Archives-September 2012

Electric field induced donor binding energy in a GaAs/AlGaAs finite quantum well are discussed. It is calculated with and without the inclusion of position dependent effective mass. We find the energy eigen values to obtain the subband energy and thereby the hydrogenic impurity binding energies. In all the calculation, we follow the variational formulism within the single band effective mass approximation. We find that results are different when the position dependent effective mass included in the Hamiltonian. Moreover, we find that the reduction of binding energy when the electric field is applied in the growth direction.

Indium sulfide (?-In₂S₃) nanopowders with tetragonal structure were synthesized by a cost effective chemical route at a low temperature using acetic acid as a complexing agent. Effect of acetic acid concentration on the structural, optical and photoluminescence properties of the synthesized In₂S₃ nanopowders were analyzed by powder X-ray diffraction, UV-Vis-NIR and photoluminescence spectroscopy at room temperature. Tunable luminescence intensity without affecting the wavelength was observed by tuning the acetic acid concentration. The optimized results on the structural, optical absorption and photoluminescence properties are presented and elaborated in the present work.

Semiconducting materials in thin film form are of great interest due to their distinctive physico-chemical properties towards optical and optoelectronic device applications. Zinc oxide (ZnO) is one of the well-known II-VI group wide-band gap semiconductor which shows the wide range of applications such as optical filters, short wavelength emission, transparent conducting, laser diodes and intense luminescence applications etc.,. In the present work the ZnO thin film was fabricated on well cleaned glass substrates by spray pyrolysis technique and the structural, surface and optical properties were investigated by powder X-ray diffraction, scanning electron microscopy and UV-vis spectroscopy at room temperature. Structural parameters such as crystallite size, microstrain and dislocation density were calculated by using Scherrer’s formula. The applicability of the spray deposited ZnO thin film towards window material in solar cell application are presented and discussed in the present work.

The proposed concept of Fpga based design and Implementation of image Architecture Using Xilinx System generator. Recent advances in synthesis tools for SIMULINK suggest a feasible high-level approach to algorithm implementation for embedded DSP systems. An efficient FPGA based hardware design for enhancement of color and grey scale images in image and video processing. The top model – based visual development process of SIMULINK facilitates host side simulation and validation, as well as synthesis of target specific code, furthermore, legacy code written in MATLAB or ANCI C can be reuse in custom blocks. However, the code generated for DSP platforms is often not very efficient. We are implemented the Image processing applications on FPGA it can be easily design.

Density functional theory (DFT) studies H₂ adsorption on transition element (TE) doped single walled carbon nanotubes (SWCNTs) using Dmol³ software. We consider transition element as Ti doped various sites on the surface of armchair (5,5) SWCNT. The simulation results shows that binding energy of H₂ adsorption on Ti doped SWCNT is much higher than pure SWCNT. We calculate the density of states for doped and pure SWCNTs, which is a show dramatic change in their structure on adsorption of H₂ molecules. This study shows that the transition element doped SWCNTs can be used as a good H₂ storage at various sites.

This paper describes the synthesis of Copper oxide nanostructures by a simple cost effective hydrothermal process. The structural analysis reveals that CuO exhibits a monoclinic crystal structure. A variety of other techniques like UV-Vis spectroscopy, Fourier Transform Infrared spectroscopy, Scanning Electron microscopy and dielectric analysis were done to study the optical, morphological and electrical characteristics of the nanomaterial.

Cadmium zinc sulfide (CdZnS) thin film was deposited on transparent conduction Indium tin oxide (ITO) coated glass substrate by a cost effective chemical bath deposition (CBD) method. Commercially purchased ITO coated glass substrate with sheet resistance 8 ?/cm2 was utilized for the deposition of CdZnS thin film under optimized chemical bath conditions. Surface texture of the fabricated CdZnS thin film was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis. The optical absorption and transmittance properties of the fabricated CdZnS thin film was investigated by UV-Vis spectroscopy in the wavelength range of 300 to 1100 nm. The investigated surface and optical properties of the fabricated CdZnS thin film towards optical applications are presented and discussed.

Gold nanoparticles have been synthesized and they have been made to self assemble on indium tin oxide (ITO) coated with 3-mercaptopropyltrimethoxysilane. An aqueous solution of gold chloride was added to tetraoctyl ammonium bromide dissolved in toluene. The mixture was stirred well. Then an aqueous solution of sodiumborohydride was added and the mixture was stirred for 4 hours at room temperature. The organic phase was washed with water in a separating funnel. The solvent was removed by evaporating the solution in vacuum to get a black solid. The black solid was suspended in ethanol and kept under refrigeration overnight. The residue was filtered and washed thoroughly with ethanol. The residue was dried. The gold nanoparticles produced were characterized by Transmission Electron Microscope (TEM). A clean indium titanium oxide electrode was prepared. It was immersed in an aqueous solution containing potassium ferro cyanide and sodium chloride solution in a three electrode cell assembly. Saturated calomel electrode was used as reference electrode. A platinum foil was used as counter electrode. Cyclic voltammogram was recorded in the potential range of -0.1v to 0.5v at a sweep rate of 50mV/s. The experiment was repeated with the ITO electrode coated with 3-mercaptopropytrimethoxysilane. It was seen from the cyclic voltammogram that the redox peaks were absent and there was decrease in the current. This suggests the formation of MPTMS monolayer which acts as a barrier. Since the redox probe has to diffuse through the monolayer, the redox current decreased compared to the bare ITO. When ITO electrode modified with MPTMS was immersed in gold nanoparticles self assembled on the monolayer of MPTMS. The gold nanoparticles were attached to the –SH groups of MPMS. When CV was run with this electrode, there was increase in redox current suggesting that the GNPs have assembled on ITO electrode modified with MPTMS. These electrodes may find application in Biosensors.

Today’s pulp and paper industry is rapidly becoming a globalized industry which belongs to the Red category that is positioning itself to deliver low-cost, high-value, fiber-based products to consumers. Employing advanced chemical- and mechanical-based technologies. pulp, paper, and tissue manufacturers have sought to provide high-quality consumer. To overcome the challenges, new synthetic nonrenewable materials have been developed that have now begun to challenge the traditional dominance paper products has had in many applications. This paper will review emerging developments of these technologies and how these new research avenues will change paper from a pass. This presentation deals the vital role of Nano technology in pulp and paper manufacturing sector.

Tin Oxide thin films were deposited by sol gel dip coating method using the acrylamide route. The films were post heated at different temperature in the range of 350-525 ^oC. X-Ray diffraction (XRD) studies indicatyed the formation of tetragonal SnO₂. The Optimum temperature for the formation of the films was 450 ^oC.Microstructural parameters were estimated from the XRD data. XPS studies indicated the peaks corresponding to Sn 3d and 01s. Transmission spectra exhibited interference fringes. Refractive Index was in the range of 2.05-2.18. Optical bandgap value was around 3.68 eV. Three fundamental Raman lines are observed which agree well with that of the bulk material.