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• Deposition of SiO x thin films on oolitic limestone by PECVD from TEOS was tested. • PECVD is effective in producing crack-free SiO x films with no damage to stone substrate. • SiO x thin films by PECVD do not increase the hydrophobicity of the stone. • SiO x thin films by PECVD maintain vapor permeability of the stone. • SiO x thin films by PECVD protect stone from biological and pollutant attack. Plasma Enhanced Chemical Vapor Deposition (PECVD) of SiO x thin films has been applied to the stone surface under laboratory conditions in order to assess its feasibility as an alternative method for stone protection. SiO x thin layers were deposited on oolitic limestone lithologies known to have been used for the construction and restoration of the Batalha Monastery in Portugal surface by PECVD from tetraethoxysilane (TEOS) as the reaction precursor, in capacitively coupled parallel-plate reactor. The thickness, morphologies and chemical properties of the deposited film were characterized by attenuated total reflectance -Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM+EDS). Laboratory simulated decay and natural aging tests were implemented to evaluate the protective effect of the deposited micron-size SiO x thin films. Results suggested that, due to the good barrier effect, SiO x films were able to isolate the stones from aggressive acidic solution, thus reducing possible dissolution-related damage. Natural aging tests proved that SiO x thin films were also able to inhibit to a high extent bio-colonization while, at the same time reducing soiling of the stone appearance. Durability and wetting property of this SiO x thin film were preliminarily assessed. This research tested, for the first time, the feasibility of applying micron-size SiO x film quickly and directly via cold plasma deposition and its versatile protection performance on carbonate stone. [ABSTRACT FROM AUTHOR]

Hexamethyldisiloxane (HMDSO) is an organosilicon compound with a modifiable bandgap, depending on the deposition conditions. This material has many unique properties due to its stability, low toxicity, and strong adhesion, making it useful as a protective barrier against corrosion, moisture, and oxidation. In this work, HMDSO films were deposited on glass substrates by the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique at different deposition times. The optical properties of HMDSO films, such as dielectric permittivity, refractive index, extinction and absorption coefficients, and band gap energy, are inferred from transmission and reflection spectra. As the deposition time increased, the real part of the dielectric constant, the refractive index, and the bandgap energy showed a decrease, dropping from 4.24 to 3.40, from 2.06 to 1.84, and from 2.85 eV to 2.03 eV, respectively. The latter result is determined using classical models such as the O'Leary-Johnson-Lim ('OJL') interband transition and the harmonic oscillator model. HMDSO and Silver are used in this study for the fabrication of optical filters using two types of structures, a multiple cavity metal–dielectric (MCMD) and the Fabry–Perot structure. The silver layers are deposited by a sputtering process. The MCMD optical filter shows a higher transmittance of about 30%, but a wide range of wavelengths is transmitted. In contrast, the Fabry–Perot filter showed high contrast but a lower transmittance of about 20%. [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]

Here we show a novel approach to characterize the gas transfer behavior of silicon-oxide (SiO x) coatings and explain the underlying dynamics. For this, we investigate the coating on a nm-scale both by measurement and simulation. Positron annihilation spectroscopy (PAS) and quantum mechanical electronic structure-based molecular dynamics simulations are combined to characterize the porous landscape of SiO x coatings. This approach analyses the influence of micropores smaller than 2 nm in diameter on gas permeation which are difficult to study with conventional methods. We lay out the main pore diameter ranges and their associated porosity estimates. An influence of layer growth on pore size and porosity was found, with an increased energy input during layer deposition leading to smaller pore sizes and a reduced porosity. The molecular dynamics simulations quantify the self-diffusion of oxygen and water vapor through those PAS deducted micropore ranges for hydrophilic and hydrophobic systems. The theoretical pore size ranges are fitting to our PAS results and complete them by giving diffusion coefficients. This approach enables detailed analysis of pore morphology on mass transport through thin film coatings and characterization of their barrier or membrane performance. This is a crucial prerequisite for the development of an exhaustive model of pore dominated mass transports in PECVD coatings. [ABSTRACT FROM AUTHOR]

