Radio Frequency Magnetron Sputtering Deposition Research Articles

The ferroelectric and piezoelectric properties of (Hf1−x Ce x )O2 films on indium tin oxide/Pt/TiO x /SiO2/(100)Si substrates obtained using a no-heating radio-frequency magnetron sputtering deposition method

The effect of composition and film thickness on the ferroelectric and piezoelectric properties of (Hf1−x Ce x )O2 films deposited without substrate heating was investigated. (Hf1−x Ce x )O2 films with various x values (x = 0.07–0.27) and thickness (150–880 nm) were deposited via RF magnetron sputtering on indium tin oxide (ITO)/Pt/TiO x /SiO2/(100)Si substrates. The crystalline phases of the films were observed by X-ray diffraction. The measurements of electrical properties revealed ferroelectric phases in the x range of 0.11–0.21. The film with x = 0.16 exhibited the maximum remanent polarization (Pr) of 15 μC cm−2, as well as the highest effective piezoelectric coefficient. In addition, the ferroelectric and structural properties remained almost unchanged with increasing film thickness. Therefore, the no-heating deposition of ferroelectric (Hf1−x Ce x )O2 films and their phase stability with respect to thickness were demonstrated in this study. This work provides a pathway for the deposition of ferroelectric (Hf1−x Ce x )O2 films on flexible, wearable sensors.

Highly sensitive self-powered solar-blind ultraviolet photodetectors based on n-Zn1-xFexO/p-Si heterojunctions

The pristine and iron-doped ZnO thin films were fabricated on p-type silicon and glass substrates using the radio-frequency magnetron sputter deposition technique. The structural, morphological, and electrical properties of the deposited thin films were analyzed using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and I-V characteristics. XRD analysis revealed the preferential growth of ZnO along the c-axis, with lattice parameter (c) values of 5.216, 5.234, and 5.241 Å for the pristine ZnO, Zn0.97Fe0.03O, and Zn0.95Fe0.05O thin films, respectively. The crystallite sizes were measured to be 13.2 nm, 16.2 nm, and 18.3 nm for the respective films. The elemental analysis of the deposited films was done under X-ray photoelectron spectroscopy (XPS), which revealed the concentrations of iron Zn0.97Fe0.03O, and Zn0.95Fe0.05O thin films were 2.93 at% and 5.14 at%, respectively. Raman spectroscopy confirmed the presence of the hexagonal wurtzite structural form in the deposited films. The I-V characteristics of the deposited films confirmed the formation of a heterojunction between the film and the silicon substrate. Furthermore, the constructed heterojunction devices were evaluated for their ability to detect ultraviolet (UV) radiations of wavelengths 365 nm and 254 nm. The devices exhibited response and recovery times of less than 1 s. The detectivity values were found to be 0.321 ×1011, 1.051 ×1011, and 2.992 ×1011 Jones for the ZnO/p-Si, Zn0.97Fe0.03O/p-Si, and Zn0.95Fe0.05O/p-Si devices, respectively, under a fixed illumination intensity of 0.812 mW/cm2 for a UVA source with a wavelength of 365 nm. These results confirm the excellent photodetection ability of the constructed devices. The mechanism of UV radiation detection by the devices has also been extensively discussed.

Numerical Modelling and Simulation for Sliding Wear Effect with Microstructural Evolution of Sputtered Titanium Carbide Thin Film on Metallic Materials

Titanium carbide materials are introduced into manufacturing industries for the reinforcement and surface protection of base materials due to their substantial ability to withstand severe environments, which include sliding wear, corrosion, and mechanical failures. A thin film of titanium carbide (TiC) is coated onto brass and copper substrates using the radio frequency magnetron sputtering (RFMS) deposition method. The coating process is carried out at constant processing parameters, which include a sputtering power of 200 W, a temperature of 80 °C, a deposition time of 180 min, and an argon (Ar) gas flow rate at 10 standard cubic centimetres per minute (SCCM). The coating, together with the base materials, is modelled and its behaviours are simulated using ANSYS Workbench R19.2 Academic, supported by Mechanical APDL solver for nonlinear finite element analysis (FEA). The deformation, equivalent stress–strain characteristics, and elastic–plastic properties of the coating are determined at applied loads of 60 N and 25 N and coefficients of friction (CoF) of 0.25 and 0.38 for the thin film deposition on brass and copper substrates. The sliding distance and the speed of the alloy steel ball used during the sliding wear operation are found to be 3 mm and 4 mm/s, respectively. The sliding wear modelling and simulation process are, however, designed for the ball-on-flat (BoF) wear technique with a dry sliding approach. Therefore, BoF wear simulations are also performed on titanium carbide–brass (TiC-Br) and titanium carbide–copper (TiC-Cu) conjugates for the evaluation of surface engineering applications such as cutting tools and in automotive, aerospace, thermomechanical, and biomedical fields. The ball used for the FEA wear simulation is made from alloy steel material (AISI 52100) with a radius of 3.175 mm.

