Morphological evolution of CdS films prepared by chemical bath deposition

In this article, the growth process of chemical bath deposited CdS films was systematically investigated. The structural, optical, and morphological properties were investigated by X-ray diffraction （XRD）, transmission electron microscope （TEM）, UV-Vis spectrophotometer, scanning electron microscope （SEM）, respectively. CdS nanocubes with size of less than 500 nm and nanocrystal-lites with diameter of less than 5 nm forming in reaction solution are observed. According to the TEM results and the SEM morphological evolution of CdS films, a crystal-lite-by-crystallite growth mechanism is proposed to eluci-date the growth process of chemical bath deposited CdS films based on the present growth mechanism.

Influence of Bath Temperature, Deposition Time and S/Cd Ratio on the Structure, Surface Morphology, Chemical Composition and Optical Properties of CdS Thin Films Elaborated by Chemical Bath Deposition

Cadmium sulphide (CdS) thin films were deposited on glass substrates by the chemical bath deposition (CBD) method, using anhydrous cadmium chloride (CdCl2) and thiourea (CS(NH2)2) as sources of cadmium and sulphur ions respectively. The influence of bath temperature (Tb), deposition time (td) aSnd [S]/[Cd] ratio in the solution on the structural, morphological, chemical composition and optical properties of these films were investigated. XRD studies revealed that all the deposited films were polycrystalline with hexagonal structure and exhibited (002) preferential orientation. The films deposited under optimum conditions (Tb = 75?C, td = 60 min and [S]/[Cd] ratio = 2.5) were relatively well crystallized. These films showed large final thickness and their surface morphologies were composed of small grains with an approximate size of 20 to 30 nm and grains grouped together to form large clusters. EDAX analysis revealed that these films were nonstoichiometric with a slight sulphur deficiency. These films exhibited also a transmittance value about 80% in the visible and infra red range.

Structural and optical studies on PVA capped SnS films grown by chemical bath deposition for solar cell application

Tin monosulphide(SnS) thin films capped by PVA have been successfully deposited on glass substrates for cost effective photovoltaic device applications by a simple and low-cost wet chemical process, chemical bath deposition(CBD) at different bath temperatures varying in the range, 50–80 °C. X–ray diffraction analysis showed that the deposited films were polycrystalline in nature, showing orthorhombic structure with an intense peak corresponding to(040) plane of SnS. These observations were further confirmed by Raman analysis. FTIR spectra showed the absorption bands which corresponds to PVA in addition to SnS.The scanning electron microscopy and atomic force microscopy studies revealed that the deposited SnS films were uniform and nanostructured with an average particle size of 4.9 to 7.6 nm. The optical investigations showed that the layers were highly absorbing with the optical absorption coefficient ～10~5 cm^(-1). A decrease in optical band gap from 1.92 to 1.55 eV with an increase of bath temperature was observed. The observed band gap values were higher than the bulk value of 1.3 eV, which might be due to quantum confinement effect. The optical band gap values were also used to calculate particle size and the results are discussed.

Structural,Morphological and Optical Properties of Well-Ordered CdO Nanostructures Synthesized by Easy-Economical Chemical Bath Deposition Technique

In this Study,Cadmium Oxide(CdO)nanostructures were synthesized by using Chemical Bath Deposition Technique.The synthesized process was carried out at room temperature.The structural and optical properties of nanostructures was characterized by XRD,SEM and UV-Vis techniques.As a result,the CdO nanostructures are oriented along(111)plane of cubic crystal structure.The morphology of CdO nanostructures showed interconnected prism-like and cauliflower-type cluster nanostructure.The UV results of this structures with high absorbtion coefficient are observed to be in accordance with the CdO nanoparticles.

Influence of Deposition Time on the Microstructure and Transport Properties of CdO Thin Films Prepared by Chemical Bath Deposition

Transparent thin films of CdO has been deposited on to glass substrates employing chemical bath deposition. The prepared films are reproducible, adherent to the substrate, pinhole free and uniform. Amongst the different process parameters, the deposition time plays a significant role in obtaining device quality transparent CdO thin films. X-ray powder diffraction (XRD) studies indicated that the thin films are polycrystalline in nature with cubic phase with a cell constant of a = 4.638 ?. The surface morphology of the prepared CdO thin films was examined by scanning electron microscopy. The films deposited at 24 hrs exhibited highest optical transmittivity (>80%) and the direct band gap energy was found to vary from 2.50 to 2.91 eV with a rise deposition time from 6 to 30 hrs. The electrical resitivity variations of these films were measured in the temperature range between 30?C and 150?C by four-probe technique.

