Morphology Of Thin Films Research Articles

Orientation and morphology control in acid-catalyzed covalent organic framework thin films.

As thin films of semiconducting covalent organic frameworks (COFs) are demonstrating utility for ambipolar electronics, channel materials in organic electrochemical transistors (OECTs), and broadband photodetectors, control and modulation of their thin film properties is paramount. In this work, an interfacial growth technique is utilized to synthesize imine TAPB-PDA COF films at both the liquid-liquid interface as well as at the liquid-solid interface on a Si/SiO2 substrate. The concentration of acetic acid catalyst in the aqueous phase is shown to significantly influence the thin film morphology of the liquid-solid growth, with concentrations below 1 M resulting in no film nucleation, concentrations of 1-4 M enabling smooth film formation, and concentrations greater than 4 M resulting in films with a higher density of particulates on the surface. Importantly, while the films grown at the liquid-liquid interface are mixed-orientation, those grown directly at the liquid-solid interface on the Si/SiO2 surface have highly oriented COF layers aligned parallel to the substrate surface. Moreover, this liquid-solid growth process affords TAPB-PDA COF thin films with p-type charge transport having a transconductance of 10 μS at a gate voltage of -0.9 V in an OECT device structure.

Impact of hydrophilic side chains on the thin film transistor performance of a benzothieno-benzothiophene derivative.

Side-chain engineering in molecular semiconductors provides a versatile toolbox for precisely manipulating the material's processability, crystallographic properties, as well as electronic and optoelectronic characteristics. This study explores the impact of integrating hydrophilic side chains, specifically oligoethylene glycol (OEG) units, into the molecular structure of the small molecule semiconductor, 2,7-bis(2(2-methoxy ethoxy)ethoxy) benzo[b]benzo[4,5] thieno[2,3-d] thiophene (OEG-BTBT). The investigation includes a comprehensive analysis of thin film morphology and crystallographic properties, along with the optimization of deposition parameters for improving the device performance. Despite the anticipated benefits, such as enhanced processability, our investigation into OEG-BTBT-based organic field-effect transistors (OFETs) reveals suboptimal performance marked by a low effective charge carrier mobility, a low on/off ratio, and a high threshold voltage. The study unveils bias stress effects and device degradation attributed to the high ionization energy of OEG-BTBT alongside the hydrophilic nature of the ethylene-glycol moieties, which lead to charge trapping at the dielectric interface. Our findings underscore the need for a meticulous balance between electronic properties and chemical functionalities in molecular semiconductors to achieve stable and efficient performance in organic electronic devices.

Janus bottlebrush compatibilizers.

Bottlebrush random copolymers (BRCPs), consisting of a random distribution of two homopolymer chains along a backbone, can segregate to the interface between two immiscible homopolymers. BRCPs undergo a reconfiguration, where each block segregates to one of the homopolymer phases, adopting a Janus-type structure, reducing the interfacial tension and promoting adhesion between the two homopolymers, thereby serving as a Janus bottlebrush copolymer (JBCP) compatibilizer. We synthesized a series of JBCPs by copolymerizing deuterated or hydrogenated polystyrene (DPS/PS) and poly(tert-butyl acrylate) (PtBA) macromonomers using ruthenium benzylidene-initiated ring-opening metathesis polymerization (ROMP). Subsequent acid-catalyzed hydrolysis converted the PtBA brushes to poly(acrylic acid) (PAA). The JBCPs were then placed at the interface between DPS/PS homopolymers and poly(2-vinyl pyridine) (P2VP) homopolymers, where the degree of polymerization of the backbone (NBB) and the grafting density (GD) of the JBCPs were varied. Neutron reflectivity (NR) was used to determine the interfacial width and segmental density distributions (including PS homopolymer, PS block, PAA block and P2VP homopolymer) across the polymer-polymer interface. Our findings indicate that the star-like JBCP with NBB = 6 produces the largest interfacial broadening. Increasing NBB to 100 (rod-like shape) and 250 (worm-like shape) reduced the interfacial broadening due to a decrease in the interactions between blocks and homopolymers by stretching of blocks. Decreasing the GD from 100% to 80% at NBB = 100 caused an increase the interfacial width, yet further decreasing the GD to 50% and 20% reduced the interfacial width, as 80% of GD may efficiently increase the flexibility of blocks and promote interactions between homopolymers, while maintaining relatively high number of blocks attached to one molecule. The interfacial conformation of JBCPs was further translated into compatibilization efficiency. Thin film morphology studies showed that only the lower NBB values (NBB = 6 and NBB = 24) and the 80% GD of NBB = 100 had bicontinuous morphologies, due to a sufficient binding energy that arrested phase separation, supported by mechanical testing using asymmetric double cantilever beam (ADCB) tests. These provide fundamental insights into the assembly behavior of JBCPs compatibilizers at homopolymer interfaces, opening strategies for the design of new BCP compatibilizers.

