Amorphous Thin Films Research Articles

Effect of Plasma Process on the WO<sub>3</sub> Thin Films

O2 plasma treatment induces a transformation in the structure of WO3 thin films, converting them into a crystalline structure. Amorphous WO3 thin films were deposited on silicon produced by pulsed DC reactive magnetron sputtering at room temperature. The as-deposited films were treated with oxygen plasma powered by an RF generator. During the plasma treatment, the pressures were set at 1 x 10-1 to 1x 10-2 mbar, while the RF supplied powers at 100 W and 200 W. The effects of plasma treatment induced modifications of structure and physical properties of WO3 thin films. Several techniques were used to characterize microstructure, phase composition and surface morphology of the films including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). An RF generator powered the O2 plasma treatment on the as-deposited films. During the plasma treatment, the pressures were set at 1.0x10-1and 1.0x10-2 while the RF powers was supplied at 100 and 200 watt, respectively. The film's crystal structure changed at 200W plasma power and 1 x 10-2 mbar operating pressure. The O2 plasma treatment significantly changed the thickness of the films, probably as a result of changes in the packing density and surface etching. The experimental results suggest that the plasma treatment excitation process after crystallization can transform the films' amorphous structure into a crystalline structure.

Low-temperature preparation of high electrical conductivity amorphous compact Zn-doped TiO2 thin films via vacuum ultraviolet for high efficient solar cells

Low-temperature preparation of high electrical conductivity amorphous compact Zn-doped TiO2 thin films via vacuum ultraviolet for high efficient solar cells

Investigation of Surface Properties and Antibacterial Activity of 3D-Printed Polyamide 12-Based Samples Coated by a Plasma SiOxCyHz Amorphous Thin Film Approved for Food Contact

Microbial contamination and biofilm formation on food contact materials (FCMs) represent critical challenges within the food supply chain, compromising food safety and quality while increasing the risk of foodborne illnesses. Traditional materials often lack sufficient microbial resistance to contamination, creating a high demand for innovative antimicrobial surfaces. This study assessed the effectiveness of a nanosized deposited SiOxCyHz coating approved for food contact on 3D-printed polyamide 12 (PA12) disk substrates, aiming at providing antimicrobial and anti-biofilm functionality to mechanical components and packaging material in the food supply chain. The coating was applied using plasma-enhanced chemical vapor deposition (PECVD) and characterized through Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and contact angle measurements. Coated PA12 samples exhibited significantly enhanced hydrophobicity, with an average water contact angle of 112.9°, thus improving antibacterial performance by markedly reducing bacterial adhesion. Microbiological assays revealed a significant (p < 0.001) bactericidal activity (up to 4 logarithms after 4 h, ≥99.99%) against Gram-positive and Gram-negative bacteria, including notable foodborne pathogens such as L. monocytogenes, S. aureus, E. coli, and S. typhimurium. SiOxCyHz-coated PA12 surfaces exhibited strong antibacterial activity, representing a promising approach for coating additive-manufactured components and equipment for packaging production in the food and pharmaceutical supply chain able to enhance safety, extend product shelf life, and reduce reliance on chemical sanitizers.

Amorphous Silicon Nitride Thin Film Withstanding Up to 1700 °C: Structure and Thermal Conductivity.

Amorphous silicon nitride (SiNx) thin films are widely used in modern microelectronics and also as thermal barrier materials in combustion engines. The structure and thermal conductivity of amorphous SiNx films upon thermal treatment are important to electronic device thermal management and thermal insulating protection of engine components. In this work, we observe dramatically different crystallization behaviors of the amorphous SiNx thin films prepared by various CVD techniques. This result is attributed to the difference in H atom concentration, coordination structure, and Si/N atomic ratio of the films, which critically influences the crystallization kinetics. The LPCVD SiNx thin film exhibits superior thermal stability, remaining fully amorphous up to 1550 °C, while the measured cross-plane thermal conductivity noticeably increases from 1.62 to 2.42 W m-1 K-1. The thermal conductivity change is understood by disclosing the atomic bonding and vibrational mode characteristics in the amorphous SiNx thin film before and after annealing. Impressively, the LPCVD SiNx thin film can endure up to 1700 °C for 20 h and still preserves a large content of the amorphous matrix, accounting for an ∼80% volume fraction. The present work provides important findings for the high-temperature stability of amorphous SiNx thin films and offers new physical insights into the thermal transport physics of amorphous dielectric solids.

