Film Deposition Research Articles

Preparation of Atomically Smooth SrTiO₃ Substrates

SrTiO3 has been used as a substrate to grow thin films of materials including high-temperature superconductors such as cuprates, ferromagnetic oxides such as manganites, and ferroelectric oxides such as BaTiO3. The use of SrTiO3 as a substrate for the deposition of manganite thin films provides an excellent template for observing unique effects observed only in ferromagnets, such as the anomalous and planar Hall effects. The as-received SrTiO3 substrates require a process that prepares atomically smooth surfaces for thin film deposition. This study focuses on using ultrasonic cleaning, water annealing, and thermal annealing in air to prepare SrTiO3 substrate surfaces and verifying their smoothness at the atomic scale using atomic force microscopy.

Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics

With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.

Thin Film Deposition and Optical Properties of Cs-Cu-I System Via Mist Deposition with Various Precursor Compositions

Thin Film Deposition and Optical Properties of Cs-Cu-I System Via Mist Deposition with Various Precursor Compositions

ALd of Metal Fluorides–Potential Applications and Current State

AbstractMetal fluoride thin films are important materials in a multitude of applications. Currently, they are mostly used in optics, but their potential in energy harvesting and storage is recognized as well. Atomic layer deposition (ALD) is an advanced thin film deposition method that has an ever‐increasing role in microelectronics. The assets of ALD are its capability to produce uniform, stoichiometric, and pure films with precise thickness control even on top of complicated structures, such as high aspect ratio trenches. These characteristics can be beneficial in applications of metal fluoride thin films but so far ALD of metal fluorides has remained much less studied and used than ALD of metal oxides, nitrides, sulfides, and pure metals. This review aims to motivate research on ALD of metal fluorides by surveying potential applications for ALD metal fluoride thin films and coatings. The basics of luminescent applications, antireflection coatings, and lithium‐ion batteries will be discussed. Next, the fundamentals of ALD will be presented followed by a comprehensive summary of the metal fluoride ALD processes published so far.

Evolution of TiAlSi thin film coatings under varying target power in DC magnetron sputtering

This study, for the first time, presents the growth, nucleation, and characteristics of TiAlSi thin films sputtered from a partially sintered Ti30Al16Si10 (at. %) composite target under controlled conditions of target power. The TiAlSi thin films were grown on soda-lime glass substrates through Direct Current (DC) sputtering at varying levels of the target power: 73.2 W, 151.2 W, and 269.5 W. The other deposition parameters: the deposition temperature, time, argon mass flow rate, substrate rotation, and deposition pressure, were kept constant at 23 °C, 150 min, 25 sccm, 5 rpm, and 10−3 mbar, respectively. The pre-sputter power, argon flow rate, and time were also kept constant at 73.2 W, 20 sccm, and 5 min, respectively. The physical properties, microstructure, crystal structure, topography, and mechanical properties of the thin film coatings were analysed. The thickness and rate of deposition of the TiAlSi thin films increased with an increase in the target power (73.2 W – 269.5 W) from 414.6 nm and 0.046 nm/s to 1358.8 nm and 0.151 nm/s, respectively. The chemical composition of all the thin films remained constant, with the formation of a uniform TiAlSi alloy with no segregation of elements. However, a thin (wetting) interlayer consisting of Si and O elements was observed between the TiAlSi layer and the glass substrate. Further, the structure sizes and roughness values of the TiAlSi thin films increased with an increase in the target power, with a maximum of 75.4 nm for the size and 4.78 nm for the RMS roughness of thin films deposited at the maximum target power (269.5 W). Lastly, mechanical analysis of the TiAlSi thin films depicted an increase in the hardness as the target power increased, with the highest hardness at maximum power (269.5 W) obtained as 4.76 GPa. Despite having the lowest elastic modulus (50.5 GPa), the coating deposited at the highest power exhibited the highest plasticity index (H/E) and plastic deformation factor (H3/E2) of 0.094 and 0.042 GPa, respectively, which indicated the high resistance to abrasive wear, cracking, and deformation, compared to thin films deposited at the lowest target power (H/E = 0.066 and H3/E2 = 0.015 GPa). This study demonstrates that target power is a significant factor in determining the growth of TiAlSi thin films during the sputtering process and can be used for better control of their physical, structural, and mechanical properties.