Optical, morphological and electrical properties of rapid thermally annealed CoPc/n-Ge heterostructures for photodiode applications

Effect of rapid thermal annealing (RTA) temperature on electrical, morphological and optical properties of cobalt phthalocyanine (CoPc)/n-Ge heterostructures is investigated. UV–Vis measurements of as-deposited and annealed CoPc thin films show the presence of Q band transition at 618 nm and 690 nm absorption wavelength suggesting π-π* transitions. A phase transition is evidenced for the 300 °C annealed CoPc sample. Further, no degradation of Q band intensities is noticed which signifies highly stable CoPc thin films even after annealing at 400 °C. AFM measurements of CoPc thin film on Ge substrate reveal an increased RMS roughness with increased annealing temperature until 200 °C and further roughness was found to be decreased for the sample annealed at 300 °C. A clear change in the morphology of CoPc thin films is observed for the 300 °C annealed sample than 200 °C annealed sample which shows an evidence for the phase transition of CoPc thin films from α-phase to β-phase. This phase transition of CoPc thin films was also confirmed using XRD measurements. FESEM with EDS measurements were carried out for the as-deposited and annealed heterostructures. The surface topography of all the samples reveals a spherical-grained morphology and the grains seem to be highly dispersed in 400 °C annealed CoPc/Ge layers. The electrical and current transport mechanisms of the Au/CoPc/n-Ge heterostructure have been explored at different annealing temperatures by using I–V and C–V characteristics. Notably, the results reveal that superior barrier parameters are observed for the heterostructure annealed at 300 °C than as-deposited heterostructure. Rapid thermal annealing of the Au/CoPc/Ge heterostructure shows its promising applications in the areas of optoelectronic or photoresponsive devices.

(Digital Only Presentation) Effects of Ink Solvent on the Screen-Printing Fabrication and Morphology of LSM-YSZ Thin Films Deposited on YSZ Substrate for Solid Oxide Electrochemical Cells

Screen-printing is a cheap and easy thin film deposition technique utilized in energy devices fabrication, specifically, in solid oxide electrochemical cells (SOCs). This technique offers simple set-up, film quality control and mass production. In this study, LSM-YSZ, a promising component material for SOCs application was deposited on YSZ electrolyte via screen-printing. Specifically, the study aimed to investigate the effect of the solvent used in screen-printing on the quality of the deposited film. LSM-YSZ precursor powders synthesized via glycine-nitrate combustion process (GNP) were screen-printed on YSZ substrate using different solvents, ethanol and alpha-terpineol. The structure, morphology, and conductivity values of the GNP LSM-YSZ thin films using two solvents were compared. Results showed that both solvents produced a uniform distribution of rhombohedral LSM and cubic YSZ thin films with porous morphologies but alpha-terpineol solvent exhibited more agglomerated particles. Despite having this morphology, alpha-terpineol is still preferred than ethanol due to its reproducibility and scalability as it is less volatile than the other one. Moreover, there was no significant difference between the measured total conductivities of the half-cells using two solvents with the values of 4.63e-3 S/cm and 2.07e-3 S/cm at 700°C, and activation energies of 0.374 eV and 0.483 eV from 500°C - 700°C, for ethanol and alpha-terpineol, respectively.