A Hollow Cathode Plasma Enhanced Chemical Vapor Deposition (HC-PECVD) reactor was used to deposit silver doped Diamond-Like Carbon (Ag-DLC) films on Ti6Al4V alloy employing two methodologies: i) producing a silicon interlayer, using tetramethylsilane (TMS) as silicon precursor, varying the argon flow of the hollow cathode; and ii) carbonitriding the substrate. Profilometry, Raman, and Secondary Ion Mass Spectrometry (SIMS), as well as nanohardness, micro-scratch, scratch, and VDI 3198 indentation tests were used to evaluate the characteristics of the films and their adhesion on the substrates. The results demonstrated that the argon flow can be used for tuning the Ag-DLC film's hardness, toughness, and adherence on silicon interlayers. The carbonitriding process, in turn, provided an improvement in the film toughness compared with non-carbonitrided samples. Considering the lower cost and easier handling of N2 compared to the silicon precursors commonly available (TMS, HDMSO, SiH4, etc.), the carbonitriding process proved more appropriate to improve the adhesion of the Ag-DLC films on the Ti6Al4V alloy. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of hydrogenated amorphous silicon (a-Si)-based detectors, utilizing electrical characterization, Raman spectroscopy, photoemission, and inverse photoemission techniques. The unique properties of a-Si have sparked interest in its application for radiation detection in both physics and medicine. Although amorphous silicon (a-Si) is inherently a highly defective material, hydrogenation significantly reduces defect density, enabling its use in radiation detector devices. Spectroscopic measurements provide insights into the intricate relationship between the structure and electronic properties of a-Si, enhancing our understanding of how specific configurations, such as the choice of substrate, can markedly influence detector performance. In this study, we compare the performance of a-Si detectors deposited on two different substrates: crystalline silicon (c-Si) and flexible Kapton. Our findings suggest that detectors deposited on Kapton exhibit reduced sensitivity, despite having comparable noise and leakage current levels to those on crystalline silicon. We hypothesize that this discrepancy may be attributed to the substrate material, differences in film morphology, and/or the alignment of energy levels. Further measurements are planned to substantiate these hypotheses. [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]

Nanostructured silicon is a promising material for many recent applications. In this work, inverted pyramidal porous silicon is synthesized by two stages metal assisted etching followed by PECVD rebuilding. At first, nanowires are obtained by conventional Ag assisted chemical etching at the surface of monocrystalline silicon wafer. Then, Inverted pyramidal (IP) macroporous structure is obtained by dipping the sample in HNO3: Ni solution after nanowire harvesting. Finally, PECVD is used to build deep holes on the porous surface template. The depth of the pyramidal holes can be tuned by deposition time and silane pressure. The macroporous structure characteristics are investigated by many techniques such as XRD, SEM, FTIR, reflectivity and impedance. Sensing tests of IP layers for different gases show their selectivity for NO2. Highlights: - PECVD growth of amorphous silicon on pyramidal porous surface leads to inverted pyramidal (IP) structure with deep pores. The depth can be tuned by PECVD deposition time. - Amorphous layer deposited by PECVD uses textured surface as pattern. - Dipping silicon nanowires in Ni:HNO3 leads to their harvesting and to shallow pyramidal pores at Si surface. - Grazing incident XRD patterns and FTIR spectra show the presence of nickel silicide nanoparticles at the surface of amorphous layer. These nanoparticles play a key role in the formation of IP pores. - Impedance analysis shows that main transfer mechanism is the hoping of charges between localized states induced by nickel silicides. - Gas detection measurements show the capability of our IP samples as selective gas sensor for NO2. [ABSTRACT FROM AUTHOR]

Abstract 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.

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]

Abstract Co-doping of phosphorus and boron elements into crystalline silicon quantum dot (c-Si QD) is an effective approach for enhancing the photoluminescence (PL) performance. In this paper, we report on the preparation of hydrogenated silicon nitride (SiNx:H) thin films embedded with phosphorus-boron co-doped c-Si QDs via plasma enhanced chemical vapor deposition route. Mixed dilution including hydrogen (H2) and argon (Ar) is applied in the in-situ deposition process for optimizing the deposition process. The P-B co-doped c-Si QD/SiNx:H thin films exhibit a wide range of PL spectra. The emission is greatly improved especially for the short-wavelength light when compared to the SiOx:H thin film containing P-B co-doped c-Si QDs. The effects of H2/Ar flow ratio on the structural and optical characteristics of thin films are systematically investigated through a series of characterizations. Experimental results show that various properties, such as crystallinity, QD size, optical band gap and doping concentrations, are effectively controlled by tuning H2/Ar flow ratio. Based on the red-shift of QCE-related PL peak, the successful P-B co-doping into Si QDs are verified. Finally, a comprehensive discussion has been made to analyze the influence of H2-Ar mixed dilution on the film growth and impurity doping in detail in this paper.