Study of optical and structural properties of CZTS thin films using copper capping layer and sulfurization to correct stoichiometry

Non-toxic, environment friendly and low cost Cu2ZnSnS4 (CZTS) thin films were deposited on sodalime glass substrates by radio frequency magnetron sputter deposition technique. Stoichiometry analysis revealed that the as-deposited films were Cu deficient. Hence, Cu capping layer was deposited, to study its’ effect on optical and structural properties of the films. These films were subsequently sulfurized in a quartz setup. Ultimately, stoichiometric CZTS films with improved Cu content up to 27.4% were obtained. The kesterite CZTS phase was identified in the samples using x-ray diffraction measurements. The morphological studies revealed that, grain size varies as a function of the thickness of Cu capping layer. The formation of undesired Cu2S and ZnS phases were also observed in the film with Cu content above and below the optimum range. Optical bandgap (Eg) of the films could also be optimized by controlling the Cu content in the film. An optimal Cu content between 24% and 26% was found to be appropriate for achieving a desired bandgap within a range of 1.55 to 1.4 eV, suitable for application in thin film solar cells. The CZTS films with corrected stoichiometry have a charge carrier density in the rage of ∼1021 cm−3, which are much better than values reported so far in the literature.

The Effect of Transient Power Ramp‐Up on Structural and Optical Properties of CuO Thin Films Prepared by Radio Frequency Magnetron Sputtering

Transition metal oxides have found application as charge transport materials (CTMs) in perovskite solar cell devices due to their better environmental stability and superior electronic properties compared to organic CTMs. Many researchers have used radio frequency (RF) magnetron sputtering to deposit inorganic CTMs on inorganic layers. However, such efforts on perovskites have been limited by the distortion of high‐energy ions of the sputtering gas energized by the RF power and temperature. The ions may also distort the interface between transparent conducting oxides and the charge transport layers, thereby increasing optical scattering. Thus, the effect of ramp power during RF magnetron sputtering deposition on the structural and optical properties of copper oxide thin films is investigated. While the optical transmittance of the films decreases with increased RF power, it remains the same for all ramped power films; however, it has a similar profile as the highest RF power film. As the ramp power increases, the X‐ray diffraction shows that the films become more polycrystalline with a monoclinic crystal structure. The energy‐dispersive X‐ray spectroscopy results reveal that the atomic concentration of copper slightly increases with the RF power, whereas oxygen concentration slightly decreases.

Mechanism of high qualified Mn-Co-Ni-O thin films grown at low temperature

High quality of Mn-Co-Ni-O (MCNO) thin films were prepared by radio frequency (RF) magnetron sputtering deposition at a very low temperature of ≤450 °C. The structure and electrical transport of the films were investigated under different growth and annealing conditions. It was found that the film can be transformed from a mixed conduction mechanism to a single variable range hopping conduction mechanism under appropriate condition. The optimized Mn3+/Mn4+ ratio in the film was close to 1, which was corresponding to the best probability of small polaron hopping, lowest activation energy, lowest room temperature resistivity, large negative resistance temperature coefficient, and the specific preferred (400) orientation. The electrical properties of the film were similar to that prepared under high temperature condition, which promotes the integration of MCNO to the present matured silicon technology. Our results provide an important avenue for the development of next generation of uncooled infrared focal plane arrays.