SrTiO3 Epitaxially Protected Si-Photocathode for Photoelectrochemical Water Splitting

Although silicon has been demonstrated to be one of the best photoelectrochemical (PEC) substrate materials thanks to its low cost, mature manufacturing technique, and high theoretical photovoltage and saturation current density [1], the development of robust Si-based PEC device has remained an existing challenge due to the fact that it is very easily susceptible to (photo)corrosion under PEC operational conditions [2]. Therefore, a suitable protective layer over the Si substrate which is able to simultaneously provide the corrosion resistance and retain a highly efficient charge transfer across the photoelectrode device is highly desired [3].To this end, we prepared high-quality SrTiO3 (STO) layer to passivate p-Si substrate via the mediation of an epitaxial enabler reduced graphene oxide (rGO) using the pulsed laser deposition (PLD) technique. STO layers with different thicknesses were prepared on both rGO-buffered and bare Si substrates to investigate the effects of epitaxy and charge carrier migration distance on the PEC performance. It was realized that very thin (3.9 nm ~ 10 unit cells) STO layer epitaxially overgrown on rGO-buffered Si showed the highest onset potential (0.326 V vs RHE, defined as potential at -0.1 mA cm-2) than the counterparts with thicker and/or non-epitaxial STO. The photovoltage and flat-band potential analyses, and the electrochemical impedance spectroscopy measurements showed that the epitaxial protected photocathode was more beneficial for charge separation, charge transfer, and the targeted redox reaction (hydrogen evolution reaction in this case) than the non-epitaxial one. The STO/rGO/Si with a smooth and highly epitaxial STO layer outperforming the direct contacted STO/Si with textured and polycrystalline STO layer underscored the importance of having well-defined passivation layer. In addition to that, numerous pinholes formed in STO/Si attributable to highly energetic bombardment process in the PLD deposition led to a rapid degradation of photocathode during PEC measurements, possibly because the electrolyte could easily penetrate into the film and consequently corrode the substrate. Single-oriented STO realized by rGO-buffered substrate potentially rendered easier path for charge migration, and the thinnest STO layer provided the shortest transportation route while maintained the robust protection ability. Polycrystalline STO in direct contacted STO/Si however presented more recombination sites which eventually impaired the PEC performance. Smooth surface of high-quality epitaxial STO layer with sub-nano roughness demonstrated to be a pivotal factor in remotely protecting underlying p-Si substrate from corrosion, while the presence of pinholes in non-epitaxial sample showed a similar degradation rate as bare Si substrate which was without any protection. We also studied the capability of STO layer in protecting underlying Si substrate from corrosion, and the long-term stability tests demonstrated the robustness of epitaxial STO layer-coated photocathode in comparison to bare Si.We demonstrated that STO layer overgrown on Si buffered with few-layer epitaxy enabler rGO could promote charge carrier transfer across the photocathode and lead to better PEC performance. Through a series of in-situ and ex-situ characterizations we verified that the addition of rGO layer could significantly alter the STO layer crystallinity and thin film morphology and, most importantly, enhance the stability of Si photocathode with only 10 unit cells layer. This study reported a facile approach for preparing a robust protection layer over photoelectrode substrate in realizing efficient and at the same time durable PEC device. Acknowledgement: This study was supported by Slovenian Research Agency (Project No. N2-0187) and the Czech Science Foundation (Project No. 21-20110K). We also thank the supports from Mr. Damjan Vengust in electron microscope observations, Mr. Jožko Fišer in Pt thin film preparation, Dr. Vasko Jovanovski in discussion of electrochemical measurements.

Ag Nps@PEDOT Nanocomposite Electrosynthesis at a Polarised Liquid|Liquid Interface

One of Material Science's main challenges is constantly searching for new versatile materials. In this sense, nanocomposites have emerged as an alternative to new substrates due to their unique properties. These hybrid systems are made up of organic polymers with inorganic components. This ideal "tandem" is made up of organic polymers (for example, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy) and polyaniline (PANI)) with conductive characteristics because of their highly p-conjugated polymeric chains, unique properties, reversible doping/de-doping processes, and controllable chemical/electrochemical properties. Inorganic compounds, such as metallic nanoparticles (NPs), in the organic matrix provide a high surface area and conductivity, acting as protuberances and highly conductive fillers to form a class of material with multidisciplinary applications [1].There are several methods to generate organic polymers; the electrochemical process is one of the most used due to its versatility and simplicity. This method implies the electrodeposition of the organic polymer on an electrode surface, eliminating the possibility of obtaining a polymeric material separated from the electrode surface and limiting the areas of applicability (polymer firmly attached to the electrode surface). In this sense, the use of a polarised immiscible liquid|liquid (L|L) interfaces is demonstrated as a novel approach for the electrosynthesis of surfactant-free organic thin films, allowing complete control over the thin film morphology [2].In this work, we present the electrosynthesis of silver nanoparticles@PEDOT nanocomposites based on EDOT polymerization (PEDOT) and the formation of silver nanoparticles by electrochemical polymerisation at a polarised L|L interface. In thermodynamic terms, the oxidant potential of silver ions is insufficient to oxidise 3,4-ethylenedioxythiophene and generate PEDOT. However, under specific conditions (detailed in this presentation), silver ions are reduced while EDOT monomers are oxidised to PEDOT. A deep knowledge of biphasic electropolymerisation coupled with silver nanoparticle formation will help advance the search for new materials for a broad spectrum of applications (antibacterial, electrocatalysis, SERS substrates, biocompatibility substrates, etc.).

