Thin Film Research Laboratory

Cochin, India

Thin Film Research Laboratory

Cochin, India
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Keerthi K.,Thin Film Research Laboratory | John K.A.,Thin Film Research Laboratory | Pradeep B.,Cochin University of Science and Technology | Benoy M.D.,Mar Athanasius College | And 2 more authors.
Journal of Alloys and Compounds | Year: 2017

By a two stage process involving vacuum evaporation and post annealing in air, deposition of crystalline delafossite silver indium oxide (AIO) thin films at a substrate temperature ∼573K is achieved. This is the lowest temperature of crystallization so far reported for delafossite AIO films. The metallic silver indium to semiconducting silver indium oxide transition is monitored by studying the structural, electrical, transport and optical properties of the films that are annealed at six different temperatures from 303 K to 623 K. A comparative study of the AIO thin films prepared by air annealing and by oxygen-plasma- enhanced reactive evaporation in vacuum is done to correlate the properties of crystalline and amorphous films obtained by the two different methods. The crystalline n-type transparent conducting silver indium oxide thin films show a preferred orientation along (101) plane and manifest better electrical conductivity and photosensitivity than the amorphous AIO. © 2016 Elsevier B.V.

Barote M.A.,Azad College | Yadav A.A.,Thin Film Research Laboratory | Suryavanshi R.V.,Azad College | Deshmukh L.P.,University of Solapur | Masumdar E.U.,Thin Film Research Laboratory
Materials Letters | Year: 2012

State-of-the-art, novel and inexpensive chemical deposition route was selected for the preparation of Cd 0.825Pb 0.175S thin films. Optimized deposition parameters were: time = 60 min, temperature = 80°C, speed of substrate rotation = 65 ± 2 rpm and pH = 10.5 ± 0.1. XRD analysis of polycrystalline Cd 0.825Pb 0.175S thin films revealed mixture of hexagonal and cubic phases. Morphological features rigorously define nucleation and subsequent growth of thin film layers. Detailed investigations on power output curves underline the boost in conversion efficiency from 0.184% to 0.245% with increase in layer thickness. Low conversion efficiency in the present case is attributed to the higher photoelectrode resistance and significant light absorption by the electrolyte. © 2012 Elsevier B.V. All rights reserved.

Barote M.A.,Azad College | Yadav A.A.,Thin Film Research Laboratory | Masumdar E.U.,Thin Film Research Laboratory
Thin Solid Films | Year: 2012

CdzPbyS thin films have been deposited on glass substrates using inexpensive chemical bath deposition technique. The aqueous solution containing precursors of Cd2 + and Pb2 + has been used to obtain good quality deposits at optimized preparative parameters. The thin film samples have been characterized through optical absorption, electrical conductivity and thermoelectric power measurement techniques. From optical studies, the absorption coefficient 'α,' is found to be of the order of 104 cm- 1. The optical absorption studies revealed direct band to band transition. The band gap energy is found to vary nonlinearly from 2.47 eV (CdS) to 0.49 eV (PbS) as the composition parameter 'x' was increased from 0 to 1. The electrical characterization revealed increased conductivity (σ) with the increased composition parameter up to x = 0.175. The electrical conductivity measurements indicate two types of conduction mechanism, namely grain boundary scattering limited and variable range hopping conductions. The activation energies of the films of different compositions were determined at low and high temperature regions. The activation energies were observed to be in the range of 0.168-0.240 eV and 0.514-0.711 eV respectively. Thermoelectric power measurements highlighted n-type behavior of the as-grown thin film samples. © 2012 Elsevier B.V.

Barote M.A.,Azad College | Deshmukh L.P.,University of Solapur | Masumdar E.U.,Thin Film Research Laboratory
Ceramics International | Year: 2013

This paper discusses chemical synthesis of Cd1-xPbxS (0≤x≤1) thin film layers and their photo-electrochemical properties with special reference to PEC parameters. Previously optimized conditions were used for the deposition. The electrode/electrolyte interfaces were then formed between the Cd1-xPbxS thin film layers and a sulphide/polysulphide (1 M) redox couple and investigated through the various photo-electrochemical (PEC) properties to assess suitability to convert solar energy into electrical energy. Increase in short circuit current (I sc) and open circuit voltage (Voc) was observed with increased composition and attain maximum at x=0.175. Power conversion efficiency and fill factor were found to be 0.163% and 46.2% respectively for the composition parameter x=0.175. © 2012 Elsevier Ltd and Techna Group S.r.l.

Keerthi K.,Thin Film Research Laboratory | Nair B.G.,Thin Film Research Laboratory | Benoy M.D.,Mar Athanasius College | Raphael R.,Thin Film Research Laboratory | Philip R.R.,Thin Film Research Laboratory
Materials Chemistry and Physics | Year: 2017

A study on crystalline silver indium tin oxide (AISO), a quaternary compound formed by tin incorporation in delafossite AgInO2 is briefed here. X-ray diffraction for structural characterization combined with energy dispersive analysis of X-rays for composition assessment confirms the formation of crystalline thin films with the rhomb-centered rhombohedral delafossite crystalline lattice. The variation in electrical conductivity (101–102 S/cm) and activation energy are correlated with carrier concentration and c-axis orientation induced by stoichiometric changes. A band gap tuning from 2.38 eV to 3.23 eV is achieved by the stoichiometry changes. © 2017 Elsevier B.V.

