RF Magnetron Sputtering Research Articles

Role of interface engineering in amorphous InGaZnO ETL for non-fullerene organic solar cells

Amorphous metal-oxide semiconductors have been developed as prospective substitutes for organic and silicon compounds, and their applications have been expanded due to their superior mobility in amorphous phase. As a result, this study demonstrated a facile approach to amend the interface quality by oxygen vacancy engineering. Here, we compared the performance of optimized oxygen-deficient (Od) and oxygen-rich (Or) amorphous indium–gallium–zinc oxide (a-IGZO) electron transport layers (ETL) for non-fullerene organic solar cells (OSCs). The ETL was fabricated using rf magnetron sputtering by changing oxygen contents. The power conversion efficiency (PCE) of Or device is 5.1 %, which was boosted to 6.6 % for Od device. The device with Od a-IGZO ETL outperforms the Or device, as the oxygen vacancies in Od device aid as electron donors, which deliver free electron carriers to IGZO film. These free electron carriers promote electron concentration, device mobility and deteriorate the resistivity, which facilitate charge transport and collection towards the electrode. Furthermore, devices improved their stability, as device with Od a-IGZO ETL retained almost 80 % of its initial PCE in ambient conditions. Consequently, interfacial engineering has played a crucial role in bringing OSC towards commercialization as it has substantial influence on charge collection and transport properties in devices.

Plasmonic Titanium Nitride Nanohole Arrays for Refractometric Sensing.

Group IVB metal nitrides have attracted great interest as alternative plasmonic materials. Among them, titanium nitride (TiN) stands out due to the ease of deposition and relative abundance of Ti compared to those of Zr and Hf metals. Even though they do not have Au or Ag-like plasmonic characteristics, they offer many advantages, from high mechanical stability to refractory behavior and complementary metal oxide semiconductor-compatible fabrication to tunable electrical/optical properties. In this study, we utilized reactive RF magnetron sputtering to deposit plasmonic TiN thin films. The flow rate and ratio of Ar/N2 and oxygen scavenging methods were optimized to improve the plasmonic performance of TiN thin films. The stoichiometry and structure of the TiN thin films were thoroughly investigated to assess the viability of the optimized operation procedures. To assess the plasmonic performance of TiN thin films, periodic nanohole arrays were perforated on TiN thin films by using electron beam lithography and reactive ion etching methods. The resulting TiN periodic nanohole array with varying periods was investigated by using a custom microspectroscopy setup for both reflection and transmission characteristics in various media to underline the efficacy of TiN for refractometric sensing.

Enhanced electrochromic performance of tungsten oxide thin films with oxygen vacancy deposited on PET by RF magnetron sputtering

Enhanced electrochromic performance of tungsten oxide thin films with oxygen vacancy deposited on PET by RF magnetron sputtering

Investigation of low-temperature deposition of SnO2 thin film for improving sensitivity of LaOCl/SnO2 heterojunction CO2 sensor using electrochemical impedance spectroscopy

In this study, LaOCl/SnO2 heterojunction CO2 sensors were fabricated by spin-coating LaOCl onto a SnO2 thin film fabricated via RF magnetron sputtering. The sensitivity of LaOCl/SnO2 heterojunction CO2 sensors tended to improve with the deposition of SnO2 thin films without intentional heating (at approximately 35 °C). Electrochemical impedance spectroscopy measurements revealed that the formation of a LaOCl/SnO2 heterojunction interface is indispensable for high-sensitivity sensors, and LaOCl acted not only as a catalyst but also as a capacitive layer in the sensors. The capacitive element of the LaOCl/SnO2 heterojunction changed under a CO2 gas atmosphere. It is confirmed that the formation of heterojunction interfaces contributes to the improvement of sensitivity. The results of this study indicate the potential applications of heterojunction gas sensors.

