CdS thin films with (1 1 1) orientation were prepared by chemical bath deposition technique at 80±5 °C using the reaction between NH4OH, CdCl2 and CS(NH2)2. The influence of annealing temperature varying from 150 °C to 250 °C was studied. X-ray diffraction studies revealed that the films are polycrystalline in nature with cubic structure. Various parameters, such as dislocation density, stress and strain, were also evaluated. SEM analysis indicated uniformly distributed nano-structured spherically shaped grains and net like morphology. Optical transmittance study showed the wide transmittance band and absence of absorption in the entire visible region. I-V characterization of p-Si/n-CdS diode and photoluminescence studies were also carried out for the CdS films.
Manganese dioxide (MnO2) films with different nanostructures were deposited on indium tin oxide (ITO) glasses by using chemical bath deposition (CBD). Deposition temperature and time were varied from 60 °C to 90 °C and from 2 h to 72 h, respectively. The samples have been characterized using an X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and an electrochemical workstation. The films deposited at 60 °C for 8 h showed that obtained nanoflowers had an amorphous nature, while those deposited at higher temperatures of 70, 80 and 90 °C showed a well-developed nanowire and nanorod morphology. However, those which were deposited at 60 °C, showed the best electrochemical properties, including a higher specific capacitance, good rate of performance and a cycling stability (93 % loss of the initial value after 10,000 cycles).
deposition of macro- and nanocrystalline PbS and CdS have been described in literature. Among the chemical methods, chemicalbath deposition (CBD) is of special interest because it is simple and highly efficient. CBD allows adjustable control of size and surface density of nanoparticles, and can be used for preparation of high-quality nanocrystalline PbS and CdS films [ 4 , 6 ]. This method has been shown to allow control of stirring period, reaction time, bath temperature, pH of solution, complexing agent and impurities [ 7 , 8 ].
Among several n-type semiconductor
Cadmium oxide (CdO) thin films were grown on glass substrates by chemical bath deposition (CBD) method for different deposition times using cadmium acetate as cationic precursor. The structural and optical characterization was carried out using XRD, TEM, and UV-Vis spectrophotometer measurements. Structural analyses with XRD confirmed cubic structure of the CdO. Average particle size estimated from Rietveld refinement method of XRD pattern corresponded well with TEM measurement. The optical band gap varied between 2.35 eV to 2.48 eV with deposition time and an increase in optical band gap with decreasing film thickness was observed. The AC electrical conduction behavior of the CdO film was investigated as a function of temperature as well as frequency. The conductivity measurements indicated localized conduction and hopping of carriers between localized states. The value of real part of dielectric constant was found to decrease with frequency and increase with temperature. The Nyquist plots at different temperatures showed the existence of both grains and grain boundaries contributing to conduction mechanism.
R. Sabarish, N. Suriyanarayanan, J.M. Kalita, M.P. Sarma, G. Wary, Vipul Kheraj and Sampat G. Deshmukh
In this report, ternary semiconducting NixBi2−xS3(x = 0.2 M and 0.5 M) thin films were synthesized in situ for the first time by a chemical bath deposition technique at different bath temperatures (60 °C, 70 °C and 80 °C). The effects of concentration and deposition temperature on the deposited films were studied by combining the results of structural, morphological, optical and electrical analyses. The growth of NixBi2−xS3 films with good crystalline nature and interconnected grain arrangement takes place due to increasing the concentration of Ni2+ ions in bismuth sulfide matrix. EDS result confirmed the stoichiometry of NixBi2−xS3 formation. Wettability test demonstrated that the surface of the film was hydrophilic in nature. The optical absorption spectra revealed that the bandgap Eg of the x = 0.5 M film deposited at 70 °C was about 1.36 eV. Current-voltage (I-V) characteristics of the x = 0.5 M film deposited at 70 °C were studied under X-ray radiation and dark condition. An X-ray detection sensitivity analysis showed that the detection sensitivity is optimum when the bias voltage applied across the film is low (~0.9 V). These findings reveal that the film with x = 0.5 M deposited at 70 °C can be used as an efficient low cost X-ray sensor.