Mathew J.P.,Thin Film Research Laboratory | Varghese G.,University of Calicut | Mathew J.,Thin Film Research Laboratory
Chinese Physics B | Year: 2012

ZnO thin films were synthesised by a new method which uses polyvinyl alcohol (PVA) as the polymer precursor. The films are annealed at different temperatures and for different annealing times. The structural parameters, like grain size, lattice constants, optical band gap, and Urbach energy, depend on the annealing temperature and time. All the films possess tensile strain, which relaxes as the annealing temperature and time increase. The photoluminescence (PL) spectra contain only ultraviolet (UV) peaks at low temperature, but as the annealing temperature and time increase, we observe peaks at the blue and green regions with a variation in the intensities of these peaks with annealing temperature and time. © 2012 Chinese Physical Society and IOP Publishing Ltd.

Patil S.S.,Thin Film Research Laboratory | Pawar P.H.,Thin Film Research Laboratory
Chalcogenide Letters | Year: 2012

Thin films of lead telluride (PbTe) of different thicknesses ranging between 500 Å to 2500 Å have been prepared by thermal evaporation technique onto precleaned amorphous glass substrates at room temperature. Selected virgin samples were annealed at temperature 523 K for 60 min. in vacuum (≈10 -5 torr). The X-ray diffraction analysis confirmed that these annealed films are polycrystalline corresponding to the rock salt (NaCl) FCC structure. From the XRD profiles, the grain size, dislocation density, micro strain and lattice constants were calculated. Resistivity of the virgin and annealed samples was measured by four-probe technique as a function of thickness and temperature. The resistivity was measured in the temperature range of 303 K to 473 K. It was observed that for virgin samples the resistivity decreases with increasing film thickness. It shows the NTC behavior of resistivity. For the annealed PbTe films the resistivity shows dramatic change resulting in oscillatory behavior with increasing film thickness Thermoelectric power has been measured by the integral method in the same temperature range and found to be positive indicating that the samples are p-type semiconducting materials. The existence of oscillations in the thermoelectric properties for both the virgin and annealed samples is attributed to quantum size effects.

Gaur M.L.,Thin Film Research Laboratory | Hankare P.P.,Shivaji University | Garadkar K.M.,Shivaji University | Delekar S.D.,Shivaji University | Bhuse V.M.,Thin Film Research Laboratory
Journal of Materials Science: Materials in Electronics | Year: 2014

Polycrystalline cadmium selenide (CdSe) thin films have been synthesized at room temperature by using chemical bath deposition method. The synthesized films were characterized by using X-ray diffraction (XRD), optical absorbance, electrical conductivity, scanning electron microscope, energy dispersive X-ray analysis, photoluminescence and photoelectrochemical (PEC) techniques. The film of 0.84 lm thickness, deposited on glass substrate showed uniform spherical morphology with an optical band gap of 1.99 eV. The XRD analysis confirmed presence of cubic structure. Scanning electron micrograph shows a typical spherical ball like morphology with large surface area, which is useful for absorption of large solar radiation. The conductivity measurements showed n type semiconducting nature of the film. A PEC cell device fabricated using 'as deposited' CdSe film as anode showed a stable conversion efficiency of 0.7 %. © Springer Science+Business Media New York 2013.

Barote M.A.,Azad college | Yadav A.A.,Thin Film Research Laboratory | Masumdar E.U.,Thin Film Research Laboratory
Chalcogenide Letters | Year: 2011

A Simple and cost effective chemical bath deposition process has been employed for the preparation of Cd1-xPbxS (x = 0.00, 0.20, 0.40, 0.60, 0.80, 1.00) thin films. Cadmium sulphate, lead sulphate and thiourea were used as the basic source materials. The effect of various preparative parameters such as bath composition, pH of the reaction solution, deposition temperature and time, speed of the substrate rotation and the complexing agent on growth process is studied and these parameters are optimized for good quality films. The colour of the 'as-deposited' thin films has changed from orange yellow to black as the composition parameter x changed from 0 to 1. The film thickness is found to be increased with increasing the composition parameter x from 0 to 1. The X-ray diffraction (XRD) studies revealed that films are polycrystalline in nature and exhibit both cubic and hexagonal structure for pure CdS but only cubic phases for pure PbS film. The energy dispersive analysis by X-rays (EDAX) studies revealed that films are cadmium rich. The energy band gap is decreased from 2.47 eV to 0.49 eV as composition parameter 'x' is increased from 0 to 1.

Mathew J.P.,Thin Film Research Laboratory | Varghese G.,University of Calicut | Mathew J.,Thin Film Research Laboratory
IOP Conference Series: Materials Science and Engineering | Year: 2015

A group of transition metal (Co,Cu,Ni) doped ZnO thin films were prepared by a low cost dip coating method. To study the effect of annealing temperature on the structural and optical properties of the grown films each film is subjected to three different annealing temperatures. From the calculation of structural parameters from the XRD spectrum, it was found that each film possesses a tensile strain and this tensile strain increases as the annealing temperature increases. This dominant behavior of tensile strain affects the optical properties of the grown film in a greater extent. © Published under licence by IOP Publishing Ltd.

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