Structure Of Cadmium Sulfide Research Articles

Different look at S-p bonding orbital in CdS, with Zn and Se series gap investigations

The electronic characteristics of Cadmium sulfide (CdS) series Zn x Cd16−x S8Se8 and Cd16Se16−x S x are investigated. According to the calculations, barely 12% Zn (X = 2) in the form Zn2Cd14Se16 is required to maximize the gap. To properly evaluate the excited states, the generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) potentials are utilized in the computations. The parent compound CdS exhibits three distinct forms of crystal structures, with the hexagonal structure being remarkably stable under the GGA and mBJ functionals. The partial density of states around the Fermi level demonstrates that the system’s electronic characteristics are determined by the interaction of S-p and Cd-s,p states. A substantial splitting of the valence band, shown by band structure analysis, suggests a greater polarization crystal field in the hexagonal CdS structure. The stereochemical activity of the S atom stimulated the CdS compound for extremely tiny displacements of 0.0014 Å and 0.043 Å for the Cd and S atoms in the [001] direction, respectively, as well as tilting of the Cd-S-Cd link. This compound exhibits lone pair properties, with three valance electrons of the p-orbital participating in covalent bonding and S-s electrons fully occupied. Furthermore, Van Hove singularities are discovered in the electron density of states due to the Cd-d atoms that support in the analysis of optical absorption spectra. Finally, the results suggest that CdS has potential for solar cells applications due to its direct wide band gap semiconductor features,

Effect of different CdS morphologies on photocatalytic water splitting performance of CdS@ZIF-67 composites

ZIF-67 has been widely used in the field of photocatalytic, however, its insensitivity to visible light responsiveness has become a major difficulty in its further development. Studies have shown that the combination of cadmium sulfide (CdS) with ZIF-67 has enough potential to address this concern, but different morphologies and sizes of CdS have a great influence on the properties of composite materials. Therefore, this study focused on the physicochemical properties, photoelectric properties, and photocatalytic water-splitting properties of the CdS@ZIF-67 composites obtained by the combination of four different CdS morphologies and ZIF-67. It was found that the CdS@ZIF-67 composites had the performance of visible light region response without the use of photosensitizer, and the specific surface area of the composite was significantly improved. Among them, the nanoparticles CdS@ZIF-67 showed the most significant improvement in photocatalytic water splitting performance, and the optimal value reached 2.21 mmol•g−1•h−1. Based on the results of this study, it can be concluded that the zero-dimensional structure of CdS is more conducive to the performance improvement of composite materials, which provides favorable evidence for the later combination of semiconductor materials and metal-organic framework materials (MOFs).

Chemical and gas sensing property tuning of cadmium sulfide thin films

A simplistic chemical bath deposition (CBD) technique was used to synthesize the hierarchical morphology of cadmium sulfide (CdS) thin films with altered chemical compositions. The novelty of the work does not lies in the surface morphology of the product, but is found in the influence of the CBD reaction time (mainly after post-optimization) on the Cd contents in the films, subsequently the presence of defects and consequently their electrical conductivity and NO2 gas sensing performance. The morphology of the CdS thin films was characterized by field-effect scanning electron microscopy and defects estimated using photoluminescence spectroscopy. The increment in the deposition time affects the precursor contents in the produced film effectively. In the case of the CdS, the Cd contents increase with the rise in the CBD deposition period. Consequently, it affects the presence of the secondary phase and the conductivity of the compound. As the concentration of the films slightly differs from the standard value, we utilized the films for the sensor application. The low-temperature gas sensing measurements of this Cd-rich CdS structure to NO2 gas were carried out, and we found encouraging outcomes.