Experimental and theoretical analysis of a Visible-Light photodetector based on cadmium sulfide fabricated on interdigitated electrodes

The wide range of applications for photodetectors, such as in space, industry, medical, and military, has garnered significant research attention in recent years. In this study, an n-type single-layer photodetector based on a Cu/CdS/Cu metal–semiconductor-metal structure with a micro interdigitated electrode array (IDE) was fabricated. The surface morphology and absorption properties of the CdS thin films were characterized using atomic force microscopy, scanning electron microscopy, and UV–Vis spectrometry. The photo response characteristics of the photodetector were recorded across wavelengths of 400–780 nm. The optoelectronic analyses of the structure revealed a maximum responsivity value of approximately 98.73 % at 405 nm incident light, with a high response time of about 0.12 s. Furthermore, the structure was theoretically studied and simulated, with the simulation results demonstrating good agreement with the measured experimental evidence. The above results indicate that the present CdS photodetector holds excellent potential for use in high-sensitivity optoelectronic integrated circuits.

Study of Structural Morphology of Electrodeposited Ni Film

Structural morphology of thin electrodeposited metallic films plays a vital role in determining the properties of the films and their application. We prepared a range of Ni electrodeposited polycrystalline films using a BIOLOGIC potentiostat and investigated the effects of varying parameters such as the deposition rate and concentration of the solution to improve control over their properties. We conducted analysis of surface morphology of thin films of area 1cm2, as well as at microstructural level of area 50x50 um2, using ex-situ AFM and in-situ HS AFM. Ex-situ AFM data helps us to do quantitative surface analysis, including slope, scaling analysis [1] and grain area calculation as a function of time, concentration, and applied potential. HS AFM provides us with information about the grain structure evolution at microstructural level [2]. The texture of films was determined by XRD analysis. For the thin films, Ni[111] orientation was dominant, but for thick films, the dominant crystallographic orientations was Ni[200].We also performed EBSD analysis for Ni thin films after milling with focused ion beam. EBSD uses backscattered electron to obtain the information of structural morphology and crystallographic orientation of thin films layer by layer. The correlation between ex-situ AFM and EBSD data helps to gain a clear understanding of the structural features of the films. Liu, L., & Schwarzacher, W. (2013). Slope analysis and scaling analysis of electrodeposited thin films. Electrochemistry communications, 29, 52-54.Koorikkat, A., Payton, O., Picco, L., & Schwarzacher, W. (2020). Imaging the Surface of a Polycrystalline Electrodeposited Cu Film in Real Time Using In Situ High-Speed AFM. Journal of the Electrochemical Society, 167(16), 162510.

19.32% Efficiency Polymer Solar Cells Enabled by Fine-Tuning Stacking Modes of Y-Type Molecule Acceptors: Synergistic Bromine and Fluorine Substitution of the End Groups.

The success of Y6-type nonfullerene small molecule acceptors (NF-SMAs) in polymer solar cells (PSCs) can be attributed to their unique honeycomb stacking style, which leads to favorable thin-film morphologies. The intermolecular interactions related to the crystallization tendency of these NF-SMAs is closely governed by their electron accepting end groups. For example, the high performance Y6 derivative L8-BO (BTP-4F) presents three types of stacking modes in contrast to two stacking modes of Y6. Hence, it is ultimately interesting to obtain more insight on the packing properties and the preferences influenced by chemical modifications such as end group engineering. This work designs and synthesizes asymmetric and symmetric L8-BO derivatives with brominated end groups and explores the stacking preferences in various modes. The asymmetric BTP-3FBr displays an optimized crystallization tendency and thin film morphology, leading to a decent power conversion efficiency (PCE) of 18.34% in binary devices and a top PCE of 19.32% in ternary devices containing 15 wt% IDIC as the second acceptor.

