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Bulk acoustic wave (BAW) filters have been proven to be of high demand in today's low power RF front-ends for mobile communication devices. Within the launch of 5G applications worldwide, especially in the region of new radio (nr-1) up to 6 GHz, defined frequency bands require filters of wide bandwidths, while simultaneously featuring steep edges and high out-of-band rejection. Due to the coexistence with 4G LTE (long term evolution) wireless standards as well as advanced data transfer concepts such as carrier aggregation, the increasing complexity of antenna systems forces the implementation of highly selective acoustic filters. In contrast to the widely used surface acoustic wave (SAW) technology, BAW filters appear with superior performance for frequencies above 1 GHz. This work describes the fabrication of a BAW-solidly mounted resonator (BAW-SMR) with a tailored material system of a-SiOCN:H as a low impedance (low-Z) material integrated within its acoustic Bragg mirror. A direct comparison to the widely used low-Z material of SiO2 with an acoustic impedance of around 13 MRayl is demonstrated by two equal resonator stacks by replacing only the uppermost low-Z thin film of the acoustic reflector. A single-mask design was chosen with platinum as a bottom electrode to ensure the most equal growth conditions for the piezoelectric aluminum nitride (AlN) layers on both reflectors' surfaces featuring either the tailored a-SiOCN:H or standard SiO2. The a-SiOCN:H thin films were deposited by plasma-enhanced chemical vapor deposition and the according acoustic impedance was priorly depicted to 7.1 MRayl, which could be exploited to achieve an increase in the effective coupling coefficient beyond 7% as well as a resonator bandwidth of more than 60 MHz. [ABSTRACT FROM AUTHOR]

Graphene/stainless steel (SUS) structures have received attention as an approach to enhancing the performance of SUS in various applications, such as energy storage and electrochemical devices. Despite many studies, the synthesis of graphene nanostructures with controllable growth orientation on SUS remains challenging. The present work demonstrates the selective synthesis of monolayer to bilayer graphene and vertical graphene (i.e., carbon nanowalls) on SUS by plasma enhanced chemical vapor deposition and also explains the associated growth mechanisms. This study indicates that the graphene nucleation density can be tuned by varying the growth temperature and CH4/H2 ratio during synthesis. It is also evident that graphene growth occurs within a mixed phase of γ-Fe and Fe3C at high temperatures, and a high carbon supply of above 900 °C triggers the transition of growth orientation from planar to vertical. [ABSTRACT FROM AUTHOR]

The annealing properties of open spaces in 90-nm-thick SiO2 deposited from tetraethylorthosilicate (TEOS) using plasma-enhanced chemical vapor deposition (PECVD) were studied with monoenergetic positron beams. From the lifetime of positronium (Ps) and an empirical model assuming a spherical open space, the mean diameter of open spaces was estimated to be 0.45 nm for PECVD-SiO2 before annealing. In the annealing temperature range below 350 °C, the size of the open spaces and their concentration increased as the temperature increased. Because initial water desorption from PECVD-SiO2 occurred in this temperature range, the observed increases in the size and concentration of spaces were attributed to the detrapping of water from such regions. Above 400 °C annealing, Ps formation was suppressed due to carrier traps introduced by the desorption of gas incorporated during TEOS decomposition. The size of the open spaces reached its maximum value (0.61 nm) after 800 °C annealing and started to decrease above 900 °C. After 1000 °C annealing, although the size of the spaces was close to that in thermally grown SiO2, their concentration remained low, which was attributed to residual impurities in the SiO2 network. [ABSTRACT FROM AUTHOR]

The concentration of vacancies and impurities in semiconductors plays a crucial role in determining their electrical, optical, and thermal properties. This study aims to clarify the nature of the interaction between positrons and ionized p-type impurities, emphasizing the similarities they share with the interaction between holes and this type of impurity. An overall strategy for investigating defects in semiconductor crystals that exhibit a combination of vacancies and p-type impurities is presented. By using positron annihilation spectroscopy, in particular, Doppler broadening of the annihilation radiation, we quantify the concentration of vacancies in epitaxial Si crystals grown by low-energy plasma-enhanced chemical vapor deposition. The vacancy number densities that we find are (1.2 ± 1.0) × 1017 cm−3 and (3.2 ± 1.5) × 1020 cm−3 for growth rates of 0.27 and 4.9 nm/s, respectively. Subsequent extended annealing of the Si samples effectively reduces the vacancy density below the sensitivity threshold of the positron technique. Secondary ion mass spectrometry indicates that the boron doping remains unaffected during the annealing treatment intended for vacancy removal. This study provides valuable insights into the intricate interplay between vacancies and ionized impurities with positrons in semiconductor crystals. The obtained results contribute to advance the control and understanding of material properties in heterostructures by emphasizing the significance of managing vacancy and dopant concentrations. [ABSTRACT FROM AUTHOR]

Growth of GeSn films directly on Si substrates is desirable for integrated photonics applications since the absence of an intervening buffer layer simplifies device fabrication. Here, we analyze the microstructure of two GeSn films grown directly on (001) Si by remote plasma-enhanced chemical vapor deposition (RPECVD): a 1000 nm thick film containing 3% Sn and a 600 nm thick, 10% Sn film. Both samples consist of an epitaxial layer with nano twins below a composite layer containing nanocrystalline and amorphous. The epilayer has uniform composition, while the nanocrystalline material has higher levels of Sn than the surrounding amorphous matrix. These two layers are separated by an interface with a distinct, hilly morphology. The transition between the two layers is facilitated by formation of densely populated (111)-coupled nano twins. The 10% Sn sample exhibits a significantly thinner epilayer than the one with 3% Sn. The in-plane lattice mismatch between GeSn and Si induces a quasi-periodic misfit dislocation network along the interface. Film growth initiates at the interface through formation of an atomic-scale interlayer with reduced Sn content, followed by the higher Sn content epitaxial layer. A corrugated surface containing a high density of twins with elevated levels of Sn at the peaks begins forming at a critical thickness. Subsequent epitaxial breakdown at the peaks produces a composite containing high levels of Sn nanocrystalline embedded in lower level of Sn amorphous. The observed microstructure and film evolution provide valuable insight into the growth mechanism that can be used to tune the RPECVD process for improved film quality. [ABSTRACT FROM AUTHOR]