Radio-frequency magnetron sputtering deposition process for In2O3:H transparent conductive oxide films for application in Cu(In,Ga)Se2 solar cells

Typical Cu(In,Ga)Se2 solar cells are deposited on an opaque molybdenum back contact. However, for applications such as bifacial, semi-transparent or tandem solar cells a transparent back contact is required, for which various transparent conductive oxides have been tested, such as indium- or fluorine-doped tin oxide, and hydrogen-doped indium oxide. Here, a radio-frequency magnetron sputtering deposition process for In2O3:H (IOH) is investigated, where H is supplied from a Ar/H2 (5%) mixed gas and oxygen is pulsed during the entire deposition at room temperature. After deposition, the films are post-annealed in vacuum to optimize their optoelectronic properties. The oxygen plays an important role for the optoelectronic properties, where a high content of oxygen allows higher transparency but also increases the film sheet resistance. Optimum oxygen and Ar/H2 partial pressures of 3.2 × 10−2 Pa and 13×10−2 Pa, respectively, were found, producing IOH films with average visible transparency of 87% and sheet resistance after annealing of 19 Ohm/sq.

Radio-frequency magnetron sputter deposition of ultrathick boron carbide films

The deposition of thick B4C films with low residual stress by conventional direct-current magnetron sputtering is accompanied by the formation of dust particulates contaminating the target, chamber, and substrates and leading to the formation of nodular defects in films. Here, we demonstrate that the formation of particulates is greatly reduced during radio-frequency magnetron sputtering (RFMS). We systematically study properties of B4C films deposited by RFMS with a substrate temperature of 330 °C, a target-to-substrate distance of 10 cm, Ar working gas pressure in the range of 4.5–12.0 mTorr (0.6–1.6 Pa), and substrate tilt angles of 0°–80°. All films are x-ray amorphous. A columnar structure develops with increasing either Ar pressure or substrate tilt. For columnar films, the column tilt angle decreases with increasing Ar pressure, which we attribute to a corresponding increase in the width of the distribution of impact angles of deposition flux. In contrast to the Keller–Simmons rule, the deposition rate increases with increasing Ar pressure, which suggests a better coupling of the RF energy to the plasma processes that lead to target sputtering at higher pressures. There is a critical substrate tilt angle above which the total residual stress is close to zero. This critical substrate tilt angle is ∼0° for an Ar pressure of 12 mTorr (1.6 Pa). The lower residual stress state, necessary for depositing ultrathick films, is characterized by a larger concentration of nanoscale inhomogeneities and decreased mechanical properties. Based on these results, RFMS deposition of 60-μm-thick B4C films is demonstrated.

Study of Optical and Electrical Properties of RF-Sputtered ZnSe/ZnTe Heterojunctions for Sensing Applications

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Zinc Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical and electrical characterization was performed. Onto an optical glass substrate, 100 nm gold (Au) thin film was deposited by Thermal Vacuum Evaporation (TVE) representing the back-contact, followed by the successive RF-MS deposition of ZnTe, ZnSe, Zinc Oxide (ZnO) and Indium Tin Oxide (ITO) thin films, finally resulting in the Au/ZnTe/ZnSe/ZnO/ITO sub-micrometric “substrate”-type configuration. Next, the optical characterization by Ultraviolet-Visible (UV-VIS) spectroscopy was performed on the component thin films, and their optical band gap values were determined. The electrical measurements in the dark and under illumination at different light intensities were subsequently performed. The Current–Voltage (I–V) characteristics in the dark are nonlinear with a relatively high asymmetry, following the modified Shockley–Read equation. From their analysis, the series resistance, shunt resistance, the ideality factor and saturation current were determined with high accuracy. It is worth noting that the action spectrum of the structure is shifted to short wavelengths. A sensibility test for the 420–500 nm range was performed while changing the intensity of the incident light from 100 mW/cm2 down to 10 mW/cm2 and measuring the photocurrent. The obtained results provided sufficient information to consider the present sub-micrometric photodiodes based on n-ZnSe/p-ZnTe heterojunctions to be more suitable for the UV domain, demonstrating their potential for integration within UV photodetectors relying on environmentally-friendly materials.

Optical study of Ga2-xSnxO3 (0 ≤ x ≤ 0.7) thin films using spectroscopic ellipsometry and cathodoluminescence

