Radio Frequency Magnetron Sputtering Technique Research Articles

Titanium Nitride-Gold Nanoislands: Harnessing Electrical and Optical Properties for Enhanced Localized Surface Plasmon Resonance Sensing

Titanium nitride-gold nanoislands (TANIs) are experimentally investigated to explore their electrical and optical properties induced by the incorporation of Au into TiN. A film is first fabricated on a glass substrate using the radio frequency (RF) magnetron sputtering technique at 300 K, with a thickness of approximately 20 nm (± 2.5 nm) and an Au:TiN ratio of 0 to 0.47. Subsequent thermal annealing provides a nanoisland structure of TiN-Au. Characterization techniques such as X-ray diffraction and X-ray photoelectron spectroscopy confirmed the presence of TiN and Au in the fabricated TiN-Au nanoislands. Spectroscopic ellipsometry measurements show that the TANIs posses excellent optical properties. Furthermore, numerical evaluations of energy dissipation are conducted to assess carrier transport deterioration due to the inelastic scattering effects in the TANIs and the inclusion of Au in the nanostructure significantly have reduced the dielectric loss tangent at energies greater than 4.5 eV, compensating for high losses and enhancing optical performance. The biosensing capability of TANIs is also demonstrated with the sensing of biotin, such that a strong biotin-phase response relationship is formed with a limit of detection of 0.842 ng/ml. This study contributes valuable insights into the electrical, optical and biosensing properties of TANIs, providing direction for sensing applications, where the optimization of the TANIs structure could bring about advancements in optical performance and pave the way for the potential design of novel plasmonic sensors.

Understanding the Anomalous Thermoelectric Behavior of Fe-V-W-Al-Based Thin Films.

We investigated the thermoelectric and thermal behavior of Fe-V-W-Al-based thin films prepared using the radio frequency magnetron sputtering technique at different oxygen pressures (0.1-1.0 × 10-2 Pa) and on different substrates (n, p, and undoped Si). Interestingly, at lower oxygen pressure, formation of a bcc-type Heusler structure was observed in deposited samples, whereas at higher oxygen pressure, we have noted the development of an amorphous structure in these samples. Our findings indicate that the moderately oxidized Fe-V-W-Al amorphous thin film deposited on the n-Si substrate possesses a large magnitude of S ∼ -1098 ± 100 μV K-1 near room temperature, which is almost double the previously reported value for thin films. Additionally, the power factor (PF) indicated an enormously large value of ∼33.9 mW m-1 K-2 near 320 K. The thermal conductivity of the amorphous thin film is also found to be 2.75 Wm-1 K-1, which is quite lower compared to bulk alloys. As a result, the maximum figure of merit is estimated to be extremely high, i.e., ∼3.9 near 320 K, which is among one of the highest reported values so far. The anomalously large value of Seebeck coefficient and PF has been ascribed to the unusual composite effect of the metallic amorphous oxide phase and insulating substrate possessing a large Seebeck coefficient.

Engineering wafer scale single-crystalline Si growth on epitaxial Gd2O3/Si(111) substrate using radio frequency sputtering for silicon on insulator application

Silicon on Insulator (SOI) technology has been the promising solution for the On-chip low-power mixed-signal systems. However, the traditional smart-cut method for SOI wafer fabrication is costly. Hence, in this work, we present an optimized methodology to fabricate a wafer scale single-crystalline Si on epitaxial Gd2O3/Si(111) substrate (SOXI) using a low-cost, high volume manufacturable (HVM)-friendly Radio Frequency magnetron sputtering technique for SOI application. The grown Si and Gd2O3 layers are physically characterized using high-resolution X-ray Diffraction and high-resolution Transmission Electron Microscopy (HRTEM). The Grazing Incidence X-ray Diffraction, Pole Figure, and HRTEM imaging confirm the formation of an epitaxial Top-Si layer on the epitaxial-Gd2O3/Si(111) substrate. Hence, we demonstrate a low-cost, HVM-friendly technique for the fabrication of SOXI wafers.