Large‐area graphene is typically synthesized on rolled‐annealed copper foils, which require transferring to other substrates for applications. This study examines large‐area graphene growth on electrodeposited (ED) copper foils—used in lithium‐ion batteries and printed circuit boards—via plasma‐enhanced chemical vapor deposition (PECVD). It reveals that, for a set plasma power, a minimum growth time ensures full graphene coverage, leading to monolayer and then multilayer graphene, showing PECVD growth on ED copper is not self‐limited. The process also beneficially modifies the ED copper substrate, like removing the surface zinc layer and changing copper grain size and orientation, thus improving graphene growth. Additionally, the study includes high‐frequency scattering parameter (S‐parameter) measurements in a coplanar waveguide (CPW) system. This involves graphene on a sapphire substrate with a silver electrode. The S‐parameter data indicate that the CPW with graphene shows reduced insertion losses in high‐frequency circuits compared to those without graphene. This underscores graphene's role in reducing insertion losses between metallic and dielectric layers in high‐frequency settings, offering valuable insights for industrial and technological applications. [ABSTRACT FROM AUTHOR]

Co-doping of phosphorus and boron elements into crystalline silicon quantum dot (c-Si QD) is an effective approach for enhancing the photoluminescence (PL) performance. In this paper, we report on the preparation of hydrogenated silicon nitride (SiNx:H) thin films embedded with phosphorus-boron co-doped c-Si QDs via plasma enhanced chemical vapor deposition route. Mixed dilution including hydrogen (H2) and argon (Ar) is applied in the in-situ deposition process for optimizing the deposition process. The P-B co-doped c-Si QD/SiNx:H thin films exhibit a wide range of PL spectra. The emission is greatly improved especially for the short-wavelength light when compared to the SiOx:H thin film containing P-B co-doped c-Si QDs. The effects of H2/Ar flow ratio on the structural and optical characteristics of thin films are systematically investigated through a series of characterizations. Experimental results show that various properties, such as crystallinity, QD size, optical band gap and doping concentrations, are effectively controlled by tuning H2/Ar flow ratio. Based on the red-shift of QCE-related PL peak, the successful P-B co-doping into Si QDs are verified. Finally, a comprehensive discussion has been made to analyze the influence of H2-Ar mixed dilution on the film growth and impurity doping in detail in this paper. [ABSTRACT FROM AUTHOR]

Tin(ii) iodide (SnI2) faces significant challenges in photodetector applications, primarily due to its sensitivity to moisture and degradation over time. Achieving uniform, high‐quality films with low impurity and defect levels is also a challenge. Potential solutions include advanced deposition techniques to improve film quality and stability, surface passivation and encapsulation, doping and alloying. In this study, SnI2 thin films have been deposited for the first time using plasma enhanced chemical vapour deposition (PECVD) technique to the best of our knowledge. Process parameters like deposition pressure and RF‐power have been optimised via non‐intrusive in‐situ V−I probe impedance analyser. SnI2 thin films have been deposited on glass & transparent conducting oxide (TCO) and p‐Si wafer at various RF‐power to make SnI2/p‐Si heterojunction followed by metallization to make Ag/SnI2/p‐Si/Ag heterojunction photodetector. Characterization techniques like thin film thickness measurement, UV‐Vis‐NIR spectroscopy, Photoluminescence spectroscopy, glancing incidence x‐ray diffraction (GIXRD), SEM and I−V measurements were carried out to study its optical, structural and electronic properties. Fabricated devices, Ag/SnI2/p‐Si/Ag heterojunction photodiode exhibits best critical performance for the film deposited at 150 W having rectifying ratio of 6.9×104 at 1.0 V and photo‐sensitivity of 1.6×104 at 100 mW/cm2 light intensity. [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]

4‐(trimethylsilyl)morpholine O(CH2CH2)2NSi(CH3)3 (TMSM) was investigated as a single‐source precursor for SiCNO films synthesis. Optical emission spectroscopy of plasma generated from TMSM/He, TMSM/H2, and TMSM/NH3 gas mixtures revealed the presence of N2, CH, H, CN, and CO species. The last two are suggested to be responsible for the lowering of carbon concentration in the films in comparison with the precursor. The refractive index ranged from 1.5 to 2.0, and bandgap varied from 2.0 to 4.6 eV, which pointed that some of the films can be used as antireflective coatings in silicon photovoltaic cell technologies and dielectric layers in electronic devices. [ABSTRACT FROM AUTHOR]