Synthesis and Blue Emission Properties of Co-Doped CdS Semiconductor Nanoparticles

Background: Cadmium sulfide (CdS) based semiconductors are of great interest for different high-end applications because they pose a direct bandgap (2.42 eV). CdS are used as the main constituent material in many applications, namely solar cells, electroluminescent, and quantum dot light-emitting diodes. Transition metal-doped CdS revealed considerable influence in the bandgap, photoluminescence properties and peak energy upon increasing the metal content. Objective: In this work, we study the single-phase cubic structure of CdS. Photoluminescence spectra revealed a strong blue emission peak located at about 445 nm. Methods: We investigate the Co-doping CdS semiconductor nanoparticles prepared via the chemical co-precipitation method using thiophenol as template, 300 °C/2h in vacuum optimum temperature and period of annealing to yield nanosized particles. Morphology and structural studies of the particles were using XRD, and TEM, respectively. Results: XRD and TEM studies for the calcined samples revealed a cubic structure. The crystalline size was in the range of 10-17 nm. Thermogravimetric analysis (TGA) was employed to stabilize the temperature of annealing for the samples. The blue shift in the spectra and the band gap value of Codoped CdS nanoparticles were estimated using UV-vis absorption spectra. Photoluminescence spectra revealed a strong blue emission peak around 445 nm indicating the presence of surface states within the bandgap region, which is a characteristic feature of nanoparticles. Conclusion: XRD analysis indicated zinc blend structure and the intensity decreased with increasing Co content. TEM images show that the particles are spherical in shape with average sizes around 13 nm. Luminescence of the synthesized nanoparticles exhibited blue emission between 400 – 500 nm with the peak located at about 445 nm. The emission intensity increased with the increase in Co concentration.

Decoration of X2C nanoparticles on CdS nanostructures for highly efficient photocatalytic wastewater treatment under visible light

It is necessary to design and fabricate effective and stable heterostructures to enhance the photocatalyst performance. In this research, we developed stable metal carbide (Mo2C and W2C) embedded cadmium sulfide (CdS) hybrid nanostructure photocatalysts to increase the light adsorption capacity and effectively enhance the photocatalytic activity.A simple hydrothermal technique was employed to effectively fabricate the CdS and CdS:X2C (X = Mo or W) hybrid photocatalyst. Microscopy studies demonstrated the surface modification of the hybrid structure due to the X2C incorporation with CdS. X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive analysis measurements were performed to characterize the hybrid structure materialization. The photocatalytic properties of CdS and CdS:X2C hybrid structures were evaluated by degrading Rhodamine B (RhB) under visible light. The polygonal shaped CdS:X2Cexhibited excellent photocatalytic activities. The highly porous structure of CdS:X2C indicated that manyexposed active facets were available due to the embedding of petal-shaped X2C, which enabled the effective adsorption and transference of RhB organic molecules to the active edges. Moreover, the hierarchical structure of CdS:X2Ccorresponded to a high light-absorption efficiency due to the increased length of light trails and enhanced interfacial shifting of the valence state electrons, which reduced the optical band-gap.

Passive near-field optical scanning imaging based on semiconductor nanowire/tapered microfiber probe

<sec>In this paper, we propose a passive near-field scanning imaging system by using the structure of cadmium sulfide (CdS) nanowire/tapered microfiber probe, which combines the near-field scanning structure and the nanowire/microfiber coupling technology. In the passive near-field scanning imaging system, a passive nanoprobe is adopted to detect the intensity change of the reflected light field on the sample surface, which not only retains the advantage of the nanoprobe for the strong restriction of the reflected light on the sample surface, but also reduces the interference of strong excitation light during detection. Through the high efficiently evanescent field coupling between the CdS nanowire and the tapered microfiber, the collected light signal is transmitted to the photodetector in the far field, and finally the imaging of the target sample morphology can be realized.</sec><sec>At first, the light field model of the nanowire/tapered microfiber probe structure is verified by the finite element analysis method. The calculated collection efficiency from the sample to the probe is about 4.65‰ and the transmission efficiency from the nanowire to the tapered microfiber is about 74.47%. The collection efficiency is improved by an order of magnitude compared with traditional metal-coated near-field probe. In the experiments, a scanning step of 20 nm and a probe-sample distance of 230 nm are selected. The nanowire/tapered microfiber probe and traditional tapered fiber probe are both used to measure the widths of different CdSe nanoribbons samples, and the atomic force microscopy measurement is used as the benchmark to calculate their measurement error, which is increased about 3 times. By changing the angle <i>θ</i> between the probe and the sample, it is found that the resolution obtained using the designed nanowire/microfiber probe is always higher than only using the tapered microfiber probe. Comparing with the tapered microfiber probe scheme, the measurement error is reduced to a value less than 7.2%.</sec><sec>In addition, compared with the active luminescence probe scheme, this passive near-field scanning scheme reduces the preparation complexity of the optical probe and the detection structure complexity of the optical system. The large microscopic illumination area can avoid the influence of the small laser spot size on imaging, and the imaging range is determined only by the travel distance of the linear stage. Therefore, our work may provide an attractive approach for developing new near-field scanning microscopy systems in the future.</sec>

