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The single solid source precursors, bis-(morpholinodithioato-s,s')-Pb and bis-(morpholinodithioat... more The single solid source precursors, bis-(morpholinodithioato-s,s')-Pb and bis-(morpholinodithioato-s,s')-Pb-Cd were prepared by direct reaction of metal chloride solution and ammonium morpholinodithiocarbamate. Lead sulphide and lead cadmium sulphide thin films were deposited on sodalime glass substrates using Metal Organic Chemical Vapour Deposition (MOCVD) technique. Preparation of the films was achieved by the pyrolysis of the prepared precursors at 400 °C with a flow rate of 2.5 dm 3 /min for 2 hours deposition period. The deposited films were characterized using Ultraviolet-Visible spectroscopy, X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). A direct optical band gap of 0.46 eV was obtained from the analysis of the absorption spectrum for lead sulphide and 2.17 eV for lead cadmium sulphide thin films. XRD revealed that both films are polycrystalline in nature, with face-centred cubic phase in PbS film and the presence of cubic and hexagonal phases of CdS and cubic phase of PbS in the PbCdS film. SEM micrographs also revealed polycrystalline nature with uniformly distributed grain estimated to be less than 1 µm in size for both films. It also showed that both films have textured surfaces. The EDX showed that both deposited films are nonstoichiometric and are cation deficient.

Materials Science in Semiconductor Processing, 2016

Journal of Materials, 2015

Materials Science in Semiconductor Processing, 2015

Applied Physics A, 2015

Stable MnS thin film was deposited from catalyst-free inorganic solution by electrochemical cell.... more Stable MnS thin film was deposited from catalyst-free inorganic solution by electrochemical cell. The film was characterized by some surface profiling techniques. Morphology revealed that film's particles were fairly distributed across substrate's surface. Crystallinity and surface growth height/roughness were observed before and after post-deposition annealing. Optical studies further showed that annealing has improved film transmittance across visible wavelength region. Reflections from planes associated with only rock salt structure of MnS were prominently identified by diffraction studies. An estimated average crystal size of 17.40 nm suggested that the deposited film is mainly composed of nanocrystalline particles. Film durability was appraised by core-level profiling of Mn and S binding energy (BE) positions during X-ray photoemission spectroscopy (XPS). The results indicated that before and after vacuum annealing, chemical states of Mn and S remained the same suggesting that the film did not undergo any form of transformation after long exposure to ambient environment. This study demonstrated sustainability of MnS electrode in extreme environmental condition.

Journal of microscopy, 2014

Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The g... more Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X-ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu2 O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot.

Journal of Modern Physics, 2011

A single solid source precursor bis-(morpholinodithioato-s,s')-Mo was prepared and molybdenum sul... more A single solid source precursor bis-(morpholinodithioato-s,s')-Mo was prepared and molybdenum sulphide thin film was deposited on sodalime glass using Metal Organic Chemical Vapour Deposition (MOCVD) technique at deposition temperature of 420˚C. The film was characterized using Rutherford Backscattering Spectroscopy (RBS), Ultraviolet-Visible Spectroscopy, Four-point Probe technique, Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Atomic Force Microscopy (AFM). A direct optical band gap of 1.77 eV was obtained from the analysis of the absorption spectrum. The sheet resistance was found to be of the order of 10 -5 Ω -1 ·cm -1 . SEM micrographs of the films showed the layered structure of the film with an estimated grain size that is less than 2 µm while XRD indicates parallel orientation of the basal plane to the substrate surface.

ABSTRACT The thermoluminescence (TL) and other properties of calcium halophosphate fluorescent co... more ABSTRACT The thermoluminescence (TL) and other properties of calcium halophosphate fluorescent coating powder were studied in detail with the sole aim of ascertaining its suitability for use as a dosimetric material. The shape of the glow curve (peaks at about 125 degrees C and 350 degrees C) as well as its fairly linear dose response even at very high doses are indicative of its suitability. Optical properties of the material were studied using Infrared spectroscopy (IR) and UV-Visible spectrophotometry. The IR spectrum shows a prominent peak at 3425.9 cm(-1) indicating the presence of OH and N-H bonds. The material absorbs sharply at wavelength between 196 nm and 220 nm. The material exhibits high transmittance at various peaks with corresponding wavelengths from 300 to 831 nm. This material can also find application in radiation therapy associated with very high accident dosimetry as well as in material testing.

The single solid source precursor, cobalt (II) acetylacetonate was prepared and characterized by ... more The single solid source precursor, cobalt (II) acetylacetonate was prepared and characterized by infrared spectroscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylacetonate, Co[C 5 H 7 O 2 ] 2 at a temperature of 420 • C. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co 2 O 3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron microscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.