The 5th generation (5G) wireless telecommunication standards with newly defined frequency bands up to 6 GHz are currently established around the world. While outperforming surface acoustic wave (SAW) filters above 1 GHz, bulk acoustic wave (BAW) resonators in multiplexers for radio-frequency front-end (RFFE) modules continuously face higher performance requirements. In contrast to free-standing bulk acoustic resonators (FBARs), solidly mounted resonator (SMR) technology uses an acoustic Bragg mirror, which has already been successfully applied for several GHz applications. In this work, we investigate the potential of amorphous hydrogenated silicon-oxycarbonitride (a-SiOCN:H) thin films synthesized with low-temperature plasma-enhanced chemical vapor deposition (PECVD) as a low acoustic impedance (low-Z) material. Compared to the state-of-the-art where in Bragg mirrors up to now SiO2 is used as standard, the acoustic impedance ratio against the high-Z material tungsten (W) is enhanced for a better device performance. To limit the expected increase in viscous loss when the acoustic impedance is reduced, to a minimum, predominantly the mass density was reduced while keeping the mechanical elasticity high. By doing so, acoustic impedance values as low as 7.1 MRayl were achieved, thereby increasing the impedance ratio of high-Z to low-Z materials from 8:1 up to 14:1. [ABSTRACT FROM AUTHOR]

In this study, we investigated the impact of SiO2 deposition temperature during plasma-enhanced chemical vapor deposition on the generation of fast hole traps, which cause surface potential pinning, in p-type GaN MOS structures. The thickness of a gallium oxide (GaOx) layer at the SiO2/GaN interface was estimated and correlated with the hole trap generation. The 200 ° C -deposited SiO2/GaN MOS structures exhibited a smaller amount of fast hole traps and a thinner GaOx interlayer than the 400 ° C -deposited samples. In the 200 ° C -deposited samples, annealing at a temperature below 600 ° C did not lead to an increase in the fast hole trap and GaOx layer thickness, while the amount of fast traps significantly increased just after 800 ° C -annealing in O2 ambient, accompanied by the growth of the GaOx interlayer. These findings suggest that the major origin of fast hole traps in SiO2/GaN MOS structures is a thermally induced defect existing inside a GaOx interlayer and that the low-temperature SiO2 deposition is effective in reducing the fast traps. [ABSTRACT FROM AUTHOR]

Flexoelectricity, a universal electromechanical coupling effect present in all dielectric materials, has garnered significant theoretical and experimental interest in recent years, particularly in ferroelectric perovskite oxides. However, nitride-based materials have received considerably less attention. In this Letter, we report the observation of direct flexoelectric effect in plasma-enhanced chemical vapor deposition silicon nitride thin film with a thickness of 200 nm. From three-point bending tests, we determined the effective flexoelectric coefficient of Si3N4 to be 1.64 ± 0.22 nC / m. Additionally, the measured flexoelectric-induced voltages are consistent with finite element computational models. This observation of the flexoelectric coupling effect could contribute to the development of silicon nitride-based micro-scale devices. [ABSTRACT FROM AUTHOR]

Temperature sensors have extensive applications in industrial production, defense, and military sectors. However, conventional temperature sensors are limited to operating temperatures below 200 °C and are unsuitable for detecting extremely high temperatures. In this paper, a method for thermal protection of molybdenum disulfide (MoS2) films is proposed and a MoS2 high temperature sensor is prepared. By depositing silicon nitride (Si3N4) films onto monolayer MoS2, not only is the issue of high-temperature oxidation effectively addressed, but also the prevention of contamination by impurities that could potentially compromise the performance of MoS2. Moreover, the width of the Schottky barrier of metal/MoS2 is reduced by using plasma-enhanced chemical vapor deposition of 400 nm Si3N4 to form an ohmic contact, which improves the electrical performance of the device by three orders of magnitude. The sensor exhibits a positive temperature coefficient measurement range of 25 °C–550 °C, with a maximum temperature coefficient of resistance of 0.89%·°C−1. The thermal protection method proposed in this paper provides a new idea for the fabrication of high-temperature sensors, which is expected to be applied in the high-temperature field. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high barrier RC film was prepared by coagulation bath coupled with PECVD. • The oxygen transmission rate of the composite film was 31.21 cm3/(m2·d). • The water contact angle of the composite film was 116.7°. • The composite film was completely degraded in soil within 35 days. Regenerated cellulose (RC) films are considered a sustainable packaging material that can replace non-degradable petroleum-based plastics. However, their susceptibility to water vapor and oxygen can limit their effectiveness in protecting products. This study introduces a novel approach for enhancing RC films to create durable, flexible, hydrophobic, high-barrier, and biodegradable packaging materials. By exploring the impact of ascorbic acid coagulation bath treatment and plasma-enhanced chemical vapor deposition (PECVD) on the properties of RC films, we found that the coagulation bath treatment facilitated the organized reconfiguration of cellulose chains, while PECVD applied a dense SiO x coating on the film surface. The results demonstrated a significant enhancement in water vapor and oxygen barrier properties of the composite film, almost reaching the level of commercial barrier films. Moreover, the composite film displayed exceptional biodegradability, fully degrading in soil within 35 days. Additionally, it showcased impressive mechanical strength, hydrophobic characteristics, and freshness preservation, positioning it as a valuable option for bio-based high-barrier packaging applications. [ABSTRACT FROM AUTHOR]

An aluminum oxide (AlOx)/silicon nitride (SiNy) dielectric stack was developed using an industrial plasma‐enhanced chemical vapor deposition (PECVD) system with low‐frequency (LF) plasma source for the surface passivation of undiffused textured p‐type crystalline silicon. The median recombination current density is 4.3 fA cm−2 as determined from photoconductance decay lifetime measurements and numerical device modeling. To the best of our knowledge, this is the first time to present a high‐quality LF‐PECVD AlOx/SiNy passivation stack on undiffused textured p‐type crystalline silicon wafers, which are cleaned with industrial processes using HF, HCl, and O3. The simulation agrees well with the measured effective carrier lifetime if the velocity parameters of 5.6 cm s−1 for holes and 803 cm s−1 for electrons are applied with a fixed negative charge density of −3 × 1012 cm−2. The process integration of developed AlOx/SiNy dielectric stack is successfully demonstrated by fabricating p‐type back junction solar cells featuring a poly‐Si‐based passivating contact at the cell rear side. As the best cell efficiency, we achieve 24.2% with an open‐circuit voltage of 725 mV on a M2‐sized Ga‐doped p‐type Czochralski‐grown Si wafer as independently confirmed by ISFH CalTeC. [ABSTRACT FROM AUTHOR]

[Display omitted] Bacterial infection of biomedical implants is an important clinical challenge, driving the development of novel antimicrobial materials. The antibacterial effect of vertically aligned graphene as a nanoarray coating has been reported. In this study, vertically aligned graphene nanosheets decorated with silver nanoparticles were fabricated to enhance antibacterial effectiveness. Vertical graphene (VG) nanoflakes were synthesized by plasma-enhanced chemical vapor deposition (PECVD). Ag nanoparticles were attached to the surface of VG through using polydopamine and achieving a sustained release of Ag+. VG loaded with Ag nanoparticles (VGP/Ag) not only prevented bacterial adhesion for a long time, but also exhibited good biocompatibility. This work provides a new venue for designing antibacterial surfaces based on combination of graphene nanoarrays with other nanomaterials, and the results indicate that this approach could be very successful in preventing implant associated infections. [ABSTRACT FROM AUTHOR]