Diagnosis of the semiconductor defect levels is essential for their device applications. The optical and electrical properties of Ga2-xSnxO3 (GTO, 0 ≤ x ≤ 0.7) films were investigated to look into the defect levels. Amorphous GTO thin films were grown on Si substrates with various Sn contents via radio frequency magnetron sputtering deposition. Thermal annealing at 900 °C for two hours was performed after the deposition of films at 500 °C to achieve the polycrystalline phase. We examined the physical properties of amorphous β-Ga2O3 thin films grown using various O2 gas flows during growth, and of the post-annealed GTO films. Using spectroscopic ellipsometry, the optical constants in the spectral range between 1.0 and 6.0 eV were determined. We estimated the optical gap energy of the GTO layers using the Tauc method. The optical gap energy was approximately 4.9 eV for amorphous β-Ga2O3 films. Optical structures owing to defects were found below optical gap energy in the spectra of the complex refractive index. Using cathodoluminescence (CL) spectroscopy, there were several peaks discovered in the range between 1.5 and 3.0 eV. The CL peaks correspond to transitions between valence (conduction band) and defect-induced gap states. We identified the 1.5 − 1.6 eV peak as the transition between defect states and the conduction band. The extinction coefficient (k) peak became sharper at 5.3 eV suggesting a strong excitonic behavior at the fundamental gap for amorphous Ga2O3 films.

Bi-Substituted Ferrite Garnet Type Magneto-Optic Materials Studied at ESRI Nano-Fabrication Laboratories, ECU, Australia

Since 2007, at the Electron Science Research Institute (ESRI) nano-fabrication laboratories, Edith Cowan University, Australia, we have devoted research efforts to the synthesis and characterization of bismuth-containing ferrite-garnet-type thin-film magneto-optic (MO) materials of different compositions. We report on the growth and characteristics of radio frequency (RF) magnetron sputtered bismuth-substituted iron-garnet thin films. We study the process parameters associated with the RF magnetron sputter deposition technique and investigate the results of optimizing process parameters. To achieve the best MO properties, we employ a few unique techniques, such as co-sputtered nanocomposite films and all-garnet multilayer structures, as well as the application of oxygen plasma treatment to amorphous garnet layers immediately following the deposition process. We demonstrated a remarkable enhancement in the MO properties of Bi-containing ferrite-type garnet thin-film materials, including record-high MO figures of merit and improved conventional and unconventional hysteresis loops of Faraday rotation. Previously unpublished research results on the forward-looking applications of magnetic garnet coatings applied to microparticles of advanced luminescent materials are reported. In the context of developing the next-generation ultra-fast optoelectronic devices, such as light intensity switches and modulators, high-speed flat panel displays, and high-sensitivity sensors, it is important to consider the desirable optical, magnetic, and magneto-optic properties that are found in highly bismuth-substituted iron garnet thin-film materials of various composition types.

Effect of the Cadmium Telluride Deposition Method on the Covering Degree of Electrodes Based on Copper Nanowire Arrays

In this work, we report the preparation of nanostructured electrodes based on dense arrays of vertically-aligned copper (Cu) nanowires (NWs) to be subsequently covered by cadmium telluride (CdTe) thin films, with great potential to be used within “substrate”-type photovoltaic cells based on AII-BVI heterojunctions. In particular, the multi-step preparation protocol presented here involves an electrochemical synthesis procedure within a supported anodic aluminum oxide (AAO) nanoporous template for first generating a homogeneous array of vertically-aligned Cu NWs, which are then further embedded within a compact CdTe thin film. In a second stage, we tested three deposition methods (vacuum thermal evaporation, VTE; radio-frequency magnetron sputtering, RF-MS; and electrochemical deposition, ECD) for use in obtaining CdTe layers potentially able to consistently penetrate the previously prepared Cu NWs array. A comparative analysis was performed to critically evaluate the morphological, optical, and structural properties of the deposited CdTe films. The presented results demonstrate that under optimized processing conditions, the ECD approach could potentially allow the cost-effective fabrication of absorber layer/collecting electrode CdTe/Cu nanostructured interfaces that could improve charge collection mechanisms, which in turn could allow the fabrication of more efficient solar cells based on AII-BVI semiconducting compounds.

Complex dielectric function, Cole-Cole, and optical properties evaluation in BiMnO3 thin-films by Valence Electron Energy Loss Spectrometry (VEELS) analysis

Valence Electron Energy Loss Spectrometry-Transmission Electron Microscopy (VEELS-TEM) analyses were found to provide important information on optical properties and the dielectric function of BiMnO3 thin films grown, via radio frequency (RF) magnetron sputter-deposition on SrTiO3 substrates. The research described in this article involved using Kramer's–Krӧnig analysis to determine bandgap, complex dielectric function, and static dielectric constant, ε* = 4.68 of the grown BiMnO3 thin films. The reflection coefficient Ґl of the BiMnO3 thin films was used to elucidate the reflection loss in the BiMnO3 thin films. The bandgap energy of the films was determined using a polynomial fit in the energy loss function (ELF) plot with an Eg = 1.63 eV. The scope of the Cole-Cole plot demonstrates the bandgap and the plasmon region in the BiMnO3 films, which is reported here for the first time. A key contribution of this article relates to describing formulations used for transforming the experimentally obtained dielectric constant components of the BiMnO3 films to produce Cole-Cole plots and applying Kramers-Krӧnig analysis to transform a single scattering energy loss function, to enable determination of the complex dielectric function ε′andε″ and structure of BiMnO3 films.