Optical Properties of Cadmium Sulphide (CdS) Thin Films Spin-Coated on Glass Substrates

Abstract: CdS thin films were synthesized on a glass substrate using spin coating method. The effects of annealing temperature on the optical properties of the prepared CdS films were investigated for different annealing temperatures of 200, 300 and 400 °C. Cadmium acetate, thiourea and ammonia were used as the source materials for the preparation of the thin films. The elemental composition, morphological, optical and structural properties of the films obtained by spin coating were investigated using Energy Dispersive X- ray Spectroscopy (EDAX), Scanning Electron Microscope (SEM), UV Spectrophotometry and X-ray diffraction (XRD) respectively. The SEM image of the unannealed film shows a spherical morphology and an irregular pattern without any void. It also shows that the film covers the substrate well. Annealing leads to an increase in transmittance with the highest transmission of 87% observed for the film annealed at 400oC. With increase in annealing temperature, optical parameters like extinction coefficient and dielectric constants show a reduction, while refractive index and skin depth exhibit an improvement. The absorption coefficient increases with increasing photon energy in the range 3.6 to 4.0 eV. The band gap values of the CdS thin film samples were found to be in the range between 3.14 eV and 3.63 eV. The bandgap is somewhat greater than the value of bulk CdS due to quantum size effect. EDX image confirmed the presence of Cadmium and Sulphur in the prepared CdS films. Annealing did not significantly change the extinction coefficient. The X-ray diffraction confirms the cubic structure of CdS deposited on glass substrate, where reflections from (111), (200), (220) and (311) planes are clearly shown with a preferential orientation along (111) plane. Debye-Scherer equation was used to determine the crystallite size of the most intense plane (111) and the value was found to be 8.4 nm. Keywords: SEM image, Spin coating, Surface morphology, Optical properties, Annealing.

An investigation on CdS1-xTex interface compound in CdS/CdTe hetero-junction solar cells by density functional theory (DFT)

Abstract In this study, we present the structural, optical and electronic properties of zinc blende cadmium sulfide (CdS) and cadmium telluride (CdTe) as well as the intermixed zinc blende ternary CdS1-xTex compound with the compositional variation of S and Te elements. The density functional theory (DFT) method by incorporating the Hubbard model has been utilized to comprehend the relationships between the change of band gap with respect to the molar fraction and its subsequent effects in electronic structures. A 2 × 2 × 2 supercell with 16 atoms has been employed in the molecular design structure of CdTe and CdS. The exchange-correlation potential has been calculated using GGA + U approximation as implemented in the QUANTUM ESPRESSO package along with BURAI software as graphical user interface (GUI). The obtained calculation outcomes are in reasonable agreement with the experimental results in the case of lattice constant and refractive index (n), however, results demonstrate some discrepancy in band gap estimations. The results also exhibit band gap bowing of the ternary CdS1-xTex alloy with the variation of molar fraction (x) which suggest the shrinking of the band gap to the lowest value at x = 0.5 as CdS0·5Te0.5.