Influence of the annealing temperature on the self-powered CuO/ZnO NRs heterojunction photodetector

In this study, the fabrication and comprehensive analysis of CuO/ZnO nanorod (NR) heterojunction photodetectors were carried out, focusing on the influence of annealing temperatures (400 °C, 500 °C, and 600 °C) on their structural, optical, and electrical characteristics. The ZnO nanorods were synthesized via a hydrothermal method, followed by a spin-coating deposition of CuO thin films. The resultant heterojunctions were subjected to different annealing treatments to determine the optimal conditions for enhanced photodetector performance. Characterization techniques such as Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive x-ray Spectroscopy (EDX), x-ray Diffraction (XRD), and UV–vis spectroscopy were employed to assess the quality and composition of the heterostructures. The analyses revealed a polycrystalline structure with monoclinic phases for CuO and wurtzite phases for ZnO. Photodetectors annealed at 400 °C exhibited the highest performance metrics, achieving a photoresponse ratio (Iph/Idark) of 26.3, photosensitivity (Sph%) of 2531.6, and a specific detectivity (D*) of 4.58 × 1010 Jones under 405 nm UV light illumination. These devices also demonstrated rapid response times of 0.8 s without any external bias, indicating effective exciton separation and charge transport facilitated by the built-in electric field at the heterojunction interface. The study underscores the critical role of annealing temperature in optimizing the photodetector properties of CuO/ZnO NRs, positioning these self-powered devices as promising candidates for future ultraviolet sensor applications in optoelectronics.

Electrodeposition and Optimisation of Amorphous NixSy Catalyst for Hydrogen Evolution Reaction in Alkaline Environment.

Anion exchange membrane (AEM) water electrolysers have shown their potential in green hydrogen production. One of the crucial tasks is to discover novel cost-effective and sustainable electrocatalyst materials. In this study, a low-cost Ni-S-based catalyst for hydrogen evolution reaction was prepared via a simple electrodeposition process from a modified Watts bath recipe. Physical characterisation methods suggest this deposit film to be amorphous. Optimisation of the electrodeposition parameters of the NixSy catalyst was carried out using a rotating disk electrode setup. The optimised catalyst exhibited excellent catalytical performance in 1 M KOH on a microelectrode, with overpotentials of 41 mV, 111 mV and 202 mV at 10, 100 and 1000 mA cm-2 with Tafel slope of 67.9 mV dec-1 recorded at 333 K. Long-term testing of the catalyst demonstrated steady performance over a 24 h period on microelectrode at 100 mA cm-2 with only 71 mV and 37 mV overpotential increase at 293 K and 333 K respectively. Full cell testing with the optimised NixSy as cathode and NiFe(OH)2 as anode showed 1.88 V after 1 h electrolysis at 500 mA cm-2 in 1 M KOH under 333 K with FAA-3-30 membrane.

Plasma-enhanced atomic layer deposition of carbon films employing a cyclic process of N2/H2 plasma and α, α’-dichloro-p-xylene as a precursor