Nonlinear optical properties and passively Q-switched laser application of a layered molybdenum carbide at 639 nm.

Molybdenum carbide (Mo2C) exhibits enormous potential applications in various optoelectronic and photonic fields due to its remarkably electrical and optical characteristics. Here, we fabricate a high-quality Mo2C film by the radio frequency magnetron sputtering deposition method. The nonlinear optical response and ultrafast dynamics are thoroughly studied based on open-aperture Z-scan and nondegenerate pump-probe experimental measurements. The open-aperture Z-scan experimental result exhibits a modulation depth of 8.5% and a saturation fluence of 0.28 mJ/cm2. Simultaneously, the relaxation time constant is fitted by a biexponential decay function, showing an ultrafast intraband carrier recovery time of 0.58 ps at 530 nm. Consequently, by employing the Mo2C film as a saturable absorber (SA), stable Q-switched Pr:YLF laser pulses with the shortest pulse width of 160 ns are generated at 639 nm. Our experimental results demonstrate excellent nonlinear optical properties of the layered Mo2C in the visible region and will further advance their potential applications in visible nonlinear optics.

Effect of implantation of nitrogen ions into VO2 thin films

Modifications in the structural and electronic properties of VO2 films induced by N+ ion implantation were investigated. VO2 films prepared by radio frequency (RF) magnetron sputtering deposition on quartz substrate were subjected to the N+ ion beam with 55 keV at different fluences (1 × 1015 and 1 × 1016 ions/cm2). Compared with the pristine VO2 film (Tc ∼ 342 K), structural and electrical phase transition temperatures were shifted around room temperature in the N+ ion implanted sample (fluence = 1 × 1015 ions/cm2). Furthermore, a higher fluence of N+ ions (fluence = 1 × 1016 ions/cm2) had significantly modified the crystalline structure of VO2 thin film, and a metallic behaviour was clearly noticed in the entire temperature range between 240 K and 373 K under this study. N+ ion implantation effectively induces the changes in the electronic structure of VO2 thin films, which are further confirmed by the X-ray absorption spectroscopy (XAS) measurements.

Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

Herein, the prospect of using amorphous Si1–x Sn x alloys as alternative temperature‐sensing active materials in microbolometers is evaluated by studying their temperature‐dependent resistive properties along with their infrared optical properties. Si1–x Sn x thin films (200 nm thick), with varying Sn concentrations, are prepared at room temperature by cosputtering from Si and Sn targets using simultaneous radio frequency and DC magnetron sputter deposition. Low beam energy X‐ray microanalysis is used to estimate the atomic concentrations of the prepared films. Atomic force microscopy analysis shows an increase in the root‐mean‐square surface roughness of the prepared Si1–x Sn x thin films, with increasing Sn content. Sheet resistance versus temperature measurements are performed yielding temperature coefficients of resistance of 3.25, 2.65, and 1.72% K−1 at resistivity values of 116.18, 27.36, and 2.34 Ω cm for Sn concentrations of 35%, 44%, and 48%, respectively. Infrared ellipsometry measurements are performed to extract the optical properties of the Si1–x Sn x thin films and optical simulations confirm that a Fabry–Pérot cavity microbolometer configuration containing an Si1–x Sn x thin film can achieve high absorptance in the 8–12 μm band. This study shows that Si1–x Sn x alloys are a suitable, simple, and low‐cost replacement for thermometer layers used in uncooled infrared microbolometers.