Static anti-solvent treatment on lead iodide in two-step deposition of methylammonium lead iodide perovskite thin films

Static anti-solvent treatment is rarely employed for perovskite thin film fabrication, even though this method is dependent only on fewer thin film growth parameters as compared to the dynamic anti-solvent application. Thus, studies on the influence of static anti-solvent treatment on the properties of perovskite thin films is important to gain insight to the growth processes, which is very scarce as well. In this study, we investigate the static anti-solvent treatment to tailor the morphology of Lead Iodide (PbI2) thin films for the fabrication of precursor-free Methylammonium Lead Iodide (MAPI) perovskite thin films through the two-step deposition method using Chlorobenzene as an anti-solvent. Remarkable influence of the anti-solvent loading time on the film morphology of PbI2 and MAPI thin films is observed. The crystallinity of PbI2 decreases upon increasing the anti-solvent loading time. A complete conversion of the precursors to MAPI along with the largest grain size are attained even at short loading times, ∼5s. Grain size does not increase considerably at higher loading times. Linear absorption studies on MAPI thin films show an increase in the Urbach energy with an increase in the loading time, which indicates an increase in the defect density. The increase in defect density with anti-solvent loading time is attributed to the concurrent decrease in the crystallinity of the PbI2 thin film. Steady-state and time-resolved photoluminescence (PL) studies performed on the MAPI thin films show highest PL intensity and life time at an optimum anti-solvent loading time (∼5s), which arises due to the trade off between largest grain size and lowest defect density. These observations not only highlights the need for an optimum crystallinity in the PbI2 thin films for the fabrication of superior quality MAPI thin films but also infers an optimum static anti-solvent loading time as the increase in grain size and life time enhances the device performance while an increase in defect density degrades the performance.

Preparation and characterization of SbSeI thin films

Metal chalcohalides are promising candidates for next-generation technologies that include energy conversion, information storage, and quantum computing. Among them, antimony selenoiodide (SbSeI) has received rising interest for different optoelectronic devices, including photovoltaics, due to its bandgap energy, strong optical absorption, stability, and earth abundant, low-cost, and low toxicity constituents. In this work, SbSeI thin films were prepared through a two-step process. At first, antimony selenide (Sb2Se3) thin films were deposited at 300 °C (Sb2Se3-300) and at room temperature (Sb2Se3-RT) onto molybdenum covered soda-lime glass substrates by a magnetron sputtering method. The formation of SbSeI thin films was performed by isothermally annealing the as-deposited Sb2Se3 thin films in sealed quartz ampoules in the atmosphere of antimony iodide (SbI3) with the presence of 100 Torr of argon pressure. The influence of the annealing temperature and time during the iodization of different types of substrates on the morphology and composition of SbSeI thin films was investigated. The well-oriented and dense single-phase SbSeI thin films with stoichiometric composition and single-crystal micro-columnar structures were achieved by annealing Sb2Se3-RT in SbI3 atmosphere at 250 °C for 5 min under 100 Torr of Ar pressure. The room temperature photoluminescence (RT-PL) of SbSeI exhibited a broad asymmetric PL band with a maximum at 1.67 eV. The low-temperature (T = 8 K) PL study of SbSeI showed a broad and asymmetric PL band at 1.4 eV, being quite distant from the bandgap. This PL band at 1.4 eV with obtained small thermal quenching activation energy of 12.7 meV is proposed to originate from the deep donor-deep acceptor pair (DD-DA) recombination.

