Chemical bath deposition of MoS2 thin film using ammonium tetrathiomolybdate as a single source for molybdenum and sulphur

Molybdenum disulphide, MoS₂, thin films have been deposited by chemical bath deposition method on glass and quartz substrate using ammonium tetrathiomolybdate as a single source precursor for Mo and S and subjected to vacuum heat treatment at different temperatures. X-ray diffraction of as-deposited film indicated its amorphous character and showed the development of poorly crystalline MoS₂ thin film on increasing annealing temperature. The film has been characterized by energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, scanning electron micrograph and the optical properties also have been studied.     

Electrochemical synthesis and characterization of zinc selenide thin films

In this work, electrochemical deposition and characterization of zinc selenide (ZnSe) thin films is reported. ZnSe thin films were deposited onto tin oxide (SnO₂) coated conducting glass substrates from an aqueous solution bath containing ZnSO₄ and SeO₂. The effect of deposition parameters such as bath temperature, deposition time and electrolyte composition on the properties of the ZnSe films has been studied. Cyclic Voltammetric studies were carried out to optimize the deposition potential for the co-deposition of Zn and Se. Deposited ZnSe films have been characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM) and optical techniques for their structural, compositional and optical properties and the results are discussed.     

Indium sulfide buffer layers deposited by dry and wet methods

Indium sulfide (In₂S₃) thin films have been deposited on amorphous glass, glass coated by tin oxide (TCO) and crystalline silicon substrates by two different methods: modulated flux deposition (MFD) and chemical bath deposition (CBD). Composition, morphology and optical characterization have been carried out with Scanning Electron Microscopy (SEM), IR-visible-UV Spectrophotometry, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectrometer. Different properties of the films have been obtained depending on the preparation techniques. With MFD, In₂S₃ films present more compact and homogeneous surface than with CBD. Films deposited by CBD present also indium oxide in their composition and higher absorption edge values when deposited on glass.     

Growth and characterization of electrosynthesized iron selenide thin films

Iron selenide (FeSe) thin films were electrodeposited onto indium doped tin oxide coated conducting glass (ITO) substrates at various bath temperatures from 30 °C to 90 °C in an aqueous electrolytic bath containing FeSO₄ and SeO₂. The deposition mechanism was investigated using cyclic voltammetry. The appropriate potential region where the formation of stoichiometric iron selenide thin films' occurs was found to be −1100 mV versus SCE. X-ray diffraction studies revealed that the deposited films are found to be hexagonal structure with a preferential orientation along (002) plane. The parameters such as crystallite size, strain, dislocation density are calculated from X-ray diffraction studies. Optical absorption measurements were used to estimate the band gap value of iron selenide thin films deposited at various bath temperatures. Scanning electron microscopy (SEM) was used to study the surface morphology. The composition of FeSe thin films was analyzed using an energy dispersive analysis by X-rays (EDX) set up attached with scanning electron microscopy. Preliminary studies for photoelectrochemical solar cells based on iron selenide thin films were carried out and the experimental observations are discussed.     

Pulsed electrodeposition and characterization of molybdenum diselenide thin film

Molybdenum dichalcogenides are semiconductors with layered type structure, which can act as efficient electrodes in the realization of photoelectrochemical solar cells. The main advantage of this molybdenum diselenide (MoSe₂) semiconductor is the prevention of electrolyte corrosion because of the phototransitions involving non-bonding d-d orbital of the Mo atoms. Polycrystalline molybdenum diselenide thin films are prepared by pulsed electrodeposition on conducting glass and titanium substrates in galvanostatic mode from an ammoniacal solution of H₂MoO₄ and SeO₂. The growth kinetics of the film was studied and the deposition parameters such as electrolyte bath concentration, bath temperature, time of deposition, deposition current, pH of the electrolyte and duty cycle of the current are optimized. X-ray diffraction analysis of the as deposited and annealed films showed the presence of highly textured MoSe₂ films with polycrystalline nature. EDAX spectrum of the surface composition confirms the nearly stoichiometric MoSe₂ nature of the film. Surface morphology studies by scanning electron microscope (SEM) shows that the films are pinhole free and of device quality nature. The optical absorption spectra show an indirect band gap value of 1.16 eV. Conductivity measurements were carried out at different temperatures and electrical constants such as activation energy, trapped energy state and barrier height were calculated.     