Optimization of a potential manufacturing process for thin-film LiCoO2 cathodes

A radio frequency (RF) magnetron sputter deposition process designed for low-cost, high-rate fabrication of LiCoO2 (LCO) thin films was developed and used to fabricate approximately phase pure cathodes with the R3¯m crystal structure, strong (104) preferred orientation and high discharge capacities. Starting from a typical set of processing conditions for LCO films, the values of key deposition and post-deposition parameters were systematically changed to increase the deposition rate, simplify the sputter deposition process and minimize process gas use without compromising the structural properties and electrochemical performance. Cathodes were deposited onto Waspaloy (58Ni-19Cr-14Co-Mo-Ti-Al-Fe [wt%]) foil current collectors to provide enhanced thermal stability during post-deposition annealing. The best properties were attained using a process pressure of 0.5 Pa, an RF power density of 5.5 W cm−2 and a post-deposition anneal in air at 600 °C for 2 h. A sintered sputter target, oxygen gas flow and substrate heating were not required. This set of conditions resulted in a high deposition rate of ∼700–790 nm h−1, allowing the formation of a relatively thick (∼2.8–3.2 µm) film in 4 h. Furthermore, high maximum specific and areal discharge capacities of 132 mAh g−1 / 62 µAh cm−2µm−1 and 172 μAh cm−2 were attained during galvanostatic cycling at a rate of 0.1 C with an organic liquid electrolyte, which are among the highest values reported. Cycling rate tests showed that the thin-film LCO cathodes could deliver capacity up to a cycling rate of at least 2 C without causing any significant cell damage.

High laser fluence ITO coatings utilizing a Fabry-Perot thin film filter to reduce effective absorption.

Laser-induced damage threshold of transparent conductors, such as Indium Tin Oxide (ITO), is limited by their high optical absorption due to free carriers. However, the effective absorption of a transparent conductor thin film can be reduced by an order of magnitude, without changing the electrical characteristics of the film, when placed in a low electric field section of a multilayer coating. A Fabry-Perot thin film interference filter has both high transmittance and low electric field positions, so it is an ideal thin film structure for this application. Although Fabry-Perot interference filters are not known as particularly high laser-induced damage resistant coatings due to their resonant characteristics, a laser-induced damage threshold (LIDT) improvement of up to 8× was observed with this technique compared to single layer ITO coatings fabricated using either radio frequency magnetron sputtering or electron-beam deposition. Additionally, an approximately 4× LIDT improvement for a Fabry-Perot interference filter has been observed by the addition of ITO into the multilayer structure.

Growth and structural characterization of Sb2Se3 solar cells with vertical Sb4Se6 ribbon alignment by RF magnetron sputtering

Sb2Se3, (ASe) thin-films were deposited as the absorber layers in photovoltaic solar cells using the radio frequency magnetron sputtering deposition technique. Starting from a binary target, high quality crystallization and good vertical alignment of Sb4Se6 ribbons were attained at growth temperatures below 300 °C, and use of an additional selenization process was unnecessary for compensating Se loss. By the structural characterization of films grown on different substrates, a strong dependence of the ribbon orientation on the substrate type was verified. This study clearly confirms that the ribbon alignment is the key factor for enhancing the performance of Sb2Se3 solar cells, in particular the short circuit current density (J sc). A photovoltaic efficiency of 0.24% and a J sc of 5 mA cm−2 were obtained by depositing ASe on Mo, in a CuInGaSe2-like solar cell structure (Al:ZnO/ZnO/CdS/ASe/Mo/Glass), while the J sc was boosted up to 27 mA cm−2 when the ASe solar cells were fabricated in superstrate configuration with an Au/ASe/CdS/FTO architecture, leading to an efficiency of 2.36%.

A comparative study of CdS thin films grown on ultra-thin glass substrates by RF magnetron sputtering and chemical bath deposition

The structural, morphological and optoelectrical characteristics of cadmium sulfide (CdS) thin films grown on ultra-thin glass substrates via Radio Frequency (RF) magnetron sputtering and chemical bath deposition (CBD) have been explored in this study. CdS thin films were characterized using the X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), UV–Vis spectrophotometer and Hall effect measurement system. As obvious from XRD investigation, the stable hexagonal wurtzite crystalline structure with (002) preferential orientation was resulted from both deposition methods. FESEM study demonstrated uniform grain structure for the sputtered films. Compositional analysis confirmed that S/Cd ratio is 0.28 for the sputtered films and 0.20 for the CBD films. AFM study exhibited spherical crystal surface formation, hills and valleys for CBD films. The optical analysis showed a band gap of 2.40 eV and 2.32 eV for the sputtering and the CBD methods, respectively. Hall effect analysis recorded carrier concentration and resistivity in the order of 1013 cm−3 and 104 Ω cm, respectively. The experimental results recommend that the CdS thin films grown by the sputtering might be favourable as the window layer for solar cell application.