Improved performance of MgxZn1-xO flexible UV photodetectors by piezo-phototronic effect through alloying treatment

MgxZn1-xO films (x = 0.22, 0.39, and 0.52) with a single hexagonal wurtzite structure were grown on flexible polyethylene terephthalate (PET) substrates using radio frequency (RF) magnetron sputtering technique. The piezo-phototronic properties of flexible ultraviolet (UV) photodetectors with MgxZn1-xO films were investigated by examining the relationship between their photoelectric characteristics and strain, and the impact of Mg alloying on their piezo-phototronic effect. As the tensile strain of the detectors increased from ε = 0 to ε = 0.2, the responsivity of Mg0.22Zn0.78O, Mg0.39Zn0.61O, and Mg0.52Zn0.48O flexible UV photodetectors increased by ∼ 260 %, ∼308 %, and ∼ 441 %, respectively, showing an enhanced piezo-phototronic effect with increasing Mg content. It could be attributed to the fact that the alloying process increased the piezoelectric coefficient of the MgxZn1-xO materials, thereby increasing the piezopotential. This work provides a technical approach for the preparation and performance optimization of novel flexible optoelectronic functional devices.

Experimental and Theoretical Analysis of Rayleigh and Leaky-Sezawa Waves Propagating in ZnO/Fused Silica Substrates.

Piezoelectric c-axis oriented zinc oxide (ZnO) thin films, from 1.8 up to 6.6 µm thick, have been grown by the radio frequency magnetron sputtering technique onto fused silica substrates. A delay line consisting of two interdigital transducers (IDTs) with wavelength λ = 80 µm was photolithographically implemented onto the surface of the ZnO layers. Due to the IDTs' split-finger configuration and metallization ratio (0.5), the propagation of the fundamental, third, and ninth harmonic Rayleigh waves is excited; also, three leaky surface acoustic waves (SAWs) were detected travelling at a velocity close to that of the longitudinal bulk wave in SiO2. The acoustic waves' propagation in ZnO/fused silica was simulated by using the 2D finite-element method (FEM) technique to identify the nature of the experimentally detected waves. It turned out that, in addition to the fundamental and harmonic Rayleigh waves, high-frequency leaky surface waves are also excited by the harmonic wavelengths; such modes are identified as Sezawa waves under the cut-off, hereafter named leaky Sezawa (LS). The velocities of all the modes was found to be in good agreement with the theoretically calculated values. The existence of a low-loss region in the attenuation vs. layer thickness curve for the Sezawa wave below the cut-off was theoretically predicted and experimentally assessed.

Development of room-temperature operable TiO2-x-based hydrogen gas sensor with light irradiation

In this research work, TiO2-x-thin films are deposited through a radio-frequency magnetron sputtering technique by varying the oxygen partial pressure (pO2) of 6.0 %, 6.4 %, and 6.8 %. The X-ray diffraction analysis depicts the formation of the anatase phase of the annealed thin film with a high crystalline nature. The existence of higher oxygen vacancies and surface roughness are confirmed by the X-ray photoelectron spectroscopy and the atomic force microscopy analyses, respectively, in the 6.0 % pO2 grown thin film. At room temperature (30 °C) and dark conditions, the optimized TiO2-x-based hydrogen gas sensor device depicts a notable response of 22.9 % on exposure to 100 ppm of H2 gas. The irradiation of the ultra-violet (UV) light (λ = 365 nm) on the sensing material promotes desorption of the oxygen species and hence improves the responsivity of the sample. The highest responsivity of 87.7 %, along with faster response and recovery time of 9.4 s and 7.8 s, respectively, is achieved under the UV light irradiation and 100 ppm of H2 gas for the sample grown at 6.0 % pO2, which signifies its potential for the development of room temperature operable hydrogen gas sensor.

Biological and Physicochemical Analysis of Sr-Doped Hydroxyapatite/Chitosan Composite Layers.

