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Chengannūr, India

Jayakrishnan R.,Christian College
Materials Science in Semiconductor Processing | Year: 2013

A thin layer of p-type Cu2O was grown over flexible 30 μm thick copper substrates. Using Injection Chemical Vapor Deposition technique, n-type In2S3 thin films were grown over the Cu 2O layer. A p-n junction was thus realized. The Cu 2O/In2S3 hetero-structure showed photovoltaic behavior. A solar cell with the structure Cu/Cu2O/In 2S3/Ag could be fabricated. An acidic texturization sequence was developed which increased the photo-sensitivity of the In 2S3 window layer. The Cu/Cu2O/In 2S3/Ag hetero-structure with the textured window layer had an open circuit voltage of 377 mV, short circuit current density of 0.118 mA/cm2 and fill factor of 33.34%. It was found that the efficiency of the solar cell depended upon the photo-sensitivity of the In2S 3 window layer. The work demonstrates the use of copper substrate for thin film solar cell fabrication. © 2013 Elsevier Ltd.

Rejikumar P.R.,Mahatma Gandhi University | Jyothy P.V.,Mahatma Gandhi University | Mathew S.,Sh College | Thomas V.,Christian College | Unnikrishnan N.V.,Mahatma Gandhi University
Physica B: Condensed Matter | Year: 2010

The effect of silver nanoparticle co-doping on the dielectric properties of holmium doped silica glasses was studied. Silver nanoparticles of size between 20 and 22 nm were produced by the sol-gel technique. One of the samples showed an icosahedral morphology of the nanocrystal formed, along with spherical morphology. It was found that the tuning of the dielectric constant values could be accomplished by co-doping. The sample, with 1 wt% of Ho, had low dielectric constant values within the range 100 Hz-3 MHz due to the formation of quasi-molecular structures of holmium. This effect was evaded to some extent with silver co-doping as a result of the interdispersion of holmium complexes. Also it was found that the co-doping produced a higher dielectric loss which was calculated from the tan δ-log f graph. The Cole-Cole parameters and the Jonscher power law parameters were also calculated and are presented. © 2009 Elsevier B.V. All rights reserved.

Lisha R.,Cochin University of Science and Technology | Hysen T.,Christian College | Geetha P.,Cochin University of Science and Technology | Avasthi D.K.,Inter University Accelerator Center | And 2 more authors.
Materials Research Express | Year: 2014

Metglas 2826 MB having a nominal composition of Fe40Ni38Mo4B18 is an excellent soft magnetic material and finds application in sensors and memory heads. However, the thin-film forms of Fe40Ni38Mo4B18 are seldom studied, although they are important in micro-electro-mechanical systems/nano-electromechanical systems devices. The stoichiometry of the film plays a vital role in determining the structural and magnetic properties of Fe40Ni38Mo4B18 thin films: retaining the composition in thin films is a challenge. Thin films of 52 nm thickness were fabricated by RF sputtering technique on silicon substrate from a target of nominal composition of Fe40Ni38Mo4B18. The films were annealed at temperatures of 400 °C and 600 °C. The micro-structural studies of films using glancing x-ray diffractometer (GXRD) and transmission electron microscope (TEM) revealed that pristine films are crystalline with (FeNiMo)23B6 phase. Atomic force microscope (AFM) images were subjected to power spectral density analysis to understand the probable surface evolution mechanism during sputtering and annealing. X-ray photoelectron spectroscopy (XPS) was employed to determine the film composition. The sluggish growth of crystallites with annealing is attributed to the presence of molybdenum in the thin film. The observed changes in magnetic properties were correlated with annealing induced structural, compositional and morphological changes. © 2014 IOP Publishing Ltd.

Mathew T.J.,Christian College | Prabhakaran Nayar S.R.,Central University of Kerala
Advances in Space Research | Year: 2012

The characteristics of the equatorial F-region zonal plasma drift during post-sunset period have been investigated using the multi-frequency HF Doppler radar. The pattern of the zonal plasma drift is such that it starts with a westward drift during the pre-sunset hours, followed by an eastward drift shortly after the E-region sunset. The zonal plasma drift is characterized by the presence of a positive vertical shear around the post-sunset period and maximum shear is observed at the time of the peak of the pre-reversal enhancement in the vertical drift. The presence of vertical shear in the zonal drift is associated with the post-sunset velocity vortex existing at the equatorial F-region. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.

Philip S.K.,Christian College | Rajasekharan K.N.,Kerala University
Synthetic Communications | Year: 2011

Novel benzo-1,2,3-triazol-1-yl-(N-aryl)amidines (1) have been conveniently synthesized by the solvent-free reaction between 1,2,3-benzotriazole and arylcyanamides under thermal=microwave conditions in good yield. The versatility of these compounds (1) as amidine transfer reagents has been established by their conversion to trisubstituted guanidines by reaction with amines under solventless, thermal=microwave conditions.

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