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R. Rathika,M. Kovendhan,D. Paul Joseph,K. Vijayarangamuthu,A. Sendil Kumar,C. Venkateswaran,K. Asokan,S. Johnson Jeyakumar 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.8
Spray deposited Molybdenum trioxide (MoO3) thin film of thickness nearly 379 nm were irradiated with 200 MeV Ag15þ ion beam at different fluences (Ø) of 5 1011,1 1012,5 1012 and 1 1013 ions/cm2. The X-ray diffraction (XRD) pattern of the pristine film confirms orthorhombic structure and the crys-tallinity decreased after irradiation with the fluence of 5 1011 ions/cm2 due to irradiation induced defects and became amorphous at higher fluence. In pristine film, Raman modes at 665, 820, 996 cm1 belong to MoeO stretching, 286 cm1 belong to MoeO bending mode and those below 200 cm1 are associated with lattice modes. Raman peak intensities decreased upon irradiation and vanished completely for the ion fluence of 5 1012 ions/cm2. The percentage of optical transmittance of pristine film was nearly 40%, while for irradiated films it decreased significantly. Red shift was observed for both the direct and indirect band gaps. The pristine film surface had densely packed rod like structures with relatively less porosity. Surface roughness decreased significantly after irradiation. The electrical trans-port properties were also studied for both the pristine and irradiated films by Hall effect. The results are discussed.
Rathika, R.,Kovendhan, M.,Joseph, D. Paul,Pachaiappan, Rekha,Kumar, A. Sendil,Vijayarangamuthu, K.,Venkateswaran, C.,Asokan, K.,Jeyakumar, S. Johnson Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11
Swift heavy ion (SHI) beam irradiation can generate desirable defects in materials by transferring sufficient energy to the lattice that favours huge possibilities in tailoring of materials. The effect of Ag<sup>15+</sup> ion irradiation with energy 200 MeV on spray deposited V<sub>2</sub>O<sub>5</sub> thin films of thickness 253 nm is studied at various ion doses from 5 × 10<sup>11</sup> to 1 × 10<sup>13</sup> ions/㎠. The XRD results of pristine film confirmed orthorhombic structure of V<sub>2</sub>O<sub>5</sub> and its average crystallite size was found to be 20 nm. The peak at 394 cm<sup>-1</sup> in Raman spectra confirmed O-V-O bonding of V<sub>2</sub>O<sub>5</sub>, whereas 917 cm<sup>-1</sup> arise because of distortion in stoichiometry by a loss of oxygen atoms. Raman peaks vanished completely above the ion fluence of 5 × 10<sup>12</sup> ions/㎠. Optical studies by UV-Vis spectroscopy shows decrement in transmittance with an increase in ion fluence up to 5 × 10<sup>12</sup> ions/㎠. The red shift is observed both in the direct and indirect band gaps until 5 × 10<sup>12</sup> ions/㎠. The surface topography of the pristine film revealed sheath like structure with randomly distributed spherical nano-particles. The roughness of film decreased and the density of spherical nanoparticles increased upon irradiation. Irradiation improved the conductivity significantly for fluence 5 × 10<sup>11</sup> ions/㎠ due to band gap reduction and grain growth.
Trends in Bioremediation of Heavy Metal Contaminations
Parasakthi JEYAKUMAR,Chandrani DEBNATH,R Vijayaraghavan,Muthusivaramapandian MUTHURAJ 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
Heavy metal contamination of the ecosystem remains one of the severe global threats. Even in trace quantities, heavy metals and metalloids such as chromium, lead, mercury, cadmium, nickel, and cobalt are toxic and carcinogenic, posing a serious threat to human life. Certain microbes and plants have evolved detoxifying pathways to fight the harmful effects of these inorganic metals, paving the door for bioremediation. Because of its environmentally benign nature, economic viability, and low labor and effort requirements, bioremediation outperforms other approaches in eliminating heavy metals. This review highlights the potential of microbes on remediation of heavy metals in the context of environmental protection and also focuses on the critical tolerance mechanisms used by these microbes in combating heavy metal contaminations. Furthermore, the bioremediation potential of bacteria, fungus, algae, plants, biosurfactants, biofilms and genetically altered microorganisms for the removal of these heavy metals was reviewed in this study. Applying these techniques as a sustainable environmental technology in the near future has shown synergistic benefits with a many-fold increase in the removal of heavy metals.
Nagarajan Balaji,Huong Thi Thanh Nguyen,박철민,주민규,Jayapal Raja,Somenath Chatterjee,R. Jeyakumar,이준신 한국물리학회 2018 Current Applied Physics Vol.18 No.1
In c-Si solar cells, surface recombination velocity increases as the wafer thickness decreases due to an increase in surface to volume ratio. For high efficiency, in addition to low surface recombination velocity at the rear side, a high internal reflection from the rear surface is also required. The SiOxNy film with low absorbance can act as rear surface reflector. In this study, industrially feasible SiO2/SiOxNy stack for rear surface passivation and screen printed local aluminium back surface field were used in the cell structure. A 3 nm thick oxide layer has resulted in low fixed oxide charge density of 1.58 1011 cm2 without parasitic shunting. The oxide layer capped with SiOxNy layer led to surface recombination velocity of 155 cm/s after firing. Using single layer (SiO2) rear passivation, an efficiency of 18.13% has been obtained with Voc of 625 mV, Jsc of 36.4 mA/cm2 and fill factor of 78.7%. By using double layer (SiO2/SiOxNy stack) passivation at the rear side, an efficiency of 18.59% has been achieved with Voc of 632 mV, Jsc of 37.6 mA/ cm2, and fill factor of 78.3%. An improved cell performance was obtained with SiO2/SiOxNy rear stack passivation and local BSF.
Surface Passivation Schemes for High-Efficiency c-Si Solar Cells - A Review
Balaji, Nagarajan,Hussain, Shahzada Qamar,Park, Cheolmin,Raja, Jayapal,Yi, Junsin,Jeyakumar, R. The Korean Institute of Electrical and Electronic 2015 Transactions on Electrical and Electronic Material Vol.16 No.5
To reduce the cost of solar electricity, the crystalline-silicon (c-Si) photovoltaic industry is moving toward the use of thinner wafers (100 μm to 200 μm) to achieve a high efficiency. In this field, it is imperative to achieve an effective passivation method to reduce the electronic losses at the c-Si interface. In this article, we review the most promising surface passivation schemes that are available for high-efficiency solar cells.
Surface Passivation Schemes for High-Efficiency c-Si Solar Cells - A Review
Nagarajan Balaji,이준신,Shahzada Qamar Hussain,박철민,Jayapal Raja,R. Jeyakumar 한국전기전자재료학회 2015 Transactions on Electrical and Electronic Material Vol.16 No.5
To reduce the cost of solar electricity, the crystalline-silicon (c-Si) photovoltaic industry is moving toward the use of thinner wafers (100 μm to 200 μm) to achieve a high efficiency. In this field, it is imperative to achieve an effective passivation method to reduce the electronic losses at the c-Si interface. In this article, we review the most promising surface passivation schemes that are available for high-efficiency solar cells.