RF Magnetron Sputtering Process Research Articles

Enhancing perovskite solar cell performance: Investigating the impact of post-annealing on the optoelectrical and structural properties of RF-sputtered NiO films via SCAPS-1D device modeling

In recent years, perovskite solar cells have garnered significant interest in the field of solar cell research and development, primarily due to their notable efficiency. However, their limited lifespan and material defects, particularly in the interface layer and during deposition or fabrication processes, pose challenges to their widespread adoption. Innovative approaches to material processing and design are essential to addressing these issues. This paper introduces a novel method for the deposition of nickel oxide (NiO) thin films aimed at enhancing the performance of perovskite solar cells. Our study involved depositing NiO films on glass substrates using an optimised RF magnetron sputtering process at room temperature. These films were then annealed at temperatures ranging from 100 to 400 °C in an open-air setting. X-ray diffraction analysis showed that pure NiO thin films were formed. These films had a cubic crystalline structure and were mostly oriented along the (200) plane. Crucially, annealing at 100 °C significantly improved the crystallinity of the NiO films, reducing the average crystallite size from 21.05 to 6.10 nm, as evidenced by field emission scanning electron microscopy. For solar cells, this kind of microstructural refinement is very important because it changes the optical band gap, which ranged from 3.81 to 3.86 eV depending on the annealing temperature, and it also has a big effect on the films' electrical properties. The outstanding electrical characteristics of the NiO film annealed at 100 °C are particularly remarkable. We used these improved NiO films in perovskite solar cells that had a structure of FTO/NiO/MAPbI3/PCBM/Ag and ran SCAPS-1D simulations to see how well they worked. The simulation results are promising, indicating an enhancement in cell efficiency with the potential to surpass 22 %. This advancement highlights the critical role of advanced thin film deposition techniques in advancing photovoltaic technology and marks a substantial step towards unlocking the full potential of perovskite solar cells.

Enhanced Photoelectrochemical Response of the ZnO/V2O5 Heterojunction Via Improved Visible-Light Absorption and Charge Carrier Separation

Planar ZnO/V2O5 heterojunctions show excellent photocurrent density and are easy to prepare using a simple physical vapor deposition technique. First, ZnO thin-film photo-electrodes were prepared by radio frequency sputtering, and then their thickness was optimized for improved photoelectrochemical (PEC) response, resulting in an optimum photocurrent density value of ∼0.7 mA/cm2 at 0.61 V vs Ag/AgCl for ZnO thin films deposited for 15 min. Thereafter, ZnO/V2O5 heterojunctions were fabricated by depositing V2O5 thin films for different deposition durations of 10, 20, and 30 min onto ZnO thin-film samples which were already optimized to further improve the PEC performance. The structural, optical, and morphological properties of pristine and heterojunction thin-film samples were investigated by X-ray diffraction, Raman spectroscopy, UV–visible spectroscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques. The maximum photocurrent density value of 1.56 mA/cm2 at 0.61 V vs Ag/AgCl was obtained for ZnO/V2O5 heterojunction photoanodes, where the top V2O5 layer was deposited by RF magnetron sputtering process which occurred for 20 min. The ZnO/V2O5 heterojunction photocurrent density was nearly twice as compared with that of the pristine ZnO photo-electrode. This improved PEC response of the ZnO/V2O5 heterojunction was due to enhanced visible-light absorption and the formation of a staggered n–n heterojunction, which facilitated the separation of electron–hole pairs at the photo-anode/electrolyte junction.

Fabrication and characterization of RF magnetron sputtered composite MoS2 and ZrN coatings on Ti3SiC2 max phase for space applications

The lubrication effect of solid-based materials has been recognized for centuries, but their use as lubricants dates back to only about 50 years. Solid lubricants are used in applications where parts operate under severe operating conditions such as extreme temperatures and very high vacuum. Solid lubricants replace liquid based lubricants for operation under extreme environmental conditions that are beyond the capability of a liquid-based lubricant such as high or very high vacuum, high and cryogenic temperatures, radiation, corrosive gases, and fretting wear. Applications such as space mechanisms, satellites, space vehicles, turbopumps, nuclear reactors, refrigeration plants, etc are examples of such operating conditions. In this research, nano scale composite coatings of MoS2with varied proportions of ZrN (5%, 10% and 20%) were deposited on Ti3SiC2 Max phase substrate using Physical Vapour Deposition (PVD). The PVD technique used was the RF magnetron sputtering process. Material characterization was carried out using Field Emission Scanning Electron Microscope (FESEM) Spectroscopy and Energy Dispersive X-Ray Spectroscopy (EDS). Addition of ZrNis observed to reduce the porosity of the self-lubricating MoS2 coating.