This work presents a comprehensive investigation into the synthesis, characterization, and thermal stability of SiGeSn nanowires (NWs) leveraging the vapor–liquid–solid growth mechanism. Utilizing plasma‐enhanced chemical vapor deposition with Sn as the catalyst and a combination of SiH4 and GeH4 as precursors, this research synthesizes tapered SiGeSn NWs of high crystalline quality. Utilizing high‐angle annular dark‐field scanning transmission electron microscopy and energy‐dispersive X‐ray spectroscopy, the study confirms the inhomogeneous distribution of Si, Ge, and Sn along the NWs' growth axis. It is observed that the concentrations of Si and Ge are significantly influenced by the NW diameter, a phenomenon attributed to the Gibbs–Thomson effect. A straightforward mathematical model is developed. This model examines the impact of the catalyst's shape and the presence of Sn on the NW surface on the internal Sn concentration and its variation along the NWs' growth axis. Additionally, the study investigates how thermal annealing at temperatures of 300 and 600 °C induces compositional changes within the NWs. These changes are markedly influenced by the heterogeneous distribution of Si, Ge, and Sn elements, leading to varying levels of compositional alterations in different segments of the NWs postannealing at distinct temperatures. [ABSTRACT FROM AUTHOR]

In recent years, significant efforts have been dedicated to understanding the growth mechanisms behind the synthesis of vertically aligned nanocarbon structures using plasma-enhanced chemical vapor deposition (PECVD). This study explores how varying synthesis conditions, specifically hydrocarbon flow rate, hydrocarbon type, and plasma power,—affect the microstructure, properties, and electrochemical performance of nitrogen-doped vertically aligned graphene (NVG) and nitrogen-doped vertically aligned carbon nanofibers (NVCNFs) hybrids. It was observed that adjustments in these synthesis parameters led to noticeable changes in the microstructure, with particularly significant alterations when changing the hydrocarbon precursor from acetylene to methane. The electrochemical investigation revealed that the sample synthesized at higher plasma power exhibited enhanced electron transfer kinetics, likely due to the higher density of open edges and nitrogen doping level. This study contributes to better understanding the PECVD process for fabricating nanocarbon materials, particularly for sensor applications. [ABSTRACT FROM AUTHOR]

Plasma-enhanced chemical vapor deposition (PECVD) was used to obtain several graphite nanowall (GNW)-type films at different deposition times on silicon and copper to achieve various thicknesses of carbonic films for the development of electrochemical sensors for the detection of anthracene. The PECVD growth time varied from 15 min to 30 min to 45 min, while scanning electron microscopy (SEM) confirmed the changes in the thickness of the GNW films, revealing a continuous increase in the series. X-ray diffraction (XRD) analysis revealed that the crystallinity of the GNW film samples increased with increasing crystallite size and decreasing dislocation density as the deposition time increased. Electrochemical characterization of the GNW-based electrodes indicated that the electroactive area and heterogeneous electron transfer rate constant were greater for the GNW 45 min film in the carbonic material series. We present the transfer of GNW films on flexible polyethylene substrates for achieving flexible electrochemical sensors for further use in anthracene determination. The flexible GNW-based electrodes were investigated using differential pulse voltammetry (DPV) in the presence of anthracene. The results showed that the highest sensitivity in anthracene detection was provided by the sensor with the GNW film obtained after 45 min of PECVD growth. The optimization of the GNW film thickness for the development of flexible electrochemical sensors on polyethylene substrates represents a successful approach for enhancing the electrochemical performance of carbonic materials. [ABSTRACT FROM AUTHOR]

Nanotwinned Cu (NT-Cu) is a promising candidate for Cu redistribution lines (RDLs). However, oxidation in NT-Cu lines is of concern because it increases electrical resistance and endangers the reliabilities of semiconductor devices such as temperature cycling tests (TCTs). In order to enhance the reliabilities, the passivation of NT-Cu lines is needed. In this study, immersion Ag/Sn and plasma-enhanced chemical vapor deposition (PECVD) SiCN were used to passivate the surfaces of NT-Cu RDLs at low operating temperatures (60 °C for immersion and 150 °C for PECVD). We found that Ag- and SiCN-capped NT-Cu lines showed negligible changes in microstructures and resistance after TCTs. As for Sn-coated NT-Cu lines, the resistance remained stable after 250 cycles of TCTs, with low oxygen signals detected. These three coating layers can block oxygen and moisture, effectively preventing oxidation and maintaining the resistance of NT-Cu RDLs during the TCT. The findings demonstrate the effectiveness of Ag, Sn, and SiCN coatings in enhancing reliability, providing options for passivation layers of NT-Cu RDLs. [ABSTRACT FROM AUTHOR]

The increase of antibiotic-resistant strains has necessitated the generation of antibacterial agents that do not induce microbial resistance. The present study was conducted to evaluate the antibacterial effect of copper-coated carbon nanotubes (Cu/CNTs) synthesized by plasma-enhanced chemical vapor deposition (PECVD) on two strains of gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. First, the PECVD method was used to deposit carbon nanotubes (CNTs) on high-resistivity silicon wafers previously decorated with nickel catalyst by an electron beam gun. These nanotubes were then coated with copper thin films (Cu, 0– 60 nm) in a vacuum evaporator using the Direct Current (DC) Magnetron Sputtering method. The morphology of PECVD-grown Cu/CNTs was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The antibacterial properties of as-synthesized Cu/CNTs against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were determined using Standard Plate Count (SPC). The results showed that increasing the coating thickness of Cu/CNTs had intensified their antibacterial activity. The SEM and TEM images confirmed the morphological modification of the samples after coating with copper. [ABSTRACT FROM AUTHOR]

In this experiment, plasma-enhanced chemical vapor deposition technology was used to deposit diamond-like carbon thin films on the surface of a 2024 aluminum alloy. The effects of deposition temperature on the microstructure, carbon, silicon, and aluminum element distribution, and film substrate adhesion of diamond-like carbon thin films were studied using field emission scanning electron microscopy, energy-dispersive spectroscopy, XRD, scratch gauge, and ultra-depth-of-field microscopy. The results showed that with the increase in deposition temperature, the thickness of DLC film decreased from 8.72 μm to 5.37 μm, and the film bonded well with the substrate. There is a clear transition layer containing silicon elements between the DLC film and the aluminum alloy substrate. The transition layer is a solid solution formed by aluminum and silicon elements, which increases the bonding strength between the film and substrate. C-Si and C-C exist in the form of covalent bonds and undergo orbital hybridization, making the DLC film more stable. When the deposition temperature exceeds the aging temperature of a 2024 aluminum alloy, it will affect the properties of the aluminum alloy substrate. Therefore, the deposition temperature should be below the aging temperature of the 2024 aluminum alloy for coating. At a deposition temperature of 100 °C, the maximum membrane substrate bonding force is 14.45 N. When a continuous sound signal appears and the friction coefficient is the same as that of the substrate, the film is completely damaged. From the super-depth map of the scratch morphology, it can be seen that, at a deposition temperature of 100 °C, a small amount of thin film detachment appears around the scratch. [ABSTRACT FROM AUTHOR]