Super-hydrophobic and Self-cleaning PVDF Film Fabricated by Chemical Bath Deposition

Self-cleaning surfaces have received a great deal of attention recently,both in theoretical studies and commercial applications.The self-cleaning surface of lotus leaf is hydrophobic and rough,showing a micro-and nano-scale morphology.The micro-reliefs of lotus leaf were mimicked using polyvinylidene fluoride(PVDF)film and nano-scale peaks on the top of the micro-reliefs were implemented by the reaction between methyltrichlorosilane and the reactive groups of PVDF film treated by oxygen plasma.A lotus-leaf-like surface of the PVDF film was clearly observed by scanning electronic microscopy(SEM)and atomic force microscope(AFM).Elemental composition analysis by X-ray photoelectron spectroscopy(XPS)revealed that the material of the nanostructure of PVDF film was polymethylsiloxane.The superhydrophobic property of the mimicked self-cleaning surface was validated by the water contact angle and sliding angle on the lotus-leaf-like PVDF film,which were 156.6° and 4°,respectively.In this case,water droplets can easily move across the PVDF film surface,carrying dirt particles away,leaving no contamination.

Preparation of Mn_3O_4 from low-grade rhodochrosite ore by chemical bath deposition method

Mn3O4was prepared with the chemical bath deposition(CBD) method. A Mn SO4 solution was obtained by the leaching and purifying of low-grade rhodochrosite ore(LGRO), which was used as raw material. The prepa ration procedures were studied and promoted. The result showed that the Mn3O4 with the highest purity and highes specific surface area could be obtained under the following processes. An Mn SO4 solution of 1.0 mol/L was added into a beaker under a flow rate of 30 m L/h. The p H of the reaction solution was adjusted to 10 using NH3 H2 O a80 °C. Then the solids were washed and dried at 200 °C fo2.5 h. The total Mn content(TMC) of Mn3O4 was 72.0 %The ionic distributions was formulated as [Mn2?[Mn2??0.3024Mn30.2937Mn4?h0.37860.0254]2O4. The average crys tallite size of Mn3O4 with a tetragonal hausmannite struc ture was found to be about 35 nm by X-ray diffraction(XRD) analysis. The BET specific surface area of the Mn3O4 measured was 32 m2/g.

Influence of In-doping on resistivity of chemical bath deposited SnS films

SnS and SnS：In films were deposited onto glass substrates by chemical bath technique. The structure and surface morphology of the SnS：In films were studied by X-ray diffraction （XRD） and scanning electron microscope （SEM） respectively. Energy dispersive spectroscopy （EDS） showed the existence of In in the films. The undoped SnS film exhibited a rather high resistivity and InCl3 could reduce the resistivity of these films by two orders approximately. The band gaps of the SnS and SnS：In films were evaluated from the optical transmission spectra.

Optical and Structural Properties of Chemical Bath Deposited Cadmium Sulphur Selenide (CdS1–xSex (0 ≤ x ≤ 1)) Thin Films

The tuneable band gap property of Cadmium-sulphur-selenide (CdS1–xSex) thin film makes it an appropriate material for a wide range of optoelec-tronic applications and this has aroused a lot of interest. In this paper, we report the study of Cadmium-sulphur-selenide (CdS1–xSex) thin films, successfully grown on commercial glass slide substrate by the chemical bath deposition technique. The effect of selenium content (x value) on the structural, and some optical properties have been studied. The bath solution contained cadmium acetate dehydrate [Cd(CH3COO)2·2H2O], so-dium selenosulphate [Na2SeSO3] and thiourea [CS(NH2)2] were used as the sources of Cd2+, Se2﹣ and S2+, respectively. Tartaric acid (C4H6O6) was used as a complexing agent. The pH of the solution was adjusted to 12 by drop-wise addition of ammonia. The bath temperature was kept at 90°C for a deposition time of 1 hour. Post deposition annealing processes of the thin films were performed in a furnace at a temperature of 400°C for two hours. Both as-deposited and annealed films were characterised by Powder X-Ray Diffraction, Scanning Electron Microscopy, UV-Visible Optical Absorption Spectroscopy and Energy Dispersive X-Ray Analysis. Optical absorption data analysis indicates that direct allowed transitions occur in the films. The band gap of the as-deposited CdS1–xSex decreased linearly from 2.34 eV to 1.48 eV, with increasing selenium content, and in the annealed samples, decreased from 1.84 eV to 1.36 eV. X-ray diffrac-tion measurements revealed, that pure CdS, and CdSe had mixed hexago-nal and cubic phases. All the remaining ternary compounds were com-posed of cubic CdS and hexagonal CdSe phases. The annealed samples showed well defined and more intense peaks, suggesting an improvement in crystallinity. The average grain size increased slightly with increasing selenium content. SEM micrographs showed that the films were compact with a smooth texture and good coverage across the entire area of the substrate.

