Sulfide Thin Films Research Articles

Analysis of Structural and Electrical Properties of Iron Sulfide (FeS2)Thin Films doped with Aluminum and Strontium impurities

Abstract: Thin films of iron sulfide (FeS2) prepared by CBD technique were doped with aluminum (Al: 0.020.04M) and strontium (Sr: 0.02-0.04M) impurities at room temperature of 26 C. X-Ray diffraction (XRD) and four-point probe were used to analyze the structural and electrical properties of the thin films. The XRD results show that 0.02M of strontium impurities produced polycrystalline structure of the thin films with diffraction peak values located at Bragg’s angles, 2Θ of 14.71, 25.03 and 34.95, while the un-doped polycrystalline FeS2 thin films have diffraction peaks at 2Θ values of 19.81, 24.43, 31.45 and 36.73. Clearly, the contributing inphase reflections for the different diffraction angles occur from different orientations of lattice planes and/or different crystallite sizes caused by the Sr impurity. On the other hand, 0.02M of aluminum dopant produced mono-crystalline structure of the FeS2 thin film with 2Θ value of 24.97 o and a broadened full width at half maximum (FWHM). It is remarkable that the single peak of the mono-crystal due to Al impurity coincides with the highest intensity and sharper peak of the un-doped FeS2 thin film. The electrical resistivity of the thin films decreased while the conductivity increased with increase in impurity concentrations with non-uniform changes occurring from 0.02M for both impurities. The film thickness remained between 0.09-0.1μm but showed a more dramatic increase with impurity concentration from 0.02M for both impurities.

Characteristics of Radio Frequency-Sputtered ZnS on the Flexible Polyethylene Terephthalate (PET) Substrate

Zinc sulfide (ZnS) thin film was deposited on the flexible polyethylene-terephtalate (PET) polymer substrate by radio frequency (RF) magnetron sputtering system. ZnS film has a critical thickness range affecting crystal structure where it shows preferred orientation with intensity peak of X-ray diffractometer at 28.4 degrees for ZnS thinner than 200 nm while hexagonal wurtzite and cubic zinc-blend (101) are co-existed for film thicker than 200 nm. Optical band gap energy (Eg) decreases with increasing RF-powers, resulting from increase in film thickness. Eg of ZnS films on PET is 3.68-3.86 eV, which is lower than that of ZnS on the rigid substrate by 0.27-0.28 eV. This is attributed to amount of incorporated oxygen to ZnS material as well as residual strain and disorder of grain boundary. Transmittance of ZnS on PET degrades due to surface defects and complex internal structure. Energy dispersive spectroscopy reveals out that ZnS film does not have a unity of Zn to S ratio, but it is close to stoichiometric composition with increasing thickness.

Analysis of Structural and Electrical Properties of Aluminium Doped Lead Sulphide (PbS) Thin Film Prepared by CBD Method

Analysis of Structural and Electrical Properties of Aluminium Doped Lead Sulphide (PbS) Thin Film Prepared by CBD Method

Chemical Bath Deposition of Lead Sulphide (PbS) Thin Film and their Characterization

Thin film deposition of PbS is conveniently carried out by chemical reactions of lead acetate with thiourea at room temperature. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), selected area electron diffraction patterns (SAED), UV-Vis-NIR spectrophotometer, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), Photoluminescence (PL) and Raman spectroscopy techniques are used for characterizing thin films. EDAX spectra shows that no impurity is present and XRD pattern indicates face centered cubic structure of PbS thin films. The average crystallite size obtained using XRD is about 15nm calculated using Scherrer’s formula and that determined from Hall-Williamson plot was found to be 18nm. SAED patterns indicate that the deposited PbS thin films are polycrystalline in nature. Blue shift due to quantum confinement was seen from the UV-Vis-NIR absorption spectra of thin film in comparison with bulk PbS. The Photoluminescence spectra obtained for thin film with different excitation sources shows sharp emission peaks at 395nm and its intensity of photoluminescence increases with increasing the excitation wavelength. Raman spectroscopy of deposited thin film was used to study the optical phonon modes at an excitation wavelength of 488nm using (Ar+) laser beam.