Journal of Modern Optics, 2014

The short life span of organic photovoltaic (OPV) cell in an ambient laboratory condition is one ... more The short life span of organic photovoltaic (OPV) cell in an ambient laboratory condition is one of the challenges hindering the realization of organic-based devices. The presence of moisture and oxygen in conjugated polymer matrix is the major factors responsible for the degradation of organic molecules. The chemical degradation of OPV cell generally depends on the nature of the semiconductor polymer used in the preparation of the devices. However, the lifespan of unprotected OPV cells often ranges in the order of few hours in simple laboratory environment. We are reporting here the lifetime of organic photovoltaic cell in ambient laboratory condition whose active layer is composed of PTB7:PCBM blend.

MRS Proceedings, 2012

The Single Solid Source precursor Cadmium Acetylacetonate, Cd[C 5 H 7 O 2 ] 2 was prepared and Ca... more The Single Solid Source precursor Cadmium Acetylacetonate, Cd[C 5 H 7 O 2 ] 2 was prepared and Cadmium Oxide thin films were deposited on Sodalime glass substrate using Metal Organic Chemical Vapour Deposition (MOCVD) technique at deposition temperature of 420 o C The films were characterized using Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) facility attached to it, X-Ray Diffractometry (XRD) and UV-visible spectrometry. SEM micrographs showed the formation of textured surface with identifiable cubic and hexagonal structures, having average grain size greater than 1 µm. XRD studies indicated the formation of polycrystalline cubic CdO phase with preferred orientation in (111) plane. A direct optical band gap of 2.10 eV was obtained from the analysis of the UV-visible spectrum with an enhanced light absorption in 750 -1000 nm spectrum range. This enhancement is as a result of light trapping by the textured crystalline structure.

Surface and Interface Analysis, 2014

Growth conditions, structural, and optical properties of MgO nanostructure have been investigated... more Growth conditions, structural, and optical properties of MgO nanostructure have been investigated. Surface composition and shift in binding energy of Mg at 50.8 eV due to oxidation were examined by core-level spectroscopy. The SEM showed that the film is dense, and grain growth and crystallinity are enhanced by post-deposition annealing. Grain distribution was appraised within the confinement of 24.51 μm 2 from the selected scan areas. X-ray diffraction studies indicated prominent peaks, which are attributed to (111), (200), and (220) reflections from fairly crystallized and randomly oriented MgO thin film. Plane (111) is found to be the preferred orientation of the film. The film transmitted well across the visible spectrum and the estimated energy band gap is 5.41 eV. Absence of catalyst in the electrolyte solution aided the purity of the sample.

The Journal of Physical Chemistry C, 2012

The electronic structure and the geometric arrangement of picene molecules adsorbed on Ag(111) we... more The electronic structure and the geometric arrangement of picene molecules adsorbed on Ag(111) were studied by means of photoemission and near-edge X-ray absorption fine-structure spectroscopies (NEXAFS). While the valence band of a picene monolayer shows a clear metallic state that evolves with alkali metal doping, in the case of a picene multilayer there is no evidence of metallic states evolving with doping. Our data suggest that the bulk ultrahigh-vacuum films of K x picene are in an insulating phase, and we attribute this behavior to a strong electron−electron Coulomb interaction that is instead screened in the monolayer. The NEXAFS profiles of different picene layers show a coverage-dependent orientation, from flat molecules (monolayer) to an orientation of ∼40°of the molecular long axis with respect to the substrate surface (multilayer). The observed molecular orientations are in disagreement with the expected crystal structure of the bulk material and may explain the presence of insulating states in strongly correlated doped picene multilayers.

The Journal of Physical Chemistry C, 2011

In-situ metalation of porphyrin molecules in ultrahigh vacuum (UHV) is of great interest for the ... more In-situ metalation of porphyrin molecules in ultrahigh vacuum (UHV) is of great interest for the characterization of pure species in a controlled environment. Here, we report the characterization of the electronic states and the molecules' geometrical adaptation during the formation of pure 2H-5,10,15,20-tetraphenylporphyrin (2H-TPP) and Fe-tetraphenylporphyrin (Fe-TPP) layers on Ag(111) single crystal. Core level absorption spectra indicate the flat conformation of the monolayer suggesting an adatom hopping instead of a surface mediated dopant diffusion for the metalation process. Photoemission points out that the interaction between Fe d z -states and Ag bands increases the monolayer metallic character already induced by the charge transfer from the substrate.

Materials Research Bulletin, 2012

ABSTRACT

Journal of Physics: Conference Series, 2013

The formation and conformational adaptation of self-assembled monolayer of 2Htetraphenylporphyrin... more The formation and conformational adaptation of self-assembled monolayer of 2Htetraphenylporphyrins (2H-TPPs) on metal surfaces, as well as their metalation processes in ultra-high vacuum (UHV), are reviewed. By means of XPS, NEXAFS and STM measurements we demonstrate that, after the annealing at 550 K, a temperature-induced chemical modification of 2H-TPP monolayer on Ag(111) occurs, resulting in the rotation of the phenyl rings parallel to the substrate plane. Moreover, independently of the conformation, we report three different methods to metalate 2H-TPP monolayers in UHV. Experimental evidence indicates that the presence of a metal atom in the TPP macrocycle influences both the conformation of the molecule and its adsorption distance.

Current Applied Physics, 2013