Hard and Highly Adhesive AlMgB14 Coatings RF Sputtered on Tungsten Carbide and High-Speed Steel

We report a new industrial application of aluminum magnesium boride AlMgB14 (BAM) coatings to enhance the hardness of tungsten carbide ceramic (WC-Co) and high-speed steel tools. BAM films were deposited by RF magnetron sputtering of a single dense stoichiometric ceramic target onto commercial WC-Co turning inserts and R6M5 steel drill bits. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. Very smooth (6.6 nm RMS surface roughness onto Si wafers) and hard AlMgB14 coatings enhance the hardness of WC-Co inserts and high-speed R6M5 steel by a factor of two and three, respectively. Complete coating spallation failure occurred at a scratch adhesion strength of 18 N. High work of adhesion and low friction coefficient, estimated for BAM onto drill bits, was as high as 64 J/m2 and as low as 0.07, respectively, more than twice the surpass characteristics of N-doped diamond-like carbon (DLC) films deposited onto nitride high-speed W6Mo5Cr4V2 steel.

Sputter epitaxy and characterization of manganese-doped indium tin oxide films with different crystallographic orientations

Epitaxial Mn-doped indium tin oxide (ITO) films were deposited on single-crystal yttria stabilized zirconia (YSZ) substrates with (111), (110), and (100) crystal plane orientations using RF magnetron sputtering. The epitaxial relationship between the Mn-doped ITO films and the YSZ substrates was studied using x-ray diffraction (XRD) patterns in the ω–2θ scan mode and XRD pole figures. The Mn-doped ITO films on the YSZ(111) and YSZ(110) substrates exhibited a higher degree of crystallinity than the film on the YSZ(100) substrate as per the x-ray rocking curves. Fluctuations in the crystalline alignment were found to significantly influence the electrical properties of Mn-doped ITO films. Ferromagnetic hysteresis loops were observed at room temperature for all the epitaxial Mn-doped ITO films, irrespective of their crystallographic orientation. The magnetic properties of the epitaxial Mn-doped ITO films suggest that a combination of delocalized charge carrier-mediated interaction and bound magnetic polaron-driven interaction is required to explain the origin of ferromagnetism in these films. The Mn-doped ITO film on the YSZ(111) substrate exhibited the most desirable characteristics in terms of crystallinity, surface smoothness, electrical conductivity, and magnetic properties.

Compositional Modification of Epitaxial Pb(Zr,Ti)O3 Thin Films for High‐Performance Piezoelectric Energy Harvesters

AbstractIn this study, Piezoelectric energy harvesters (PEHs) are fabricated based on epitaxial Pb(Zr,Ti)O3 (PZT) thin films deposited by an RF magnetron sputtering with varied Zr/[Zr+Ti] ratio. For a compatibility with micro‐electromechanical systems, the epitaxial PZT thin films are deposited on Si substrates (PZT/Si). The morphotropic phase boundary (MPB) are formed in the compositional range of 0.44 ≤ Zr/[Zr+Ti] ≤ 0.51 of the epitaxial PZT/Si, which is far broader than that of the bulk PZT. Meanwhile, effective transverse piezoelectric coefficient (|e31,f|) values are evaluated by the direct and converse piezoelectric effects using the unimorph cantilever method. Among the compositions, the rhombohedral‐dominant MPB (MPB‐R) of Zr/[Zr+Ti] = 0.51 exhibits a direct |e31,f| of 10.1 C m−2 and a relative permittivity (εr) of 285, leading to the maximum figure of merit of 40 GPa in this study. On the other hand, the maximum converse |e31,f| of 14.0 C m−2 is measured from the tetragonal‐dominant MPB (MPB‐T) of Zr/[Zr+Ti] = 0.44. At a resonance frequency, the MPB‐T presents a high output power density of 301.5 µW−1/(cm2 g2) under an acceleration of 3 m−1 s−2, which is very promising for the high‐performance PEH applications.

