Fabrication Of Thin Films Research Articles

Fabrication and application of two-dimensional tungsten disulfide thin film

To form a tungsten disulfide film, a tungsten trioxide film is deposited first and then hydrogen sulfide is injected into the furnace tube to sulfide the tungsten trioxide film in a high-temperature environment. Due to the need to accurately control the thickness of tungsten trioxide, the power of the RF sputtering machine was reduced as much as possible in a stable condition in the experiment and the bias voltage during each process was monitored. In this experiment, a sapphire substrate and a silicon substrate with 200[Formula: see text]nm silicon dioxide are used. Then use optical instruments such as Raman optics, ellipsometers and high-resolution electron transmission microscopes, atomic force microscopes and other instruments for further measurement. The analysis results show that we have successfully made tungsten disulfide films of different thicknesses. Moreover, two-dimensional tungsten disulfide thin film has a response to light, gas and pH and related devices have been successfully fabricated in experiments. Among them, comparing the single-layer film and the double-layer film, the film quality of the double-layer film is better. The quality of the film grown on the sapphire substrate is also better than the quality of the film grown on the silicon dioxide substrate.

Fabrication of Large-Area Multi-Stimulus Responsive Thin Films via Interfacially Confined Irreversible Katritzky Reaction.

Fabrication of large-area thin films through irreversible reactions remains a formidable task. This study reports a breakthrough strategy for in situ synthesis of large-area, free-standing, robust and multi-stimulus responsive thin films through a catalyst-free and irreversible Katritzky reaction at a liquid-liquid interface. The as resulted films are featured with adjustable thickness of 1-3 μm and an area up to 50 cm2. The thin films exhibit fast photo-mechanical motions (a response time of ca 0.1 s), vapor-mechanical motions, as well as photo-chromic and solvato-chromic behaviors. It was revealed that the reason behind the observable motions is proton transfer from the imine groups to the carbonyl structures within the film induced by photo- and/or dimethyl sulfoxide-stimulus. In addition, the films can harvest anionic radicals and the radicals as captured can be efficiently degraded under UV light illumination. This study provides a new strategy for fabricating smart thin films via interfacially confined irreversible Katritzky reaction.

Palladium enhanced electrochemical supercapacitive performance of chromium oxide thin films synthesized by sputtering process

Recently, the use of transition metal oxide electrodes for supercapacitor applications has increased due to the possibility of variable mixed valence states. The present study has established the use of Pd-Cr2O3 composite thin films as a working electrode for high-performance supercapacitors. The reactive dc magnetron co-sputtering method has been used for the fabrication of thin film of Cr2O3 and Pd-Cr2O3 on SS-304 substrate. X-ray diffraction and X-ray photoemission spectroscopy techniques were used to examine the surface chemistry and phase purity of chromium oxide and Pd-Cr2O3 composite thin films. The incorporation of Pd in Cr2O3 delivers a drastic change in the surface morphology. Due to the modified morphology and electronic properties, a noticeable improvement in the electrochemical properties of Pd-Cr2O3 electrode is observed. The obtained value of specific capacitance for this electrode is 401 Fg−1 at 0.1 mAcm−2 scan rate and within the potential window range 0 to +1.2 V. This value of specific capacitance is almost twice in comparison to the Cr2O3 based electrode. The Pd-Cr2O3 composite thin film shows a good cycle retention capability of 8000 cycles with 87.5 % retention. The obtained value of energy density and power density for Pd-Cr2O3 electrode was 80.2 Whkg−1 and 3.23 kWkg−1, respectively at 0.1 mAcm−2. Consequently, this composite material electrode can be seen as a promising advancement for electrodes in supercapacitor devices.

