Film Deposition Research Articles

Bottom Contact Engineering for Ambient Fabrication of >25% Durable Perovskite Solar Cells.

The bottom contact in perovskite solar cells (PSCs) is easy to cause deep trap states and severe instability issues, especially under maximum power point tracking (MPPT). In this study, sodium gluconate (SG) is employed to disperse tin oxide (SnO2) nanoparticles (NPs) and regulate the interface contact at the buried interface. The SG-SnO2 electron transfer layer (ETL) enabled the deposition of pinhole-free perovskite films in ambient air and improved interface contact by bridging effect. SG-SnO2 PSCs achieved an impressive power conversion efficiency (PCE) of 25.34% (certified as 25.17%) with a high open-circuit voltage (VOC) exceeding 1.19V. The VOC loss is less than 0.34V relative to the 1.53eV bandgap, and the fill factor (FF) loss is only 2.02% due to the improved contact. The SG-SnO2 PSCs retained around 90% of their initial PCEs after 1000h operation (T90 = 1000h), higher than T80 = 1000h for the control SnO2 PSC. Microstructure analysis revealed that light-induced degradation primarily occurred at the buried holes and grain boundaries and highlighted the importance of bottom-contact engineering.

Deposition of TiC Film by Surface Wave Plasma with Titanium Counter Electrode

Deposition of TiC Film by Surface Wave Plasma with Titanium Counter Electrode

Bioinspired AlFeO3 Memristor with Sensing, Storage, and Synaptic Functionalities

AbstractIn conventional designs, sensory systems are segregated from memory and computing units. The conversion and transmission of data from analog sensing domains to digital storage result in inefficient power utilization and increased latency. Here, a multifunctional memristor capable of detecting gamma radiation while also serving as a data storage device and an artificial synapse is reported. Large‐scale integration of oxide‐based memristors for artificial neural networks faces major challenges due to the sneak‐path current issue in crossbar arrays. Consequently, material combinations and fabrication variables significantly shape nanoscale processes, which are essential in determining resistive switching properties and functionalities. Resistive switching in AlFeO3 is studied using different electrode materials (silver (Ag), gold (Au), chromium (Cr), fluorine‐doped tin oxide, and silicon), embedding metal (Ag, Au) nanocrystals to engineer a class of tunable memories capable of functioning as selector, memory, artificial synapse, and dosimeter. Techniques like electrode engineering, nanocrystal seeding, and temperature‐dependent thin film deposition are employed to tune resistive and threshold switching functionalities. Accessing different functionalities requires changing the electrode materials or changing the synthesis conditions of the AlFeO3 resistive switching layer and are not interconvertible in the same device simultaneously. The devices emulate critical neural functions and demonstrate interconversion dynamics between short‐term and long‐term plasticity.

Sustained Area-Selectivity in Atomic Layer Deposition of Ir Films: Utilization of Dual Effects of O3 in Deposition and Etching.

Area-selective deposition (ASD) based on self-aligned technology has emerged as a promising solution for resolving misalignment issues during ultrafine patterning processes. Despite its potential, the problems of area-selectivity losing beyond a certain thickness remain critical in ASD applications. This study reports a novel approach to sustain the area-selectivity of Ir films as the thickness increases. Ir films are deposited on Al2O3 as the growth area and SiO2 as the non-growth area using atomic-layer-deposition with tricarbonyl-(1,2,3-η)-1,2,3-tri(tert-butyl)-cyclopropenyl-iridium and O3. O3 exhibits a dual effect, facilitating both deposition and etching. In the steady-state growth regime, O3 solely contributes to deposition, whereas in the initial growth stages, longer exposure to O3 etches the initially formed isolated Ir nuclei through the formation of volatile IrO3. Importantly, longer O3 exposure is required for the initial etching on the growth area(Al2O3) compared to the non-growth area(SiO2). By controlling the O3 injection time, the area selectivity is sustained even above a thickness of 25nm by suppressing nucleation on the non-growth area. These findings shed light on the fundamental mechanisms of ASD using O3 and offer a promising avenue for advancing thin-film technologies. Furthermore, this approach holds promise for extending ASD to other metals susceptible to forming volatile species.