Operando Dissolution of RF Magnetron-Sputtered Thin-Film LiCoO2 Cathodes during Galvanostatic Cycling: In Situ Evaluation of Dissolution and Performance Data

Operando Dissolution of RF Magnetron-Sputtered Thin-Film LiCoO₂ Cathodes during Galvanostatic Cycling: In Situ Evaluation of Dissolution and Performance Data

Two spin-valve GMR thin films on half wheatstone bridge circuit for detecting green-synthesized Fe3O4@Ag nanoparticles-labeled biomolecule

The availability of low-cost, rapid, and easy-to-use instruments for detecting biomolecules is critical in giant magnetoresistance (GMR) based biosensors. This research reports the performance of two spin-valve (SV) GMR thin films on half Wheatstone bridge circuits for detecting biomolecules. The SV thin films with the structure of Ta(2 nm)/Ir20Mn80(10 nm)/Co90Fe10(3 nm)/Cu(2.2 nm)/Co84Fe10B4(10 nm)/Ta(5 nm) used as sensing element was fabricated using RF magnetron sputtering on Si/SiO2 substrate. The Fe3O4 magnetic nanoparticles as a label were synthesized by coprecipitation method based on the green synthesis route using Moringa oleifera (MO) extract. Furthermore, the utilization of Ag nanoparticles to form Fe3O4@Ag was also green-synthesized by the aqua-solution method using MO extract. The nanoparticles exhibited soft ferromagnetic behavior with the saturation magnetization of 55.0 emu/g for Fe3O4 and 43.4 emu/g for Fe3O4@Ag. A small amount of magnetic nanoparticles-ethanol solution was dropped onto each sensing element surface on half Wheatstone bridge. For comparison, one thin film was also investigated as a quarter Wheatstone bridge circuit. Based on this research, two sensors have faster magnetic switching and saturation than one sensor, confirmed by the left-shifting of Hs(sv) from 12.4 Oe down to 10.5 Oe for two sensors of the Fe3O4 sample. BSA is used as a biomarker to observe the performance of biosensors. The sensor on the half-bridge circuit in detecting Fe3O4@Ag/BSA achieved a better sensitivity of 0.51 mV/mg/mL than that of the quarter bridge of 0.46 mV/mg/mL. A small limit-of-detection of 0.5 mg/mL was achieved for Fe3O4@Ag/BSA. Moreover, the excellent reproducibility and stability of the sensor were confirmed by relative signal deviation ranges of 2–13 % for 60 s. Therefore, the half-bridge configuration is reliable for achieving competitive performance with green-synthesized magnetic labels in GMR as biosensors in encouraging more responsive detection.

Crystallization features and physical properties of the thin-film heterostructure of lead zirconate titanate – lead oxide

Various diagnostic techniques aimed at studying the structure and physical properties (synchronous thermal analysis, atomic force microscopy operating in the current measurement mode, electron-probe X-ray spectral microanalysis, dynamic method for determining the pyroelectric response) were used to study the crystallization features and physical properties of the thin-film heterostructure PZT – PbO1+x formed by a two-stage technique of RF magnetron sputtering of a ceramic target. During the first stage, amorphous films were deposited on a “cold” platinized silicon substrate, while the second stage involved high-temperature annealing in air. It was shown that annealing of amorphous films and crystallization of the intermediate pyrochlore phase are accompanied by additional oxidation of the structure resulting in the formation of lead orthoplumbate and lead dioxide and additional oxidation of organic inclusions. The presence of a liquid phase of lead oxide contributes to the formation of the pyrochlore phase. It was found that lead oxide layers have significantly higher through conductivity than perovskite blocks. It was assumed that the increased conductivity of lead oxide layers is associated with lead dioxide, which has high conductive properties. Self-polarized thin films were detected to have an abnormal electrical response to the strobing thermal exposure, including the typical pyroelectric response, local photoconductivity shunted by layers of the perovskite phase, and through photoconductivity. The presence of photoconductivity is also associated with the conductive properties of lead dioxide

Transparent artificial synapses based on Ag/Al-doped ZnO/ITO memristors for bioinspired neuromorphic computing