Controlling the dewetting morphologies of thin liquid films by switchable substrates

Controlling the dewetting morphologies of thin liquid films by switchable substrates

Abnormal high stability halide perovskite thin films and solar cells to alpha and gamma irradiations with varying fluence

Solar cells (SCs) and thin films made of methylammonium lead tri-iodide (MAPbI3) have demonstrated remarkable robustness when irradiated with alpha (He2+) and gamma radiations from americium-241. This study investigates changes in the structure, absorption, and surface morphology of perovskite thin films, as well as the photoelectronic properties of MAPbI3 SCs, with and without irradiation with He2+. According to the XRD analysis, tetragonal MAPbI3 showed increased crystallinity and a decrease in compression micro-strain with an increased flux of He2+. UV–Vis absorption remained unchanged until the flux exceeded 7.36 x 1012 He2+ cm−2. The bandgaps for irradiated films decreased similarly to pristine films up to a dose of 3.07 x 1012 He2+cm−2, with significant differences observed beyond this point. Digital images showed significant changes in thin films irradiated at fluences exceeding 3.07 x 1012 He2+ cm−2, with pits forming in grains responsible for the changes, confirmed by scanning electron microscopy. In conclusion, this study found that MAPbI3 thin films and SCs can withstand doses of He2+ up to 3.07 x 1012 He2+ cm−2 in a He2+ radiation environment.

Growth dynamics of nanocolumnar thin films deposited by magnetron sputtering at oblique angles

The morphology of numerous nanocolumnar thin films deposited by the magnetron sputtering technique at oblique geometries and at relatively low temperatures has been analyzed for materials as different as Au, Pt, Ti, Cr, TiO2, Al, HfN, Mo, V, WO3 and W. Despite similar deposition conditions, two characteristic nanostructures have been identified depending on the material: a first one defined by highly tilted and symmetric nanocolumnar structures with a relatively high film density, and a second one characterized by rather vertical and asymmetric nanocolumns, with a much lower film density. With the help of a model, the two characteristic nanostructures have been linked to different growth dynamics and, specifically, to different surface relaxation mechanisms upon the incorporation of gaseous species with kinetic energies above the surface binding energy. Moreover, in the case of Ti, a smooth structural transition between the two types of growths has been found when varying the value of the power used to maintain the plasma discharge. Based on these results, the existence of different surface relaxation mechanisms is proposed, which quantitatively explains numerous experimental results under the same conceptual framework.

Diselenophene-Dithioalkylthiophene Based Quinoidal Small Molecules for Ambipolar Organic Field Effect Transistors.

This work presents a series of novel quinoidal organic semiconductors based on diselenophene-dithioalkylthiophene (DSpDST) conjugated cores with various side-chain lengths (-thiohexyl, -thiodecyl, and -thiotetradecyl, designated DSpDSTQ-6, DSpDSTQ-10, and DSpDSTQ-14, respectively). The purpose of this research is to develop solution-processable organic semiconductors using dicyanomethylene end-capped organic small molecules for organic field effect transistors (OFETs) application. The physical, electrochemical, and electrical properties of these new DSpDSTQs are systematically studied, along with their performance in OFETs and thin film morphologies. Additionally, the molecular structures of DSpDSTQ are determined through density functional theory (DFT) calculations and single-crystal X-ray diffraction analysis. The results reveal the presence of intramolecular S (alkyl)···Se (selenophene) interactions, which result in a planar SR-containing DSpDSTQ core, thereby promoting extended π-orbital interactions and efficient charge transport in the OFETs. Moreover, the influence of thioalkyl side chain length on surface morphologies and microstructures is investigated. Remarkably, the compound with the shortest thioalkyl chain, DSpDSTQ-6, demonstrates ambipolar carrier transport with the highest electron and hole mobilities of 0.334 and 0.463 cm2 V-1 s-1 , respectively. These findings highlight the excellence of ambipolar characteristics of solution-processable OFETs based on DSpDSTQs even under ambient conditions.

MBE growth of SnTe films on GaAs substrates with ZnTe buffer layers

SnTe (100) single-domain thin films have been previously grown on GaAs substrates by molecular beam epitaxy but obtaining excellent crystallinity can be difficult. In this paper, ZnTe buffer layers are introduced to improve the crystallinity of SnTe films. The effects of the molecular beam flux ratio (JTe/JSn) and growth temperature (Tg) on the crystallinity are investigated to achieve high-quality layers. The surface morphology and electrical properties of the SnTe thin films are also evaluated in addition to the conventional X-ray diffraction (XRD)measurements. The crystallographic properties of the grown samples are shown to be significantly improved by introducing a ZnTe buffer layer. XRD (θ–2θ) full width at half maximum of the lowest value obtained so far is about 0.14°. It is also found that lowering JTe/JSn to 0.6 results in a reduced growth rate, and an increased growth temperature (Tg = 220 °C) promotes the migration of atoms at the growth front. Both effects contribute to improvement in the crystallographic quality, including the layer surface smoothness. The cross-sectional transmission electron microscopy observation of the sample indicates the abrupt interface formation with different lattice structures. It is also found that low growth temperatures (below 200 °C) are not favorable for the SnTe layer growth, which is confirmed by the surface morphology.