A novel concept and process were proposed for the plasma-enhanced atomic layer deposition (PE-ALD) of carbon films. α, α’-dichloro-p-xylene (DCX) was used to form the adsorption layer, which was modified using nitrogen/hydrogen (N2/H2) plasma. Through iterative molecular chemisorption and end-group substitution processes, the selective and precise control of carbon deposition by PE-ALD was achieved. The growth per cycle of this process was estimated to be 0.02–0.05 nm/cycle. To determine the chemical reactions that occurred during the PE-ALD process, the IR spectra observed using in-situ Fourier transform infrared spectroscopy were analyzed. The decrease in the Si-OH bond at 3740 cm−1 and the saturation of the increase in CH bending at 1250 cm−1 revealed that the deposition of a DCX monolayer via a dehydrochlorination reaction with isolated OH bonding on SiO2 has been successfully achieved. The change in N(−H)x stretching during the N2/H2 plasma treatment indicated the substitution of exposed C-Cl bonding with C-NH2 bonding on the chemisorbed DCX monolayer surface. Additionally, the composition of the carbon films after 200-cycle PE-ALD was analyzed. Finally, the realization of the concept for PE-ALD of carbon film was confirmed by surface analysis.

Experimental Study on Improving the Recovery Rate of Low-Pressure Tight Oil Reservoirs Using Molecular Deposition Film Technology

The intricate geological characteristics of tight oil reservoirs, characterized by extremely low porosity and permeability as well as pronounced heterogeneity, have led to a decline in reservoir pressure, substantial gas expulsion, an accelerated decrease in oil production rates, and the inadequacy of traditional water injection methods for enhancing oil recovery. As a result, operators encounter heightened operational costs and prolonged timelines necessary to achieve optimal production levels. This situation underscores the increasing demand for advanced techniques specifically designed for tight oil reservoirs. An internal evaluation is presented, focusing on the application of molecular deposition film techniques for enhanced oil recovery from tight oil reservoirs, with the aim of elucidating the underlying mechanisms of this approach. The research addresses fluid flow resistance by employing aqueous solutions as transmission media and leverages electrostatic interactions to generate nanometer-thin films that enhance the surface properties of the reservoir while modifying the interaction dynamics between oil and rock. This facilitates the more efficient displacement of injected fluids to replace oil during pore flushing processes, thereby achieving enhanced oil recovery objectives. The experimental results indicate that an improvement in oil displacement efficiency is attained by increasing the concentration of the molecular deposition film agent, with 400 mg/L identified as the optimal concentration from an economic perspective. It is advisable to commence with a concentration of 500 mg/L before transitioning to 400 mg/L, considering the adsorption effects near the well zone and dilution phenomena within the reservoir. Molecular deposition films can effectively reduce injection pressure, enhance injection capacity, and lower initiation pressure. These improvements significantly optimize flow conditions within the reservoir and increase core permeability, resulting in a 7.82% enhancement in oil recovery. This molecular deposition film oil recovery technology presents a promising innovative approach for enhanced oil recovery, serving as a viable alternative to conventional water flooding methods.

Preparation of molybdenum disulfide/bentonite nanohybrid and its tribological properties as lubricant for water-based drilling fluids

In recent years, with the increase in energy demand and gradual scarcity of medium and shallow oil and gas resources, oil and gas exploration has shifted to special wells such as deep wells, ultra-deep wells, and extended reach wells. These complex wellbore structures inevitably increase the torque and friction between the casing and the drill pipe during drilling, which aggravates friction and wear, and leads to accidents such as drill sticking and drill breakage in severe cases. In this study, molybdenum disulfide/bentonite (MoS2/Bent) nanohybrids as drilling fluid lubricant were synthesized by hydrothermal method using sodium molybdate (Na2MoO4) and thiourea (CH4N2S) as raw materials and bentonite as carrier. The as-synthesized MoS2/Bent nanohybrid was characterized by X-ray powder diffractometer, transmission electron microscopy, Fourier transform infrared spectroscopy, and the high temperature resistance and tribological properties of MoS2/Bent nanohybrid were evaluated in base slurry. The results show that the friction coefficient of MoS2/Bent nanohybrid drilling fluid before aging is reduced by 74 % and the wear rate is reduced by 97 % compared with the base slurry. After high-temperature aging at 240 °C, the friction coefficient is reduced by 77 % and the wear rate is reduced by 90 %. The excellent friction reducing and antiwear performance is attributed to the formation of low shear strength MoS2 deposition film and oxide tribofilm on the surface of the friction pair during the rubbing process.