Structure and optical properties of chunk and powder CdS film prepared by electron beam deposition

Cadmium sulfide (CdS) thin films have been prepared from powder and chunk sources using electron beam deposition method. Structure, morphology and optical properties of the films have been investigated. CdS films typically exhibit a strong cubic orientation, while source materials from which the films are made exhibit hexagonal orientations. Grain size of CdS films deposited from chunk sources is 1.8 times larger than that from powder. CdS particles are observed on the surfaces of all films, but fewer particles are from chunk sources than that from powder. Optical band gaps of CdS films deposited from chunks and powder are 2.4 and 2.45 eV, respectively. CdS/CdTe solar cells were fabricated and their J–V characteristic is studied.

AC CONDUCTIVITY AND DIELECTRIC PROPERTIES OF PULSED LASER DEPOSITED CdS THIN FILMS

Cadmium Sulphide (CdS) thin films with different thicknesses were prepared by pulsed laser deposition technique using Nd:YAG laser with wavelength 1064 nm. AC electrical conductivity was studied in the frequency range 100–1000 KHz as a function of temperature. AC conductivity increased with increasing the frequency. The values of the activation energy of the AC conduction were calculated for CdS thin films of different thicknesses at various frequencies. The dielectric constant and dielectric loss were investigated as a function of temperature at different frequencies.

Influence of Source - Substrate Distance of Cu<sub>4</sub>SnS<sub>4</sub> Thin Films Grown by Co-Evaporation

Copper tin sulphide (Cu4SnS4) thin films were prepared on glass substrates by the thermal co-evaporation technique by varying the source - substrate distance (SSD) in the range, 10 25 cm at a constant substrate temperature of 400°C. The influence of SSD on the chemical as well as physical properties of as-grown Cu4SnS4films was investigated. The EDS analysis revealed that the evaporated films are stoichiometric at a SSD of 20 cm. X-ray diffraction analysis confirmed the presence of Cu4SnS4phase in the layers following the orthorhombic crystal structure. The films showed a strong (311) peak as the preferred orientation. The evaluated crystallite size of the films decreased with the increase of SSD. From the SEM analysis, it was observed that needle like grains were distributed on the surface of the substrate and its size decreased with increasing SSD. The energy band gap was estimated using the optical transmittance data that varied in the range, 1.25 1.34 eV with the change of SSD.

STRUCTURAL, OPTICAL, AND ELECTRICAL CHARACTERIZATION OF SPRAY PYROLYSED INDIUM SULFIDE THIN FILMS

Indium sulfide (In2S3) thin films were deposited onto the glass substrates by a low cost simple spray pyrolysis technique at 300°C temperature. Aqueous solution of indium chloride and thiourea were used to deposit the binary In-S film. The deposited thin films were annealed at 400° and 500°C temperatures and characterized structurally, optically and electrically using EDX, X-ray diffraction, UV-visible spectroscopy and four probe van der Pauw methods. The optical constants such as refractive index and extinction coefficient are calculated from absorbance and transmittance data from 300 to 1100 nm wavelength. The optical transmittance increased after annealing at 400° and 500°C. The band gap energy was reduced from 2.90 to 2.50 eV after annealing the as deposited films. The electrical conductivity as well as the activation energy was increased after annealing the samples.

Flash Evaporation of CdS Thin Film

Cadmium Sulfide (CdS) thin films with thickness (150) nm were deposited by flash evaporation technique (FET) at room temperature. CdS thin films were annealed at temperatures (373 and 473) K. X-ray diffraction (XRD) indicated that the grown CdS films had hexagonal phase with preferential orientation in the (002) direction. Optical absorption measurements indicated direct band gap values in the range 4.1eV and decreased with the increase of annealing temperature. The electrical measurements of the films were studied at annealing temperature (373 and 473) K. The D.C. conductivity for all deposited films within the temperature range (293-493) K were decreased with increasing annealing temperatures. The activation energies (Ea1, Ea2) increased from 0.0598 to 0.155eV and from 0.247 to 0.746eV respectively with the increase of annealing temperature. The films have been n-type conductivity and carrier's concentration decreased with the increase of annealing temperatures.

Electrical properties of organic–inorganic semiconductor heterojunction

Conducting polyaniline (PANI) was prepared by chemical oxidation polymerization in the presence of excess hydrochloric acid. Zinc sulfide (ZnS) thin films were deposited on glass substrates at the pressure of 10−5 mbar by thermal resistor evaporation technique. The solution of conducting PANI has been printed on pellet of ZnS using spin-coating technique. I–V characteristics of ZnS thin film and printed conducting PANI have been recorded at room temperature. The results indicated that I–V of conducting PANI shows non-ohmic behavior and I–V characteristic of conducting PANI printed ZnS, a PANI–ZnS heterojunction, shows the rectification effect and confirms that a diode can be fabricated by using simple technique.