Polycrystalline silicon, a molecular dynamics study: II. Grains, grain boundaries and their structure

Polycrystalline silicon (poly-Si) is an excellent material for use in microelectronic devices, both in electrical and mechanical applications. Its mechanical and electrical properties are widely adjustable, its processing technology is compatible with existing microcircuit manufacturing technology, and its availability and recyclability are at a high level. Here, we focus on investigating the properties of poly-Si that distinguish it from other forms of silicon, that is, grains, grain boundaries, and the conditions and treatments that determine grain and grain boundary properties. Starting from the molecular dynamics simulations of the deposition of thin poly-Si films under different growth conditions we study the properties of the films, grains, and grain boundaries as a function of growth time, growth temperature, and post-annealing. We aim to get data and information that will form the essential basis for future research on the electrical properties of poly-Si. The main results are: (i) the effect of post-annealing on the distribution of the grain size and grain boundary thickness (ii) the distribution of the grain orientations, and (iii) the density of the 3- and 5-bonded atoms as a function of deposition temperature.

Polycrystalline silicon, a molecular dynamics study: I. Deposition and growth modes

Polycrystalline silicon (poly-Si) significantly expands the properties of the ICT miracle material, silicon (Si). Depending on the grain size and shape and grain boundary structure, the properties of poly-Si exceed what single-crystal (c-Si) and amorphous (a-Si) silicon can offer, especially for radio frequency (RF) applications in microelectronics. Due to its wide range of applications and, on the one hand, its theoretically and technologically challenging microstructure, poly-Si research is the most timely (Ding et al 2020 Mater. Charact. 161 110174; Zhao and Li 2019 Acta Mater. 168 52–62). In this report, we describe how we simulate and analyse the phenomena and mechanisms that control the effect of poly-Si deposition parameters on the structure of the deposited poly-Si films using classical molecular dynamics simulations. The grain shape and size, degree of crystallinity, grain boundary structure and the stress of poly-Si films are determined depending on the growth temperature, temperature distribution in the growing film, deposition flux, flux variation and the energy transferred to the film surface due to the deposition flux. The main results include: (i) the dependence of the crystallinity profile of the deposited poly-Si films on the stress, temperature and the different parameters of the deposition flux, (ii) growth modes at the early stages of the deposition, (iii) interaction and stability of seed crystallites at the early stage of the deposition of poly-Si films and the transition from the isolated crystallite growth to the poly-Si growth, (iv) interplay of the temperature, crystallinity, crystal shape and heath conductivity of different Si phases, (v) four different stages of crystallite growth are described: nucleation, growth, disappearance and retardation.

Amine plasma polymers deposited on porous hydroxyapatite artificial bone with bipolar pulsed discharges

A recent in vivo study [Kodama et al., Sci. Rep. 11, 1 (2021)] showed that porous artificial bones coated with amine-containing polymers deposited by plasma-enhanced chemical vapor deposition (PECVD) significantly enhanced bone regeneration. This article reports the chemical and physical properties of amine plasma polymers (PPs) formed under the same deposition conditions, including the film stability for up to two months, the effects of sterilization on the chemical compositions of the films, and the penetration of amine PPs into the inner surfaces of interconnected microscopic pores of the amine PP-coated porous artificial bone. It was found that, immediately after the plasma polymerization process, approximately 20% of nitrogen atoms on the surface of the deposited amine PP formed primary amines. However, the value decreased to approximately 5% over one month if the sample was exposed to ambient air. The relative concentration of primary amines also decreased to a similar value after the sample was sterilized by autoclaving or ethylene oxide gas. Molecular dynamics simulations were used to examine possible formation mechanisms of nitriles in deposit films under the PECVD conditions and found that ion impact can significantly reduce the nitrile content.

Dimension-Controlled VO2 Film for Optoelectronic Logic Gates and Information Encryption.