Engineering Optimization of Producing High-Purity Dichlorosilane in a Fixed-Bed Reactor by Trichlorosilane Decomposition.

High-purity dichlorosilane (DCS) is an important raw material for thin film deposition in the semiconductor industry, such as epitaxial silicon, which is mainly produced by trichlorosilane (TCS) catalytic decomposition in a fixed-bed reactor. The productivity of DCS is strongly dependent on the controlling of the TCS decomposition reaction process, associated with the cost in practical application. In this study, we have performed computational fluid dynamics (CFD) simulation on the TCS decomposition reaction kinetics in a cylindrical fixed-bed reactor, in which the effects of catalyst bed height, feed temperature, and feed flow rate are stressed to predict the conversion rate of TCS and the generation rate of DCS. This indicates that the increase of bed height helps the reaction to proceed adequately, but too large a bed height does not improve the DCS generation rate. Meanwhile, the feed temperature and reactor temperature have important effects on the DCS generation rate. However, it is found that changing the feed flow rate and L/D ratio cannot effectively improve the DCS generation rate while the bed volume remains constant. Furthermore, we have designed a fixed-bed reactor to verify the simulation results, which are in good agreement with each other. These results are of significance for the practical industrial production of high-purity DCS in a fixed-bed reactor.

Effect of annealing on ion-beam-sputtered hafnium oxide thin films properties

HfO2 films are high laser damage-threshold and low-absorption thin-films that can be utilized for a broad range of optoelectronic and optical applications. In this study, HfO2 thin films were prepared via dual ion beam sputtering followed by annealing in the atmosphere at temperatures ranging from 200 to 700 °C. The optical properties, microstructure, film stress, and absorption loss of the HfO2 films at various annealing temperatures were then systematically characterized. The results revealed that the properties of the films were improved after annealing at temperatures below 500 °C. Specifically, at an optimal annealing temperature of 400 °C, the residual stress of the films was minimized close to zero and the absorption loss was as low as 1 ppm. However, at annealing temperatures reaching 600 °C, the films began to crystallize, leading to the deterioration of their optical properties. Optimizing the process parameters for HfO2 thin film deposition is crucial for developing the next generation of high-performance laser optics.

STUDY ON THE PROPERTIES OF DIAMOND FILMS ON CEMENTED CARBIDE SUBSTRATES BY SURFACE IMPLANTATION PRETREATMENT PROCESS

The deposition of diamond films on tungsten carbide-based tools can greatly improve the life and performance of cutting tools. However, the deposition of diamond coatings on cemented carbide (WC-Co) suffers from poor film-base bond strength. In this paper, diamond coatings were deposited of phytocrystalline metal micropowders (pure, Nb, Ti, Ta) pretreatment method and the properties of diamond films were analyzed by energy spectrometry (EDS), scanning electron microscopy (SEM), Raman spectroscopy and bonding strength test of diamond films. The results show that through the experiment of the pretreatment process of surface implanted crystal metal micropowder, the best implanted crystal metal micropowder was obtained, the surface quality of implanted crystal titanium (Ti) coating was improved, the diamond Raman peaks were sharp and the indentation cracks had a crack diameter of 389 [Formula: see text]m, which is small and has the highest bond strength. The pretreatment process of phytocrystalline diamond micropowder can deposit high-performance diamond coatings and improve the bonding strength between the coating and the substrate film base.