Biosynthesis of bioplastic polyhydroxybutyrate (PHB) from microbes isolated from paddy/sugarcane fields and fabrication of biodegradable thin film

Polyhydroxybutyrate (PHB) is a polyhydroxyalkanoate (PHA) family microbial polyester. Three Gram-negative bacteria that produce PHB, Acinetobacter baumannii, Enterobacter hormaechei, and Pseudomonas xanthomarina were isolated and cultured in nitrogen-limited minimal salt media. The pH and culture media were further optimized with various glucose and peptone as carbon and nitrogen sources to improve PHB production. FTIR, UV–vis, NMR, TGA, and XRD were used to characterize the PHB produced. The optimal pH for PHB production by Acinetobacter baumannii, Enterobacter hormaechei, and Pseudomonas xanthomarina was discovered to be 6.5, 7.5, and 7.5, respectively. P. xanthomarina produced the highest PHB (7.5 gm/L) in the optimized culture media. Furthermore, PHB-starch thin films were prepared and characterized by XRD before their biodegradability was investigated. The degradation study reveals that 25% of PHB-starch blended thin film has been degraded within 30 days.

Optimization of Laser-Wavelength Dependence for Open-Air Atmospheric Pressure Pulsed Laser Deposition of AlCrFeMnTi High-Entropy Alloy for Tailored Surface Properties.

High-entropy alloys (HEAs) have garnered significant attention in different fields due to their exceptional mechanical and physical properties, making them promising candidates for various applications. Several techniques, including physical vapor deposition and pulsed laser deposition (PLD), have been employed for the fabrication of HEA thin films. In this study, we explore a novel approach to synthesizing the lightweight HEA (LWHEA) AlCrFeMnTi using PLD in air at atmospheric pressure with a particular focus on the influence of the laser wavelength on the deposition process and the resulting alloy characteristics. This research investigates the impact of different laser wavelengths on the LWHEA's characterization and the optimization of laser wavelength dependence in air at atmospheric pressure PLD of LWHEA AlCrFeMnTi for tailored surface properties such as phase composition, microstructure, and corrosion resistance. Systematically varying the laser wavelength was attempted to optimize the deposition conditions. This was aimed at achieving enhanced properties and precise control over the alloy's composition. This work contributes to a deeper understanding of the open air PLD process for LWHEAs and sheds light on the role of the laser wavelength in tailoring their properties, which can have significant implications for the development of advanced materials for aerospace, automotive, and other high-performance applications. Ultimately, this research aims to provide valuable insights into the design and fabrication of LWHEAs with tailored properties through laser-based deposition techniques.

Fabrication and Characterization of Boron-Implanted Silicon Superconducting Thin Films on SOI Substrates for Low-Temperature Detectors

Fabrication and Characterization of Boron-Implanted Silicon Superconducting Thin Films on SOI Substrates for Low-Temperature Detectors

Fabrication of CZTS Thin Film on Flexible Cu-Foil Substrate by Two-Stage Process

In this research, CZTS thin films grown on flexible Cu-foil with varying sulfurization times. Various characterization methods were employed, including X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), optical transmission, and photoluminescence (PL) measurements. Distinctive diffraction peaks characteristic of the kesterite CZTS phase were observed in the XRD analysis, occurring around at 2θ= 28.45° (112), 47° (220/204), and 56° (312/116). Additionally, some secondary phases such as Cu2S and SnS were identified. Raman spectroscopy confirmed the presence of the kesterite phase, with a prominent peak detected at approximately ~336 cm-1, attributed to sulfur atom vibrations within the kesterite structure. Apart from CZTS structure, minor peaks suggesting the presence of the Cu2SnS3 (CTS) phase was detected. EDX analysis revealed compositions with Cu-poor content and Zn-rich content across all samples, with slight variations in sulfurization dwell times affecting the chemical composition. SEM imaging at different magnifications showed alterations in surface morphology and grain structures. Films sulfurized for 30 s and 60 s displayed a granular structure morphology, while extending the dwell time to 120 s resulted in a more compact surface morphology. Optical band gap values ranged between 1.57 and 1.60 eV. PL measurements consistently exhibited strong PL emission around 1.25 eV for all samples, attributed to various transitions within the CZTS structure. The absence of observable band-to-band transitions in the PL measurements indicated the presence of intrinsic defect levels and recombination centers within CZTS. Overall, it was demonstrated in this study that CZTS thin films can be produced on flexible Cu-foils with short sulfurization times, thereby expanding the application areas of CZTS thin-film solar cells.