Simultaneous measurement of charge carrier density, mobility, and their transients with four electrical contacts: Frequency-multiplexed Hall effect method

The frequency multiplexed Hall effect method (FMHM) simultaneously measures time-dependent Hall Rxy(t) and longitudinal resistance Rxx(t) in arbitrary shaped samples using only four electrical contacts. FMHM applies the Onsager reciprocity relations along with three independent current sources and three lock-in amplifiers at three different frequencies. Transient FMHM measures samples with time-dependent Rxx(t) and Rxy(t) in the Drude limit at fixed magnetic field B. Parametric FMHM measures Rxx[A(t)] and Rxy[A(t)], where A(t) is an time-dependent control parameter such as B(t) or temperature T(t). Transient FMHM is demonstrated in the Drude regime at fixed magnetic field B to measure photoconductivity transients n(t) and μ(t) in GaN/AlGaN two-dimensional electron systems and on Zn0.3In1.4Sn0.3O3 amorphous oxide thin films. Parametric FMHM is demonstrated both in the Drude regime to study the temperature dependence of persistent photoconductivity n(T) and μ(T) and in the quantum Hall regime to study the magnetic-field dependence of Rxx(B) and Rxy(B) in GaAs quantum wells.

Characterization of ion track-etched conical nanopores in thermal and PECVD SiO2 using small angle X-ray scattering.

Conical nanopores in amorphous SiO2 thin films fabricated using the ion track etching technique show promising potential for filtration, sensing, and nanofluidic applications. The characterization of the pore morphology and size distribution, along with its dependence on the material properties and fabrication parameters, is crucial to designing nanopore systems for specific applications. Here, we present a comprehensive study of track-etched nanopores in thermal and plasma-enhanced chemical vapor-deposited (PECVD) SiO2 using synchrotron-based small-angle X-ray scattering (SAXS). The nanopores were fabricated by irradiating the samples with 89 MeV, 185 MeV, and 1.6 GeV Au ions, followed by hydrofluoric acid etching. We present a new approach for analyzing the complex highly anisotropic two-dimensional SAXS patterns of the pores by reducing the analysis to two orthogonal one-dimensional slices of the data. The simultaneous fit of the data enables an accurate determination of the pore geometry and size distribution. The analysis reveals substantial differences between the nanopores in thermal and PECVD SiO2. The track-to-bulk etching rate ratio is significantly different for the two materials, producing nanopores with cone angles that differ by almost a factor of two. Furthermore, thermal SiO2 exhibits an exceptionally narrow size distribution of only 2-4%, while PECVD SiO2 shows a higher variation ranging from 8% to 18%. The impact of different ion energies on the size of the nanopores was also investigated for pores in PECVD SiO2 and shows only negligible influence. These findings provide crucial insights for the controlled fabrication of conical nanopores in different materials, which is essential for optimizing membrane performance in applications that require precise pore geometry.

Interface-enhanced ion migration in amorphous alumina thin film on a substrate

Interface-enhanced ion migration in amorphous alumina thin film on a substrate

Annealing-Assisted Fast Crystallization of Silver-Mediated Amorphous Germanium Thin Films with Enhanced Thermoelectric Efficiency

Annealing-Assisted Fast Crystallization of Silver-Mediated Amorphous Germanium Thin Films with Enhanced Thermoelectric Efficiency

Predictions of molecular orientation and charge mobility in organic vacuum-deposited thin films by multiscale simulation