As the fields of photonics and information technology develop, a lot of novel applications based on VO2 material, such as optoelectronic computing and information encryption, have been developed. While the performance of these devices was not only closely associated with the VO2 phase transition properties but also depended on their dimensional characteristics. In the current study, we conducted the dimension-controlled vanadium dioxide (VO2) film growth, resulting in the epitaxial 2-dimensional (2D) VO2 film and well-distributed 3-dimensional (3D) VO2 crystal film deposition, respectively. It was revealed that, unlike the 2D film, the pronounced localized surface plasmon resonance dominated the near-infrared spectrum across the phase transition for the 3D VO2 film due to the naturally formed meta-surface structure, which showed a transmittance valley in the infrared spectrum after metallization. Based on this distinct infrared spectrum feature in the 3D VO2 film, we proposed an optoelectronic logic gate controlled by the input voltage and the probing Vis/IR light. By detecting the transmittance states of the probing light with different wavelengths, we achieved multistate encoding functions and demonstrated the information encryption application. This new conception device also showed great potential for some other applications such as optoelectronic coupled computing, information encryption, and optical near-field sensing computing.

Tilted fiber Bragg grating pH sensor based on polyaniline reaction deposition film layer

Tilted fiber Bragg grating pH sensor based on polyaniline reaction deposition film layer

Correlation between Crystallite Characteristics and the Properties of Copper Thin Film Deposited by Magnetron Sputtering: Bias Voltage Effect

This work investigates the properties of copper thin films deposited by magnetron sputtering. The substrate is biased by a negative voltage (Vs), which controls the energy ions bombardment during the deposition of the thin films. In order to focus solely on the ions energy contribution, the power supply was fixed and the working pressure was selected at 5 Pa. This ensures energetic sputtered particles completely thermalized, by a sufficient number of collisions with the Argon gas. X-ray diffraction analysis revealed that substrate voltage Vs affects essentially the structure and size of the formed crystallites. The preferred orientation (111) and the larger crystallite size (30 nm) were achieved at Vs = - 60 V. The Cu (111)/(200) peak intensity ratio is maximal (12.55) at - 60 V, corresponding to the lowest resistivity value (6.33 mW.cm). Optimum corrosion resistance of the deposited thin film was achieved at -60 V. At high crystallite sizes, nanoindentation analysis showed a thin film that is more elastic (133 GPa) and less hard (1.96 GPa).

Inkjet Printing of Cobalt Ferrite for Hard Ferromagnetic Thick Films Manufacturing

Inkjet printing is a versatile and cheap technique for the fabrication of films, offering unique advantages in terms of scalability, precision, and customization. In recent years, there has been a growing interest in utilizing inkjet printing technology for the deposition of magnetic films with tailored properties. Cobalt ferrite (CoFe2O4) stands out due to its exceptional magnetic properties, including high coercivity, saturation magnetization, and excellent chemical stability. This paper presents a comprehensive study on the inkjet printing of cobalt ferrite magnetic films, focusing on the manufacturing process, especially on the different factors that could lead to stable multilayer depositions to achieve high thicknesses: ink solid loading, drop spacing, substrate temperature, and interlayers drying. Finally, the microstructure of the samples is investigated to identify the occurring defects after sintering between 800 and 1000 °C. The magnetic properties of the films are determined, revealing a maximum coercivity of 1.98 kOe and a magnetic saturation of 78.25 emu cm−3.

Microstructure Evolution and Electrical Behaviors for High-Performance Cu2O/Zr-Doped β-Ga2O3 Heterojunction Diodes.