Fabrication and characterization of HfxAl(1-x)Oy ceramic targets and thin films by RF sputtering

The potential of HfO2 as a memory semiconductor material with ferroelectric properties in thin-film deposition has been recently analyzed. In this study, the preparation, composition, and physical properties of Al-doped hafnium oxides were analyzed. HfxAl(1-x)Oy (HAO) [x = 0.33, 0.5, and 0.67] powders were prepared by controlling the ratio of Hf to Al and using ball milling. The HAO powder was calcined at 1000 °C in a furnace and then sintered in a temperature range of 1000–1600 °C by a solid-state reaction method to fabricate high-quality targets with high densities. The density and crystal size increased with the sintering temperature. The 1600-°C Hf0.67Al0.33Oy target was optimal for thin-film deposition. In addition, the target properties were affected by an increase in the HfO2 content x. The crystal structures and sizes, surface free energies, contact angles, and band gaps of the HAOs were evaluated to analyze their potential as high-k dielectric materials. HAO is a promising high-k dielectric and memory material, valuable for further studies on ferroelectric gate oxide materials. This study contributes to the increasing number of studies on the ferroelectricity of HfO2 thin films and provides a fundamental understanding of this material and its potential for novel device applications.

A BaTiO3-based flexible ferroelectric capacitor for non-volatile memories

BaTiO3 (BTO) ferroelectric films, which are renowned for their lead-free compositions, superior stability, and absence of a wake-up effect, are promising candidate materials in the field of non-volatile memories. However, the prerequisites for high-temperature conditions in the fabrication of ferroelectric thin films impose constraints on the substrate choice, which has limited the advancement in non-volatile memories based on single-crystal flexible BTO films with robust ferroelectric properties. Herein, a technique has been developed for the fabrication of flexible devices using a pulsed laser deposition system. BTO ferroelectric films have then been deposited onto a flexible mica substrate, with SrTiO3 (STO) serving as a buffer layer. The obtained flexible BTO devices exhibited excellent ferroelectricity, with a maximum polarization (2Pmax) of up to 42.58 μC/cm2 and a remnant polarization (2Pr) of up to 21.39 μC/cm2. Furthermore, even after 1000 bending cycles, the bipolar switching endurance remained high at 1012 cycles. After 104 s, the flexible BTO device still maintained excellent polarization characteristics. These results make the flexible BTO ferroelectric thin film a potential candidate for the next generation of non-volatile memories.

High-speed blade-coating using liquid crystalline organic semiconductor Ph-BTBT-10

We have investigated the fabrication of crystalline thin films of a liquid crystalline organic semiconductor (2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene: Ph-BTBT-10) by high-speed blade-coating at 140 mm s−1. Uniform crystalline Ph-BTBT-10 films were fabricated at temperatures over 50 °C, which is the temperature of the liquid crystal phase, without inhomogeneous recrystallization, despite the high-speed blade-coating. Transistors fabricated using these films showed a high average carrier mobility of 4.8 cm2 Vs−1 for 26 devices, with a coefficient of variation of only 7.3%. We concluded that liquid crystalline organic semiconductors are useful materials for high-speed meniscus-guided-coating for practical use.

Electrically conductive gold films formed by sintering of gold nanoparticles at room temperature initiated by ozone

Understanding and controlling the sintering behaviour of gold nanoparticles is important in the field of ligand-protected nanoparticles for their use as precursors for thin film fabrication. Lowering the temperature of the sintering event of gold nanoparticles by facilitating desorption of the ligand through oxidation can provide compatibility of sintered gold nanoparticle thin films onto heat-sensitive substrates. Here we examine the processes by which 1-butanethiol-protected gold nanoparticles sinter under an ozone-rich environment. Upon heating, an ozone-rich environment significantly reduces the temperature of the sintering event when compared to sintering under ambient conditions. At room temperature, exposure to an ozone-rich environment induces sintering over a period of 2.5 h. Upon exposure to ozone, the surface-bound butanethiol ligands are oxidised to 1-butanesulfonic acid which facilitates sintering.