In this work, the significant lifetime improvement of negative bias thermal instability (NBTI) is demonstrated by the introduction of a thin SiN layer fabricated by plasma enhanced atomic layer deposition (PEALD) in stress memorization technique (SMT). The thin SiN film is deposited before the plasma enhanced chemical vapor deposition (PECVD) of SiN layer with a high tensile stress. It is revealed that the possible H2 escape accompanied with interface de-passivation can be effectively suppressed by this thin PEALD SiN layer, which may further reduce the interface states at Si/gate dielectric interface. Hence, about 500% NBTI lifetime improvement for PMOSFETs is demonstrated without obvious performance degradation for both NMOSFETs and PMOSFETs. [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]

In addition to the plasmon-mediated resonant coupling mechanism, the excitation of hot electron induced by plasmon presents a promising path for developing high-performance optoelectronic devices tailored for various applications. This study introduces a sophisticated design for a solar-blind ultraviolet (UV) detector array using linear In-doped Ga2O3 (InGaO) modulated by platinum (Pt) nanoparticles (PtNPs). The construction of this array involves depositing a thin film of Ga2O3 through the plasmonenhanced chemical vapor deposition (PECVD) technique. Subsequently, PtNPs were synthesized via radio-frequency magnetron sputtering and annealing process. The performance of these highly uniform arrays is significantly enhanced owing to the generation of high-energy hot electrons. This process is facilitated by non-radiative decay processes induced by PtNPs. Notably, the array achieves maximum responsivity (R) of 353 mA/W, external quantum efficiency (EQE) of 173%, detectivity (D*) of approximately 1013 Jones, and photoconductive gain of 1.58. In addition, the standard deviation for photocurrent stays below 17% for more than 80% of the array units within the array. Subsequently, the application of this array extends to photon detection in the deep-UV (DUV) range. This includes critical areas such as imaging sensing and water quality monitoring. By leveraging surface plasmon coupling, the array achieves high-performance DUV photon detection. This approach enables a broad spectrum of practical applications, underscoring the significant potential of this technology for the advancement of DUV detectors. [ABSTRACT FROM AUTHOR]

This paper presents the results of the study of the electron temperature in argon and argon-acetylene plasma of DC glow discharge. The optical-emission method was used to determine the main parameter of the complex plasma. The dependence of the electron temperature on the operating pressure, voltage, and discharge time was determined from the intensity of spectral lines. The source voltage was varied from 1 kV to 1.5 kV, and the pressure was maintained between 0.1-1 torr. As a time-dependent function, the electron temperature was calculated every 20 seconds during a 200-second discharge. The results showed that in argon plasma, as the pressure increases, the electron temperature decreases up to a pressure value of 0.4 torr, subsequent increase leads to an increase in temperature. Also, with the increase in source voltage, a decrease in electron temperature within the error limits is observed. In addition, in dust plasma (PECVD in Ar-C2H2), the electron temperature as a function of pressure and source voltage showed a trend similar to that observed in argon plasma. However, the electron temperature in dust plasma increases as a function of time at the initial moment, after which it decreases sharply with time. [ABSTRACT FROM AUTHOR]

In this work, voltage linearity of plasma-enhanced chemical vapor deposited silicon nitride (N) and stacked silicon dioxide-silicon nitride-silicon dioxide (ONO) metal-insulator-metal (MIM) capacitors with other important parameters are investigated as a function of frequencies. Analog and mixed analog radio frequency integrated circuits require excellent voltage linear MIM capacitors. It was found that nitride voltage linearity coefficient β is between – 950 and 180 ppm/V and quadratic coefficient α is between −400 and 900 ppm/V2 in 1 Khz to 5 MHz frequency range. ONO has β between −120 and 190 ppm/V whereas α between −88 and 95 ppm/V2 in the same applied frequencies range, indicating prospective for precision analog circuit applications. The calculated capacitive density and dielectric constant of N and ONO MIM capacitors at 1 MHz are 1.98 fF/μm2 and 7.8 and ONOs are 1.03 fF/μm2 and 6.2, respectively. [ABSTRACT FROM AUTHOR]

The regularities of the influence of the growth temperature on the geometrical parameters, the concentration of the dopant nitrogen and the type of defects formed in carbon nanotubes grown on a molybdenum sublayer are established in this paper. It is shown that the best piezoelectric and resistive properties are observed in nitrogen-doped carbon nanotubes (N-CNTs) grown at a temperature of 525°C, which is due to the highest concentration of dopant nitrogen and high aspect ratio of nanotubes. Based on the results of thermodynamic analysis, the dependence of the dopant nitrogen concentration and the defect type on the tendency to form molybdenum nitrides and carbides during the growth of N-CNTs is shown. The obtained results can be used in the development of nanopiezotronic devices based on arrays of vertically aligned N-CNTs: nanogenerators, strain sensors and memory elements. [ABSTRACT FROM AUTHOR]