Electronic, Structural, and Optical Properties of Zinc Blende and Wurtzite Cadmium Sulfide (CdS) Using Density Functional Theory

Zinc blende (zb) and wurtzite (wz) structure of cadmium sulfide (CdS) are analyzed using density functional theory within local density approximation (LDA), generalized gradient approximation (GGA), Hubbard correction (GGA + U), and hybrid functional approximation (PBE0 or HSE06). To assure the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The relaxed atomic position for the CdS in zb and wz structure is obtained by using total energy and force minimization method following the Hellmann–Feynman approach. The structural optimization and electronic band structure properties of CdS are investigated. Analysis of the results shows that LDA and GGA underestimate the bandgap due to their poor approximation of exchange-correlation functional. However, the Hubbard correction to GGA and the hybrid functional approximation give a good bandgap value which is comparable to the experimental result. Moreover, the optical properties such as real and imaginary parts of the dielectric function, the absorption coefficient, and the energy loss function of CdS are determined.

Investigation of the effect of Manganese doping in CdS nanocrystalline thin films

Undoped and Manganese (Mn) doped nanocrystalline cadmium sulphide (CdS) thin films were successfully grown onto indium tin oxide coated glass substrates using an aqueous wet chemical synthetic route. The effect of doping on the structural, optical and morphological properties was investigated using x-ray diffraction (XRD), Raman spectroscopy, Uv–Vis spectroscopy, photoluminescence and atomic force microscopy. XRD spectra revealed a single peak corresponding to (002) plane of hexagonal crystal structure of CdS. The shift in the peak position is also observed in doped samples confirming incorporation of Mn2+ ions into CdS crystal lattice. Photoluminescence emission bands were analyzed for the physical understanding of doping mechanism in CdS lattice.4T1 → 6A1 energy transition corresponding to emission band 550 nm is observed. The blue shift observed in absorption spectra in Mn doped sample indicates the decrease in particle size. Raman spectra exhibit two peaks corresponding to longitudinal optical phonon mode (LO) at 298 cm−1 and its overtone at 594 cm−1. Mn doped CdS sample shows red shift in the LO peaks representing incorporation of Mn2+ ions into CdS crystal lattice. The increased intensity of LO peak is associated to enhanced coupling between LO phonon and surface plasmon. Uniform, void free adherent nanocrystalline thin films were observed by atomic force microscopy.

Temperature and Interfacial Layer Effects on the Electrical and Dielectric Properties of Al/(CdS-PVA)/p-Si (MPS) Structures

In the present study, cadmium sulphide (CdS) nanopowders were prepared by using a simple physical ball milling technique, and their x-ray diffraction (XRD) analysis confirmed the formation of hexagonal wurtzite structure of CdS. The morphology of CdS nanopowders was characterized by scanning electron microscope (SEM). Dielectric and electrical properties of the manufactured Al/(CdS-PVA)/p-Si (MPS) type structures were investigated by capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements as functions of temperature and applied bias voltage at 500 kHz. Some main parameters of the structure such as real and imaginary parts of complex dielectric constants, e′(= e′–je″), loss tangent (tan δ), a.c. electrical conductivity (σac), and real and imaginary parts of complex electric modulus, M*(= M′ + jM″) of the structure were investigated in the temperature range between 230 K and 340 K. Ln(σac)–q/kT curve showed a linear behavior. The value of activation energy (Ea) was obtained as 0.0601 eV at 5.0 V from the slope of this curve. Moreover, argand diagrams of complex modulus were studied to determine relaxation process of these structures.

An X-ray spectroscopy study of CdS nanoparticles formed by the Langmuir–Blodgett technique on the surface of carbon nanotube arrays

The composition and electronic structure of cadmium sulfide (CdS) nanoparticles formed by the Langmuir–Blodgett (LB) technique on clean silicon wafers and the surface of vertically aligned carbon nanotube (CNT) arrays are studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The samples were annealed in a vacuum at 175 °C and 225 °C to remove the organic matrix of the LB film. From the analysis of the XPS data the increased concentration of sulfate groups on the surface of CdS nanoparticles formed on CNTs and the electron density transfer from CdS to CNTs are determined. An increase in the LB film annealing temperature causes an increase in the degree of crystallinity and the CdS crystallite size and a decrease in the photoluminescence intensity of a CdS–CNT hybrid.