Thermally Evaporated Metal Halide Perovskites and Their Analogues: Film Fabrication, Applications and Beyond.

Metal halide perovskites emerge as promising semiconductors for optoelectronic devices due to ease of fabrication, attractive photophysical properties, their low cost, highly tunable material properties, and high performance. High-quality thin films of metal halide perovskites are the basis of most of these applications including solar cells, light-emitting diodes, photodetectors, and electronic memristors. A typical fabrication method for perovskite thin films is the solution method, which has several limitations in device reproducibility, adverse environmental impact, and utilization of raw materials. Thermal evaporation holds great promise in addressing these bottlenecks in fabricating high-quality halide perovskite thin films. It also has high compatibility with mass-production platforms that are well-established in industries. This review first introduces the basics of the thermal evaporation method with a particular focus on the critical parameters influencing the thin film deposition. The research progress of the fabrication of metal halide perovskite thin films is further summarized by different thermal evaporation approaches and their applications in solar cells and other optoelectronic devices. Finally, research challenges and future opportunities for both fundamental research and commercialization are discussed.

Enhancement of ZT in Bi0.5Sb1.5Te3 Thin Film through Lattice Orientation Management.

Thermoelectric power can convert heat and electricity directly and reversibly. Low-dimensional thermoelectric materials, particularly thin films, have been considered a breakthrough for separating electronic and thermal transport relationships. In this study, a series of Bi0.5Sb1.5Te3 thin films with thicknesses of 0.125, 0.25, 0.5, and 1 μm have been fabricated by RF sputtering for the study of thickness effects on thermoelectric properties. We demonstrated that microstructure (texture) changes highly correlate with the growth thickness in the films, and equilibrium annealing significantly improves the thermoelectric performance, resulting in a remarkable enhancement in the thermoelectric performance. Consequently, the 0.5 μm thin films achieve an exceptional power factor of 18.1 μWcm-1K-2 at 400 K. Furthermore, we utilize a novel method that involves exfoliating a nanosized film and cutting with a focused ion beam, enabling precise in-plane thermal conductivity measurements through the 3ω method. We obtain the in-plane thermal conductivity as low as 0.3 Wm-1K-1, leading to a maximum ZT of 1.86, nearing room temperature. Our results provide significant insights into advanced thin-film thermoelectric design and fabrication, boosting high-performance systems.

Fabrication of Bi-doped In2S3 thin films for highly sensitive UV photodetector applications

Fabrication of highly sensitive, high-speed photodetectors, especially using cost-effective and less toxic materials, has attracted continuous attention due to their outstanding advantages. In this report, we present different properties of Bi-doped (0,1, 3, and 5 wt%) In2S3 thin films for UV photodetectors. Bi-doped (0, 1, 3, and 5 wt%) In2S3 thin films were coated on glass substrates at a temperature of 350 °C using a low-cost nebulizer spray pyrolysis method. X-ray diffraction XRD analysis confirmed the cubic phase β-In2S3 for all the deposited films and high crystallinity is obtained for 1 wt% Bi-doped film. The presence of densely packed grains in 1 wt% Bi-doped In2S3 thin film and also small grains observed for undoped In2S3 sample is evident form morphology studies. Bi doping has caused an enhancement of optical absorption and incorporation of 1 wt% of Bi3+ into In2S3 has shifted the optical band gap from 2.87 to 2.78 eV. Current − Voltage characteristics and Current–Time characterization are used to know the key parameters of the photodetectors. Among all fabricated photodetectors, the In2S3 thin film doped with 1 wt% Bi showed superior photodetector performance with calculated Responsivity (R), Detectivity (D*), and External quantum efficiency (EQE) values of 0.65 AW−1, 15 × 1010 Jones, 125 % respectively. Transient photo-response analysis showed low rise and fall time of 3.21 and 3.78 s respectively for the 1 wt% Bi-doped sample. Optimally doped In2S3: Bi (1 wt%) thin film is most suited to fabricate photo sensing-based optoelectronic devices in UV region of the spectrum.