Tailoring of CdS Nano Films Through CBD-Isochronal Synthesis For PV Applications

ABSTRACTCadmium Sulphide (CdS) thin films have been prepared on ultrasonicated glass substrates using a specially designed chemical bath deposition technique via isochronal synthesis. The structural properties have been determined through XRD. The nanostructures have been identified in FE-SEM images. The chemical analysis has been carried out through EDAX. Optical analysis and PL studies were carried out on these films. The growth conditions and the characterization results exhibit strong dependence on the pH of the precursor solution as well as the temperature of the bath. Cu doping has been employed on the tailored films to make them low resistive and efficient for window layer applications.

Rapid Fabrication of ZnS Thin Film and Microsphere by Microwave-Assisted Chemical Solution Method

A rapid preparation route, microwave-assisted chemical solution method, has been developed for the fabrication of zinc sulfide (ZnS) thin film and powder with shape of microsphere. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical measurement. XRD results indicated that the structures of as-obtained products are wurtzite. The SEM and AFM photographs show that uniform ZnS microsphere with size of less than 1 μm and homogeneous thin film could be obtained from solution under adequate conditions with thiourea as sulfide source. The results show that microwave-assisted chemical solution method is really a time saving method to fabricate the ZnS thin film and nanostructured microspheres.

Studies on the photochemical deposition (PCD) of II–VI compound semiconductor thin films of ZnS from aqueous solution

Zinc sulphide (ZnS) thin films were depositedon Indium oxide coaled glass substrates by Photo Chemical Deposition (PCD) with starting precursor of Zinc sulphate and sodium thiosulphate as a source material for Zn and S respectively. In addition the pH was varied (3 to 8) using sulphuric acid by adding up in the precursor. Later the ZnS thin films were annealed at 500°C and it was found that crystalline structure was improved. Zinc blende crystalline structure was observed on the thin films using X-ray diffractometer (XRD). The morphological behavior was observed using Scanning electron microscope (SEM) and it reveals that the size of the grain increases after annealing at 500°C. UV-spectrometer was used to analyze the aqueous solution optical behavior before and after deposition. The average thickness of thin film was estimated as ∼1.02 micron measured by stylus profilometer method.

COBALT(II)/NICKEL(II) COMPLEXES OF DITHIOACETYLACETONE [M(SacSac)2](M = Co, Ni) AS SINGLE SOURCE PRECURSORS FOR COBALT/NICKEL SULFIDE NANOSTRUCTURES

Cobalt(II)/Nickel(II) complexes of 4-thiopent-3-ene-2-thione (SacSac), [ M(SacSac) 2]( M = Co, Ni ) have been used as single source precursors (SSPs) for the preparation of cobalt/nickel sulfide thin films by aerosol-assisted chemical vapor deposition (AACVD). Cobalt or nickel sulfide nanoparticles were grown by thermal decomposition of the precursor in hot trioctylphosphine oxide (TOPO) or hexadecylamine (HDA). XRD analysis showed that all samples of cobalt or nickel sulfide are of the sulfur deficient phases ( Ni9S8, Co9S8, Ni7S6 , or Ni3S2 ). SEM and TEM analysis showed that nickel sulfide formed nanowires, nanorods and spheres; cobalt sulfide formed plate like structures and spheres. The chemical compositions of the nanoparticles can be controlled by varying temperature or the capping agents.

Structural and Optical Properties of CdS Thin Films Grown by Sputtering

Cadmium sulfide (CdS) thin films with (111) preferential orientation were grown on glass substrates at room temperature by radio frequency (R.F.) magnetron sputtering. The structural and optical properties of CdS films have been investigated by X-ray diffraction, Scanning Electron Microscope micrographs, PL spectra and transmittance spectra. The grain sizes have been evaluated. The transmission spectra of the obtained films reveal a relatively high transmission coefficient (80%) in the visible range. All these results show that the grain sizes increased while the optical band gap decreased with increasing the thickness of CdS films.