In this work results are presented on the evaluation of HAp, HApSr, HAp_CS, and HApSr_CS layers deposited on Ti substrates regarding L929 cell viability and cytotoxicity as well as antimicrobial activity against Staphylococcus aureus, in connection with their physicochemical properties. The HAp and HApSr layers generated by radio-frequency magnetron sputtering technique were further covered with chitosan by a matrix-assisted pulsed laser evaporation technique. During the plasma depositions, the Ti substrates were heated externally by a home-made oven above 100 °C. The HApSr_CS layers generated on the unpolished Ti substrates at 100 °C and 400 °C showed the highest biocompatibility properties and antimicrobial activity against Staphylococcus aureus. The morphology of the layer surfaces, revealed by scanning electron microscopy, is dependent on substrate temperature and substrate surface roughness. The optically polished surfaces of Ti substrates revealed grain-like and microchannel structure morphologies of the layers deposited at 25 °C substrate temperature and 400 °C, respectively. Chitosan has no major influence on HAp and HApSr layer surface morphologies. X-ray photoelectron spectroscopy indicated the presence of Ca 2p3/2 peak characteristic of the HAp structure even in the case of the HApSr_CS samples generated at a 400 °C substrate temperature. Fourier transform infrared spectroscopy investigations showed shifts in the wavenumber positions of the P-O absorption bands as a function of Sr or chitosan presence in the HAp layers generated at 25, 100, and 400 °C substrate temperatures.

Tuning the Topo-Morphological properties of ITO Films using Al-Ag interlayer for Low-Resistance Optoelectronics Devices

Indium tin oxide (ITO) is recently attracting intense attention for application as transparent conducting electrode in different optoelectronic devices including solar cells, liquid crystal displays and organic light emitting diodes. This is attributed to their high optical transmittance in the visible region and good electrical conductivity. In this work, surface topological-morphological (topo-morphological) and electrical properties of ITO based multilayer films with aluminum-silver (Al-Ag) metal interlayer (ITO/Al-Ag/ITO) are investigated after post annealing treatment at 300-500oC by atomic force microscopic (AFM), field emission scanning electron microscopy (FESEM), four-point probe and hall-effect techniques respectively. The ITO/Al-Ag/ITO films are deposited by direct current and radio frequency magnetron sputtering techniques on p-type Si at room temperature. The results showed a smooth surface topology by as-deposited film with films smoothness improving after post annealing treatment as analyzed by AFM method. Sharp crystallites peaks were obtained by all the films with smaller peaks diffusing and recombining to form larger films with increasing post-annealing temperature. The films root means square roughness increased as the temperature increases with film annealed at 500oC showing a superior and enhanced microstructure. Compared to as-deposited film, careful observation shows that surface morphology smoothness increased with increase in temperature with films annealed at 400oC and 500oC showing highest increasing surface smoothness pattern as determined by FESEM technique. Similarly, higher grain sizes are observed especially by films annealed at 400oC and 500oC due to the heat absorption which causes the particles to expand thereby narrowing the grain boundaries and subsequently improve the surface smoothness. These FESEM findings are consistent with AFM measurements confirming the high surface property and enhanced grain size with increasing post annealing temperature. The films exhibit decreased electrical resistivity and sheet resistance while carrier concentration and Hall mobility increased with increasing post annealing treatment indicating highest corresponding values of...

Highly aligned pyrolytic graphite blades for neutron monochromatization

Highly aligned pyrolytic graphite blades for neutron monochromatization have been fabricated successfully from smaller commercial highly oriented pyrolytic graphite (HOPG) crystals. These blades of a large coverage area, 136 mm wide × 2 mm high, are achieved with minimum increase of the mosaic over that of the original HOPG crystal. A specialized crystal cleavage device and soldering device are developed for the fabrication process. Furthermore, an optimized intermittent mode of the radio frequency magnetron sputtering technique is employed to deposit indium on HOPG crystals. The devices and procedure reported here could be applied to the development of the focusing monochromators and analyzers in neutron scattering instruments using a sizable neutron beam.

Hemocompatibility and Preangiogenic Attributes of SiBxCyNzOm Coatings for Biomedical Applications.