Studies on electrosynthesized zinc mercury selenide alloys

Zn_1-x Hg _x Se ternary alloy thin films with x ranging from 0.14 to 0.5 have been deposited on conducting glass substrates by electrodeposition from aqueous bath containing ZnSO₄, HgCl₂ and SeO₂ at bath temperatures from 30 °C to 80 °C. The influence of deposition parameters on the crystallinity, composition, band gap and lattice constants of the film is studied. The films deposited at the potentials between −0.4 V and −1.0 V vs SCE at 70 ° C were characterized by X-ray diffraction (XRD), Energy dispersive X-ray (EDX), scanning electron microscope and optical absorption technique. Photoelectrochemical (PEC) solar cells based on Hg _x Zn_1-x Se thin film electrodes were constructed and the effects of annealing and photo etching on solar cell parameters were studied.     

Effect of heat treatment on microstructural and optical properties of CBD grown Al-doped ZnO thin films

Investigations on the effect of annealing temperature on the structural, optical properties and morphology of Al-doped ZnO thin films deposited on glass substrate by chemical bath deposition have been carried out. X-ray diffraction studies revealed that deposited films are in polycrystalline nature with hexagonal structure along the (0 0 2) crystallographic plane. Microstructural properties of films such as crystallite size, texture coefficient, stacking fault probability and microstrain were calculated from predominant (0 0 2) diffraction lines. The UV-Vis-NIR spectroscopy studies revealed that all the films have high optical transmittance (>60%) in the visible range. The optical band gap values are found to be in the range of 3.25-3.31 eV. Optical constants have been estimated and the values of n and k are found to increase with increase of heat treatment. The films have increased transmittance with increase of heat treatment. Al-doped ZnO thin films fabricated by this simple and economic chemical bath deposition technique without using any carrier gas are found to be good in structural and optical properties which are desirable for photovoltaic applications. Scanning electron microscopic images revealed that the hexagonal shaped grains that occupy the entire surface of the film with its near stoichiometric composition.     

Effect of samarium addition and annealing on the properties of electrodeposited ceria thin films

Samarium (Sm)-doped ceria (CeO₂) (SDC) is a promising material for high temperature electrochemical devices. Our work demonstrates that thin SDC films can be prepared by a cost-effective electrodeposition method at a low-temperature (30 °C) and − 0.8 V/SCE (saturated calomel electrode) potential. Analysis of the structural properties of the obtained SDC films, as-grown and annealed at 600 °C, has been carried out by X-ray diffraction (XRD). Morphology and film composition were studied using scanning electronic microscopy and energy dispersive X-ray analysis. Vibrational properties were determined by Raman spectroscopy. The effects of samarium addition into the deposition bath on the final film composition have been studied. According to XRD results, film crystallographic properties are directly linked to the percentage of Sm incorporated in the CeO₂ lattice. We report on the electrochemical deposition of the SDC films performed over a large range of Sm additions (0-30%). The effect of temperature annealing has been studied as well.     

Effect of complexing agent on growth process and properties of nanostructured Bi2S3 thin films deposited by chemical bath deposition method

Nanostructured Bi₂S₃ thin films have been prepared onto amorphous glass substrates by chemical bath deposition method at room temperature using bismuth nitrate and sodium thiosulphate as cationic and anionic precursors with EDTA as complexing agent in aqueous medium. The X-ray diffraction study reveals that the films deposited without the complexing agent are amorphous in nature and becomes nanocrystalline in the presence of EDTA. The resistivity for the films prepared from EDTA complexed bath is decreased due to the improvement in grain structure. The decrease in optical bandgap and activation energy is observed as the thickness of the film varies from 45 to 211 nm on account of the variation of the volume of complexing agent in reaction bath. Studies reveal that the growth mechanism of Bi₂S₃ gets affected in the presence of complexing agent EDTA and shows impact on structural, electrical and optical properties.     

Electrodeposition of wide band gap InGaxSyOz thin films for solar cell applications

Indium-Gallium-sulfide-oxide thin films were deposited onto F-doped SnO₂-coated glass by electrochemical deposition from an aqueous bath. The films were deposited at three different ratios of gallium to indium in the precursor bath; namely [Ga/In] = 2/8, 5/5 and 8/2. The impact of the gallium content on the composition, optical transmission, structure, photosensitivity, electrical resistivity and morphology of the deposited films was investigated. The films deposited at [Ga/In] = 5/5 and 8/2 had an energy gap as high as 3.5 eV. The X-ray diffraction spectrum of the film deposited at [Ga/In] = 2/8 contained weak peaks of indium metal, but the In peaks were absent in the spectra of the films deposited at [Ga/In] = 5/5 and 8/2. The photosensitivity of the film was observed by means of photoelectrochemical measurements, which confirmed that all the films showed n-type conduction. Finally, the film has been used as a buffer layer to fabricate a SnS-based thin film solar cell.     