In organic semiconductors, elucidation of structures in the amorphous thin films is important because it determines crucial factors for device performance. The amorphous structures determine densities of states, electronic couplings, and reorganization energies, all of which affect current and light-emitting characteristics of devices. However, due to the amorphous nature, the detailed molecular-level structure, especially the distribution, has not been well characterized. Here, we fabricate organic amorphous thin films by molecular dynamic simulations mimicking the experimental deposition process. The simulation clearly exhibits that the molecules are oriented with a broad distribution with respect to the substrate; the average orientation successfully reproduced the experiments quantitatively. We also conduct charge transport simulations. The horizontal molecular orientation results in an increase in hole mobility as in the experiment. The origin of the increased mobility in horizontally oriented systems is found to be the narrowing of the site energy distribution and the reduction of pairs with exceptionally large electronic couplings.

Electron microscopy studies on interfacial solid-state reactions induced by electronic excitation.

We have studied the effects of electron irradiation on Pt/a-SiOx thin films by transmission electron microscopy and electron diffraction. Pt2Si was formed by 75 keV electron irradiation at 298 K and 90 K. Such a low temperature synthesis of Pt2Si can be attributed to the dissociation of a-SiOx induced by electronic excitation; Si-O bonds dissociate through Auger decay of core-holes generated by electronic excitation, and then, dissociated Si atoms form Pt-Si bonds. The morphology of Pt islands extensively changed during Pt2Si formation even at 90 K. Coalescence and growth of metallic particles are not due to thermal effects during electron irradiation but to athermal processes accompanied by silicide formation. To maintain the reaction interface between metallic particles and the dissociated Si atoms by electronic excitation, a considerable concomitant morphology change occurs. Similarly, Fe2Si was synthesized by using the same technique. In this way, we have demonstrated a versatile method for selectively forming nanoscale metal silicides in electron irradiated areas at room temperature. We also propose a new mechanism for crystallization of amorphous alloys which is mediated by additional solute atoms produced by electronic excitation. Crystallization of amorphous Pd-Si alloy thin films can be realized by 75 keV electron irradiation at 90 K via the electronic excitation, where both knock-on damage and a possible thermal crystallization can be excluded. Supply of dissociated Si to the Pd-Si layer may cause instability of the amorphous phase, which serves as the trigger for the remarkable structural change; ie, additional solute atom mediated crystallization.

Conversion of centimeter-scale amorphous niobium oxide thin films into crystalline niobium disulfide (NbS2): Synthesis and stability

Conversion of centimeter-scale amorphous niobium oxide thin films into crystalline niobium disulfide (NbS2): Synthesis and stability

Numerical simulation and performance analysis of amorphous zinc oxynitride thin film transistor (a-ZnON TFT) for large area display applications

Numerical simulation and performance analysis of amorphous zinc oxynitride thin film transistor (a-ZnON TFT) for large area display applications

Corrigendum to “Amorphous TiNiSn thin films for mechanical flexibility in thermoelectric applications” [Thin Solid Films 807 (2024) 140534

Corrigendum to “Amorphous TiNiSn thin films for mechanical flexibility in thermoelectric applications” [Thin Solid Films 807 (2024) 140534

Kinetics and mechanisms of 4-chloroguaiacol removal by adsorption onto a novel amorphous carbon thin film synthesized from Hamelia patens leaves

Kinetics and mechanisms of 4-chloroguaiacol removal by adsorption onto a novel amorphous carbon thin film synthesized from Hamelia patens leaves

Enhanced corrosion resistance of magnesium alloy via surface transfer of microwave-synthesized, non-toxic, and ultra-smooth nitrogen-doped amorphous carbon thin film

Enhanced corrosion resistance of magnesium alloy via surface transfer of microwave-synthesized, non-toxic, and ultra-smooth nitrogen-doped amorphous carbon thin film

Effect of carbon addition on CuZr-based amorphous thin film under tension: Insights from molecular dynamics simulations

Effect of carbon addition on CuZr-based amorphous thin film under tension: Insights from molecular dynamics simulations