In current clinical practices related to orthopedics, dental, and cardiovascular surgeries, a number of biomaterial coatings, such as hydroxyapatite (HAp), diamond-like carbon (DLC), have been used in combination with metallic substrates (stainless steel, Ti6Al4V alloy, etc.). Although SiBCN coatings are widely explored in material science for diverse applications, their potential remains largely unexplored for biomedical applications. With this motivation, the present work reports the development of SiBxCyNzOm coatings on a Ti6Al4V substrate, employing a reactive radiofrequency (RF) magnetron sputtering technique. Three different coating compositions (Si0.27B0.10C0.31N0.07O0.24, Si0.23B0.06C0.21N0.22O0.27, and Si0.20B0.05C0.19N0.20O0.35) were obtained using a Si2BC2N target and varying nitrogen flow rates. The hydrophilic properties of the as-synthesized coatings were rationalized in terms of an increase in the number of oxygen-containing functional groups (OH and NO) on the surface, as probed using XPS and FTIR analyses. Furthermore, the cellular monoculture of SVEC4-10 endothelial cells and L929 fibroblasts established good cytocompatibility. More importantly, the coculture system of SVEC4-10 and L929, in the absence of growth factors, demonstrated clear cellular phenotypical changes, with extensive sprouting leading to tube-like morphologies on the coating surfaces, when stimulated using a customized cell stimulator (StimuCell) with 1.15 V/cm direct current (DC) electric field strength for 1 h. In addition, the hemocompatibility assessment using human blood samples revealed clinically acceptable hemolysis, less erythrocyte adhesion, shorter plasma recalcification, and reduced risk for thrombosis on the SiBxCyNzOm coatings, when compared to uncoated Ti6Al4V. Taken together, the present study unambiguously establishes excellent cytocompatibility, hemocompatibility, and defines the preangiogenic properties of SiBxCyNzOm bioceramic coatings for potential biomedical applications.

Investigation on thermoelectric properties of SnSe thin films as prepared by RF magnetron sputtering

In this work, we investigated the thermoelectric properties of SnSe (Tin Selenide) thin films onto SiO2/Si-wafer substrates as prepared by RF (radio frequency) magnetron sputtering technique. The sputtering conditions used base pressure below 5.5 10−4 Pa and working pressure at 0.93 Pa within the Ar atmosphere as a flow rate fixed 40 sccm. The RF sputtering power was applied at 80 W and sputtering time for 30 min. After thin film deposition, as-deposited thin films were annealed by the vacuum annealing method at 300–450 °C. The crystal structure, morphology and film thickness, and atomic composition of SnSe thin film were carried out by X-ray diffraction (XRD), the field emission scanning electron microscope (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques, respectively. The thermoelectric properties (electrical resistivity; ρ) and Seebeck coefficient; S) were measured by the ZEM-3 method to calculate the power factor (PF) value. The results showed that the as-deposited thin films had improved the crystallography of SnSe from amorphous to crystalline phases after thin films were annealed at a temperature range of 300–400 °C. At room temperature, the maximum power factor of 0.35 mW m˗1 K˗2 (ρ = 202 mΩ m and S = 165 μV K˗1) could be found to estimate the dimensionless Figure of Merit (ZT) values around 0.44 for annealing thin film sample at 400 °C.

The Impact of Temperature and Power Variation on the Optical, Wettability, and Anti-Icing Characteristics of AZO Coatings

The structural, wettability, and optical characteristics of aluminum-doped zinc oxide (AZO) thin films were studied with the objective of understanding the impact of deposition power and deposition temperature. Thin films were deposited using a radio frequency (RF) magnetron sputtering technique. The power output of the RF was augmented from 200 to 260 W, and the temperature was increased from 50 to 200 °C, which led to the development of a (002) peak for zinc oxide. The study of film thickness was carried out using the Swanepoel envelope method from data obtained through the UV-Vis spectrum. An increase in surface roughness value was shown to be connected with fluctuations in temperature as well as increases in deposition power. The findings revealed that as deposition power and temperature increased, the value of optical transmittance decreased, ranging from 70% to 90% based on the deposition parameters within the range of wavelengths that extend from 300 to 800 nm. The wettability properties of the samples were studied, and the maximum contact angle achieved was 110°. A Peltier apparatus was utilised in order to investigate the anti-icing capabilities, which revealed that the icing process was slowed down 3.38-fold. This work extends the understanding of the hydrophobicity and anti-icing capabilities of AZO thin films, specifically increasing both attributes which provide feasible options for purposes requiring resistance to ice.