Design, fabrication and characterization of MoS2self-lubricating pure MoS2Coatings for space applications using PVD magnetron sputtering

Tribological components cost just a fraction of the whole spacecraft, but they often lead to failures that partially or completely disrupt the spacecraft. Mechanical components used in space applications have to withstand extreme and severe environmental conditions such as very high or very low cryogenic temperatures, high vacuum, corrosive elements and radiation. MoS2 is the most widely used lubricating material in space applications. It possesses a lamellar structure with strong covalent bonds within layers and simultaneously weak van der Wall’s interlayer bonds, resulting in easy shearing of the crystals in the direction parallel to the basal planes, hence acting as a good solid lubricant.In this research, a thin film nano scale coating of MoS2 was deposited on steel using Physical Vapour Deposition (PVD). The PVD technique used was the RF magnetron sputtering process. Material characterization was performed using X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy. According to the results, the developed MoS2 nano coatings have a polycrystalline structure with basal planes that are oriented perpendicular to the substrate surface.

Design, fabrication and characterization of circular ZnO TFT for UV detection applications

Here-in this work, we for the first time report a circular zinc oxide (ZnO) based thin film transistor (TFT) and experimentally demonstrate its applicability as ultraviolet (UV-365 nm) photo-detector. The circular TFT has been fabricated through RF-magnetron sputtering process. Prior to fabrication the design is simulated in Atlas TCAD. The morphological, and optical properties of fabricated TFT were analyzed through scanning electron microscope (SEM), atomic force microscope (AFM), x-ray diffraction and UV-spectrometer and ellipsometry. The dark condition measurements revealed saturation current of 1 μA, considerable carrier mobility of 0.08 cm2V-1s-1 and ON-state to OFF-state drain current ratio of 105. Illuminating the device by UV light leads to substantial increment in ON-state as well as OFF-state current reducing to current ratio to 104. It is observed that for wavelength of 290 nm and applied bias of 10V, the responsivity was measured to be about 4.17 A/W yielding a rejection ratio of 7.28×105. The employment of circular structural design for TFT can open up new dimensions and possibilities to improve the performance in photo-detection applications. This indicates that the fabricated circular TFT was highly sensitive towards UV wavelengths and can be a potential candidate for solar blind applications.

Design and performance analysis of ZnO nanorods/MoS2/p-Si piezo-photovoltaic energy harvester

In this paper, a novel ZnO nanorods/MoS2 /p-Si thin-film structure which exhibits high device current density due to piezotronics impact of polarization charges with the light intensity of 100mWcm−2 has been discussed. A comprehensive coverage of modeling, simulation, fabrication, and experimental assessment of the Piezo-Photovoltaic energy harvester that exploits the external mechanical energy alongside electromagnetic radiation range between 200 nm and 900 nm has been enunciated. The geometry of the structure has been designed optimally to achieve the best piezo and photovoltaic performances using modelling and simulation studies. The various layers of the proposed structure have been deposited using RF-magnetron sputtering and thermal evaporation process techniques and tested under AM 1.5 G. The piezotronics offers to tune the charge control by the influence of strain and creates the piezo current. The piezo effect increases the short circuit current density by 2 % resulting in 30.6 mAcm−2 with a compressive pressure of 100kPa. The proposed structure exhibits improved efficiency of 28.86 % due to combined piezo and photovoltaic effects.