Beta-gallium oxide (β-Ga2O3) is emerging as a promising ultrawide band gap (UWBG) semiconductor, which is vital for high-power, high-frequency electronics and deep-UV optoelectronics. It is especially significant for flexible wearable electronics, enabling the fabrication of high-performance Ga2O3-based devices at low temperatures. However, the limited crystallinity and pronounced structural defects arising from the low-temperature deposition of Ga2O3 films significantly restrict the heterojunction interface quality and the relevant electrical performance of Ga2O3-based devices. In this work, cuprous oxide (Cu2O)/Zr-doped β-Ga2O3 heterojunction diodes are fabricated by magnetron sputtering without intentional substrate heating, followed by an investigation into their microstructure and electrical behaviors. Zr doping can markedly enhance the Ga2O3 crystallinity at low substrate temperatures, transforming the amorphous structure of pristine Ga2O3 films into the crystallized β phase. Moreover, crystalline β-Ga2O3 facilitates the epitaxial growth of the Cu2O phase, suppressing the formation of detrimental secondary phase CuO at the heterojunction interface. Benefiting from the high-quality heterojunction interface, the Cu2O/Zr-doped β-Ga2O3 heterojunction diode exhibits a near-ideal electrical behavior with a low ideality factor of 1.6. The consistent electrical parameters extracted from current-voltage (J-V) and capacitance-voltage (C-V) measurements also confirm the high quality of β-Ga2O3. This work highlights the potential for the low-temperature production of high-quality β-Ga2O3-based heterojunction devices through Zr doping.

Characterization of plasma polymerized acetonitrile film for fluorescence enhancement and its application to aptamer-based sandwich assay.

Among biosensing systems for sensitive diagnoses fluorescence enhancement techniques have attracted considerable attention. This study constructed a simple multilayered structure comprising a plane metal mirror coated with a plasma-polymerized film (PPF) as an optical interference layer on a glass slide for fluorescence enhancement. Plasma polymerization enables the easy deposition of organic thin films containing functional groups, such as amino groups. This study prepared PPFs using acetonitrile as a monomer, and the influences of washing and the output powers of plasma polymerization on PPF thickness were examined by Fourier transform infrared spectroscopy. This is because controlling the PPF thickness is vital in fluorescence enhancement. Multilayered glass slides prepared using a silver layer with 84 nm-thick acetonitrile PPFs exhibited 11- and 281-fold fluorescence enhancements compared with those obtained from the substrates with a bare surface and only modified by the silver layer, respectively. Oligonucleotides labeled with a thiol group and cyanine5 were successfully immobilized on the multilayered substrates, and the fluorescence of the acetonitrile PPFs was superior to that of the allylamine and cyclopropylamine PPFs. Furthermore, an aptamer-based sandwich assay targeting thrombin was performed on the multilayered glass slides, resulting in an approximately 5.1-fold fluorescence enhancement compared with that obtained from the substrate with a bare surface. Calibration curves revealed the relationship between fluorescence intensity and thrombin concentration of 10-1000 nM. This study demonstrates that PPFs can function as materials for fluorescence enhancement, immobilization for biomaterials, and aptamer-based sandwich assays.

Influence of a plasma focus device on the structural and optical properties of highly conductive AZO thin films

In the present work, we deposited Al-doped ZnO (AZO) thin films on microscope glass slides at different pressures (5, 10, 20, and 30 mTorr) using an EAEA-PFD (Plasma Focus Device of the Egyptian Atomic Energy Authority) without any extra heat treatment. Argon gas provided the radiant energy needed to form a crystalline AZO film. This study investigated the deposition and features of AZO thin films. The impact of changes in work pressure on the microstructure, morphology, and optical attributes of AZO films was reported. The results demonstrated that varying the work pressure significantly affects the microstructure, morphology, crystallinity, optical absorbance, and optical energy gap. The microstructure and morphology were evaluated through XRD and scanning electron microscopy (SEM). The optical properties were analyzed using a UVvis double-beam spectrophotometer within a wavelength range from 300 to 1100 nm. XRD patterns indicating a zinc-blende structure and the Williamson–Hall approach were used to estimate the structural parameters. The estimated trend in the particle size of the AZO film demonstrates a decrease from 82 ± 5 nm to 48 ± 5 nm as the pressure increases. The calculated energy gap, Egopt, increases from 3.53 eV to 3.69 eV with increasing work pressure. The conductivities in terms of both optical and electrical decreased with increasing work pressure of the AZO films.

Biocompatible Hybrid Graphenic Thin Coatings on Flexible Substrates through Matrix-Assisted Pulsed Laser Evaporation (MAPLE).