Improved Process Stability and Light Detection in Phototransistors via Inverted MoS2/a‐IGZO Heterojunction Integration

The integration of molybdenum disulfide (MoS2) with other semiconductors to form heterojunction phototransistors demonstrates potential for optoelectronic applications due to their strong interaction with light and tunable bandgaps. Conventionally, bottom‐gate phototransistors based on MoS2 and amorphous indium–gallium–zinc oxide (a‐IGZO) are fabricated by deposition of the a‐IGZO film on the gate dielectric, followed by deposition of the MoS2 film, resulting in a MoS2/a‐IGZO heterojunction. In this study, an inverted MoS2/a‐IGZO (or denoted as a‐IGZO/MoS2) heterojunction integration for bottom‐gate phototransistors, where the MoS2 film is deposited on the gate dielectric first, followed by the deposition of the a‐IGZO film, is presented. This configuration is designed to enhance the processability and electrical properties of the phototransistor. Under visible light exposure with a low optical power density of 5.3 μW cm−2, the a‐IGZO/MoS2 heterojunction phototransistor demonstrates significantly improved photoresponsivity (1.6, 2.8, and 17 A W−1 at 635, 520, and 405 nm wavelengths, respectively) compared to the MoS2 single‐channel phototransistor. Time‐dependent photoresponse measurements reveal that the a‐IGZO/MoS2 heterojunction phototransistor responds more quickly to light changes and generates a tenfold‐greater photocurrent than that of the MoS2 single‐channel phototransistor.

An Optical Au3+ Sensor Based on layer-by-layer PEI/PAA-Rho thin Films on ITO.

This study presents the development of a sensitive and selective gold ion (Au3+) sensor utilizing layer-by-layer (LbL) assembled thin films composed of polyethylenimine (PEI) and poly (acrylic acid) (PAA) conjugated with rhodamine (Rho). The first study revealed that the polymeric sensors (PAA-Rho) demonstrated significant selectivity and sensitivity in their colorimetric and fluorescence responses to Au3+ compared to other metal ions. In their spirolactam form, the polymeric sensors were non-fluorescent but could selectively transform into the fluorescent ring-opened amide form upon interaction with Au3+ ions, resulting in fluorescence enhancement and observable color changes. Common co-existing metal ions showed negligible interference in the detection of Au3+. The LbL sensor exhibited a linear increase in absorbance with the addition of bilayers, confirming successful film deposition. Surface morphology analysis using SEM, along with structural confirmation via ATR-FTIR and XRD, further validated the sensor's capability to detect cation. Results demonstrated that the LbL sensor exhibited selectivity for Au3+ ions within the range 1 × 10-6 to 1 × 10-3 M. This approach offers an easily understandable and intrinsically sensitive means for detecting Au3+ ions in both environmental and biological applications.

Synthesis of chemical bath deposited Manganese oxide thin films for high performance supercapacitor

The present study addresses the growing need for high-performance supercapacitors, emphasizing the benefits of Manganese oxide (MnO2) thin film as a promising electrode material. Thin film deposition of MnO2 is achieved through Chemical Bath Deposition (CBD) method by varying the deposition time on the stainless steel substrate. In order to investigate impact of deposition time on various physico-chemical properties of MnO2 thin films, different characterizations were carried out like X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, cyclic voltammetry, Galvanostatic charge–discharge analysis. The deposited MnO2 thin films are subsequently studied for their electrochemical properties in a 1 M KOH electrolyte solution. Remarkably, the best specific capacitance is obtained about 296.5 F/g at current density of 0.5 A/g, with 86.42 % retention after 5000 cycles, highlighting the excellent electrochemical performance of the MnO2 thin films deposited at 6 hrs of reaction time. This work highlights valuable insights into the CBD deposited MnO2 thin films for supercapacitor applications, providing a foundation for the development of an efficient, low-cost, and scalable energy storage devices.

Warpage analysis of multilayer thin film/substrate systems using the Eigenstrain method

Warpage resulting from the deposition of films on substrates remains a persistent challenge that significantly impacts the application of numerous advanced devices. To precisely evaluate warpage in multilayer thin film/substrate systems, we employ the eigenstrain method in the warpage analysis. An analytical model is developed to predict warpage and residual stress in multilayer film/substrate system based on classical laminate theory. We introduce a novel concept termed “Eigenstress”, which serves as the fundamental cause of warpage and characterizes the influence of the manufacturing process on warpage. Theoretical analysis and simulation demonstrate that warpage is entirely determined by eigenstress and other process-independent parameters. This model also explains that there is little interaction between thin films deposited on the same substrate. An experimental method is studied for measuring eigenstress using a standard plate. The measured eigenstress differs significantly from the corresponding thermal stress. We also propose a critical condition and its governing equation for warpage in multilayer film/substrate systems. Experimental results confirm that adding a compensation layer on a warped substrate can considerably reduce warpage. The warpage model based on “Eigenstress” provides a theoretical foundation for accurately predicting and controlling warpage in multilayer thin film/substrate systems.

