nanocrystalline thin films
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2021 ◽  
Vol 19 (51) ◽  
pp. 41-53
Author(s):  
Hawraa Hadi Abass ◽  
Bushra A Hasan

AlO-doped ZnO nanocrystalline thin films from with nano crystallite size in the range (19-15 nm) were fabricated by pulsed laser deposition technique. The reduction of crystallite size by increasing of doping ratio shift the bandgap to IR region the optical band gap decreases in a consistent manner, from 3.21to 2.1 eV by increasing AlO doping ratio from 0 to 7wt% but then returns to grow up to 3.21 eV by a further increase the doping ratio. The bandgap increment obtained for 9% AlO dopant concentration can be clarified in terms of the Burstein–Moss effect whereas the aluminum donor atom increased the carrier's concentration which in turn shifts the Fermi level and widened the bandgap (blue-shift). The engineering of the bandgap by low concentration of AlO dopant makes ZnO: AlO thin films favorable for the fabrication of optoelectronic devices. The optical constants were calculated and was found to be greatly affected by the increasing the doping ratio.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vishnu Chauhan ◽  
Deepika Gupta ◽  
Nikhil Koratkar ◽  
Rajesh Kumar

AbstractSwift heavy ions (SHI) irradiation of Nickel (Ni) beam with different ions fluence bring the modifications in the functional properties of radio frequency (RF) grown zirconium oxide (ZrO2) nanocrystalline thin films. X-ray diffraction analysis affirms the monoclinic to tetragonal phase transformation and diminishing of peak at higher fluence 1 × 1014 and 2 × 1014 ions/cm2 induced by electronic excitation caused by SHI. Zirconium oxide thin films exhibit the same thickness (195 nm) of virgin and irradiated samples and whereas the nanocrystalline thin films have the elemental composition in proper stoichiometry (1:2) as analyzed by rutherford backscattering spectroscopy (RBS). Photoluminescence measurements confirm the blue emission of virgin and irradiated sample recorded at excitation wavelength 270 to 310 nm. The intensity of obtained emission bands varies with fluence which is interpreted in terms of generation and annihilation of defect centers. The characteristic Ag and Bg Raman modes of monoclinic and tetragonal ZrO2 are obtained at different positions. Moreover, the nanocrystalline ZrO2 thin films exhibits the most prominent absorption phenomenon in the visible range and the irradiation cause significant decrease in band gap to 3.69 eV compare to the virgin ZrO2 sample (3.86 eV). XPS analysis indicates the shifting of the core levels Zr 3d and O 1s towards higher binding energy and spin—orbit splitting of different states. The findings in this research justify that the irradiated thin films can be a potential candidate for designing of new materials, intense radiation environments, nuclear reactors, nuclear waste systems, clean energy sources.


2021 ◽  
Author(s):  
BRIJLATA SHARMA ◽  
Rajesh Lalwani ◽  
Ruby Das ◽  
Devi Singh Raghuwanshi

Abstract In the present work, we have successfully fabricated undoped and Ni-doped Nanocrystalline CdS thin film on an ultrasonically cleaned glass substrate employing the Sol-Gel spin coating technique. The structural and spectroscopic properties of the films were investigated using XRD spectra, UV-Vis spectroscopy and photoluminescence spectra respectively. The X-Ray diffraction spectra revealed the polycrystalline nature of films with cubic structure and (111) as preferred orientation. The average particle size evaluated by the Debye-Scherrer formula lying in the range 6.65nm to 12.05 nm for the deposited films. According to UV-VIS Spectroscopy, the average transmittance of films in the visible region varies between 70–90%. The optical band gap of CdS thin film was evaluated from absorption spectra. The bandgap of the deposited films is in the range of 2.48 eV to 2.70 eV which is higher than that of bulk CdS (2.42eV). This verifies the blue shifting in band edge of CdS Nanocrystalline thin films due to the quantum confinement effect. Photoluminescence spectra of the thin film showed that the fundamental band edge emission peak centred at 485nm also called blue band emission.


2021 ◽  
Vol 127 (3) ◽  
Author(s):  
R. Siva Prakash ◽  
C. Mahendran ◽  
J. Chandrasekaran ◽  
R. Marnadu ◽  
S. Maruthamuthu ◽  
...  

2021 ◽  
Vol 1762 (1) ◽  
pp. 012036
Author(s):  
V Dzhurkov ◽  
Z Levi ◽  
D Nesheva ◽  
T Hristova-Vasileva ◽  
P Terziyska

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