This work reports the production of biocompatible thin layers for biomedical applications based on a graphene-like material (GL), a graphene-related material (GRM) obtained from carbon black. GL was combined in a hybrid fashion with polydopamine (pDA), a mussel-inspired water-resistant wet adhesive bonding obtained by the oxidative polymerization of dopamine (DA), and polyvinyl pyrrolidinone (PVP), a nontoxic synthetic polymer with intrinsic adhesion properties, to obtain a tighter adhesion of the thin layer to the substrate (silicone slices). Matrix-assisted pulsed laser evaporation (MAPLE) was used to coat PDMS slices with thin films of GL-pDA and GL-PVP directly from their frozen suspensions in water. The results indicate that the relevant chemical-physical characteristics of both thin films (evidenced by FTIR and AFM) were maintained after MAPLE deposition and that the films exhibit uniformity also at the nanometric level. After deposition, the GL-pDA and GL-PVP films underwent a biological survey toward murine fibroblasts (NIH3T3), human keratinocytes (HaCAT), and human cervical adenocarcinoma epithelial-like (HeLa) cells to assess the feasibility of this approach. Results indicate that both the GL-pDA and GL-PVP films did not perturb the biological parameters evaluated, including cytoskeleton alterations. Both hybrid films enhanced the effects of GL on cellular vitality across all cell lines. Specifically, the GL-pDA film exhibited a more stable effect over time (up to 72 h), whereas the GL-PVP film behaved similarly to the GL film in NIH3T3 and HeLa cell lines after long-term exposure. These promising results make the GL-pDA and GL-PVP films potential candidates for the manufacture of coated flexible devices for biomedical applications.

Layer-by-Layer Nanoparticle Assembly for Biomedicine: Mechanisms, Technologies, and Advancement via Acoustofluidics.

The deposition of thin films plays a crucial role in surface engineering, tailoring structural modifications, and functionalization across diverse applications. Layer-by-layer self-assembly, a prominent thin-film deposition method, has witnessed substantial growth since its mid-20th-century inception, driven by the discovery of eligible materials and innovative assembly technologies. Of these materials, micro- and nanoscopic substrates have received far less interest than their macroscopic counterparts; however, this is changing. The catalogue of eligible materials, including nanoparticles, quantum dots, polymers, proteins, cells and liposomes, along with some well-established layer-by-layer technologies, have combined to unlock impactful applications in biomedicine, as well as other areas like food fortification, and water remediation. To access these fields, several well-established technologies have been used, including tangential flow filtration, fluidized bed, atomization, electrophoretic assembly, and dielectrophoresis. Despite the invention of these technologies, the field of particle layer-by-layer still requires further technological development to achieve a high-yield, automatable, and industrially ready process, a requirement for the diverse, reactionary field of biomedicine and high-throughput pharmaceutical industry. This review provides a background on layer-by-layer, focusing on how its constituent building blocks and bonding mechanisms enable unmatched versatility. The discussion then extends to established and recent technologies employed for coating micro- and nanoscopic matter, evaluating their drawbacks and advantages, and highlighting promising areas in microfluidic approaches, where one distinctly auspicious technology emerges, acoustofluidics. The review also explores the potential and demonstrated application of acoustofluidics in layer-by-layer technology, as well as analyzing existing acoustofluidic technologies beyond LbL coating in areas such as cell trapping, cell sorting, and multidimensional particle manipulation. Finally, the review concludes with future perspectives on layer-by-layer nanoparticle coating and the potential impact of integrating acoustofluidic methods.

