Cadmium Sulfide Thin Films Research Articles

Ultrasonic Spray Deposited CdS-GO Composite Films for Solar Cell Applications

In the present study, the synthesis and characterization of cadmium sulfide (CdS) and graphene oxide (GO) composite films are investigated. These films have the potential to be utilized in solar cell applications due to their unique optical and electric properties. A chemical bath deposition was used to prepare the CdS thin films, while the hammer method was used to synthesize GO sheets. In this comparative study, spray deposition was used to prepare CdS-GO composite films with different ratios of CdS to GO. The spray deposition method used in this study offers a simple and cost-effective way to prepare large-area films for practical applications. The structural, and optical, properties of the composite films were characterized using X-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy measurements. The results show that the CdS-GO composite films exhibit enhanced optical properties as compared to the pure CdS films. The band gap energy of the composite films decreased with increasing GO content, indicating improved optical properties. These findings suggest that CdS-GO composite films have the potential for use in solar cell applications. I-V characteristics were obtained using a solar cell tester kit to analyse the applications of fabricated conducting films in the field of solar cells.

In-depth opto-electrical analysis of Ni:CdS film towards the performance as Ag/Ni:CdS/FTO Schottky diode

Nickel doped cadmium sulfide (Ni:CdS) thin films are deposited onto glass and FTO substrate using spray pyrolysis technique. The effect of annealing temperature on the thin films and its morphological, microstructural, optical dispersion, linear-nonlinear and electrical, properties are extensively investigated by using various techniques such as field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM), X-ray diffraction (XRD) and ultraviolet visible (UV-VIS) diffuse reflectance spectroscopy. Morphological studies revealed that doped thin films surface is almost homogeneous and well-covered. Peaks associated with Ni, Cd and S elements are present in EDS analysis, which confirm the composition of the films. The energy band calculation using the Tauc plot from the recorded absorption spectra reveals the decrement in the energy gap from 3.75 eV to 3.61 eV and the refractive index is in the range of 2.57–2.62. The effect of annealing temperature on complex dielectric constant are also analyzed. Moreover, the dispersion of refractive index is calculated in terms of Wemple-DiDomenico approach. Third order susceptibility and nonlinear refractive index are calculated of Ni:CdS films. The designed Ag/Ni:CdS/FTO Schottky diode is tested under illumination conditions, and the empirical diode parameters, viz. ideality factor, barrier height, series resistance etc. are influenced by annealing temperature.

Effect of pulsed hydrogen and helium plasma irradiation on the formation of solid solutions in the thin-film CdTe/CdS heterosystem

The interphase interaction of cadmium sulfide and cadmium telluride thin film layers under irradiation with pulses of hydrogen and helium plasma was investigated by the X-ray diffraction method. CdS/CdTe heterosystem samples were obtained by the hot wall method on glass substrates with a transparent FTO electrode. During deposition of CdS layers 0.3–0.32 µm thick, the temperature of the evaporator zone was 590 °C, and the substrate temperature was 395 °C. CdTe layers 3.8–4.0 µm thick were deposited at an evaporation zone temperature of 520 °C and a substrate temperature of 497 °C. After deposition, the “chloride” treatment of the heterosystem was carried out. The “chloride” treatment consisted in the deposition of a cadmium chloride film 0.7 μm thick on the surface of a CdTe by thermal vacuum evaporation without heating the substrate and by annealing the entire structure in air at a temperature of 410-415 °C for 20 min. The composition of the solid solutions was determined from the lattice period according to Vegard's rule. In the initial state, along with the cubic phase of cadmium telluride, the presence of CdTe1-xSx solid solutions with a sulfur concentration of 3 % and 8.2 % is observed. After irradiation of the CdS/CdTe heterosystems with hydrogen plasma pulses, the entire base layer turned into a solid solution with a sulfur concentration of 3 %. At the same time, two more phases of CdTe1-xSx solid solutions with sulfur concentrations of 6 % and 11.5 % were observed. The relative concentration of the cadmium telluride phase in the initial state was 84 %, after irradiation with hydrogen plasma pulses it was 82 %. In the initial state, the phases of solid solutions with sulfur content of 3 % and 8.2 % had relative concentrations of 7 % and 9 %, respectively; after irradiation, their relative concentrations became 15 % and 3 %, respectively. After irradiation of the CdS/CdTe heterosystem with helium plasma pulses, the entire base layer turned into a solid solution with a sulfur concentration of 1.5 %. In this case, two more phases with a sulfur concentration of 3.7 % and 7.9 % were observed. The relative concentration of cadmium phase telluride after irradiation with hydrogen plasma pulses decreases to 79 %. After irradiation, the relative concentration of the phase of solid solutions with sulfur contents of 3 % and 8.2 % increases to 17 % and 12 %, respectively. The experimentally observed difference in the evolution of the phase composition of the CdS/CdTe film heterosystem under irradiation with hydrogen and helium plasma pulses may be due to the fact that irradiation with more massive helium atoms leads to a greater thermal effect, which causes melting.