The optical characterization of non-absorbing, homogeneous, isotropic polymer-like thin films with correlated, differently rough boundaries is essential in optimizing their performance in various applications. A central aim of this study is to derive the general formulae necessary for the characterization of such films. The applicability of this theory is illustrated through the characterization of a polymer-like thin film deposited by plasma-enhanced chemical vapor deposition onto a silicon substrate with a randomly rough surface, focusing on the analysis of its rough boundaries over a wide range of spatial frequencies. The method is based on processing experimental data obtained using variable-angle spectroscopic ellipsometry and spectroscopic reflectometry. The transition layer is considered at the lower boundary of the polymer-like thin film. The spectral dependencies of the optical constants of the polymer-like thin film and the transition layer are determined using the Campi–Coriasso dispersion model. The reflectance data are processed using a combination of Rayleigh–Rice theory and scalar diffraction theory in the near-infrared and visible spectral ranges, while scalar diffraction theory is used for the processing of reflectance data within the ultraviolet range. Rayleigh–Rice theory alone is sufficient for the processing of the ellipsometric data across the entire spectral range. We accurately determine the thicknesses of the polymer-like thin film and the transition layer, as well as the roughness parameters of both boundaries, with the root mean square (rms) values cross-validated using atomic force microscopy. Notably, the rms values derived from optical measurements and atomic force microscopy show excellent agreement. These findings confirm the reliability of the optical method for the detailed characterization of thin films with differently rough boundaries, supporting the applicability of the proposed method in high-precision film analysis. [ABSTRACT FROM AUTHOR]

Titanium alloys have a high cost of production and exhibit low resistance to abrasive wear. The objective of this work was to carry out diamond-like carbon (DLC) coating, with dissimilar thicknesses, on Ti-22Nb-6Zr titanium alloys produced by powder metallurgy, and to evaluate its microabrasive wear resistance. The samples were compacted, cold pressed, and sintered, producing substrates for coating. The DLC coatings were carried out by PECVD (plasma-enhanced chemical vapor deposition). Free sphere microabrasive wear tests were performed using alumina (Al2O3) abrasive suspension. The DLC-coated samples were characterized by scanning electron microscopy (SEM), Vickers microhardness, coatings adhesion tests, confocal laser microscopy, atomic force microscopy (AFM), and Raman spectroscopy. The coatings did not show peeling-off or delamination in adhesion tests. The PECVD deposition was effective, producing sp2 and sp3 mixed carbon compounds characteristic of diamond-like carbon. The coatings provided good structural quality, homogeneity in surface roughness, excellent coating-to-substrate adhesion, and good tribological performance in microabrasive wear tests. The low wear coefficients obtained in this work demonstrate the excellent potential of DLC coatings to improve the tribological behavior of biocompatible titanium alloy parts (Ti-22Nb-6Zr) produced with a low modulus of elasticity (closer to the bone) and with near net shape, given by powder metallurgy processing. [ABSTRACT FROM AUTHOR]

This study investigates the effect of silicon carbon nitride (SiCN) as an interlayer for ZnO-based resistive random access memory (RRAM). SiCN was deposited using plasma-enhanced chemical vapor deposition with controlled carbon content, achieved by varying the partial pressure of tetramethylsilane (4MS). Our results indicate that increasing the carbon concentration enhances the endurance of RRAM devices but reduces the on/off ratio. Devices with SiCN exhibited lower operating voltages and more uniform resistive switching behavior. Oxygen migration from ZnO to SiCN is examined by x-ray diffraction and x-ray photoelectron spectroscopy analyses, promoting the formation of conductive filaments and lowering set voltages. Additionally, we examined the impact of top electrode oxidation on RRAM performance. The oxidation of the Ti top electrode was found to reduce endurance and increase low resistive state resistance, potentially leading to device failure through the formation of an insulating layer between the electrode and resistive switching material. The oxygen storage capability of SiCN was further confirmed through high-temperature stress tests, demonstrating its potential as an oxygen reservoir. Devices with a 20 nm SiCN interlayer showed significantly improved endurance, with over 500 switching cycles, compared to 62 cycles in those with a 5 nm SiCN layer. However, the thicker SiCN layer resulted in a notably lower on/off ratio due to reduced capacitance. These findings suggest that SiCN interlayers can effectively enhance the performance and endurance of ZnO-based RRAM devices by acting as an oxygen reservoir and mitigating the top electrode oxidation effect. [ABSTRACT FROM AUTHOR]

Germanium–tin (GeSn) alloys at sufficiently high Sn concentration, above several atomic percent, are the only group IV semiconductor exhibiting a direct bandgap and have generated much recent interest for optoelectronic applications into the mid-infrared region. Because the large lattice mismatch between GeSn and Si results in considerable strain for thin layers and a high defect density for thicker strain-relaxed layers, most reported GeSn growths incorporate a Ge buffer layer rather than depositing directly on Si substrates. Published reports of GeSn growth directly on Si utilize specialized precursors such as higher order germanes (Ge2H6, Ge3H8, or Ge4H10) or SnD4. In this paper, we report GeSn films with up to 10.6% Sn grown directly on Si substrates by remote plasma-enhanced chemical vapor deposition using GeH4 and SnCl4 precursors. These alloys have been characterized in detail using x-ray diffraction (XRD), transmission electron microscopy (TEM), and Rutherford backscattering spectrometry with channeling (RBS-C), as well as Raman spectroscopy (RS) and optical microscopy. The films studied are almost fully relaxed, with small residual strain observed, particularly in thinner films, and contain a high interface density of misfit dislocations that increases with Sn concentration. The defect density decreases toward the surface. Good agreement is found between the various characterization methods for the Sn content (XRD and RBS-C), lattice parameter measurement (XRD and TEM), and defect characterization (RBS-C, TEM, and RS). Such characterization of GeSn grown directly on Si substrates is essential to allow growth parameters to be optimized for the realization of the attractive optoelectronic properties of these alloys. [ABSTRACT FROM AUTHOR]