Effect of Deposition Working Power on Physical Properties of RF-Sputtered CdTe Thin Films for Photovoltaic Applications.

The main objective of this study was to determine the variation in the properties of cadmium telluride (CdTe) thin films deposited on a p-type Si substrate by the radio frequency magnetron sputtering technique at four different working powers (70 W, 80 W, 90 W, and 100 W). The substrate temperature, working pressure, and deposition time during the deposition process were kept constant at 220 °C, 0.46 Pa, and 30 min, respectively. To study the structural, morphological, and optical properties of the CdTe films grown under the mentioned experimental conditions, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical spectroscopy were used. For a better analysis of the films' structural and optical properties, a group of films were deposited onto optical glass substrates under similar deposition conditions. The electrical characterisation of Ag/CdTe/Al "sandwich" structures was also performed using current-voltage characteristics in the dark at different temperatures. The electrical measurements allowed the identification of charge transport mechanisms through the structure. New relevant information released by the present study points towards 90 W RF power as the optimum for obtaining a high crystallinity of ~1 μm nanostructured thin films deposited onto p-Si and optical glass substrates with optical and electrical properties that are suitable for use as absorber layers. The obtained high-quality CdTe nanostructured thin films are perfectly suitable for use as absorbers in CdTe thin-film photovoltaic cells.

Highly oriented crystalline si on epitaxial Gd2O3/Si(111) substrate using low-cost Radio Frequency sputtering for Silicon on Insulator application

Silicon-on-Insulator (SOI) technology has been the center of attraction with the advancement in Radio Frequency (RF) technology and the advent of Internet-of-Things due to its low-power operation with reduced parasitic and short-channel effects. However, the state-of-the-art smart-cut method used for the SOI wafer is costly. Alternatively, the notion of using the Si channel layer on epitaxial rare-earth oxide has been proposed. In literature, the existing techniques used to achieve the same, such as Molecular beam Epitaxy or reduced-pressure chemical vapor deposition technique, are either costly or non-high-volume manufacturable. In this context, we propose a method to fabricate the highly oriented crystalline Si(111) channel layer (Top-Si) on an epitaxial Gd2O3/Si(111) virtual substrate (SOXI) utilizing the solid phase epitaxy using the high-volume manufacturing friendly (HVM), low-cost RF magnetron sputtering technique. First, we have shown the multicrystalline Si and epitaxial Gd2O3 layer grown on Si(111) substrate, as confirmed using high-resolution X-ray diffraction (HRXRD) and Transmission Electron Microscopy (TEM). Second, we investigated the impact of rapid thermal annealing at 850 °C on the heterostructure using HRXRD and TEM. It is observed that the high-temperature annealing transforms the Top-Si layer into the highly oriented crystalline Si(111) layer by fusing smaller grains towards larger grains. Hence, we demonstrate a low-cost, HVM-friendly technique for the fabrication of SOXI wafers.

Fabrication of garnet solid electrolytes via sputtering for solid-state batteries

In this study, the deposition of Li7La3Zr2O12 (LLZO) thin films onto MgO substrates was successfully achieved using the radio frequency magnetron sputtering technique. The deposition process was carried out at various substrate temperatures to investigate their influence on the film properties The as-deposited films were initially amorphous; however, they could be crystallized into the cubic phase by increasing the deposition temperature above 100 °C. Upon raising the deposition temperature to 200 °C, the peaks in the X-ray diffraction pattern became sharper and more intense, indicating an increase in the volume fraction and crystallite size of LLZO.At 200 °C, the film consisted predominantly of the conductive crystalline LLZO phase, resulting in a remarkably high ionic conductivity of about 10−4S cm−1. The film deposited at 300 °C exhibited the second phase, i.e., the La2Zr2O7 phase, which resulted from excessive lithium losses. These findings highlight the importance of controlling the deposition temperature to achieve the desired crystalline phase and optimize the electrical properties of LLZO thin films.