Monitoring the chemical and structural changes during progressive aqueous alteration of silica thin films deposited by CVD process : accurate thickness loss rates measurements

This study investigates the alteration behaviour in aqueous KOH solution (pH 4) of CVD amorphous silica thin films exhibiting different network qualities. The hydrolysis of the networks was elucidated through ERDA (Elastic Recoil Detection Analysis) hydrogen depth profiles acquired throughout the alteration process. Thickness loss rates were successfully calculated showing remarkably low initial rates ranging from 2.5 to 4.8 nm/day, directly correlated with the initial network quality. A minimal rate as low as 0.5 nm/day, comparable to bulk silica performances, was recorded indicating the limited hydration and hydrolysis mechanisms leading to the release of H4SiO4. These phenomena are occurring with a cyclic hydrolysis–dissolution process. These findings represent the first available dataset on dissolution rates of CVD-deposited silica films. This comprehensive investigation has facilitated the accurate correlation of CVD deposition temperature and, therefore, the network quality of silica films to the chemical and mechanical response to aqueous alteration.

Optimizing and Understanding amorphous SiN Thin Film Deposition for GaN-High-Electron-Mobility Transistors Using Machine Learning and Causal Discovery

Optimizing and Understanding amorphous SiN Thin Film Deposition for GaN-High-Electron-Mobility Transistors Using Machine Learning and Causal Discovery

Optical and Electrical Properties of Amorphous Carbon Thin Films Grown from Mushroom Waste Oil using Chemical Vapor Deposition (CVD)

Amorphous carbon thin films have been successfully deposited using the Chemical Vapor Deposition (CVD) technique with various amounts of natural oyster mushroom (P.ostreatus) waste oil as carbon precursors onto the glass substrates. This study examined the impact of varying precursor amounts on the assessment of the properties of amorphous carbon thin films, especially the optical and electrical characteristics. The lower part of the oyster mushroom, which is normally discarded, was harvested and extracted into mushroom waste oil using Soxhlet extraction. CVD technique was used for the deposition of amorphous carbon, where mushroom waste oil was used as a precursor and glass as a substrate. Then, UV-Vis spectroscopy, current-voltage (I-V) measurement, and Raman spectroscopy were utilized for characterization. The findings demonstrate that the thin films show a combination of sp3 and sp2 bonded carbon atoms, which is common for amorphous carbon. The lowest optical band gap, 0.37 eV, and the highest electrical conductivity, 1.51 x 10-5 S.cm-1 was deposited at 2 ml of oyster mushroom waste oil. These results indicate that amorphous carbon grown from mushroom waste oil is capable of being a ‘green’ alternative as a source for carbon-based solar cells in the future.

Band Gap Energy and Lattice Distortion in Anatase TiO2 Thin Films Prepared by Reactive Sputtering with Different Thicknesses.

TiO2 is an abundant material on Earth, essential for the sustainable and cost-effective development of various technologies, with anatase being the most effective polymorph for photocatalytic and photovoltaic applications. Bulk crystalline anatase TiO2 exhibits a band gap energy EgA = 3.2 eV, for tetragonal lattice parameters aA = 0.3785 nm and cA = 0.9514 nm, but these characteristics vary for amorphous or polycrystalline thin films. Reactive magnetron sputtering has proven suitable for the preparation of TiO2 coatings on glass fiber substrates, with structural and optical characteristics that change during growth. Below a minimum thickness (t < 0.2 μm), the films have an amorphous nature or extremely small crystallite sizes not observable by X-ray diffraction. Afterwards, compressed quasi-randomly orientated crystallites are detected (volume strain ΔV = -0.02 and stress σV = -3.5 GPa for t = 0.2 μm) that evolve into relaxed and preferentially (004) orientated crystallites, reaching the standard anatase values at t ~ 1.4 μm with σV = 0.0 GPa. The band gap energy increases with lattice distortion according to the relation ∆Eg (eV) = -6∆V, and a further increase is observed for the thinnest coatings (∆Eg = 0.24 eV for t = 0.05 μm).