Peculiarities of ZnCdSe Nanolayers by Chemical Deposition

In this work, the results on the investigation of the precularity near the solar spectrum region, of Zn1.xCdxSe nanofilms, nanoscale heterojunction prepared on silikon and alumminium substrates by precipitation from aqueous solutions are presented. The temperature dependence of dark and light conductivity, spectrum and optical quenching of primary and impurity photoconductivity are investigated. The obtained results show that when controlling ionic composition and HT （heat-treatment） conditions, one can purposely control the properties of Zn1-xCdxSe （0 ≤ x ≤ 0.6） films, achieve the appropriate degree of compensation of different recombination levels and traps attributed to intrinsic defects or impurities, which result in high level of photoelectrical parameters near the IR region. Just after deposition the photoconductivity spectrum maximum of Zn1-xCdxSe （0 〈 x 〈 0.6） films is observed at λ1 = 0.545 ＋ 0.495/am versus the film composition.

Optical and Morphological Studies of Chemical Bath Deposited Nanocrystalline Cd_1-xZn_xS Thin Films

Cadmium Zinc Sulfide, Cd1-xZnxS thin films were deposited by chemical bath deposition technique at bath temperature of 75°C. The morphology of the films was analyzed by scanning electron microscope, the optical constants of the films were estimated from the transmission and reflection spectra of the films in the wavelength range of 300 - 900 nm. The films had a transmittance between 75% and 85% and optical band gap in the range 2.8 - 3.4 eV. The dependence of the refractive index of the films on the wavelength was investigated using the single oscillator model, from which the dispersion parameters were determined. The high frequency dielectric constant εL and the ratio of the carrier concentration to the effective mass N/m* were estimated based on the Spitzer and Fan model. Both εL and N/m* show a decrease in value with increase in Zinc content.

In-situ monitored chemical bath deposition of planar NiO x layer for inverted perovskite solar cell with enhanced efficiency

As a convenient,low-cost and up-scalable solution route,chemical bath deposition(CBD)has exhibited impressive advantages in fabricating electron transporting materials like SnO_(2),achieving record efficien-cies for regular n-i-p perovskite solar cells(PSCs).However,for the hysteresis-free and potentially more stable inverted p-i-n PSCs,CBD processing is rarely studied to improve the device performance.In this work,we first present a CBD planar NiO x film as the efficient hole transport layer for the inverted per-ovskite solar cells(IPSCs).The morphologies and semiconducting properties of the NiO x film can be ad-justed by varying the concentration of[Ni(H 2 O)x(NH 3)6-x]2+cation via in-situ monitoring of the CBD re-action process.The characterizations of ultraviolet photoelectron spectroscopy,transient absorption spec-troscopy,time-resolved photoluminescence suggest that the CBD planar NiO x film possesses enhanced conductivity and aligned energy band levels with perovskite,which benefits for the charge transport in the IPSCs.The devices based on planar NiO x at 50°C and low nickel precursor concentration achieved an enhanced efficiency from 16.14%to 18.17%.This work established an efficient CBD route to fabricate planar NiO x film for PSCs and paved the way for high performance PSCs with CBD-prepared hole transporting materials.