Times effect on morphological, structural and optical behaviors of cds thin films for photoelectrochemical cells application

Cadmium Sulphide thin films have been successfully electrodeposited on a conducting Indium-Tin-Oxide (ITO) glass substrate, with different deposition time (10 min, 20 min, and 30 min). The Scanning electron microscopy (SEM), UV-Vis spectrophotometry, X-ray diffraction (XRD), and Atomic force microscopy (AFM) were used to characterize the morphological of films obtained. Moreover, Mott–Schottky (MS) measurements and Photoelectrochemical (PEC) measurements were carried out to study their structural, optical and electrical properties respectively. XRD result points to high crystallinity oriented along (002) planes. The studies reveal that the optical transmission increases with decreasing time of deposition. Mott-Schottky and Photoelectrochemical studies indicates that the CdS thin films display n-type semiconductor, which allows used as layer in photovoltaic cell applications.

Study of CdS/CdS Nanoparticles Thin Films Deposited by Soft Chemistry for Optoelectronic Applications.

Chalcogenides semiconductors are currently being studied as active layers in the development of electronic devices in the field of applied technology. In the present paper, cadmium sulfide (CdS) thin films containing nanoparticles of the same material as the active layer were produced and analyzed for their application in fabricating optoelectronic devices. CdS thin films and CdS nanoparticles were obtained via soft chemistry at low temperatures. The CdS thin film was deposited via chemical bath deposition (CBD); the CdS nanoparticles were synthesized via the precipitation method. The construction of a homojunction was completed by incorporating CdS nanoparticles on CdS thin films deposited via CBD. CdS nanoparticles were deposited using the spin coating technique, and the effect of thermal annealing on the deposited films was investigated. In the modified thin films with nanoparticles, a transmittance of about 70% and a band gap between 2.12 eV and 2.35 eV were obtained. The two characteristic phonons of the CdS were observed via Raman spectroscopy, and the CdS thin films/CdS nanoparticles showed a hexagonal and cubic crystalline structure with average crystallite size of 21.3-28.4 nm, where hexagonal is the most stable for optoelectronic applications, with roughness less than 5 nm, indicating that CdS is relatively smooth, uniform and highly compact. In addition, the characteristic curves of current-voltage for as-deposited and annealed thin films showed that the metal-CdS with the CdS nanoparticle interface exhibits ohmic behavior.

Effect of substrate type on the physical properties of thermally evaporated CdS thin films for CdTe/CdS solar cells applications