Today's computing systems to meet the enormous demands of information processing have driven the development of brain-inspired neuromorphic systems that can perform fast and energy-efficient calculations. In this study, Al-doped ZnO (AZO: ZnO to Al2O3 = 98:2 wt%) films with over 95 % light transmission were prepared by RF magnetron sputtering, and a structurally simple Ag/AZO/ITO memristor was fabricated. Moreover, the sustained potentiation/depression behavior of the memristor allows it to mimic artificial synapses that exhibit biological synaptic and neuronal functions such as short-term/long-term plasticity and paired-pulse facilitation.These results will contribute to the research and development of high-performance artificial synapses.

Electron Beam-Initiated Grafting of Methyl Methacrylate on Silicon Nanowires: Investigating Optical and Structural Properties

Silicon nanowire (SiNW) is a one-dimensional nanostructured material that had been widely studied due to its potential applications in various fields. Combination of polymers and nanostructured materials offers great potential for enhanced material with many possible applications. The investigation focuses on how this grafting process influences the optical properties of SiNWs, aiming to uncover potential applications for these hybrid materials. This paper comprehensively presents the methodology and characterization of these SiNWs-MMA hybrid materials, exploring their potential applications. The experimental process begins with the preparation of six SiNWs using RF magnetron sputtering, involving the deposition of an Au catalyst and subsequent growth of SiNWs. The radiation-induced grafting involves exposing SiNWs to electron beams and subsequently grafting MMA onto the surface. The outcomes reveal that the grafting percentage of MMA onto SiNWs increases with higher radiation doses, leading to a polymer layer covering the SiNWs. This grafting is confirmed through Fourier-transform infrared (FTIR) spectroscopy, which shows characteristic peaks of MMA on the surface. X-ray diffraction (XRD) analysis demonstrates changes in crystallite size, microstrain, and dislocation density upon grafting, which are attributed to stress relief and the effect of polymer on SiNWs’ lattice. Field emission scanning electron microscopy (FESEM) images exhibit the increasing MMA layer on SiNWs as the grafting percentage increases. UV-visible spectroscopy shows that the introduction of MMA increases the optical band gap of SiNWs, attributed to changes in surface roughness due to the carbon from MMA. This study introduces a novel method of hybridizing SiNWs with MMA through radiation-induced grafting. The detailed characterization of the resulting SiNWs-MMA hybrid materials sheds light on their structural and optical properties. These findings hold the promise of innovative applications in various technological fields, further advancing nanotechnology.

Heteroepitaxial growth of β-Ga2O3 thin films on single crystalline diamond (111) substrates by radio frequency magnetron sputtering

In this work, we demonstrate the first achievement in heteroepitaxial growth of β-Ga2O3 thin films on single crystalline diamond (111) wafers using RF magnetron sputtering. A single monoclinic (β-phase) structure with a monofamily {01} plane was obtained. XRD pole figure shows (02) and (002) textures of the (01) β-Ga2O3 plane parallel to (111) diamond with six distinct rotational domains, confirming successful epitaxial growth. Collectively, this research provides valuable insights into the epitaxial growth of β-Ga2O3 on diamond via sputtering, paving the way for scalable β-Ga2O3/diamond heterostructures for future electronic and optoelectronic applications with not only high performance but also effective self-thermal management.

High-performance of laser annealed ITO/Cr-Ag/ITO multilayered thin film for transparent conducting application.