Integration of Ferroelectric K0.5Na0.5NbO3 films on Si at 400 ℃

In this work, polycrystalline K0.5Na0.5NbO3 (KNN) thin films were successfully integrated on Si at 400 ℃ via a RF magnetron sputtering process. These films showed a polycrystalline bulk-like orthorhombic phase with mixed (00l) and (110) orientations, as was supported by X-ray diffraction and piezoelectric force microscopy analyses. Without a post-deposition annealing process, these films already showed a clear ferroelectric polarization-electric field (P-E) hysteresis loop, characterized by a remnant polarization ~11μC/cm2 and a coercive field of ~280 kV/cm. This polarization response shows a good aging resistance (~2 years). A dielectric constant of ~230 and a low loss tangent of ~1.8 % (@1 kHz) were achieved in the KNN film. Lastly, large dielectric tunabilities of ~50 % (@ 1 MHz) was revealed for the KNN film, illustrating their good potential for applications in tunable dielectrics.

Control of Hydrogen Concentration in Ingazno Thin Film Using Cryopumping System

Recently, amorphous metal-oxide semiconductors (AOSs) such as indium gallium zinc oxide (IGZO) have attracted great attention with their lower power consumption and higher mobility than amorphous silicon in the display field. However, the threshold voltage (Vth) shift of IGZO thin film transistor (TFT) caused by their poor reliability leads to the drop panel luminance. Therefore, improvement of IGZO TFT reliability is necessary, which is largely influenced by oxygen vacancy and hydrogen. In particular, hydrogen has shown different roles inside the IGZO active layer by hydrogen concentration. At lower concentration, the hydrogen passivation of oxygen deficiency region induces the improvement of initial electrical characteristics and reliability [2]. Meanwhile, Vth shift and degradation reliability are generated at higher concentration owing to the hydrogen related defect states [3]. Therefore, controlling excess hydrogen is necessary for reliability enhancement.In this work, IGZO thin film was fabricated by cryopumping system instead of a turbo molecular pump (TMP) for radio frequency sputtering to reduce hydrogen concentration. Cryopump is an adsorption type that enables excellent evacuation ability of hydrogen and moisture taking up most of the partial pressure in high vacuum. As a result, deposition of IGZO thin film with lower hydrogen impurity is available. The hydrogen concentration in the IGZO thin film using both cryopump and TMP was quantitatively analyzed by elastic recoil detection (ERD) analysis. Then, electrical characteristics of the self-aligned top-gate structure TFTs fabricated by both pumps were measured with bias stress conditions.To sum up, we showed the improved reliability of IGZO TFT by controlling excess hydrogen using cryopumping system. Fig.1. (a) Schematic of RF magnetron sputtering process with cryopump. (b) TOF-SIMS depth profiles of hydrogen concentration in IGZO film using TMP and cryopump Acknowledgment This work was supported by the Korea Evaluation Institute of Industrial Technology(KEIT) grant funded by the Korea government (MOTIE) (No. 2021-11-1283) References Chung, Ui-Jin, et al. "15‐1: Invited Paper: Manufacturing Technology of LTPO TFT." SID Symposium Digest of Technical Papers. Vol. 51. No. 1. 2020.Hanyu, Yuichiro, et al. "Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors." Applied Physics Letters 103.20 (2013): 202114.Mativenga, Mallory, et al. "Origin of light instability in amorphous IGZO thin-film transistors and its suppression." Scientific reports 11.1 (2021): 1-12 Figure 1

The effect of sputtering Ar gas pressure on optical and electrical properties of flexible ECD device with WO3 electrode deposited by RF magnetron sputtering on ITO/PET substrate

In this study, the electro-optical properties of a flexible electrochromic device (ECD) with WO3 film were investigated according to the pressure of Ar gas during RF magnetron sputtering process. The ECD was fabricated using WO3 film as the cathode electrode and NiO as the anode electrode. Both electrodes were deposited using RF magnetron sputtering over indium tin oxide coated on polyethylene terephthalate film (PET/ITO). The electrolyte for the ECD used the lithium percolate mixed with poly methyl methacrylate and propylene carbonate to form the gel type electrolyte. The sputtering time was controlled while measuring with a thickness/rate monitor (Sycon STM-100) to have the identical WO3 film thickness at different Ar pressures. Also, argon working gas pressure in sputtering chamber was varied at 5 mTorr, 10 mTorr, and 15mTorr, respectively. The deposition rate of WO3 film was 14 nm/min for Ar gas pressure 5 mTorr then after the pressure was increased until 15 mTorr the deposition rate was 8.6 nm/min. The sputtering process was operated until the thickness of the WO3 film reach 250 nm. In order to investigate electro-optical properties of the ECD, such as coloration efficiency (CE), transmittance of bleached state (Tb), transmittance of coloured state (Tc), optical modulation, bleaching time, and coloration time were analyzed. The ECD with Ar pressure at 5 m Torr for WO3 film shows the coloration efficiency was 57.58 cm2C-1, Tb was 17%, Tc was 5%. Also, the bleaching time was 15 s, and coloration time was 30 s. When the sputtering pressure was increased to 15 mTorr, the ECD showed the better optical properties but the bleaching time and coloration time was rise to 50 s, and 58 s, respectively. The ECD at 15mTorr show the higher optical modulation of 55%.