Impact of H-Related Chemical Bonds on Physical Properties of SiNx:H Films Deposited via Plasma-Enhanced Chemical Vapor Deposition

SiNx:H film deposition via plasma-enhanced chemical vapor deposition has been widely used in semiconductor devices. However, the relationship between the chemical bonds and the physical and chemical properties has rarely been studied for films deposited using tools in terms of the actual volume production. In this study, we investigated the effects of the deposition conditions on the H-related chemical bonding, physical and chemical properties, yield, and quality of SiNx:H films used as passivation layers at the 28 nm technology node. The radiofrequency (RF) power, electrode plate spacing, temperature, chamber pressure, and SiH4:NH3 gas flow ratio were selected as the deposition parameters. The results show a clear relationship between the H-related chemical bonds and the examined film properties. The difference in the refractive index (RI) and breakdown field (EB) of the SiNx:H films is mainly attributed to the change in the Si–H:N–H ratio. As the Si–H:N–H ratio increased, the RI and EB showed linear growth and exponential downward trends, respectively. In addition, compared with the Si–H:N–H ratio, the total Si–H and N–H contents had a greater impact on the wet etching rates of the SiNx:H films, but the stress was not entirely dependent on the total Si–H and N–H contents. Notably, excessive electrode plate spacing can lead to a significant undesired increase in the non-uniformity and surface roughness of SiNx:H films. This study provides industry-level processing guidance for the development of advanced silicon nitride film deposition technology.

Deposition characteristics and influence regularity of sputtered products in a low-power RF gridded ion thruster

RF ion thruster has a broad prospect of development via its simple structure, high specific impulse and electrode-less discharge. During the RF operating process, an important but ignored generally issue is that the high-energy metal particles generated by sputtering grid system can diffuse towards the ionization chamber and then deposit on the wall to form a conductive film. As a result, the RF power feed can be significantly inhibited which affects the thruster perform and reliability. In this work, the axial distribution of film thickness on the ionization chamber has been measured which has the characteristic of nonlinear distribution. And the film roughness can be significantly affected due to the gradient of film thickness and deposition temperature. Another corresponding measurement of plasma parameter evolutions in the ionization chamber has been carried out within 6000 min of thruster operation. Results shows that the presence of the deposited film can result in a ∼30 % decrease in the plasma density, which weakens the grid sputtering erosion and subsequently leads to a decrease in film growth rate. The combination of contributed to the degradation of the thruster performance, with the effect of deposited film accounting for about 41 %.

Exploring Negative Ion Behaviors and Their Influence on the Properties of DC Magnetron Sputtered ITO Films under Varied Power and Pressure Conditions

Abstract In this study, ITO films were deposited on silicon and quartz substrates by magnetron sputtering technology in pure argon. Using EQP plasma diagnostic technology, we study the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incident on the substrate surface, with special attention to the production of high-energy negative oxygen ions, and elucidate the mechanism behind its production. At the same time, the structure and properties of ITO films were systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films. Combined with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide (TCO) thin films, it provides valuable physical understanding for the optimization of TCO thin film deposition process.

Stabilizing Solution–Substrate Interaction of Perovskite Ink on PEDOT:PSS for Scalable Blade Coated Narrow Bandgap Perovskite Solar Modules by Gas Quenching

The development of scalable 1.25 eV mixed Pb–Sn perovskite solar modules by blade coating lags behind Pb‐based perovskites due to limited understanding of solution–substrate interaction of the perovskite ink on PEDOT:PSS and subsequent gas quenching. To address this challenge, the wet film deposition and quenching process to better understand narrow bandgap perovskite film formation on PEDOT:PSS are studied. It is found that the wetting of Pb–Sn perovskite ink on PEDOT:PSS is highly unstable over relevant coating time scales, causing the contact angles to decrease rapidly from 42° to 16° within seconds. This instability leads to localized irregularities in the wet film, resulting in uneven solvent extraction and inhomogeneous nuclei density. As a result, rough perovskite films with voids at the buried interface are obtained. To overcome this problem, a quasistatic wetting process by reducing the blade coating speed is developed, thereby stabilizing the wetting behavior of Pb–Sn perovskite precursor ink on PEDOT:PSS. This optimized process facilitates the deposition of high‐quality, void‐free Pb–Sn perovskite films with uniform thickness over 8 cm of coating length using moderate (1.4 bar) N2 quenching. 20% efficient narrow bandgap perovskite solar cells and minimodules with 15.8% active area efficiency on 15.9 cm2 are achieved.