Cadmium Sulfide (CdS) thin films were grown on crystal quartz as a nonconductive substrate, and Indium tin oxide (ITO) and Fluorine doped tin oxide (FTO) as transparent conducting oxide (TCO) films. The thin films with the thickness of 100 nm were fabricated at 150 °C under the pressure of 2 × 10−5 mbar using the thermal evaporation method. The x-ray diffraction (XRD) results showed that all grown CdS films had cubic crystal structures with the preferred orientation (111) and a crystallite size between 11.72 nm and 14.84 nm. Raman spectra also revealed an increase in peak intensity and shift toward single-crystal mode in the films grown on TCOs. The homogeneous and uniform surfaces of CdS films were shown in scanning electron microscopy (SEM) images. The optical parameters of the deposited CdS thin films such as absorption, transmission, refractive index, extinction coefficient, and real and imaginary parts of dielectric constant, were improved. The energy band gap of the films was decreased from 2.45 eV for the CdS/quartz film to 2.36 eV for the CdS/FTO one. The key electrical parameters of the deposited films on TCO, such as conductivity, mobility and carrier concentration, as calculated by the Hall effect measurement system, were enhanced too. High efficient heterojunction cadmium telluride (CdTe)-based solar cells with the experimentally grown CdS films were designed by SCAPS-1D simulator. The efficiency of the designed cells with CdS/quartz, CdS/ITO, and CdS/FTO layers was obtained to be 19.40%, 21.23%; and 21.16%, respectively. The impact of the CdTe absorber layer thickness and device temperature on the photovoltaic parameters of the simulated cells was then investigated. The optimized cell was obtained for an Au/CdTe/CdS/ITO structure with the efficiency of 22.80% by employing a 3 μm thickness of the CdTe layer at a device temperature of 300 K.

Studies on the Optical Dispersion Parameters and Electronic Polarizability of Cadmium Sulphide Thin Film

Thin film of Cadmium Sulphide (CdS) was deposited onto a precleaned transparent glass substrate by chemical bath deposition technique from a bath containing Cadmium acetate, ammonium acetate, thiourea and ammonium hydroxide. The deposition time was varied from 10 minutes to 50 minutes at an interval of 20 minutes keeping the bath at a constant temperature of using 78HW-1 constant magnetic stirrer. CdS thin film was characterized by UV-Visible spectrophotometer within the wavelength range of 280 nm – 920 nm using Single – Beam Helios Omega UV – VIS spectrophotometer. The optical parameters; extinction coefficient, refractive index and dielectric constant of CdS thin film were analyzed from the absorption spectra and were found to be affected by the deposition time. The optical band gap energy was obtained by Tauc’s equation and were found to decrease from 3.78 eV – 3.70 eV as the deposition time increases. The dispersion parameters (dispersion energy , oscillation energy , moment of optical dispersion spectra and , static dielectric constant and static refractive index ) were calculated using theoretical Wemple-DiDomenico model. The result show that only and behaved differently but other parameters increase as the deposition time increases. The oscillator strength , oscillator wavelength , high frequency dielectric constant and high frequency refractive index were calculated using single Sellmeier oscillator model. While behaved differently other parameters increase as the deposition time increased. Also, Lattice dielectric constant , N/m* and plasma resonance frequency were equally obtained. While decrease with increase in deposition time, N/m* increase with deposition time. The electronic polarizability of CdS thin film was estimated by Lorenz - Lorentz equation and Clausius Mossotti local field polarizability model. The value is an indication that the films showed good response on the application of photon energy. However, its response reduces as the deposition time increases.

Effects of Heat Treatment in Air Atmosphere on Dip Coating Deposited CdS Thin Films for Photo Sensor Applications

Objective: In this report, photo sensitive materials with enhanced charge carriers have been prepared using dip coating technique. Methods: Cadmium sulphide (CdS) is N-type semiconductor compound belonging to II-VI group. CdS nanoparticles were synthesized using non-aqueous chemical method and characterized by ultraviolet-visible (UV-Vis) absorption spectroscopy, photoluminescence (PL) and transmission electron microscopy. CdS films were deposited on fluorine doped tin oxide (FTO) glass slides using dip coating method at different dip times and heat treated in air and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDAX), mapping and atomic force microscopy (AFM). Results: Quantum confinement effect was observed in UV-Vis absorption spectra of CdS nanoparticles. Quenching of luminescence intensity and blue shift at smaller wavelengths were observed in PL spectra. Presence of highly dense rectangular shaped grains in CdS films and increment in particle sizes with increase in dip time were shown by AFM images. Selected area electron diffraction images showed ring patterns indicating polycrystalline nature of CdS nanoparticles. Increase in crystallite size and decrease in crystal defects by heat treatment in air and increment in grain size with increase in dip time were shown by SEM images. XRD analysis of CdS films showed polycrystalline nature. Conclusion: In previous work, preparation of dip coating deposited CdS films on FTO glass substrates for optoelectronic device applications such as photo sensors has not been reported. In this study, I-V characteristics of heterojunctions under dark and illumination conditions were discussed. Experimental results obtained in our study and their comparison with previous reports were also discussed.