Modulation of electrical properties of sputtered Ta2O5 films by variation of RF power and substrate temperature

Dielectric thin films are important building blocks of microelectronic devices, and hence, research on the development of high-k dielectric thin films has drawn tremendous research interest. In this research, thin films of tantalum oxide (Ta2O5), a high-k dielectric material, are deposited on the Si substrate by the radio frequency (RF) magnetron sputtering technique. During the deposition of Ta2O5 thin film, the sputtering parameters such as sputtering power and substrate temperature were systematically varied, and post-deposition structural, morphological, and electrical properties of sputtered Ta2O5 films are studied by x-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscope, capacitance–voltage (C-V) and current–voltage (I-V) measurement techniques. The annealed Ta2O5 thin film at the temperature of 900 °C for 1 h possesses polycrystalline nature with β—phase orthorhombic crystal structure. The film deposited at 150 W and substrate temperature at room temperature has shown comparatively lower surface roughness, which depicts the energy, and mobility of adatoms greatly influenced by RF power and substrate temperature. With the increase in sputtering power, the oxide charge density (Qox) is found to increase. On the other hand, Qox is found to decrease with the increase in substrate temperature. The film deposited at RF power of 150 W and substrate temperature of 300 °C is found to be of high dielectric constant, low oxide and interface charge density, and lower leakage current.

Effects of applied negative bias voltage on the optical and structural properties of CaF2 coatings deposited by RF magnetron sputtering

Calcium fluoride (CaF2) is a ceramic material exhibiting versatile properties including broadband transparency, lubrication at high temperature, and mechanical stability. In the current research, aimed at improving optically-driven infrared detection devices, CaF2 coatings were deposited on sapphire. One challenge concerning this CaF2/sapphire system is the significant difference between their coefficients of thermal expansion, which can cause adhesion failure. To avoid such failure, we first studied the behavior of thick CaF2 coatings on silicon substrates where adhesion issues are expected to be more pronounced, then employed thin CaF2 coatings, initially on silicon and subsequently on sapphire substrates.Deposition was carried out by radio frequency magnetron sputtering technique in an argon atmosphere at a fixed power of 4.4 W/cm2. Substrate bias voltage was varied from 0 to - 150 V in order to explore voltage impact on properties of the obtained CaF2 coatings.Coatings deposited with low negative bias voltages presented an inhomogeneous surface with a columnar structure that remained firmly attached to the substrate; optical transmission for these coatings was reduced relative to that for bare sapphire. Alternatively, while coatings deposited with high negative bias voltages became dense and uniform, they were also subjected to high surface reactivity causing formation of CaO/Ca(OH)2 phases and defects, as well as delamination that reduced optical transmission. In contrast, only samples deposited with moderate bias voltages exhibited a sufficiently dense, highly adhesive layer, resulting (relative to that for bare sapphire) in improved optical transmission. Thin CaF2 coatings deposited with −100 V improved transmittance (at a wavelength of 1.9 μm) from almost 88.5 %–92 %, representing approximately a 30 % decrease in radiation loss caused by absorbance, scattering, and reflectance effects. Even though the optical values of transmittance for increased wavelength (up to 5 μm) were reduced, these values still surpassed those obtained for sapphire alone.

High quality Mn-Co-Ni-O based infrared detectors enhanced by Pt nanoparticle decoration

The work developed a series of infrared detectors based on the Mn-Co-Ni-O (MCNO) films, which were grown using a radio frequency (RF) magnetron sputtering technique. It was observed that the characteristics of MCNO films were significantly impacted by the annealing temperature. Elevating the in-situ annealing temperature from 550 to 750 °C improved the performances of MCNO films. Additionally, it was found that in situ annealing was more advantageous than ex-situ annealing of 750 °C for the properties of MCNO films. The response value (light to dark) increased from 2.5 to 17.7 at 15 V bias, representing a 6.08-fold enhancement, and the response time decreased to 11.8 ms from 19.9 ms. Furthermore, sputtering Pt nanoparticles on the surface of the MCNO film further improved the I-V characteristics in the dark, resulting in a high on/off ratio of 38.15, which is five times higher than that without the Pt nanoparticles modification. This impressive improvement in photoproperties can be attributed to the Pt nanoparticles/MCNO film barrier, plasma resonance effect generated by the Pt nanoparticles, the extinction of the Pt nanoparticles, and the reduction of surface resistance caused by the Pt nanoparticles. This highlights the potential of metal nanoparticles in the development of infrared detectors.

