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Jorhāt, India

Saikia D.,Sibsagar College | Gogoi P.K.,Dibrugarh University | Saikia P.K.,Dibrugarh University
Chalcogenide Letters | Year: 2010

A modified chemical bath deposition technique have been reported for the controlled synthesis of polycrystalline and single crystalline CdS thin films on glass substrates. The method involves the preparation of aqueous solutions containing cadmium acetate and thiourea as source material for cadmium and sulfur components. The influence of different preparative parameters such as bath pH, and pre-deposition heat treatment of the reactants on the structural and optical properties of the films were investigated by X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), UV-visible and photoluminescence spectroscopy. All films deposited with pre-deposition heat treatment were polycrystalline in nature while the films deposited without pre-deposition heat treatment were single crystalline in nature. From the shift in optical band gap, particle sizes were calculated using effective mass approximation (EMA) and were found to be in good agreement with those determined from XRD broadening. The SEM analysis shows that the CdS films were also nano-crystalline in nature. Source

Saikia P.,Dibrugarh University | Saikia P.K.,Dibrugarh University | Saikia D.,Sibsagar College
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2011

A multijunction solar cell with the structure ZnSe/ZnTe/CdTe has been fabricated on tin oxide coated glass substrate by vacuum evaporation method. The multijunction ZnSe/ZnTe/CdTe solar cell showed remarkably higher conversion efficiency over the single layer ZnSe/CdTe solar cell. The conversion efficiency of the multijunction ZnSe/ZnTe/CdTe solar cell was found to depend on the thickness of the CdTe layer. Optical band gaps of each of the layers in the multijunction solar cell were calculated from the UV-Vis absorption spectra. The photovoltaic parameters of the cells were measured and the cell showed its best performance with the following set of photovoltaic parameters: Isc = 1.52 mA, Voc = 765 mV, conversion efficiency ≈ 10% and fill factor = 65.05%. Source

Rahman I.,Sibsagar College
Journal of Entomological Research | Year: 2012

Studies on plant extracts of Polygonum hydropiper L. and Pogostemon parviflorus Benth. at 2.0% concentration in chloroform were evaluated against bunch caterpillar, Andraca bipunctata Walker. Showed 100% mortality of larvae. Fractionation of effective crude extracts by column chromatography and their bioassay revealed that the fraction No III (ethyl acetate/petroleum ether, 1:5) of P. hydropiper and No IV (ethyl acetate/petroleum ether, 1:3) of P. parviflorus were most effective against the caterpillar causing 100 and 96.67% mortality respectively. The LD 50 of the chloroform extracts of P. hydropiper and P. parviflorus were found to be 724.44 mg/kg and 750.00 mg/kg in male albino mice, respectively. Subcutaneous injection of sub-lethal dose of the extracts into male mice once a week for 6 weeks failed to express any significant influence on WBC, RBC count and serum cholesterol. Source

Saikia D.,Sibsagar College | Saikia P.K.,Dibrugarh University | Gogoi P.K.,Dibrugarh University | Das M.R.,CSIR - Central Electrochemical Research Institute | And 2 more authors.
Materials Chemistry and Physics | Year: 2011

CdS/PVA nanocomposite thin films have been deposited on glass substrates by in situ thermolysis of precursors dispersed in polyvinyl alcohol (PVA). The synthetic technique reported in this study is free from complexing agent and hence no need to control the pH of the solution as in the case of conventional CBD. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis spectroscopy, and photoluminescence (PL) spectra. The XRD and SAED results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that CdS/PVA films showed quantum confinement effect. From the shift in optical band gap, particle sizes were calculated using effective mass approximation (EMA) method and it was found to be in agreement with the results obtained from TEM observations. The SEM results indicated that as grown films were homogeneous with no visible pinholes and cracks. The film prepared at100 ?C was found to be suitable for application as a window layer in solar cell. © 2011 Elsevier B.V. All rights reserved. Source

The performance of thermally deposited CdS thin film transistors doped with Ag has been reported. Ag-doped CdS thin films have been prepared using chemical method. High dielectric constant rare earth oxide Nd2O3 has been used as gate insulator. The thin film trasistors are fabricated in coplanar electrode structure on ultrasonically cleaned glass substrates with a channel length of 50 μm. The thin film transistors exhibit a high mobility of 4.3 cm2 V-1 s-1 and low threshold voltage of 1 V. The ON-OFF ratio of the thin film transistors is found as 105. The TFTs also exhibit good transconductance and gain band-width product of 1. 15 × 10-3 mho and 71 kHz respectively. © 2013 Pleiades Publishing, Ltd. Source

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