Decoration of MWNTs by CdS Nanoparticles Using Magnetron Sputtering Method

Carbon nanotubes (CNTs) modified with semiconductor nanocrystalline particles may find wide applications due to their unique properties. Here Cadmium Sulfide (CdS) nanoparticles were successfully grown on Multi-Walled Carbon Nanotubes (MWNTs) via a magnetron sputtering method for the first time. The CdS/MWNTs sample was characterized with X-ray diffraction (XRD), Field Emission Scanning and High Resolution Transmission Electron Microscopies (SEM/TEM) and four point probe. The obtained images show clearly the decoration of the MWNTs by the CdS nanoparticles, and the XRD measurements indicate the CdS structure as hexagonal type. Moreover, the physical properties of the CdS/MWNTs were compared with the physical properties of the CdS nanoparticles grown on the silicon. Electrical measurements of CdS and CdS/MWNTs reveal that CdS/MWNTs has lower resistivity than the CdS sample which may be due to the higher carrier concentrations.

Synthesis and Study of CdS Thin Films Prepared with Different KMnO4 Activation Time

The growth and properties of cadmium sulfide (CdS) thin films were prepared in a controlled manner using chemical bath deposition (CBD) method for different KMnO4 activation time such as 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min on glass substrates. CdS thin films are deposited on KMnO4 activated glass substrates at 85°C with pH value of 10 for 30 min deposition time. In the chemical bath deposition (CBD) technique, KMnO4 activation time plays an important role in the growth of the CdS film. The structure of the CdS film changes with respect to the rate of deposition. The size of the particles is affected by the nucleation rate if the solution does not contain the constant number of Cd2+ and S2− ions throughout the deposition process. This change in structure of CdS is confirmed by the XRD, SEM, and AFM analysis, and the ion-by-ion nucleation growth is also examined. The optical property of the prepared CdS thin film is scrutinized using UV-Vis-NIR absorption analysis.

Cadmium sulfide activated zinc oxide coatings deposited by liquid plasma spray for room temperature nitrogen dioxide detection under visible light illumination

Zinc oxide (ZnO) is well-known to be used as a gas sensing material. However, due to its high operation temperature, the chemical and thermal stability of ZnO based gas sensors are relatively low. In recent years, some researchers adopt light illumination as activated source to replace heating and obtain high gas sensing performance at low temperature. The study that follows is an attempt to use cadmium sulfide (CdS) as sensitizer to activate ZnO at room temperature with assistance of visible-light illumination. CdS–ZnO coatings were deposited by liquid plasma spray with aqueous solution containing zinc acetate and cadmium sulfide as precursors. The crystal structure of as-sprayed CdS–ZnO coatings was characterized by X-ray diffractometer (XRD) and field-emission scanning electron microscopy (FE-SEM). The sensing performance of sensors based on CdS–ZnO coatings were tested with 1ppm nitrogen dioxide (NO2) at room temperature illuminated under various visible lights. The results demonstrated that the LPS process was a straightforward method for deposition of high performance CdS–ZnO sensitive layers and the obtained sensors showed high responses to NO2 at room temperature.

Synthesis and Characterization of Cadmium Sulfide Nanoparticles by Chemical Precipitation Method.