Potential of Hawleyite Cadmium Sulphide (CdS) Nanofilms for PV Cell Applications

The search for suitable materials as buffer layer in the development of photovoltaic cell necessitates the study. The objective is thus, to synthesize and characterize CdS nanofilm for photovoltaic cell application. Thin films of Cadmium Sulphide were deposited on degreased glass substrate, from a bath containing the precursors via Chemical Bath Deposition (CBD) technique. The Physical, Structural, and optical properties were investigated by X-Ray diffractometer, Scanning Electron microscopy (SEM), surface profilometer, Energy dispersive X-ray spectroscopy (EDX) and spectrophotometer. The 9 hours CdS sample showed peak intensities at 30.95o and 51.77o with hkl values of (1 1 1) and (2 2 0). The 12 hours sample showed peak intensities at 30.95o and 51.55o with hkl values of (1 1 1) and (2 2 0). The planes of cubic phase correspond to the mineral Hawleyites for both samples. The average Crystallite grain size for the 9 hours sample is 27.72nm and 38.99nm for the 12 hours samples. The Scanning Electron microscopy analyses illustrate the morphology and the level of uniformity of the CdS coating across the surface of the 9 hours sample and 12 hours samples. The micrographs although slightly similar, the 12 hours sample appeared to be more uniformly coated when compared to the 9 hours sample. Electron-Dispersive X-ray Spectroscopy (EDX) indicated the percentage composition of Cadmium and Sulphide present in the both 9 hours and 12 hours samples, with Cadmium having an average composition of 26.45% and sulphide 8.65% for the 9 hours sample, and 61.95% for Cadmium and 16.43% for Sulphide in the 12 hours CdS sample. The Spectrophotometer was used to investigate the behavior of both samples in the UV (≤ 400nm), Visible and part of the Infrared region. The bandgap energies of both 9 hours and 12 hours sample were 2.36eV and 2.257eV respectively. The average value for the optical conductivity for 9hours sample is 5.099 x 1013 and 7.75 x 1013 for 12 hours sample. The average values of the extinction coefficients, k for 9 hours sample is 1.07 x 109 and 2.02 x 109 for 12 hours sample. The average thickness value of CdS Sample deposited for 9 hours is 14.10 x10-9m while that of the CdS sample deposited for 12 hours is 14.5 x 10-9m. The results affirm the choice of CdS film as buffer layer of the photovoltaic cells.

Investigations on tailoring physical properties of RF magnetron sputtered Cadmium Sulphide thin films

The effect of nitrogen (N2) partial pressure on the structure and bandgap tunability of RF magnetron sputtered Cadmium Sulphide (CdS) thin films is investigated by varying N2 partial pressure in Ar/N2 mixture. In presence of N2, films have a polycrystalline structure with (002) preferential orientation, which leads to defect-free, continuous, dense, and fibrous structures with increased roughness. The average optical transmittance increased to > 80 at 500–2500 nm for 30 % N2 partial pressure, whereas the band gap decreases from 2.45 eV to 2.30 eV with increasing N2 concentration. This work shows that the bandgap of sputtered CdS thin films can be tuned with the variation of N2 concentration for customized applications.

SCAPS 3201 simulation of tunable heterostructured p-CdTe and n-CdS thin films-based solar cells

This paper presents a numerical simulation using SCAPS 3201 and an electrometer for the investigation of electrical behavior at the interface of heterostructured Cadmium telluride and cadmium sulfide thin films. The paper also explicitly compares the theoretical and experimental results of the synthesized materials via the electrodeposition route. Parameters such as electrical conductivity types and energy band gaps used in the simulation were obtained from the various analytical procedure employed in contrast to the conventional mode of application of the SCAPS simulation. In most research works on CdTe/CdS-based solar cells, the conductivity type, p-type, and n-type used in the SCAPS simulation were based on assumption. However, in this study, photoelectrochemical (PEC) cell measurement of the material's conductivity type helped in the identification of p-type CdTe and n-type CdS. The material's properties were examined using an X-ray Diffractometer (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectrophotometer (UV-VIS), (PEC), and electrometer. The energy band gaps at varied cathodic potentials and the grain size of the CdTe thin films were estimated as 1.47–1.89 eV and 56 nm while that of the CdS was estimated at 2.37–2.46 eV and 115 nm. The results indicate a noticeable drastic improvement in the performance of electrodeposited p-CdTe and n-CdS thin film-based solar cells, which aid the tuning of the growth potential. The extracted electrical parameters (JSC = 15.22, Voc = 749, FF = 0.82 and QE = 9.0% at 520 nm) using SCAPS and electrometer are evidence of the improvement made and the results from both the SCAPS and electrometer are in tandem.