A novel laser annealing treatment was used to enhance the optoelectronics, and the morphological properties of ITO/Cr-Ag/ITO (ICAI) thin film are presented. The multilayer thin film was deposited using the RF magnetron sputtering technique and annealed using an Nd:Yag laser. The ICAI properties were characterized using X-ray diffraction, an atomic force microscope, field emission scanning electron microscope, energy dispersive X-ray, UV–visible spectroscopy, four and two-probe point probe. These techniques show the high quality of the thin film and the improvement of the properties caused by the laser annealing. The XRD shows that laser annealing improves the crystalline quality of the film. The AFM and FESEM exhibit uniform and high surface quality, where the roughness was decreased, and the grain size was enlarged. The optical transmittance was increased from 80 to 90 %, similar to the bandgap from 3.35 to 3.79 eV The electrical measurements show a significant decrease in the resistivity, and an Ohmic contact improved with laser annealing. The annealed structure has recorded a high figure of merit of 174 × 10−3 Ω−1. These results demonstrate that laser annealing treatment significantly enhances the thin film's properties. Therefore. The ICAI structure can replace the other transparent conducting material with a low annealing temperature and low energy.

Effects of Oxygen Defects in Zr Oxide-Based Thin Films on Oxygen Reduction Reaction in Acidic Media

Zirconium oxide thin films were prepared by RF magnetron sputtering as model catalysts for oxygen reduction reaction (ORR) in acidic media. The effects of sputtering conditions on ORR activity in acidic media was investigated. The effect of the deposition temperature on the ORR activity depended on whether the deposition atmosphere contained oxygen (Ar+O2, Ar+N2+O2) or only nitrogen (Ar+N2). In the range of 300-800 °C of the deposition temperature, the electrodes prepared in an Ar+N2 showed higher ORR activity. XRD and XPS results showed that the tetragonal phase grew in an Ar+N2 atmosphere, while a mixed phase of tetragonal and monoclinic phases grew in an Ar+O2 atmosphere. It was found that Zr oxide thin film with a high proportion of tetragonal phase showed high ORR activity.

A Highly Transparent β-Ga2O3 Thin Film-Based Photodetector for Solar-Blind Imaging

Ultra-wide bandgap Ga2O3-based optoelectronic devices have attracted considerable attention owing to their special significance in military and commercial applications. Using RF magnetron sputtering and post-annealing, monoclinic Ga2O3 films of various thicknesses were created on a c-plane sapphire substrate (0001). The structural and optical properties of β-Ga2O3 films were then investigated. The results show that all β-Ga2O3 films have a single preferred orientation (2(_)01) and an average transmittance of more than 96% in the visible wavelength range (380–780 nm). Among them, the sample with a 90-minute sputtering time has the best crystal quality. This sample was subsequently used to construct a metal-semiconductor-metal (MSM), solar-blind, ultraviolet photodetector. The resulting photodetector not only exhibits excellent stability and sunblind characteristics but also has an ultra-high responsivity (46.3 A/W) and superb detectivity (1.83 × 1013 Jones). Finally, the application potential of the device in solar-blind ultraviolet imaging was verified.

Studies on photovoltaic properties of BFO/WO3 bilayer thin films for solar energy harvesting applications

BFO possess high remnant polarization (∼100 μC/cm2) and low direct band gap (∼2.7 eV) having potential for photovoltaic (PV) applications. In the present work, WO3 insulating layer is utilized with BFO and BFO/WO3 bilayer thin film structure is fabricated for reducing the leakage current along with possessing the low band gap and high ferroelectric polarization. In BFO/WO3 bilayer structure, the WO3 nanostructured thin film layer was fabricated utilizing rf-magnetron sputtering technique under the optimized parameters while BFO thin film layer was fabricated by altering the incident energy of excimer laser (150 mJ − 250 mJ) in Pulsed Laser deposition technique. BFO/WO3 bilayer structure prepared at 200 mJ laser energy demonstrated the superior ferroelectric properties (Ps = 63.24 µC/cm2 and Pr = 25.94 µC/cm2) with high values of short circuit photocurrent density (Jsc = ∼18 mA/cm2) and open-circuit voltage (Voc = ∼320 mV) under the UV illumination of Intensity = 160 mW/cm2 and λ = 355 nm. Obtained results suggest the utilization of prepared BFO/WO3 bilayer thin film structures on future novel energy harvesting purposes.