(Cu,Fe, Co,or Ni)-doped tin dioxide films deposited by spray pyrolysis: Doping influence on thermal stability of the film structure

The results of doping influence on thermal stability of the SnO₂ film morphology are presented in this article. The SnO₂ films doped by Fe, Cu, Ni, Co (16 at.%) were deposited by spray pyrolysis from 0.2 M SnCl₄–water solution at T_pyr 350–450 °C. The annealing at 850–1030 °C was carried out in the atmosphere of the air. The change of such parameters as film morphology, the grain size, texture and the intensity of X-ray diffraction (XRD) peaks have been controlled. For structural analysis of tested films we have been using X-ray diffraction, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM) techniques. It was established that the doping does not improve thermal stability of both film morphology and the grain size. It was made a conclusion that the increased contents of the fine dispersion phase of tin oxide in the doped metal oxide films, and the coalescence of this phase during thermal treatment are the main factors, responsible for observed changes in the morphology of the doped SnO₂ films.     

Effect of complexing agents: investigations on structural,morphological, topographical and optical analysis of copper iron sulphide thin films deposited by chemical bath deposition method

Copper iron sulphide (FeCuS₂) thin films deposited by chemical bath deposition method using ferrous sulphate and copper sulphate as cationic sources and sodium sulphide as anionic source with complexing agents, EDTA and Leishman stain were reported. The structural, optical and morphological studies were carried out using X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV–Visible spectroscopy techniques. The X-ray spectrum reveals that the films are polycrystalline nature and also showed the deposition of cubic phases at room temperature. The SEM images for prepared films have clear morphology influenced by the complexing agents used in deposition process. The result of AFM studies shown that the particles in the film have grain size around ~?60–70 nm and also have almost similar thickness. Based on the optical absorbance spectra the FeCuS₂ film exhibited a high absorbance in the visible region. The absorption edge shifted toward lower wavelength with varying complexing agents. The band gap value obtained was found to be 3.57–3.85 eV. From these results, it is indicated that the prepared films are suitable candidate for solar cell applications.     

An electrochemical technique to deposit thin films of PbTe

PbTe thin films were deposited electrochemically on transparent conducting oxide coated (TCO) glass substrates from a solution of lead acetate and TeO₂ at low pH. A lead (Pb) strip was used as a sacrificing anode and the TCO glass acted as the cathode, which were short-circuited externally. Depositions were carried out at different temperatures of the bath to study the growth kinetics and grain growth. X-ray diffraction technique, scanning electron microscopy, infrared spectroscopy and resistivity measurements were carried out to characterize the deposited films. The films were polycrystalline in nature with a cubic phase.     

Chemical bath deposition of CdS highly-textured, columnar films

Chemical bath deposition (CBD) is one of the most common techniques for depositing CdS films. While there have been many studies on these films, and considerable characterization of their morphologies, most of this characterization has been by either X-ray diffraction or plan-view electron microscopy. With the exception of epitaxial films deposited on single crystal substrates, there has been little characterization of the cross-sectional structure of CBD CdS films. We show how, using a CdSO₄ bath and ethylenediamine as complexant, dense, columnar films of predominantly cubic CdS can be very reproducibly obtained. The initial growth is disordered, but preferential growth perpendicular to the polar face results in highly textured growth. A similar, if somewhat less ordered, morphology is obtained from a commonly-used ammonia bath using CdCl₂ as the source of Cd. Although not explicitly recognized, chloride baths in the literature exhibited sharp X-ray diffraction peaks and this is now connected with the growth mode these baths have in common with ethylenediamine baths.     

Effect of the solution pH on the growth of spray-deposited CuInS2 thin films

The effect of solution pH on the growth of spray deposited CuInS₂ thin films has been investigated. Solutions with pH 1.5, 2.4, 3.5 and 4.5 are used to deposit the films on glass substrates held at 550 K. The films have been characterized using optical absorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. At pH 1.5, no film formation is observed. Films deposited from 2.4 pH solution contain binary phase Cu_{2 S}. Near stoichiometric, single phase CuInS₂ films with chalcopyrite structure are formed when solution pH=3.5. Films deposited from 4.5 pH solution are also found to be single phase, near stoichiometric CuInS₂ and exhibited chalcopyrite structure. However, an additional optical absorption process is observed which is attributed to a sub-band gap absorption.     