Study the Doping Effect of Lead(Pb) on the Optical Properties of Cadmium Sulfide (CdS) Thin Films.

The optical properties of pure and doped Cadmium Sulfide thin films have been stadied in the present work. Cadimum Sulfide can be doped by the Lead of (5%,10%,15%,20%) which prepared by chemical spray pyrolysis technique were deposited on (350ºC) glass substrates. The optical properties– Trasmittance (T), Absorbtance (A), Energy band gap (Eg), Absorption coefficient(α) and Extinction Coefficient (ko) - within wave length range (330-1100)nm. The cadmium sulfide (pure) thin flims were found to exhibit hight trnsmittance abute (82-86)%, the transmittance decreases with the increasing the doped ratio by the lead(Pb).The direct band gap energy of films decreases from (2.40eV) for the pure thin films to (2.35,2.31,2.25,2.19 eV) for the doped by lead at (5%,10%,15%,20%).

Study of the Optical properties for CdS before and after irradiated by CO2 laser for different exposure times

Cadmium sulphide (CdS) thin films were deposited on glass substrates using thermal vacuum evaporation technique at pressure (10-6) Torr at room temperature then samples irradiated by CO2 laser of power (1 watt) and wave length (10.6) μm at distance 10 cm from the source during different exposure times (3, 5, 10, 15) sec. The absorbance spectra was recorded using UV-visible spectrophotometer .Optical properties such as transmission , reflection ,absorption coefficient (α), optical band gap (Eg), extinction coefficient (K), refractive index (n), and complex dielectric constants (er&ei) were evaluated from absorbance spectra. The results shows that the laser irradiation cause increased in reflectance R, absorption coefficient a, the extinction coefficient K, the refractive index n and the real part and imaginary part of dielectric constant while irradiation cause decrease in the transmittance T and the value of the energy gap Eg.

Development of an ultrafast photo-switch device using surface passivated nanocrystalline CdS thin film

The development of an ultrafast optical switch is demonstrated in this work using a surface passivated nanocrystalline cadmium sulfide (CdS) thin film. The optical switching ratio of the Ag/CdS/Ag device, after surface passivation with nitrocellulose, is 2.1 × 104 in just 0.4 ms under a constant bias of 10 V and blue light (380 nm) of intensity ∼7.4 mW/cm2, which is 100 times higher than the native device. This is because the surface sulphur vacancy defects are suppressed, increasing the concentration of photo-generated free carriers.

Effect of gold on photo luminescence properties of Cadmium Sulphide thin films deposited by pulsed laser deposition

Cadmium Sulphide (CdS) on gold (Au) nanoparticle thin films were deposited by pulsed laser deposition (PLD) on sapphire and Silicon (Si) substrates. The films were analyzed by X-ray photo electron spectroscopy (XPS) to determine the binding energy of the constituent elements, atomic force microscopy (AFM) for surface morphology, X-ray diffraction (XRD) for crystal structure, photo luminescence (PL) and UV–VIS measurements for optical properties. The results of XPS analysis and spectroscopic ellipsometric characterization revealed the formation of CdS films. The films surface shows uniform smooth topography and having Hexagongal phase crystalline structure. The optical absorption spectra of CdS films deposited at room temperature (RT) showed absorption edge at around 580 nm which blue-shifted at high deposition temperature of 300 °C. The band edge photoluminescence of CdS films observed at 590 nm was enhanced with Au nanoparticle films present as the bottom of the layer attributed to the plasmonic related optical coupling between two materials. However, when the nanoparticles were deposited on top layer the luminescence was found to be quenched due to the internal absorption of the Au films due to plasmon resonance. The results of the study reveal that the optimum controlled deposition of Au nanoparticles with CdS thin films will be useful for fabrication of efficient opto-electronic devices.