In this Letter, we present a p-GaN gate enhancement-mode GaN-on-Si high-electron mobility transistor fabricated using Mg-acceptor re-passivation realized through ammonia plasma treatment. The gate-to-source and gate-to-drain access regions of the device were treated with ammonia plasma using a plasma-enhanced chemical vapor deposition system, resulting in the formation of a high-resistivity GaN cap layer. The fabricated device has a high threshold voltage (VTH) of 2.0 V and a low gate reverse leakage current (IGR) of 10−11 A/mm. A breakdown voltage (BVOFF) of 670 V together with a specific on-resistance (Ron,sp) of 0.87 mΩ cm2 was obtained in a device with LGD = 6 μm. The measured dynamic on-resistance (Ron,d) at a quiescent drain voltage (Vds,q) of 600 V with a stress time of 10 and 120 s is 1.06 and 1.34 times of the static on-resistance (Ron,s), respectively. Good thermal stability of VTH and gate current IG were observed after a thermal stress at 175 °C for 100 h. The developed fabrication techniques exhibit a great potential to be applied into GaN power transistors. [ABSTRACT FROM AUTHOR]

The high surface area and transfer-less growth of graphene on dielectric materials is still a challenge in the production of novel sensing devices. We demonstrate a novel approach to graphene synthesis on a C-plane sapphire substrate, involving the microwave plasma-enhanced chemical vapor deposition (MW-PECVD) technique. The decomposition of methane, which is used as a precursor gas, is achieved without the need for remote plasma. Raman spectroscopy, atomic force microscopy and resistance characteristic measurements were performed to investigate the potential of graphene for use in sensing applications. We show that the thickness and quality of graphene film greatly depend on the CH4/H2 flow ratio, as well as on chamber pressure during the synthesis. By varying these parameters, the intensity ratio of Raman D and G bands of graphene varied between ~1 and ~4, while the 2D to G band intensity ratio was found to be 0.05–0.5. Boundary defects are the most prominent defect type in PECVD graphene, giving it a grainy texture. Despite this, the samples exhibited sheet resistance values as low as 1.87 kΩ/□. This reveals great potential for PECVD methods and could contribute toward efficient and straightforward graphene growth on various substrates. [ABSTRACT FROM AUTHOR]

Graphene (Gr) and carbon nanotubes (CNTs), the two intriguing carbon nanomaterials, have presented great potential in serving as high‐performance electrocatalysts in lithium−sulfur (Li−S) chemistry. The concurrent management of both materials would achieve a promoted synergistic effect. Nevertheless, there still remains a lack of an effective material synthesis route. Herein, a single‐step plasma‐enhanced chemical vapor deposition (PECVD) strategy is devised to prepare Gr@CNTs heterostructures with strong bonded connections. In the PECVD system, the damaged sidewalls generated in CNT tubes can serve as appropriate nucleation sites for further Gr growth. The formation mechanisms are thoroughly explored in aspects of both experimental characterizations and theoretical calculations. To confirm the validity of this approach, thus‐constructed Gr@CNTs architectures are employed as the sulfur host, enabling boosted redox kinetics of polysulfides. This project provides fundamental insight into the mechanism exploration for single‐step PECVD growth of Gr@CNTs heterostructure, hence promoting the practical application prospect of carbon nanomaterials toward Li−S systems. [ABSTRACT FROM AUTHOR]

In this study, for the first time, the optimization of applied pressure for achieving the one of the best tribological properties of diamond-like carbon (DLC) coating on graphite surface using plasma-enhanced chemical vapor deposition (PECVD) method was investigated. Raman spectroscopy and microscopy methods were used to characterize the applied coating. Additionally, the mechanical properties of the coating were investigated through nanoindentation testing. The wear resistance of coating has been tested as functional test. The results indicated that with increasing gas pressure, the sp3 hybridization percentage decreases, while the ID/IG ratio increases. The average roughness values for the uncoated sample and the coated samples at working pressures of 25, 30, and 35 mTorr were obtained as 1.6, 5.1, 3, and 2.4 nm, respectively. The results of hardness and wear tests showed that these properties were optimized by reducing the applied gas pressure. The highest hardness was 11.59 GPa, and the best sample in terms of the mechanical properties of the coating was the sample applied at a gas pressure of 25 mTorr. Results show that the optimal sample in tribological performance is the one applied at a working pressure of 25 mTorr. Because this sample demonstrates the lowest coefficient of friction, and wear depth. [ABSTRACT FROM AUTHOR]

In this article, we enhance the optical properties of hydrogenated silicon nitride (SiNx:H) thin film by optimization of deposition conditions using plasma‐enhanced chemical vapor deposition (PECVD). Specifically, the impact of varying NH3:SiH4 gas ratios (GRs) on the optical and structural properties of the SiNx:H film has been investigated. A ratio of 1.2 results in an optimal refractive index of 2.05, a thickness of 75.60 nm, and a deposition rate of 1.01 nm s−1, achieving the highest optical transmittance of 92.63% at 350 °C. Lower ratios, such as 0.5, produce higher refractive indices up to 2.43 but with reduced transmittance and thinner films (53.67 nm at 84.43% transmittance). The bandgap of GR 1.2 at 350 °C is also calculated as 3.23 eV using Tauc's plot. Fourier transform infrared spectroscopy analysis shows significant variations in SiH hydrogen bonding configurations at different temperatures, affecting SiH and SiNH bond densities. These are crucial for understanding the films' electronic and optical behaviors, with the highest hydrogen content for SiH noted at 3.30 × 1022 cm−3 at 350 °C. This research provides a detailed understanding of how precise control over GRs during PECVD can fine‐tune SiNx film properties, offering guidelines for producing high‐quality SiNx:H layer. [ABSTRACT FROM AUTHOR]

With the continuous advancements in electronics towards downsizing and integration, efficient thermal dissipation from chips has emerged as a critical factor affecting their lifespan and operational efficiency. The fan-less chip cooling system has two critical interfaces for thermal transport, which are the contact interface between the base and the chip dominated by thermal conduction, and the surface of the fins dominated by thermal radiation. The different thermal transfer modes of these two critical interfaces pose different requirements for thermal management materials. In the study, a novel approach was proposed by developing graphene thermal transport functional material whose morphology could be intentionally designed via reformed plasma-enhanced chemical vapor deposition (PECVD) methods to meet the diverse requirements of heat transfer properties. Specifically, graphene with multilevel branching structure of vertical graphene (BVG) was fabricated through the hydrogen-assisted PECVD (H2-PECVD) strategy, which contributed a high emissivity of ∼ 0.98. BVG was deposited on the fins' surface and functioned as the radiation enhanced layer to facilitate the rapid radiation of heat from the heat sinks into the surrounding air. Meanwhile, the well-oriented vertical graphene (OVG) was successfully prepared through the vertical electric field-assisted PECVD process (EF-PECVD), which showed a high directional thermal conductivity of ∼ 53.5 W·m−1·K−1. OVG was deposited on the contact interface and functioned as the thermal conduction enhanced layer, allowing for the quick transmission of heat from the chip to the heat sink. Utilizing this design concept, the two critical interfaces in the chip cooling system can be jointly enhanced, resulting in a remarkable cooling efficiency enhancement of ∼ 30.7%, demonstrating that this novel material possessed enormous potential for enhancing the performance of cooling systems. Therefore, this research not only provided new design concepts for the cooling system of electronic devices but also opened up new avenues for the application of graphene materials in thermal management. [ABSTRACT FROM AUTHOR]

