 3.30 eV.

Photocatalytic Degradation of Methylene Blue by NiO Thin Films under Solar Light Irradiation

2019 ◽  
Vol 56 ◽  
pp. 152-157 ◽  
Author(s):  
Abdelouahab Noua ◽  
Hichem Farh ◽  
Rebai Guemini ◽  
Oussama Zaoui ◽  
Tarek Diab Ounis ◽  
...  
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Sol Gel ◽  
Visible Region ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Light Irradiation ◽  
Solar Light ◽  
Solar Light Irradiation

Nickel oxide (NiO) thin films were successfully deposited by sol-gel dip-coating method on glass substrates. The structural, morphological and optical properties in addition to the photocatalytic activity of the prepared films were investigated. The results show that the films have a polycrystalline NiO cubic structure with dense NiO grains and average optical transmittance in the visible region. The photocatalytic properties of the films were studied through the degradation of methylene blue and 89% of degradation was achieved for 4.5h of solar light irradiation exposure which indicates the capability of NiO photocatalytic activity.

scholarly journals Preparation of Glass Plate-Supported Nanostructure ZnO Thin Film Deposited by Sol-Gel Spin-Coating Technique and Its Photocatalytic Degradation to Monoazo Textile Dye

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Mohammad Hossein Habibi ◽  
Mohammad Khaledi Sardashti
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Photocatalytic Degradation ◽  
Spin Coating ◽  
Sol Gel ◽  
Glass Plate ◽  
Zno Thin Films ◽  
Visible Range ◽  
Textile Dye ◽  
Axis Orientation

Glass plate-supported nanostructure ZnO thin films were deposited by sol-gel spin coating. Films were preheated at275∘Cfor 10 minutes and annealed at 350, 450, and550∘Cfor 80 minutes. The ZnO thin films were transparent ca 80–90% in visible range and revealed that absorption edges at about 370 nm. Thec-axis orientation improves and the grain size increases which was indicated by an increase in intensity of the (002) peak at34.4∘in XRD corresponding to the hexagonal ZnO crystal. The photocatalytic degradation of X6G an anionic monoazo dye, in aqueous solutions, was investigated and the effects of some operational parameters such as the number of layer and reusability of ZnO nanostructure thin film were examined. The results showed that the five-layer coated glass surfaces have a very high photocatalytic performance.

The influence of Mg doping on the dielectric and tunable properties of (Ba0.6Sr0.4)0.925K0.075TiO3 thin films fabricated by sol–gel method

2006 ◽  
Vol 290 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Xiaohua Sun ◽  
Shishang Guo ◽  
Gengzhu Wu ◽  
Meiya Li ◽  
Xing-Zhong Zhao
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Mg Doping ◽  
Tunable Properties

scholarly journals Epoxy/Silicone Blend Loaded with N-Doped CNT Composites: Study on the Optoelectronic Properties

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Younes Ziat ◽  
Hamza Belkhanchi ◽  
Maryama Hammi ◽  
Ousama Ifguis
Keyword(s):  
Thin Films ◽  
Urbach Energy ◽  
Optical Transition ◽  
Sol Gel ◽  
Visible Range ◽  
Visible Spectroscopy ◽  
Glass Substrates ◽  
Optical Gap ◽  
Ito Glass ◽  
Uv Visible

Thin films of epoxy/silicone loaded with N-CNT were prepared by a method of sol-gel and deposited on ITO glass substrates at room temperature. The properties of the loaded monolayer samples (0.00, 0.07, 0.1, and 0.2 wt% N-CNTs) were analyzed by UV-visible spectroscopy. The transmittance for the unloaded thin films is 88%, and an average transmittance for the loaded thin film is about 42 to 67% in the visible range. The optical properties were studied from UV-visible spectroscopy to examine the transmission spectrum, optical gap, Tauc verified optical gap, and Urbach energy, based on the envelope method proposed by Swanepoel (1983). The results indicate that the adjusted optical gap of the film has a direct optical transition with an optical gap of 3.61 eV for unloaded thin films and 3.55 to 3.19 eV for loaded thin films depending on the loading rate. The optical gap is appropriately adapted to the direct transition model proposed by Tauc et al. (1966); its value was 3.6 eV for unloaded thin films and from 3.38 to 3.1 eV for loaded thin films; then, we determined the Urbach energy which is inversely variable with the optical gap, where Urbach’s energy is 0.19 eV for the unloaded thin films and varies from 0.43 to 1.33 eV for the loaded thin films with increasing rate of N-CNTs. Finally, nanocomposite epoxy/silicone N-CNT films can be developed as electrically conductive materials with specific optical characteristics, giving the possibility to be used in electrooptical applications.

scholarly journals Optical Properties of Sn Doped ZnO Thin Film Prepared Using Sol-Gel Method for Optical Limiting Application

2021 ◽  
Vol 24 (3) ◽  
pp. 38-42
Author(s):  
Marwa Mudfer Alqaisi ◽  
◽  
Alla J. Ghazai ◽  
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Optical Properties ◽  
Sol Gel ◽  
Visible Region ◽  
Optical Limiting ◽  
Pure Zinc ◽  
Gel Method ◽  
Sol Gel Method ◽  
Doped Zno

In this work, pure Zinc oxide and tin doped Zinc oxide thin films nanoparticles with various volume concentrations of 2, 4, 6, and 8V/V% were prepared by using the sol-gel method. The optical properties were investigated by using UV-Visible spectroscope, and the value exhibits the direct allowed transition. The average of transmittance was around ~(17-23) %in visible region. The optical energy band gap was calculated with wavelength (300-900) nm for pure ZnO and Sn doped ZnO thin films which decreases with increasing concentration from 3.4 eV to 3.1 eV respectively and red shift. The real dielectric(εr) and the imaginary dielectric εiare the same behavior of the refractive index(n) the extinction coefficient (k) respectively. The optical limiting properties were studied by using an SDL laser with a wavelength of 235 nm. ZnO and doping thin films an found efficient as optic limiting and depend on the concentration of the all samples.

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