Preparation of High-Performance Metal-Free UV/Near Infrared-Shielding Films for Human Skin Protection.

A series of metal-free UV/near infrared (NIR)-shielding coatings are successfully fabricated by shielded cathodic arc plasma evaporation (CAPE) and substrate-biased RF magnetron sputtering processes. The UV/NIR-shielding coatings comprising quarter-wave stacks of TiO2/SiO2 multilayers and high-conductivity sputter-deposited ITO films with a thickness in the range of 200–600 nm could block IRA and IRB radiations, respectively. The total thicknesses of UV/near infrared-shielding films are in the range from 375 nm to 1513.8 nm. The anatase-phase TiO2 films with absorption edge located at ~375 nm were deposited by shielded CAPE at ~100 °C. Further, the well-crystallized ITO films were found to have high free-electron concentrations (1.12 × 1021 cm−3), resulting in strong absorption of IRB due to the plasmon resonance absorption. The optimal optical design and ITO film thickness were investigated, and the TiO2(SiO2/TiO2)3 multilayer combined with an ITO film thickness of 400 nm was found to provide a high NIR-shielding rate of 94.8%, UVB to UVA-shielding rate of 92.7%, and average visible light transmittance of 68.1%. Further, human skin cells protected by a UV/NIR-shielding coating showed significantly decreased reactive oxygen species generation and inflammatory cytokine expression as compared to those of unprotected cells. The results demonstrate that the development of multifunction coatings have potential for transparent heat insulation windows and human skin protection against UV/IR radiations.

Alumina Thin film Coatings at Optimized Conditions using RF Magnetron Sputtering Process

Alumina Thin film Coatings at Optimized Conditions using RF Magnetron Sputtering Process

Design of Neural Network Model and its Application to Coating Performance Prediction

316L stainless steel has excellent mechanical properties and good corrosion resistance. It is used as a medical implant material, but it is susceptible to pitting corrosion to precipitate harmful ions and lead to the failure of the material. To solve the above problems, the surface modification method is used to solve it, and it is now widely accepted. Among them, magnetron sputtering technology has been widely used because of its advantages such as good adhesion and other advantages. The parameters of the RF magnetron sputtering process have a great influence on the performance of the coating, and the influence of each parameter has a non-linear mapping ability. The artificial neural network is used to build a model to predict the performance of the coating. It is highly targeted and practical. The establishment of artificial neural network is a prediction model from sputtering process parameters to coating performance, which can save pre-research time and improve work efficiency. The establishment of artificial neural network uses the strong nonlinear mapping ability of artificial neural network, combined with the measured value of Hf-based coating performance to establish a model to predict the effect of Hf-based coating sputtering process parameters on the performance of the coating. The simulation results indicate the prediction The error between the value and the measured value meets the BP network design requirements ≤0.3.