Cadmium sulfide (CdS) nanoparticles were synthesized by chemical precipitation method using cadmium chloride (CdCl2), sodium sulfide (Na2S) and water as a solvent by varying temperatures from 20-80 degrees C. The nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), High-resolution transmission electron microscopy (HR-TEM) and UV-Visible spectroscopy. XRD pattern revealed cubic crystal structure for all the synthesized CdS nanoparticles. Raman spectra showed first and second order longitudinal optical (LO) phonon vibrational modes of CdS. The size of CdS nanoparticles was found to be in the range of 15-80 nm by FE-SEM analysis, in all cases. The atomic percentage of cadmium and sulfur was confirmed to be 1:1 from EDS analysis. TEM micrograph depicts the spherical shape of the particles and the size is in the range of 15-85 nm while HR-TEM images of CdS nanoparticles exhibit well-resolved lattice fringes of the cubic structure of CdS. The optical properties of CdS were examined by UV-Visible spectroscopy which showed variation in absorption band from 460-480 nm. The band gap was calculated from the absorption edge and found to be in the range of 3.2-3.5 eV which is greater than the bulk CdS.

OPTICAL AND STRUCTURAL PROPERTIES OF PbCdS TERNARY THIN FILMS DEPOSITED BY CHEMICAL BATH DEPOSITION

Thin films of PdCdS ternary compound have been successfully deposited using chemical baths containing cadmiumacetate, lead acetate thiourea and ammonia. The films were characterised using a variety of techniques. X-ray diffractionanalysis revealed that a number of prominent high intensity diffraction peaks originating from reflections of the tetragonallead sulphide structure. Several smaller low intensity peaks related to reflections of the hexagonal structure of cadmiumsulphide, were also observed. Scanning electron microscopy showed a compact layer with a surface composed of platelikeshaped nanocrystals of different dimensions with well defined boundaries. Energy dispersive X-ray spectroscopyconfirmed the presence of lead cadmium and sulphide. The band gap determined from optical absorption spectroscopywas found to be 1.9 eV.

Optical sensor based on a single CdS nanobelt.

In this paper, an optical sensor based on a cadmium sulfide (CdS) nanobelt has been developed. The CdS nanobelt was synthesized by the vapor phase transportation (VPT) method. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) results revealed that the nanobelt had a hexagonal wurtzite structure of CdS and presented good crystal quality. A single nanobelt Schottky contact optical sensor was fabricated by the electron beam lithography (EBL) technique, and the device current-voltage results showed back-to-back Schottky diode characteristics. The photosensitivity, dark current and the decay time of the sensor were 4 × 104, 31 ms and 0.2 pA, respectively. The high photosensitivity and the short decay time were because of the exponential dependence of photocurrent on the number of the surface charges and the configuration of the back to back Schottky junctions.

Single CdS nanowire photodetector fabricated by FIB

In this paper, a photodetector based on single cadmium sulfide (CdS) nanowire was fabricated using focused ion beam (FIB) technique. The nanowire manipulation, transferring and electrode fabrication process by the FIB and its influence on the photodetector performance were studied. CdS nanowire was synthesized by Vapor–Phase–Transport (VPT) method. CdS powder was thermally evaporated at 950°C in the Argon (Ar) gas as the source material. High Resolution Transmission Electron Microscope (HRTEM) and X-ray Diffraction (XRD) experiment results showed that the nanowire presented wurtzite CdS structure and good crystal quality. The photoresponse time and recovery time of the photodetector were 150ms and 53ms, respectively. The photosensitivity was 2.83, and the low sensitivity was caused by the deposition of Ga on the surface of the nanowire and electrode gap during the FIB fabricating process.

Structure of cadmium sulfide nanoparticle micelle in aqueous solutions

The structure of cadmium sulfide (CdS) micelle in stable aqueous solution of ethylenediaminetetraacetic acid was determined by dynamic light scattering, small-angle X-ray scattering and neutron scattering. The micelle aggregate is a single CdS nanoparticle with an average size of about 3 nm, the nanoparticle organic shell and the solvation shell are about 1 nm and 5 nm thick, respectively. These parameters were confirmed by the scanning semi-contact atomic force microscopy and powder X-ray diffraction studies of dry micelle cores isolated by high-speed centrifugation. The CdS micelle was correctly described by a simple double-shell model and was found to possess the structure corresponding to CdS quantum dots.