Reusability, Long‐Life Storage and Highly Sensitive Zirconium Nitride (ZrN) Surface‐Enhanced Raman Spectroscopy (SERS) Substrate Fabricated by Reactive Gas‐Timing Rf Magnetron Sputtering

AbstractTransition metal nitrides (TMN) are promising material alternative to replace noble metals in the field of plasmonic applications, especially surface‐enhanced Raman spectroscopy (SERS). Here we demonstrate a practical surface enhanced Raman spectroscopy (SERS) substrate using zirconium nitride (ZrN) thin films grown by reactive gas‐timing (RGT) rf magnetron sputtering. The tailored properties of ZrN thin film exploited for SERS activity could be achieved to obtain a highly sensitive ZrN thin film SERS substrate with the enhancement factor (EF) of 1.24 × 106 and 4.8 %RSD at 1626 cm‐1 toward methylene blue (MB) analyte which are comparable to the optimized Au sputtered thin films (EF=1.18 × 106 and with 5.1%RSD). We find that the spatial plasmonic hotspots on the surface of ZrN SERS substrate controlled by the turn‐on timing of Ar:N2 sputtered gas sequence, leading to the discrete conductive surface profile, strongly relates to non‐stoichiometric composition and the degree of (200)‐oriented texture at the surface of ZrN thin film. Furthermore, ZrN thin film SERS substrates exhibit an excellent recyclability more than 30 cycles with simple cleaning process and a storage time longer than 6 months. The detection and reusability of ZrN SERS substrate on the low concentration of trinitrotoluene (TNT) for homeland security are also performed.

Investigation of corrosion and wear performance of TiNbTaZr/Cr-Mo PVD coatings on 316L SS in Hanks's solution for improved biomedical applications

316L stainless steel is popular due to its strength, durability, and especially cost-effectiveness in biomedical implant applications. However, the primary drawback of those materials is damage by corrosion and wear over prolonged exposure to the body's physiological environment. Thus, surface modification or coatings are essential to mitigate the corrosion and wear sensitivity of 316L implant materials. In this study, the corrosion and wear performance of TiNbTaZr/Cr-Mo PVD coatings on 316L stainless steel (SS) for improved biomedical applications have been investigated comprehensively. The coatings were deposited using an RF magnetron sputtering PVD system, and their morphological, structural, and wettability properties were characterized through SEM-EDS, GI-XRD, and contact angle measurements. The coatings' hardness was compared by using the Knoop hardness method and their surface roughness was analyzed by using a profilometer. Electrochemical corrosion tests and wear studies were conducted in both dry and simulated body fluid (SBF) conditions. The results indicated that the coatings exhibited nano-sized grain structures with no instances of delamination or cracking and consisted of a stable β-phase. The hardness of the coatings was significantly higher than that of the uncoated 316L sample. Contact angle measurements showed improved hydrophilicity for both coatings compared to uncoated 316L SS. Furthermore, the TNTZ-Mo coating demonstrated superior corrosion resistance and reduced wear under SBF conditions, making it a promising material for biomedical applications.

Al doping and defect regulation of sputtered CdZnTe films based on Al–AlN transition layers

CdZnTe films with less defects and high quality were fabricated on aluminum-rich AlN (Al–AlN) transition layers by RF magnetron sputtering technique. The Al doping and regulation effect on defect states, structure and photoelectrical performance of CdZnTe films were minutely investigated by XRD, HRTEM, SEM, XPS, Photoluminescence and Photoelectric characteristics. Results strongly suggested the self-doping process of Al from Al–AlN transition layers, which helped to compensate the defect density of Cd vacancy in CdZnTe films, thus improving crystallization, response performances and resistivity of Al-doped CdZnTe films. Electrical characterization implied the formation of good ohmic contact between electrodes and Al-doped CdZnTe films. Under 254 nm UV light illumination, the surface dark current of optimal Al-doped CdZnTe film was 25 times smaller than that of non-doped film, and rise and decay times were 3.4 and 2.8 times faster, indicating the feasibility of high quality film detectors for solar-blind UV detection.