Precipitation of Molybdenum Oxides in Supersaturated Zinc Oxide Thin Films

Zinc oxide thin films saturated with molybdenum were prepared by RF magnetron sputtering process using zinc oxide and molybdenum targets for the co-sputtering. The sputtering power for zinc oxide was kept constant while that for molybdenum was varied from 0 watt to 35 watt. We found that the molybdenum-doped zinc oxide thin film change their color from transparent to grayish color as molybdenum sputtering power increases. The color change of the zinc oxide film suggests that the molybdenum changes its valance state as the molybdenum sputtering power was varied.A surprising finding about the study is the electrical conductivity increases and then decreases with molybdenum sputtering power. The increase of electrical conductivity should be attributed to the increase of donor concentration as more molybdenum atoms are incorporated. The decrease of conductivity, on the other hand, is not so well reported. Hall measurement study shows that the conductivity decrease is caused by decreased electron concentration. However, the electron mobility increases steadily with increased molybdenum sputtering power even though the electron concentration decreases. This is an indication that the electrical conduction no longer occurs through the molybdenum-doped ZnO grains.We propose that the conduction changes from grains to grain boundaries as molybdenum sputtering power increases. It means molybdenum is precipitated at the grain boundaries and forms conducting channels besides zinc oxide grains. The high mobility conduction channel is desired for devices using electron transport layers in their structures. The electrochemical solar cells are one of the devices that may benefit from the finding of molybdenum-doped oxide. We would like to present the valance change of molybdenum along with the conduction behavior, and would also like to predict the band alignment between zinc oxide and molybdenum oxide in the molybdenum-doped zinc oxide thin films. X-ray diffraction, UV-vis spectrophotometry, and x-ray photoelectron spectroscopy will be presented to show the conclusion that the electron mobility increase was attributed to the grain boundary conduction.

Precipitation of Molybdenum Oxides in Supersaturated Zinc Oxide Thin Films

Zinc oxide thin films saturated with molybdenum were prepared by RF magnetron sputtering process. A surprising finding about the study is the electrical conductivity increases and then decreases with molybdenum sputtering power. Hall measurement study shows that the conductivity decrease is caused by decreased electron concentration. However, the electron mobility increases steadily with increased molybdenum sputtering power in the same range even though the molybdenum incorporation still increases. This is an indication that the electrical conduction no longer occurs through the molybdenum-doped ZnO grains. We conclude that the conduction changes from grains to grain boundaries as molybdenum sputtering power increases. It means molybdenum is precipitated at the grain boundaries and forms conducting channels besides zinc oxide grains. The high mobility conduction channel might be desired for devices using electron transport layers in their structures.

Characteristics of Silicon Nitride Deposited Thin Films on IT Glass by RF Magnetron Sputtering Process

Silicon nitride thin films are deposited by RF (13.57 MHz) magnetron sputtering process using a Si (99.999 %) target and with different ratios of Ar/N2 sputtering gas mixture. Corning G type glass is used as substrate. The vacuum atmosphere, RF source power, deposit time and temperature of substrate of the sputtering process are maintained consistently at 2 ~ 3 × 10−3 torr, 30 sccm, 100 watt, 20 min. and room temperature, respectively. Cross sectional views and surface morphology of the deposited thin films are observed by field emission scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy. The hardness values are determined by nano-indentation measurement. The thickness of the deposited films is approximately within the range of 88 nm ~ 200 nm. As the amount of N2 gas in the Ar:N2 gas mixture increases, the thickness of the films decreases. AFM observation reveals that film deposited at high Ar:N2 gas ratio and large amount of N2 gas has a very irregular surface morphology, even though it has a low RMS value. The hardness value of the deposited films made with ratio of Ar:N2=9:1 display the highest value. The XPS spectrum indicates that the deposited film is assigned to non-stoichiometric silicon nitride and the transmittance of the glass with deposited SiO2-SixNy thin film is satisfactory at 97 %.

Development of ZnO nanostructure film for pH sensing application

Nanostructured zinc oxide sensing film was deposited on the Si/SiO2/Pt substrate by the RF magnetron sputtering process. The film was characterized by FESEM (field-emission scanning electron microscope) and XRD (X-ray diffraction) for their morphology and structural analysis. The FESEM results show that the film morphology is in nanophase with an average nanostructure size of ~ 50 nm. XRD results show that the film is polycrystalline. The AFM (atomic force microscopy) and Raman spectroscopy were done to analyze the surface roughness and the structural properties of the film, respectively. FTIR (Fourier-transform infrared spectroscopy) was used to analyze the presence of ZnO. Further, the ZnO nanostructure film has been explored for pH sensing for pH (4–12). The sensitivity of the film was found to be 31.81 mV/pH. The drift characteristics of the film were also done to find out the stability of the film.