Synthesis and characterization of Mn-doped Sb2S3 thin films (TFs) prepared by chemical bath deposition (CBD) at room temperature have been documented and their structural, optical, morphological, magnetic and photovoltaic properties have been examined for the first time. Their structural properties reveal that the Mn-doped Sb2S3 TF has an orthorhombic phase structure of Sb2S3, and that the grain size of the Mn-doped Sb2S3 TF (72.9 nm) becomes larger than that of undoped Sb2S3 TF (69.3 nm). It has been observed that Mn content causes the Sb2S3 TF band gap to decrease. This situation clearly correlates with band tailing due to the impurities that are involved. The morphological properties have revealed that the shape of the Mn-doped Sb2S3 TF is more uniform than the shape of its undoped counterpart. The study on its magnetic properties has demonstrated that the Mn-doped Sb2S3 TF exhibits paramagnetic behavior. Its paramagnetic Curie-Weiss temperature was found to be -4.1 K. This result suggests that there is an anti-ferromagnetic interaction between Mn moments in the Mn-doped Sb2S3 TF. Incident photon to electron conversion efficiency (IPCE) and J-V measurements were also carried out for the Mn-doped Sb2S3 TF for the first time. The results have indicated that the Mn-doped Sb2S3 TF can be utilized as a sensitizer to improve the performance of solar cells. Another important observation on the photovoltaic properties of Mn-doped Sb2S3 TF is that the spectral response range is wider than that of undoped Sb2S3 TF. Our study suggests that the introduction of dopant could serve as an effective means of improving the device performance of solar cells.
A.K. Sharma, S.S. Potdar, M.A. Yewale, Deepak B. Shirgaonkar, K.S. Pakhare, B.M. Sargar, M.V. Rokade and U.M. Patil
Cadmium oxide (CdO) thin films were synthesized using chemical bath deposition (CBD) method from aqueous cadmium nitrate solution. The bath temperatures were maintained at room temperature (25 °C) and at higher temperature (80 °C). The structural studies revealed that the films showed mixed phases of CdO and Cd(OH)2 with hexagonal/monoclinic crystal structure. Annealing treatment removed the hydroxide phase and the films converted into pure CdO with cubic, face centered crystal structure. SEM micrographs of as-deposited films revealed nanowire-like morphology for room temperature deposited films while nanorod-like morphology for high temperature deposited films. However, cube-like morphology was observed after air annealing. Elemental composition was confirmed by EDAX analysis. Band gap energies of the as-deposited films varied over the range of 3 eV to 3.5 eV, whereas the annealed films showed band gap energy variation in the range of 2.2 eV to 2.4 eV. The annealed films were successfully investigated for NH3 sensing at different operating temperatures and at different gas concentrations. The room temperature synthesized film showed a response of 17.3 %, whereas high temperature synthesized film showed a response of 13.5 % at 623 K upon exposure to 24 ppm of NH3.
Nanocrystalline zinc sulfide thin films were prepared on glass substrates by chemical bath deposition method using aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent trisodium citrate in alkaline medium at 80 °C. The effect of deposition time and annealing on the properties of ZnS thin films was investigated by X-ray diffraction, scanning electron microscopy, optical transmittance spectroscopy and four-point probe method. The X-ray diffraction analysis showed that the samples exhibited cubic sphalerite structure with preferential orientation along 〈2 0 0〉 direction. Scanning electron microscopy micrographs revealed uniform surface coverage, UV-Vis (300 nm to 800 nm) spectrophotometric measurements showed transparency of the films (transmittance ranging from 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °C for 120 min, the transmittance increased up to 87 %. Moreover, the electrical conductivity of the deposited films increased with increasing of the deposition time from 0.35 × 10−4 Ω·cm−1 to 2.7 × 10−4 Ω·cm−1.
V. Balasubramanian, P. Naresh Kumar and D. Sengottaiyan
The effect of deposition temperature on the structural, optical and electrical properties of copper bismuth sulphide (CuBiS2) thin films deposited by chemical bath deposition onto glass substrates at different deposition temperatures (40 °C, 50 °C, 60 °C and 70 °C) for 5 hours deposition time period was investigated. The obtained films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and optical absorption spectra. All deposited films were polycrystalline and had an orthorhombic structure. Their grain size had changed with deposition temperature and their compositions were nearly stoichiometric. The optical band gap value was decreased from 2.44 eV to 2.33 eV with increasing the film thickness. Electrical parameters such as mobility and type of electrical conduction were determined from the Hall effect measurements. They showed that the obtained films have n-type conductivity and mobility values of the copper bismuth sulphide (CuBiS2) films have changed with deposition temperature.
optical properties, formation of different phases and phase relations have been investigated [ 14 – 21 ]. However, none of them is as simple and economical as the method described in this study. The optical properties and surface tension of nanoparticles are very sensitive to the method of preparation, crystallite size and doping. However, the CBD (chemicalbath deposition) method is one of the simplest chemical methods in which the nanoparticles can be prepared quickly with very good crystallinity.
In the present paper, we have attempted to produce thin films of