Deposition and Characterization of Spray Pyrolytic Cadmium Sulphide Thin Film

Deposition and Characterization of Spray Pyrolytic Cadmium Sulphide Thin Film

Growth-control of hexagonal CdS-decorated ZnO nanorod arrays with low-temperature preheating treatment for improved properties and efficient photoelectrochemical applications.

The limitations of oxide semiconductor-based solar cells in achieving high energy conversion efficiencies have prompted incessant research efforts towards the creation of efficient heterostructures. Despite its toxicity, no other semiconducting material can fully replace CdS as a versatile visible light-absorbing sensitizer. Herein, we explore the aptness of preheating treatment in the successive ionic layer adsorption and reaction (SILAR) deposition technique and improve the understanding of the principle and the effects of a controlled growth environment on thus-formed CdS thin films. Single hexagonal phases of nanostructured cadmium sulfide (CdS)-sensitized zinc oxide nanorods arrays (ZnO NRs) have been developed without the support of any complexing agent. The influences of film thickness, cationic solution pH and post-thermal treatment temperature on the characteristics of binary photoelectrodes have been investigated experimentally. Interestingly, the preheating-assisted deposition of CdS, which is rarely applied for the SILAR technique, resulted in improved photoelectrochemical performance similar to the post-annealing effect. The X-ray diffraction pattern revealed that optimized ZnO/CdS thin films were polycrystalline with high crystallinity. Examination of the morphology of the fabricated films via field emission scanning electron microscopy showed that film thickness and medium pH altered the growth mechanism of nanoparticles, thereby changing their particle sizes, which had a significant influence on the film's optical behavior. The effectiveness of CdS as a photosensitizer and the band edge alignment for ZnO/CdS heterostructures were evaluated using ultra-violet visible spectroscopy. Facile electron transfer in the binary system as evidenced in electrochemical impedance spectroscopy Nyquist plots, therefore, promotes higher photoelectrochemical efficiencies from 0.40% to 4.30% under visible light illumination as compared with the pristine ZnO NRs photoanode.

Influence of Molar Concentrations on Chemical Bath Deposited Cadmium Sulphide Thin Films

Thin films (TFs) of cadmium sulphide (CdS) have been deposited at 300K on soda-lime substrates. The effect of the molar concentrations was investigated using the X-ray diffraction (XRD) and UV-Vis Spectrophotometer. The XRD measurements show that the TFs were crystalline and increases with increasing molarities. The optical characteristics of the films were studied at spectra range of 300 – 950 nm. It indicated that the band gap energy ranged between 1.80 to 1.83 eV. The films exhibited a high transmittance in the visible and near infrared regions with a low reflectance values within same regions. Other optical constants like extinction coefficient (K), refractive index (n), real (Ɛᵣ) and imaginary (Ɛᵢ) dielectric constants and optical conductivity (σ) were determined with respect to photon energy (eV). These properties of CdS TFs confirm that the material could be beneficial in various optoelectronics applications.

Studies on Sn doped cadmium sulfide thin films as highly selective green light photosensors

Studies on Sn doped cadmium sulfide thin films as highly selective green light photosensors

Electrical Characterization of Chemically Grown CdS and CdTe Thin Films for Solar Cell Application

Thin films of Cadmium Sulphide (CdS) and Cadmium Telluride (CdTe) have gained a great deal of interest due to their potential applications in solar cells. Deposition of CdS and CdTe thin films were performed on Soda Lime glass and FTO substrate at 400℃ and 300℃ respectively using spray pyrolysis technique. The Hall Effect property was measured for the deposited CdS and CdTe films. These results shows the resistivity and mobility of CdS films deposited at 400℃ were 1.588×104 Ωcm and 5.619×102 cm2/Vs, respectively, The annealed CdTe thin film had a resistivity value of 1.016×104 Ωcm, while the annealed and etched CdTe thin film had a resistivity value of 4.52×104 Ωcm, The resultant films are observed to be good to make a solar cell with CdS as a window layer and CdTe as absorber layer.