Cubic gauche nitrogen (cg-N) has received wide attention for its exceptionally high energy density and environmental friendliness. However, traditional synthesis methods for cg-N predominantly rely on high-pressure techniques or the utilization of nanoconfined effects using highly toxic and sensitive sodium azide as precursor, which substantially restrict its practical application. On the basis of the first-principles simulations, we found that adsorption of potassium on the cg-N surface exhibits superior stabilization compared to sodium. Then, we chose safer potassium azide as precursor for synthesizing cg-N. Through plasma-enhanced chemical vapor deposition treatment, the free-standing cg-N was successfully synthesized without the need for high-pressure and nanoconfined effects. It demonstrated excellent thermal stability up to 760 K, and then rapid and intense thermal decomposition occurred, exhibiting typical thermal decomposition behaviors of high-energy-density materials. The explosion parameters were also measured using laser-induced plasma spectroscopy. Our work has substantially promoted the practical application of cg-N as HEDMs. [ABSTRACT FROM AUTHOR]

This study reports a direct approach to synthesizing vertically aligned carbon nanorod arrays (VA-CNRA) using microwave plasma-enhanced chemical vapor deposition (MW-PECVD) at 300 °C, on cobalt (Co) catalyst nanoparticles grown by thermal annealing (750 °C) of 10 nm thick Co layer deposited by radio frequency (RF) magnetron sputtering. To grow the VA-CNRA, the gas ratio in the plasma was optimized, focusing on the kinetics of the source gas dissociation and recombination. The reduced concentrations of acetylene (C 2 H 2) impede the optimal alignment of CNRA in the absence of the steric hindrance, resulting in their horizontal growth along the direction of gas flow via the "kite-mechanism". However, at a higher gas flow ratio, the attractive van der Waals potential among the CNRs was anticipated to induce aggregation when they arrive in proximity and vertical growth alignment of the nanorods via the higher deposition rates. Carbon nanorod films were analyzed using various spectroscopic techniques to understand the growth orientations, which suggests that the carbon nanorods were formed via the base-growth mechanism. Nano flower-like VA-CNRA were formed at higher C 2 H 2 /H 2 ratios. Notably, a distinct flower-like structure with whisker-like nanostructure petals was formed at a C 2 H 2 /H 2 flow ratio of ∼0.57. Compared to other nanorod structures, VA-CNRA, grown at optimal gas ratio, exhibited superior crystalline graphite, with 76 % sp 2 C C bonding along with a maximum of I 2D /I G , and a minimum of I D /I G intensity ratio in the Raman data. High-resolution TEM confirmed robust growth of CNRs, with an average diameter of ∼370 ± 3 nm. This innovative method enables large-scale production of VA-CNRA with high surface areas for energy applications. [ABSTRACT FROM AUTHOR]

This study investigates carbon-nitrogen thin films as active materials in photocatalytic methanol reforming, addressing the need for eco-friendly fuels with minimal waste and non-metallic photocatalysts. Additionally, it explores the synthesis of these materials using plasma-enhanced chemical vapor deposition (PECVD) from acrylonitrile or acetonitrile. This area has limited prior attention in carbon-nitrogen materials synthesis, particularly with subsequent application in methanol reforming offering potential advancements in clean energy production. The aim is to develop effective, environmentally friendly sources of hydrogen, where photocatalysts play a crucial role. The studies involved also characterization for morphology, and chemical structure. The results confirmed the activity in hydrogen production through methanol reforming, achieving a promising rate of 82 ± 6 μmol h−1 cm−2. [Display omitted] • Facile preparation of carbon-nitrogen films by cold plasma. • Non-metallic carbon-nitrogen catalysts for hydrogen production. • Hydrogen production rate of 32–82 μmol h−1 cm−2 over studied materials. [ABSTRACT FROM AUTHOR]

We present a study of the structural features of polycrystalline a diamond film (PCDF) synthesized by the microwave plasma-enhanced chemical vapor deposition method from a hydrogen/pentane mixture and consider its photoelectric response to synchrotron radiation. Raman spectroscopy analysis of the PCDF cross-section revealed the presence of sp2-hybridized inclusions. As the distance from the PCDF growth surface increases, the amount of the non-diamond phase also increases, while its morphology changes from amorphous to crystalline graphite-like carbon. The investigation of the photoelectric response of PCDF was carried out at the "Cosmos" station using synchrotron radiation from the VEPP-4M storage ring. The PCDF detector exhibited maximum sensitivity at low bias voltage. This effect was attributed to the increased efficiency of collecting photo-induced charge carriers from the diamond to the sp2-hybridized inclusions followed by their subsequent transport through conductive paths along the boundaries between diamond crystallites. [ABSTRACT FROM AUTHOR]