In2S3 thin films with potential use as window layers in photovoltaic devices

In this study, we use the Haacke’s figure of Merit (FOMH) as a valuable parameter for determining suitable Indium Sulphide thin films among a set of samples processed with different deposition parameters, in order to use them as window layers in the usual configuration of photovoltaic devices. Two sets of In2S3 thin films were deposited by radiofrequency (RF) magnetron sputtering technique with an average thickness around 90 nm and using different deposition parameters. One set of samples was processed using different RF power in the range of 75–250 W at room temperature, the second set was obtained using different substrate temperatures 24 °C–350 °C keeping a constant RF power at 75 W. The FOMH consider optical and electrical properties of In2S3 thin films in order to evaluate the feasibility of the thin film to be used as a window layer in photovoltaics devices. The In2S3 thin films processed by RF-Sputtering were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Ultraviolet-Visible spectroscopy, Raman spectroscopy, x-ray diffraction (XRD) and four-probe method. The In2S3 thin films had a high optical transmittance of 84% and the energy band gap values of the films decreased from 2.48 to 2.38 with the increase in substrate temperature and deposition power. The estimated grain size decreasing from 65 to 45 nm as the RF power increased. Additionally, the crystallinity of the selected In2S3 thin films was analyzed by Raman and XRD and showing that the cubic and tetragonal β-In2S3 phases can coexist in the films. The In2S3 thin films showed resistivity vales around Higher values of FOMH were obtained for In2S3 thin films processed at 75 W, 250 W, 100 °C and 300 °C, therefore these layer are feasible candidates to be used as window layers in photovoltaic devices.

Tunable room-temperature ferromagnetism in RF magnetron sputtered Al2Cr2Cu2O8 thin film

Metal oxide solid solution thin films containing ternary mixtures of Alumina (Al2O3), Chromia (Cr2O3) and Cupric oxide (CuO) were successfully prepared combinatorially on FTO, quartz glass and Si substrates using radio frequency (RF) magnetron sputtering (vertical geometry; on-axis sputtering) technique with RF powers of 200 W and 100 W. XRD analysis prove the development of tetragonal phase Al2Cr2Cu2O8 in sputtering target. Al2Cr2Cu2O8 film deposited on Si wafer and quartz glass exhibits amorphous nature, whereas, the film deposited on FTO substrates exhibit crystalline structure with tetragonal phase owing to polycrystalline nature of the FTO substrates. Formation of high compositional purity with acceptable stoichiometric ratio of ternary metal oxide mixtures of Al2Cr2Cu2O8 was ascertained from the EDX spectra. The thicknesses of Al2Cr2Cu2O8 thin films are found to be in the ranges from 259 to 314 nm. Optical study showed that the optical energy band gap of Al2Cr2Cu2O8 thin film deposited on quartz substrates increased to 3.84 eV from 3.78 eV with decreasing RF power from 200 W to 100 W. The spin orbital splitting (SOS) between Cr 2p1/2 - Cr 2p3/2 and Cu 2p1/2 - Cu 2p3/2 were measured to be 9.9 eV and 19.3 eV by XPS for 200 W sputtered Al2Cr2Cu2O8 film on quartz substrate, which are the characteristics of Cr3+ and Cu2+ oxidation states, respectively. In addition, XPS analysis also confirms the presence of various oxygen vacancies in Al2Cr2Cu2O8 thin films (as-deposited and 1000 °C annealed films) on quartz substrate with RF power of 200 W, which is the most favorable condition for the presence of room temperature ferromagnetic properties observed in the present study.