Controlling properties of GaN/dielectric interfaces is crucial for determining the characteristics of MOS-HEMT devices and their stability. Interface properties are largely affected by the techniques and specific conditions of dielectric deposition. In this work, a Taguchi design of experiment was applied to study the effect of plasma parameters during deposition of SiOx by PECVD for passivation of n-GaN. SiOx/GaN MIS capacitors were fabricated and characterized by capacitance measurement at a high probing frequency of 1 MHz. The interface states density, hysteresis and flatband voltage were analyzed and modeled in relation with the flow of SiH4, plasma power, chamber pressure and temperature. Excellent fits could be obtained on a single model including linear terms for all studied parameters and quadratic terms for the flow of SiH4 and temperature. We show that it is possible to obtain some control of the flatband voltage while maintaining a good interface quality. Positive flatband voltages are potentially of interest to enable normally-off operation for MOS-HEMTs and this could be obtained mainly by using a high SiH4/N2O ratio. To the contrary, negative flatband voltage values often ensure the most stable operation of MOS-HEMTs and this was achieved with a low SiH4/N2O and high plasma power. MIS capacitors with near-zero flatband voltage were also obtained with low SiH4/N2O ratio and low plasma power. Hysteresis and interface states density in relation with deposition plasma conditions are also analyzed in order to offer the best trade-offs depending on the end applications of MOS-GaN devices. By demonstrating the great impact of plasma conditions during dielectric deposition on electronic properties of MIS devices, we show that the process of gate insulation can be optimized to simultaneously control the density of defects and fixed charge at the interface.

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

In this work we investigate the release of hydrogen gas from PECVD silicon nitride thin films in the cavities of MEMS based inertial sensors. Firstly, material characterization is conducted on two types of PECVD silicon nitride thin films to study the release of hydrogen gas with analytical methods. The release of hydrogen gas from these materials in encapsulated cavities of MEMS sensors, and its influence on the cavity pressure is also investigated experimentally with the help of functional microchips of MEMS based inertial sensors. Based on our findings and reports from other works, we propose steps by which change in the cavity pressure of the investigated microchip occurs over its different fabrication processes. We suggest that hydrogen gas is released form PECVD silicon nitride thin films at high temperatures during wafer bonding, which can then diffuse in cavities at low pressure over the lifetime of the sensor.

Abstract Integrating resistive memory or neuromorphic memristors into mainstream silicon technology can be substantially facilitated if the memories are built in the back-end-of-line (BEOL) and stacked directly above the logic circuitries. Here we report a promising memristor employing a plasma-enhanced chemical vapour deposition (PECVD) bilayer of amorphous SiC/Si as device layer and Cu as an active electrode. Its endurance exceeds one billion cycles with an ON/OFF ratio of ca. two orders of magnitude. Resistance drift is observed in the first 200 million cycles, after which the devices settle with a coefficient of variation of ca. 10% for both the low and high resistance states. Ohmic conduction in the low resistance state is attributed to the formation of Cu conductive filaments inside the bilayer structure, where the nanoscale grain boundaries in the Si layer provide the pre-defined pathway for Cu ion migration. Rupture of the conductive filament leads to current conduction dominated by reverse bias Schottky emission. Multistate switching is achieved by precisely controlling the pulse conditions for potential neuromorphic computing applications. The PECVD deposition method employed here has been frequently used to deposit typical BEOL SiOC low-k interlayer dielectrics. This makes it a unique memristor system with great potential for integration.