Pulsed laser deposition of MoS2 thin films at different mean kinetic plasma energies

In recent years, molybdenum disulfide has become a material of great interest for research for electronic and optoelectronic applications due to its 2-dimensional graphene-like structure and its bandgap within the visible spectrum. In this work, thin films of MoS2 were grown using pulsed laser deposition on glass substrates at room temperature and at deposition pressure of 2 × 10−5 Torr. We ablated a MoS2 target obtained by compressing high-purity powders, with a Nd-YAG pulsed laser with a wavelength of 1064 nm, 6 ns pulse width, and 10 Hz repetition rate. Laser produced plasmas were diagnosed by means of the time-of-flight technique using a Langmuir planar probe, from which mean kinetic energy and density of ions were estimated. Experimental control is more reliable using plasma parameters rather than fluence. The crystalline properties of the deposits were characterized using Raman spectroscopy and X-Ray diffraction; their chemical analysis was carried out by X-ray photoelectron spectroscopy; their thickness and morphology were characterized using atomic force microscopy and scanning electron microscopy, respectively. Results are discussed as a function of mean kinetic energy variations. It was observed that as the mean kinetic energy of the plasma decreased, the crystallinity improved and the crystal size increased.

Synergic Effect of N and Se Facilitates Photoelectric Performance in Co-Hyperdoped Silicon.

Femtosecond-laser-fabricated black silicon has been widely used in the fields of solar cells, photodetectors, semiconductor devices, optical coatings, and quantum computing. However, the responsive spectral range limits its application in the near- to mid-infrared wavelengths. To further increase the optical responsivity in longer wavelengths, in this work, silicon (Si) was co-hyperdoped with nitrogen (N) and selenium (Se) through the deposition of Se films on Si followed by femtosecond (fs)-laser irradiation in an atmosphere of NF3. The optical and crystalline properties of the Si:N/Se were found to be influenced by the precursor Se film and laser fluence. The resulting photodetector, a product of this innovative approach, exhibited an impressive responsivity of 24.8 A/W at 840 nm and 19.8 A/W at 1060 nm, surpassing photodetectors made from Si:N, Si:S, and Si:S/Se (the latter two fabricated in SF6). These findings underscore the co-hyperdoping method's potential in significantly improving optoelectronic device performance.

Deposition of nanocomposite carbon-based thin films doped with copper and fluorine

This paper is focused on plasma-enhanced chemical vapor deposition (PECVD) of novel carbon-based thin films. Unique thin films were deposited from a mixture of methane, hydrogen, and a precursor containing fluorine and copper: (hfac)copperVTMS (hfac = hexafluoroacetylacetonato and VTMS = vinyltrimethylsilane). Using the (hfac)copperVTMS precursor in PECVD deposition results in the advantageous chemical composition of carbon-based thin films while maintaining sufficient mechanical properties. Furthermore, with optimized plasma parameters, the films deposited on the substrate exhibit a nanocomposite structure. This nanostructured surface can increase the surface area, which is beneficial for various applications, including antibacterial and antiviral properties. The radiofrequency glow discharge at low pressure (≈70Pa) and power P=25W and P=250W was used for deposition. Deposited thin films were analyzed using X-ray photoelectron spectroscopy, water contact angle measurement, atomic force microscopy, and nanoindentation techniques. Despite the doping of carbon-based thin films with soft copper, the prepared films exhibited sufficient mechanical properties, which are crucial for the future implementation of this deposition process.