The high toxicity of hydrogen sulfide combined with poor sensitivity at room operating temperature urge for the development of new sensitive materials for sensors complying with this requirement, as well as a fast response and low cost. In this work, we have successfully developed materials for surface acoustic wave (SAW) sensors sensitive to H2S gas that provide a reversible response at room temperature. The sensitive materials were created by plasma-enhanced chemical vapor deposition of a-CH films using methane as a precursor with argon and argon admixed with hydrogen or nitrogen and applied on piezoelectric quartz substrates. Smooth films, with an AFM root mean square below 1.5 nm, were obtained in all cases, although slight topographical variations were noted, depending on the gas types. XPS detected varying degrees of oxidation, indicating that the assisting gases played a crucial role in introducing oxygen-containing functional groups, thus influencing the material's surface chemistry and sensitivity response. A hydrogen plasma treatment was applied on the a-CH deposited sensors as a further sensor preparation step. The hydrogen plasma treatment resulted in significant modifications in the topographical features, including roughness increase and notable variations in the surface aspect ratios, as confirmed through AFM data analysis, which involved advanced pixel height analysis and line profile processing. X-ray photoelectron spectroscopy (XPS) studies indicated the formation of new functional groups, increased defect density, and a significant reduction in electron transitions following hydrogen plasma treatment. The sensors demonstrated a reversible response to H2S gas within 8 to 20 ppm concentration ranges, effectively detecting these levels. The sensitivity of the sensors was significantly enhanced, up to 39% through hydrogen plasma treatment, reaching an improved overall performance in detecting low concentrations of H2S down to 0.9 ppm. These findings highlight a-CH thin films as an excellent candidate for next-generation SAW sensors. The study also suggests the potential for experimenting with various assisting gases during plasma deposition and additional plasma treatments to push detection capabilities to below ppm levels. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Solid state detectors composed of GeSn (germanium-tin) alloys offer improved capabilities compared with mercury cadmium telluride detectors. GeSn detectors may be smaller in size and weight, capable of operating with a noncryogenic detector, and provide increased sensitivity. Recent advances in nonequilibrium remote plasma-enhanced chemical vapor deposition growth enable GeSn crystalline growth with up to 10% Sn concentration, free of surface migration. Absorption spectroscopy combined with Tauc analysis results in 0.79, 0.73, 0.69, 0.59, 0.57, and 0.51 eV direct bandgap energies for GeSn samples with 0%, 2.7%, 4.6%, 6.6%, 7.1%, and 8.0% Sn, respectively. These absorption bandgap energies closely agree with density functional theory energies within ±0.05 eV. However, the rate of change of indirect bandgap narrowing as a function of Sn content is more diverse than a numerical result. The current research evidences that the indirect-to-direct transition crossover point occurs at a Sn content greater than 8%. From the analysis of the Urbach tail, the optical bandgap exhibits a potential structure disorder in the Urbach region. For example, this disorder may cause bandgap narrowing by more than 50% of the intrinsic bandgap energy in the highest Sn content (e.g., 8% Sn) sample. The surface Fermi level approximation validates p-type Fermi level pinning very close to the valence band maximum, often seen in highly doped semiconductors. [ABSTRACT FROM AUTHOR]

GeSn films were simultaneously deposited on Si (100), Si (111), c-plane sapphire (Al2O3), and fused silica substrates to investigate the impact of the substrate on the resulting GeSn film. The electronic, structural, and optical properties of these films were characterized by temperature-dependent Hall-effect measurements, x-ray diffractometry, secondary ion mass spectrometry, and variable angle spectroscopic ellipsometry. All films were polycrystalline with varying degrees of texturing. The film on Si (100) contained only GeSn (100) grains, 40.4 nm in diameter. The film deposited on Si (111) contained primarily GeSn (111) grains, 36.4 nm in diameter. Both films deposited on silicon substrates were fully relaxed. The layer deposited on Al2O3 contained primarily GeSn (111) grains, 41.3 nm in diameter. The film deposited on fused silica was not textured, and the average grain size was 35.0 nm. All films contained ∼5.6 at. % Sn throughout the layer, except for the film deposited on Al2O3, which contained 7.5% Sn. The films deposited on Si (111), Al2O3, and fused silica exhibit p-type conduction over the entire temperature range, 10–325 K, while the layer deposited on the Si (100) substrate shows a mixed conduction transition from p-type at low temperature to n-type above 220 K. From ∼175 to 260 K, both holes and electrons contribute to conduction. Texturing of the GeSn film on Si (100) was the only characteristic that set this film apart from the other three films, suggesting that something related to GeSn (100) crystal orientation causes this transition from p- to n-type conduction. [ABSTRACT FROM AUTHOR]

In this study, arrays of μLEDs in four different sizes (5 × 5 μm2, 10 × 10 μm2, 25 × 25 μm2, 50 × 50 μm2) were fabricated using a flip-chip bonding process. Two passivation processes were investigated with one involving a single layer of SiO2 deposited using plasma-enhanced chemical vapor deposition (PECVD) and the other incorporating Al2O3 deposited by atomic layer deposition (ALD) beneath the SiO2 layer. Owing to superior coverage and protection, the double-layers passivation process resulted in a three-order lower leakage current of μLEDs in the 5 μm chip-sized μLED arrays. Furthermore, higher light output power of μLEDs was observed in each chip-sized μLED array with double layers passivation. Particularly, the highest EQE value 21.9% of μLEDs array with 5 μm × 5 μm chip size was achieved with the double-layers passivation. The EQE value of μLEDs array was improved by 4.4 times by introducing the double-layers passivation as compared with that of μLEDs array with single layer passivation. Finally, more uniform light emission patterns were observed in the μLEDs with 5 μm × 5 μm chip size fabricated by double-layer passivation process using ImageJ software. [ABSTRACT FROM AUTHOR]

SiBCN films are synthesized by plasma-enhanced chemical vapor deposition at a reduced pressure and 500-600 °C. Organoelement silicon and boron compounds are selected as precursors, namely, hexamethyldisilazane HN(SiMe3)2 and triethylaminoborane Et3N·BH3 that were not used previously in the synthesis of SiBCN films. Vapor flows of initial compounds and additional gas (ammonia) were separately supplied to the reactor without premixing. The chemical bonding structure, elemental composition, surface morphology, and film deposition rate are studied by FTIR, XPS, wave dispersive X-ray spectroscopy, SEM, and Raman spectroscopy techniques. The surface morphology analysis of the samples shows that the films are smooth, homogeneous, and uniform without features. Variation of precursor concentrations in the initial mixture allows changes in the film composition in a wide range. The boron concentration in four-component coatings reaches 45 at.%. The study of chemical bonding structures of the films reveals the occurrence of Si–C, Si–N, B–N, C–H bonds along with the hybrid BCnN3–n bond. [ABSTRACT FROM AUTHOR]

Suppression of secondary electron emission (SEE) from metal surfaces is crucial for enhancing the performance of particle accelerators, spacecraft, and vacuum electronic devices. Earlier research has demonstrated that either etching the metal surface to create undulating structures or coating it with materials having low secondary electron yield (SEY) can markedly decrease SEE. However, the effectiveness of growing vertical graphene (VG) on laser-etched metal surfaces in suppressing SEE remains uncertain. This study examined the collective impact of these methods by applying nanoscale arrays of VG coating using plasma-enhanced chemical vapor deposition on Ni substrates, along with the formation of micrometer-sized microcavity array through laser etching. Comparative tests conducted revealed that the SEY of the samples subjected to VG coating on a microcavity array was lower compared to samples with either only a microcavity array or VG coating alone. Additionally, the crystallinity of VG grown on substrates of varying shapes exhibited variations. This study presents a new method for investigating the suppression of SEE on metal surfaces, contributing to the existing body of knowledge in this field. [ABSTRACT FROM AUTHOR]

Gallium selenide (GaSe) thin films on silicon(111) have been first grown by plasma-enhanced chemical vapor deposition (PECVD) using high-purity elemental gallium and selenium as the precursors. The reactive plasma components formed in the gas phase have been studied by optical emission spectroscopy. All grown films have a stoichiometry similar to that of GaSe. An increase in the plasma discharge power to 50 W and higher leads to the formation of an ε-GaSe phase, an improvement in the structural quality of the films, and an increase in the grain sizes with simultaneous grain compaction. [ABSTRACT FROM AUTHOR]