Dynamic wire-pull rubber diaphragm for rapid formation and spatio-temporal investigation of multi-shape free-standing liquid films

Quantitative manufacturing and characterization of thin films are relevant in different scientific and industrial fields. Especially, for the studies of fluid dynamics, the experimental verification of theoretical models creates the need of a free-standing liquid film formation. Driven by the lack of fast and accurate liquid film forming technology, we present a novel device able to fabricate thin free-standing liquid films, which is based on a dynamic and adjustable diaphragm, the opening of which allows for the rapid formation of a self-supported liquid film confined in a wire-pull rubber band. The quantitative thickness mapping of the film formation and its time-resolved evolution are performed by digital holography in real-time. This builds up a strategy that allows for the accurate liquid film formation with controllable size and volume. As the results, multi-shape and multi-material thin films under controllable and stable conditions are successfully formed, including free-standing water, soapy water and glycerol films. A label-free spatio-temporal analysis method for flow dynamics is proposed: The full-field time series of film thickness is reassembled in a new coordinate system composed of radius, time, and thickness. Such spatio-temporal analysis reveals details of leveling and drainage processes. To the best of our knowledge, this is the first full-field quantitative thickness analysis of multi-shape and multi-material thin films. The proposed Dynamic Wire-pull Rubber Diaphragm (DWRD) together with the digital holography add-on offer characterization abilities with an unprecedented level of details allowing for a deeper understanding of the underlying thin film dynamics that can be useful in several different scientific and technological fields as biotechnology, life science, and nanotechnology.

Effects of cold plasma treatment on the biological performances of decellularized bovine pericardium extracellular matrix-based films for biomedical applications

Aim: Since decades, decellularized extracellular matrix (dECM)-derived materials have received worldwide attention as promising biomaterials for tissue engineering and biomedical applications. Soluble dECM is a versatile raw material that can be easily engineered into the desired shapes and structures. However, there are still some limitations restricting its use, including low hydrophilicity and smooth surfaces, which negatively influence cell adhesion/spreading. The objective of the present study was to investigate surface modification by nitrogen/hydrogen (N2/H2) low-pressure cold plasma treatment as a potential technique to improve the biological response of bovine pericardium dECM films. Methods: Bovine pericardium dECM was enzymatically digested and lyophilized prior to the preparation of thin films via solvent-casting method. Changes in surface properties after plasma treatment were investigated using water contact angle (WCA) and X-ray photoelectron spectroscopy (XPS) measurements. Immunofluorescence staining and resazurin assay for human dermal fibroblasts (HDFs) cultured on the dECM films were used to assess the bioactivity of dECM films. Finally, the hemocompatibility of the films was investigated via clotting time and hemolysis assay. Results: WCA and XPS results revealed that oxygen (O)- and N-containing functional groups were incorporated onto the film surface and an increase in hydrophilicity was observed after plasma treatment. In vitro experiments showed that cell adhesion in plasma-treated dECM films is much faster if compared to the untreated controls. Moreover, the fibroblast proliferation increased after plasma surface modifications. Finally, the hemocompatibility analysis results indicated a delayed blood clotting and no hemolytic effects for all the tested samples. Conclusions: These findings confirmed the potential of dECM as raw material for biocompatible thin films fabrication. Additionally, plasma surface treatment emerged as an eco-friendly and cost-effective strategy to enhance in vitro cell attachment and proliferation on dECM films, expanding their applications in biomedicine.

Synergistic Effect of He for the Fabrication of Ne and Ar Gas-Charged Silicon Thin Films as Solid Targets for Spectroscopic Studies.

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He-Ne and He-Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble's size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as "solid" targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen.

Solution Processing Silicon Heterojunction Photocathode for Efficient and Stable Hydrogen Production.