Pulsed Laser Deposition ZnS Buffer Layers for CIGS Solar Cells

Polycrystalline ZnS films were prepared by pulsed laser deposition （PLD） on quartz glass substrates under different growth conditions at different substrate temperatures of 20, 200, 400, and 600 ℃, which is a suitable alternative to chemical bath deposited （CBD） CdS as a buffer layer in Cu（In,Ga）Se2 （CIGS） solar cells. X-ray diffraction studies indicate the films are polycrystalline with zinc-blende structure and they exhibit preferential orientation along the cubic phase β-ZnS （111） direction, which conflicts with the conclusion of wurtzite structure by Murali that the ZnS films deposited by pulse plating technique was polycrystalline with wurtzite structure. The Raman spectra of grown films show Al mode at approximately 350 cm^-1, generally observed in the cubic phase β-ZnS compounds. The planar and the cross-sectional morphology were observed by scanning electron microscopic. The dense, smooth, uniform grains are formed on the quartz glass substrates through PLD technique. The grain size of ZnS deposited by PLD is much smaller than that of CdS by conventional CBD method, which is analyzed as the main reason of detrimental cell performance. The composition of the ZnS films was also measured by X-ray fluorescence. The typical ZnS films obtained in this work are near stoichiometric and only a small amount of S-rich. The energy band gaps at different temperatures were obtained by absorption spectroscopy measurement, which increases from 3.2 eV to 3.7 eV with the increasing of the deposition temperature. ZnS has a wider energy band gap than CdS （2.4 eV）, which can enhance the blue response of the photovoltaic cells. These results show the high-quality of these substitute buffer layer materials are prepared through an all-dry technology, which can be used in the manufacture of CIGS thin film solar cells.

Influence of Thickness on the Photosensing Properties of Chemically Synthesized Copper Sulfide Thin Films

We report here the influence of thickness on the photosensing properties of copper sulfide (CuS) thin films. The CuS films were deposited onto glass substrate by using a simple and cost effective chemical bath deposition method. The changes in film thickness as a function of time were monitored. The films were characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FE-SEM), optical measurement techniques and electrical measurement. X-ray diffraction results indicate that all the CuS thin films have an orthorhombic (covellite) structure with preferential orientation along (113) direction. The intensity of the diffraction peaks increases as thickness of the film increases. Uniform deposition having nanocrystalline granular morphology distributed over the entire glass substrate was observed through FE-SEM studies. The crystalline and surface properties of the CuS thin films improved with increase in the film thickness. Transmittance (except for 210 nm thick CuS film) together with band gap values was found to decrease with increase in thickness. I-V measurements under dark and illumination condition show that the CuS thin films give a good photoresponse.

SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

The SnS thin films were synthesized by chemical bath deposition （CBD）, dip coating and successive ionic layer adsorption and reaction （SILAR） techniques. In them, the CBD thin films were deposited at two tem- peratures： ambient and 70℃. The energy dispersive analysis of X-rays （EDAX）, X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscopy （SEM） and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I-V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

Growth mechanism of CdS film prepared by chemical bath deposition

In this paper, sodium citrate was adopted as a complexing agent and ammonia merely served as pH adjustor to investigate the growth mechanism of CdS film The growth rate, structural properties, surface morphology microstructure, and optical properties of CdS films were studied by profilometer, X-ray diffractometer（XRD）scanning electron microscopy（SEM）, transmission elec tron microscopy（TEM）, and spectrophotometer, respec tively. The SEM images show that CdS films prepared with higher ammonia concentration have lower nucleation density on substrate. SEM and EDS results show that the formation of Cd（OH）2is not required in the growth of CdS film. As the ammonia concentration increases, the sites tha previously adsorbed S2-are taken by OH-which leads to lower S2-density on substrate. CdS film forms through direct reaction of Cd2？with the S2-which are adsorbed on the substrate. Lower S2-density on the substrate results in the decrease of particle density on the substrate. The as deposited CdS films have relatively high-average trans mittance（＊80 %） in the wavelength range from 500 to1,000 nm which makes them suitable to be used in sola cell.

Top gate ZnO-Al2O3 thin film transistors fabricated using a chemical bath deposition technique

ZnO thin films were prepared by a simple chemical bath deposition technique using an inorganic solution mixture of ZnCl2 and NH3 on glass substrates and then were used as the active material in thin film transistors （TFTs）. The TFTs were fabricated in a top gate coplanar electrode structure with high-k Al203 as the gate insulator and AI as the source, drain and gate electrodes. The TFTs were annealed in air at 500℃ for 1 h. The TFTs with a 50μm channel length exhibited a high field-effect mobility of 0.45 cm2/（V.s） and a low threshold voltage of 1.8 V. The sub-threshold swing and drain current ON-OFF ratio were found to be 0.6 V/dec and 10 6, respectively.