Studies on physical properties of tin oxide films

This paper reports the study of some physical properties of thin films of tin oxide, such as the structural properties, surface morphology and optical transmission and reflection. The thin films of tin oxide were deposited by the method of thermal evaporation under vacuum. Transmission electron microscopy (TEM) was used to study the structural properties and the atomic force microscopy (AFM) method was used to study the surface morphology of thin films of tin oxide. The absorption and extinction coefficients of the investigated thin layers were determined from the transmittance and reflectance spectra recorded in the range of wavelengths between 190 and 1100 nm.

Soil improvement by biomass polyions and compaction: Reinforcement, biodegradation resistance, and retention of heavy metal ions

Biomass-based alternatives to soil improvement by cement in geotechnical applications are increasingly considered owing to their renewability and low carbon footprint. We have elaborated a method of soil improvement by which soil is treated with self-organizing biomass-derived polyions, carboxymethyl cellulose (CMC), and chitosan (CS) and is consequently compacted by rammer. CMC and CS interact electrostatically and self-assemble into interpolyelectrolyte complexes (IPEC) having the morphology of thin films imparting the superior mechanical properties to the soil composite. Curing of soil with CMC and CS at m(CMC+CS)/m(soil) ratios below 1% and compaction improved the unconfined compressive strength (qu) of soil up to 500 kPa in a wet state (ca. 17% moisture content) and 2.5 MPa in a dry state (ca. 0% moisture content). Due to the superior complexing properties of CMC and CS towards transition metal ions, soil treatment with IPEC notably suppressed the leaching of Cu2+, Pd2+, and Cd2+ metal ions from the soil. Despite the intrinsic biodegradability of CMC and CS, their IPEC complexes and soil-IPEC composites showed good resistance toward biodegradation by the cellulase enzyme. Excellent soil reinforcement, suppressed biodegradability, and chemical functionality of biomass-derived IPECs hold promise in utilizing renewable polymers in geotechnical practices of ground improvement addressing the needs of the sustainable use of resources.

Unveiling the multifaceted impact of C2H2 flow on SiCN CVD coatings: Mechanical mastery and beyond

This comprehensive study systematically investigates the influence of C2H2 flow rates on silicon carbonitride (SiCN) thin films deposited on p-type c-Si (100) substrates through Chemical Vapor Deposition (CVD). Across a range of C2H2 flow rates (1–15 sccm), the study quantitatively analyzes surface morphology, crystallinity and mechanical characteristics. Analyzing the data quantitatively: Surface morphologySEM and AFM analyses unveiled distinctive surface patterns influenced by varying C2H2 flow rates. Surface roughness exhibited a quantitative increase, rising from 1.2 nm at 1 sccm to 2.4 nm at 15 sccm. Ftir analysisFTIR spectroscopy identified three major vibrational signatures in SiCN thin films: Si-Hn wagging, n-SiC, and Si–C stretching. Notably, the intensity of the n-SiC peak demonstrated a quantitative rise with increasing C2H2 flow rate. XRD analysisXRD confirmed the quantitative impact of C2H2 flow rates on crystallinity. The SiCN thin film deposited at 15 sccm exhibited the highest crystallinity, with a quantified crystallite size of 15 nm. Nanoindentation testingHardness and Young's modulus were quantitatively assessed through nanoindentation testing. SiCN thin films showed a quantitative increase in both hardness and Young's modulus with rising C2H2 flow rates. The film deposited at 15 sccm demonstrated the highest hardness (i.e. 19.23 GPa) and Young's modulus (i.e. 271.56 GPa).In summary, this study establishes the significant impact of C2H2 flow rates on the quantitative aspects of surface morphology, crystallinity, and mechanical properties of SiCN thin films. Notably, the film deposited at 15 sccm emerges as distinctive, exhibiting the highest quantitative values for crystallinity, hardness and Young's modulus. This comprehensive analysis enhances the understanding of intricate relationship between C2H2 flow rates and the multifaceted properties of SiCN thin films.