Cold Deposition of Zinc Sulfide Optical Waveguides Using Thermoelectric Device

Zinc sulfide (ZnS) thin films as the waveguide medium have been deposited onto oxidized silicon wafer substrates at cold temperature (Tcold = –50oC) and ambient temperature (Tambient = 25oC) by thermal evaporation technique. The surface morphology of ZnS films were pictured with an atomic force microscopy (AFM) and the surface roughness were calculated from the AFM images. The propagation losses of the samples were measured using a scanning detection technique attached to a prism coupler. The AFM results revealed that the surface of cold deposited ZnS film is rougher than the surface of ambient deposited ZnS film. The propagation losses of the cold deposited ZnS waveguide are consistently lower than the ambient deposited ZnS waveguide at all measured wavelengths.

Fabrication and Study Zinc Sulfide Schottky Barrier Detectors

Schottky barrier photodiode of zinc sulfide (ZnS) thin film have been fabricated by thermal evaporation method. The ntype ZnS thin films of thickness 400 nm were deposited onto glass substrates at 150°C. The photodiode was form by evaporation of gold thin films on the n-type ZnS films and evaluated as UV near visible detectors. ZnS thin films were checked by using X-ray diffraction (XRD); the result shows that the films were polycrystalline. The lattice constant for ZnS films was calculated and it was 5.41A°. The absolute quantum efficiency of the photodiode was measured for wavelengths between 200-600 nm. The responsivety of the prepared photodiodes of different thickness of gold thin films (50, 80&100 nm) was measured for wavelengths at the range as mentioned above. These detectors have negligible response to wavelengths longer than 340 nm which correspond to energies less than the band gap of the zinc sulfide. Finally the barrier height of diode was measured by the C-V method and found as low as 1.9 V.

Synthesis and characterisation of ZnS optical thin films through cathodic electrodeposition technique

Zinc sulphide (ZnS) thin films were deposited on iridium tin oxide glass by a cathodic electrodeposition technique. The phase compositions, morphologies and optical properties of the prepared thin films were characterised. Both X‐ray diffraction and atomic force microscopy analyses show the growth of ZnS thin films is highly preferential along (200) orientation and the crystallisation of the thin films improves with increasing the solution pH values. The ultraviolet absorption spectra of the films reveal a broad absorption peak ∼300 nm and the bandgap of the as deposited films ranges from 3·42 to 3·71 eV.

Optoelectronic Characterization of Chemical Bath Deposited Cd<sub>x</sub>Co<sub>1-x</sub>S Thin Film

Cadmium Cobalt Sulphide (CdxCo1-xS) thin film was deposited on microscopic glass substrate using chemical bath deposition technique at room temperature from aqueous solutions of Cadmium Chloride, Cobalt Chloride and Thiourea in which ammonium solution was used as complexing agents. The optical properties were characterized using the absorbance and transmission measurement from Unico UV-2102 PC spectrophotometer, at normal incidence of light in the wavelength range of 200 - 1000 nm. We report the deposition and optimization of the growth parameter with respect to time which showed that the band gap energy and the composition verified from the extended Vegard’s law are highly dependent on deposition time. The average transmittance of the film in VIS-NIR region ranges between 30% and 78% with absorbance range of 0.15 - 0.47 within the same wavelength range. The film was also observed to exhibit poor reflectance (11 x = 0.75; 0.83 and 0.94), respectively. Other optical and dielectric properties of the films were also characterized. Based on the exhibited properties of the film, it can be concluded that it is a promising material for selective coatings for solar cells; effective coatings for poultry houses; use as antireflective coating materials, and for fabrication of optoelectronic devices.

PVA assisted growth of hydrophobic honeycomb network of CdS thin films

A simple, facile and inexpensive method of polyvinyl alcohol (PVA) assisted chemical bath deposition (CBD) is adopted for the growth of hydrophobic honeycomb network of cadmium sulfide (CdS) thin films. Further their physical properties were characterized by X-ray diffraction (XRD), Raman spectroscopy, filed emission scanning electron microscopy (FESEM), contact angle measurement and optical studies. The XRD pattern shows that CdS films are oriented along (3 3 0) plane. The presence of characteristic bonds of CdS is observed from Raman shift experiment. The FESEM images reveal porous and interconnected honeycomb-like morphology. Air trapping in the pores of honeycomb network prevents water from adhering to the film results into hydrophobicity having contact angle of 141°. The CdS film showed a direct band gap with energy 2.5 eV.