A nitrogen-doped nanocrystalline electrochemical graphite sensor for the sensitive determination of oleuropein (OL) from extra virgin olive oils (EVOOs) is presented. The sensor was developed by the deposition of nanocrystalline graphite (NCG) using plasma-enhanced chemical vapour deposition (PECVD) on silicon wafers. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD) were used to characterise the microstructure and morphology of the developed materials. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were used to investigate the electrochemical properties of the material and the performance of the sensor. The developed sensor showed good analytical performance against OL over a concentration range of 5.00–500.00 µM, with a good detection limit of 3.93 µM and a good sensitivity of 0.057 µA µM−1. The reproducibility of the electrochemical sensor was excellent, with a relative standard deviation (RSD) of 8.56% for seven measurements. [ABSTRACT FROM AUTHOR]

A room-temperature photoluminescence (PL) study of amorphous Si/amorphous silicon oxynitride multilayer films prepared by plasma-enhanced chemical vapor deposition is reported. The PL peak position can be tuned from 800 nm to 660 nm by adjusting the oxygen/nitride ratio in the a-SiOxNy:H sublayer. The Fourier transform infrared (FTIR) absorption spectra indicate that the shift of the PL peak position is accompanied by an increase in the Si-O-Si absorption peak's intensity, which induces the structural disorder at the interface, resulting in an increase in band gap energy. The effects of size on the photoluminescence spectrum have been studied. As a result, it has been observed that the addition of oxygen atoms introduces a large number of localized states at the interface, causing a blue shift in the emission peak position. With an increase in oxygen atoms, the localized states tend to saturate, and the quantum phenomenon caused by the a-Si sublayer becomes more pronounced. It is found that, as the thickness of the a-Si sublayer decreases, the increase in the [O/N] ratio is more likely to cause an increase in disordered states, leading to a decrease in luminescence intensity. For a-Si/a-SiOxNy:H samples with thinner a-Si sublayers, an appropriate value of [O/N] is required to achieve luminescence enhancement. When the value of [O/N] is one, the enhanced luminescence is obtained. It is also suggested that the PL originates from the radiative recombination in the localized states' T3- level-related negatively charged silicon dangling bond in the band tail of the a-Si:H sublayer embedded in an a-Si/a-SiOxNy:H multilayer structure. [ABSTRACT FROM AUTHOR]

The use of copper (Cu) and silver (Ag) nanoparticles in coatings can eliminate surface microbial contamination. This study compared antibacterial activity of Cu- (Cu/CNTs) and Ag-coated carbon nanotubes (Ag/CNTs) synthesized by plasma-enhanced chemical vapor deposition (PECVD) against Escherichia coli and Staphylococcus aureus. Initially, the PECVD technique was applied to deposit the CNTs on high-resistivity silicon wafers previously decorated by nickel catalyst using an Electron Beam Gun. Then, the nanotubes were coated by Cu and Ag thin films in a vacuum evaporator using the Direct Current (DC) Magnetron Sputtering method. Finally, the antibacterial effects were determined by Standard Plate Count (SPC, with film thicknesses of 0, 10, 30 and 60 nm) and Disk Diffusion Test (based on zone of inhibition (ZOI) with nanoparticle concentrations of 5, 10 and 15 µg/mL). According to the SPC findings, the highest antibacterial activity of Cu/CNTs was found for the film thickness of 60 nm against E. coli (66%), and the lowest activity was related to the film thickness of 19 nm against S. aureus (28.8%). The antibacterial activity of Ag/CNTs was about 70% against E. coli with the highest thickness and about 34.12% against S. aureus. The lowest ZOI was measured for the bare CNTs at a concentration of 5 µg/mL (12 mm), and the highest ZOI was related to Ag/CNTs with a concentration of 15 µg/mL against S. aureus (18 mm). To conclude, the carbon nanotube composites coated with copper or silver nanoparticles can be used to control bacterial growth in aqueous solutions.

In this study, undoped hydrogenated amorphous silicon (a-Si:H) thin films deposited under moderate dilution ratios of silane by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) have been investigated using steady-state photoconductivity and improved dual beam photoconductivity (DBP) methods to identify changes in multiple gap states in annealed and light-soaked states. Four different gap states were identified in annealed state named as A, B, C, and X states. The peak energy positions of these Gaussian distributions are consistent with those recently identified by Fourier transform photocurrent spectroscopy (FTPS). After in situ light soaking, their density increases with different rates as peak energy positions and half-widths remain unaffected. The electron-occupied A and B states located below the dark Fermi level and their density and ratios in the annealed and light-soaked states correlate well with those defects detected by time-domain pulsed electron paramagnetic resonance (EPR) experiments. The A, B, and X states located closer to the middle of the bandgap anneal out at room temperature in dark and define the "fast" states. However, the C states show no sign of room temperature annealing such that they must define the "slow" states in undoped a-Si:H. The results found in this study indicate that the anisotropic disordered network is a more appropriate model than previously proposed defect models based on the continuous random network to define the nanostructure of undoped a-Si:H, where multiple defects, D0 and non-D0 defects, can be identified by using the improved DBP method. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ion‐based electrochemical random‐access memory (ECRAM) is proposed for synaptic applications owing to its promising characteristics that have the potential to accelerate data processing through neuromorphic systems. However, attaining ideal synaptic functionalities and constructing high‐density vertical synapse arrays are challenging due to issues related to uncontrolled ion migration and constraints in 3D multi‐stacking. Here, a breakthrough using 3D stackable Li ion‐based vertical‐sensing ECRAM (VS‐ECRAM) is presented with an ion‐permeable ultrathin WS2 electrode synthesized through low‐temperature (200 °C) atmospheric‐pressure plasma‐enhanced chemical vapor deposition (AP‐PECVD). The direct AP‐PECVD of the WOx channel layer induces WS2 formation in the surface region, which exhibits sufficient electrical conductivity to function as an electrode. By utilizing the WS2 electrode as an ion‐barrier layer in the VS‐ECRAM synapse, excellent weight update linearity and cycling variability are achieved due to the finely controlled ion migration. Furthermore, a two‐layer stacked 3D VS‐ECRAM is successfully fabricated through the vertical WS2 formation, and independent weight updates without any disturbance are confirmed. Finally, a high pattern recognition accuracy of 95.22% is obtained using a multi‐layer perceptron‐based neural network. Therefore, the proposed 3D stackable WS2‐based VS‐ECRAM exhibits a strong potential for application in high‐density neuromorphic devices with excellent synaptic performances. [ABSTRACT FROM AUTHOR]