Investigate the Structural and Optical Properties of RF-Sputtered V2O5 thin films deposited at different Power

In this work, the structural and optical properties of V2O5 have been presented. Thin films were manufactured by the RF magnetron sputtering process. The nanostructures and some optical properties of deposit thin films at different sputtering RF power in a plasma chamber were investigated. The structural investigation was performed with X-Ray Diffraction (XRD) measurements and Atomic Force Microscopy (AFM). The results obtained from both methods have revealed that as-deposited films were polycrystalline in nature. The texture of the films was observed that , the crystallite and grain size were increased with increasing the sputtering power. Optical properties were determined by transmission measurements in the spectral range from (250 to 1100 nm) . An Optical energy gap of sputtered films and its dependency to sputtering power of plasma have been measured. It was found that the energy gap decreased with increasing the used power. The energy band gap was found to be in the ranged of (3.02 eV to 2.90 eV) when the sputtering power varying from (75 nm to 150 Watt).

Microstructure and ferroelectric properties of bi-excess Bi4Ti3O12 thin films grown on Si and Pt/Ti/SiO2/Si substrates

Bismuth layer-structured ferroelectric Bi4Ti3O12 thin films have been deposited on n-type Si(111) and Pt(111)/Ti/SiO2/Si substrates using rf-magnetron sputtering process. The effects of substrates and annealing treatments on microstructure and ferroelectric properties were investigated. Scanning electron microscopy and X-ray diffraction patterns exhibited that the as-deposited thin films were noncystalline and transformed to crystalline Bi4Ti3O12 phase with a second phase of Bi12TiO20 after annealed at 700 °C. Ferroelectric properties showed that as-deposited thin film in metal-ferroelectric-semiconductor capacitor form and annealed thin film in metal-ferroelectric-metal form exhibited typical ferroelectric behaviors, wherein the values of remnant polarization were around 0.8 µC/cm2 and 4.8 µC/cm2, respectively.

Silicon Oxycarbide Platform for Integrated Photonics

In this article we present silicon oxycarbide (SiOC) as a potential dielectric platform for integrated photonic applications. By controlling the amount of carbon and oxygen in the composition of SiOC films, which in this work are deposited by using a reactive RF magnetron sputtering process, the refractive index of the material can be widely tuned from less than that of silica 1.40 to almost that of silicon carbide (3.0), while keeping high transparency in the near-infrared wavelength range. An in-depth analysis of the structural, morphological and optical properties of the deposited SiOC thin films is reported, pointing out the relationship between the change in the film composition and the tuneability of the refractive index. Single mode optical waveguides with a refractive index contrast of up to 28% and propagation loss as low as 2 dB/cm at 1550 nm are demonstrated. An integrated Mach-Zehnder interferometer is presented as a first example of PIC realized on high refractive index SiOC platform. Results show that SiOC is a promising alternative to conventional dielectric platforms for the realization of PICs.

Effect of RF/DC Magnetron Sputtering Process Parameters for Improving Efficiency of Solar PV Cell

The biggest disadvantage of solar cells is that it has low solar power conversion efficiency typically 14%. So as to improve the power conversion performance, several attempts was made by researchers and once such technique is to reduce the reflection by providing textures on the solar cells. This texture will reduce the reflectance and thereby increase the solar power conversion efficiency. In this work, an investigational study was conducted to improve an energy efficiency of solar PV cells. Here Cu, Ag, Al was deposited for metallization purpose at specific places by using RF and DC magnetron sputtering process. The input parameters such as power, deposition time and substratum temperature were optimized during the sputtering process and the corresponding coating thickness, optical properties and surface topography were investigated. The coating thickness and surface roughness were increased as power increased from 15W to 45W. Average surface roughness (Ra) of 6nm and was obtained at the optimum power of 45W and deposition rate of 5-7 mins. The surface morphology and topography was characterized by using SEM and AFM which shows uniform coating with spherical shaped with densely packed nanostructures with increase in grain size were observed and elemental composition were confirmed by using EDAX. The absorption and reflection were investigated by using UV-VIS-NIR spectrometer indicates that the optical absorption increased from 1.2% to 1.68% at the wavelength range from 250 to 314nm. The reflection was reduced from 13.4% to 3.67% and the conversion efficiency was increased from 14.22% to 16.63%. This paper reports the complete experimental details, results and analysis.