Properties of electrochemically deposited CdTe thin films: annealing effect

CdTe thin film have been deposited onto stainless steel and fluorine doped tin oxide coated glass substrates from aqueous acidic bath using electrodeposition technique. The different preparative parameters, such as deposition time, bath temperature, pH of the bath have been optimized by photoelectrochemical (PEC) technique get good quality photosensitive material. The deposited films are annealed at different temperature in presence of air. Annealing temperature is also optimized by PEC technique. The film annealed at 200 °C showed maximum photosensitivity. Different techniques have been used to characterize the as deposited and also annealed (at 200 °C) CdTe thin film. The X-ray diffraction (XRD) analysis showed the polycrystalline nature and a significant increase in the XRD peak intensities is observed for the CdTe films after annealing. Optical absorption shows the presence of direct transition with band gap energy 1.64 eV and after annealing it decreases to 1.50 eV. Energy dispersive analysis by X-ray study for the as-deposited and annealed films showed nearly stoichiometric compound formation. Scanning electron microscopy reveals that spherically shaped grains are more uniformly distributed over the surface of the substrate for the annealed CdTe film. Photovoltaic output characteristics and spectral response of the annealed film have been carried. The fill factor and power conversion efficiency (η) of the cell are found to be 71 and 3.89 %.     

Study of structural,optical and electrical parameters of ZnSe powder and thin films

Nanocrystalline ZnSe powder and thin film forms have been synthesized via chemical bath deposition technique. The ZnSe thin films are deposited onto ultrasonically clean glass substrates in an aqueous alkaline medium using sodium selenosulphate as Se^2? ion source. The ZnSe powder and thin film are characterized by structural, optical and electrical properties. It is confirmed from X-ray diffraction study that cubic phase is present in ZnSe thin film form with (111) as preferred orientation and hexagonal phase is present in ZnSe powder form with (100) as preferred orientation. Optical absorption measurement indicates the existence of direct allowed optical transition with a wide energy gap and blue shift in the fundamental edge has been observed in both cases. The optical band gap of ZnSe powder is greater than the thin film. The electrical conductivity (both dark and photoconductivity) measurements are also carried out in different temperature range and variation in activation energy has been calculated.     

Fabrication and characterization of n-CdSe0.7Te0.3/p-CdSe0.15Te0.85 solar cell

Hot wall deposited CdSe_xTe_1−x where 0 ≤ x ≤ 1 thin films for solar cell applications have been prepared from a compound synthesized by direct reaction of high purity Cd, Se and Te elements. Crystal structure and composition of the films were analyzed by X-ray diffraction, scanning electron microscope and EDAX. X-ray diffraction studies carried out on pseudo-binary system revealed that the films are polycrystalline in nature with CdSe_0.7Te_0.3 film exhibiting hexagonal structure and CdSe_0.15Te_0.85 film exhibiting cubic zinc blende structure. The type of conduction was determined by Hall studies. A novel solar cell with structure n-CdSe_0.7Te_0.3/p-CdSe_0.15Te_0.85 has been fabricated and the efficiency was found to be 3.13%.     

Synthesis of nanocrystalline iron oxide ultrathin films by thermal decomposition of iron nitropruside: Structural and optical properties

Ultrathin films of nanocrystalline α-Fe₂O₃ have been deposited on glass substrates from an inorganic precursor, iron nitropruside. This is a novel route of synthesis for iron oxide thin films on glass substrates, by annealing the precursor thin film in air at 650 °C for 15 min. The films were characterized using TG-DTA analysis, X-ray diffraction, UV-visible, FESEM, AFM and Raman measurements. X-ray diffraction and Raman analyses revealed that the deposited films contain α-phase of Fe₂O₃ (hematite). The synthetic route described here provides a very simple and cost-effective method to deposit α-Fe₂O₃ thin films on glass substrates with band gap energy of about 2.75 eV. The deposited films were found to show catalytic effect for the photo-degradation of phenol.     

Structural, optical and photoelectrochemical properties of electrodeposited CdSe thin films

Cadmium Selenide thin films have been electrodeposited from an acidic bath using CdSO₄ as a cadmium source and SeO₂ as a selenium source at pH=3 on to stainless steel and fluorine-tin oxide coated glass substrates. The CdSe films have been characterized by X-ray diffraction, scanning electron microscopy and optical absorption. X-ray diffraction spectra showed that CdSe is polycrystalline with single hexagonal phase. The intensity of the (0 0 2) peak increases remarkably by annealing in nitrogen atmosphere. A microstructural study revealed that the films were uniform and well covered the substrate. Optical absorption studies showed that the bandgap of the CdSe is 1.70 eV. It is observed that the conductivity of the CdSe films increases by annealing in nitrogen atmosphere. The photoelectrochemical activities of CdSe films deposited on stainless steel and fluorine-tin oxide coated glass have been studied by using CdSe/ 1 M NaOH-1 M Na₂S-1 MS / C cell configuration and it is found that films deposited on stainless steel give better performance, photoelectrochemical (PEC) studies also reveal that the CdSe has n-type conductivity.