Efficient and stable photocathodes are crucial for the development of photoelectrochemical (PEC) water-splitting devices. Silicon heterojunction (SHJ) solar cell is one of the most advanced photovoltaic cells. However, due to the instability of its outermost indium tin oxide (ITO) layers in the electrolyte, a protective layer needs to be introduced on its surface. Previously reported high-quality protective layers almost all involved the use of expensive thin film manufacturing techniques such as atomic layer deposition (ALD). In this work, for the first time, a new strategy is proposed of modifying SHJ-based photocathode with yttrium hydroxide (Y(OH)3) through two-step solution methods to simultaneously improve the stability and activity. The optimized SHJ photocathode exhibits a high applied bias photon-to-current efficiency (ABPE) of 8.4% under simulated 100mWcm-2 (1 Sun) with an AM 1.5G filter in 0.5m KOH. Furthermore, the obtained SHJ photocathode demonstrates excellent stability of at least 110h at 0.3V versus RHE. In this work, combining facile direct current magnetron sputtering with a solution treatment technique provides a novel design strategy, which lowers the threshold for preparing high-quality protective layer, and paves the way for developing economic, efficient, and stable SHJ-based PEC devices.

The fabrication of ultra-wide bandgap GeO2 thin films by DC magnetron sputtering: The impacts of growth temperature and post-annealing process

Ultra-wide bandgap semiconductors (UWBSs), possessing the bandgap greater than 4 eV, have emerged as an advanced platform for optoelectronic device applications. The exploration of novel UWBSs becomes compelling research focus on the solar blind photodetectors (SBPDs). Here, we have deposited ultra-wide bandgap GeO2 films on c-plane sapphire substrates using direct-current (DC) magnetron sputtering method and investigated the effects of the growth and annealing temperatures on surface morphologies, crystal structure, oxygen vacancies, and bandgap energies of GeO2 films. The high quality GeO2 film with the hexagonal phase can be obtained at the growth temperature of 500 °C, which transforms to the mixture of hexagonal and tetragonal phases after annealing at 900 °C. By analyzing the energy loss spectra of O 1s peaks, GeO2 films exhibit the ultra-wide bandgap ranging from 5.78 to 5.90 eV, which is verified by optical transmittance measurements. Moreover, 200 nm SBPDs based on GeO2 films have been fabricated and an obvious improvement in the photoresponse current of the annealed device has been found due to the induced additional electrons by the hole capture of oxygen vacancies. Our findings on the development of ultra-wide bandgap GeO2 films pave a way towards the realization of robust and high-performance SBPDs.

Inkjet‐Printed Red‐Emitting Flexible LEDs Based on Sustainable Inks of Layered Tin Iodide Perovskite

AbstractInkjet printing has emerged as a promising technique for the fabrication of halide perovskite (HP) thin films, as it enables precise and controlled deposition of the perovskite ink on a variety of substrates. One main advantage of inkjet printing for the fabrication of HP thin films is its ability to produce uniform films with controlled thickness and high coverage, which is critical for achieving high‐performance devices. Additionally, inkjet printing allows for the deposition of patterned thin films, enabling the fabrication of complex device architectures such as light‐emitting diodes (LEDs). In this work, flexible LEDs based on inkjet printed Pb‐free HP thiophene‐ethylammonium tin iodide (TEA2SnI4) are produced that has gained attention as a potential alternative to Pb‐based HPs in optoelectronic devices due to its lower toxicity, environmental impact, and high performance. The role of ink solutions is compared using pure solvents: toxic dimethyl formamide (DMF) and more eco‐friendly dimethyl sulfoxide (DMSO). Red‐emitting devices (λmax = 633 nm) exhibit, in ambient conditions, a maximum external quantum efficiency (EQEmax) of 0.5% with a related brightness of 21 cd m−2 at 54 mA cm−2 for DMSO‐based LEDs. The environmental impacts of films prepared with DMSO‐based solvents ensure only 40% of the impact caused by DMF.