Considering the potential for morphological changes and the adjustment of the sp3/sp2 ratio in diamond-like carbon (DLC) coatings, and consequently the possibility of adjusting the properties of self-lubricating, hardness, and wear of these coatings, the present study investigates the effect of varying the power applied during the deposition of coatings using plasma-enhanced chemical vapor deposition (PECVD) method. Raman spectroscopy, Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM), nanoindentation, wear, and wear depth tests were employed for this purpose. The results obtained from the Raman spectroscopy indicated that the percentage of sp3 hybridization, as well as the amount of internal stress, increased with the higher applied power of the coating. AFM results also reveal an increase in surface roughness with increasing applied power, and FESEM results indicate a reduction in the diameter of DLC grains with increasing applied power. Moreover, the alternating increase in hardness and modulus of elasticity, along with a decrease in friction coefficient and wear depth, are among the other effects of increasing the applied power. Therefore, the results of this research suggest an enhancement in the tribological properties of the applied coating at higher powers (up to 250 W). [ABSTRACT FROM AUTHOR]

Copper-filled vertically aligned carbon nanotubes (Cu@VACNTs) were grown directly on Cu foil substrates of 0.1 mm thicknesses at different temperatures via plasma-enhanced chemical vapor deposition (PECVD). By circumventing the need for additional catalyst layers or intensive substrate treatments, our in-situ technique offers a simplified and potentially scalable route for fabricating Cu@VACNTs with enhanced electrical and thermal properties on thin Cu foils. Comprehensive analysis using field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) mappings, and X-ray diffraction (XRD) revealed uniform Cu filling within the VACNTs across a range of synthesis temperatures (650 °C, 700 °C, and 760 °C). Field emission (FE) measurements of the sample synthesized at 700 °C (S700) showed low turn-on and threshold fields of 2.33 V/ μ m and 3.29 V/ μ m, respectively. The findings demonstrate the viability of thin Cu substrates in creating dense and highly conductive Cu-filled VACNT arrays for advanced electronic and nanoelectronics applications. [ABSTRACT FROM AUTHOR]

To achieve a highly reliable IGZO transistor, silicon nitride thin film, as a passivation layer, has been extensively investigated in recent years, mainly due to readily available fabrication, along with good barrier performance. Here, we found out that larger amount hydrogen residuals was observed in the PECVD deposited SiNx passivation layer, more stable the IGZO oxide device exhibited, which is abnormal behavior to that commonly known in the literatures. Given that FT‐IR and SIMS analysis with various controlled SiNx thin film upon different deposition conditions, the plasma parameters such as power, pressure, source gas ratio could affect hydrogen ion diffusivity into the IGZO layer during the deposition and the chemical composition of hydrogen residuals in the resulting SiNx layer, which is more dominant, rather than absolute hydrogen contents itself, to the initial electrical properties as well the stability of the IGZO transistor device. [ABSTRACT FROM AUTHOR]

We present a method to model the gas permeation through silicon-oxide thin film coatings that are afflicted with nanoscale defects. With it, we are able to give an estimation of the diffusion coefficient in bulk by subtracting the influence of the defects. The model is based on data obtained from positron annihilation spectroscopy, which is processed to yield possible defect allocation patterns of the coatings. For a systematic evaluation of these patterns, a path through the coating is calculated and then subjected to in-depth analysis to evaluate the used approach as well as to interpret the results for insights on the permeation mechanisms. The model appears to function as intended and no unexpected behaviour is observed. The defect volume share is overestimated, which can be retraced to the underlying algorithm, and a correction method is applied to the resulting bulk diffusion coefficient. The model gives reasonable results both for oxygen and water vapor permeation. These results can be used in following works that build on the presented model. [ABSTRACT FROM AUTHOR]

Abstract Large‐area graphene is typically synthesized on rolled‐annealed copper foils, which require transferring to other substrates for applications. This study examines large‐area graphene growth on electrodeposited (ED) copper foils—used in lithium‐ion batteries and printed circuit boards—via plasma‐enhanced chemical vapor deposition (PECVD). It reveals that, for a set plasma power, a minimum growth time ensures full graphene coverage, leading to monolayer and then multilayer graphene, showing PECVD growth on ED copper is not self‐limited. The process also beneficially modifies the ED copper substrate, like removing the surface zinc layer and changing copper grain size and orientation, thus improving graphene growth. Additionally, the study includes high‐frequency scattering parameter (S‐parameter) measurements in a coplanar waveguide (CPW) system. This involves graphene on a sapphire substrate with a silver electrode. The S‐parameter data indicate that the CPW with graphene shows reduced insertion losses in high‐frequency circuits compared to those without graphene. This underscores graphene's role in reducing insertion losses between metallic and dielectric layers in high‐frequency settings, offering valuable insights for industrial and technological applications.

Abstract A Hollow Cathode Plasma Enhanced Chemical Vapor Deposition (HC-PECVD) reactor was used to deposit silver doped Diamond-Like Carbon (Ag-DLC) films on Ti6Al4V alloy employing two methodologies: i) producing a silicon interlayer, using tetramethylsilane (TMS) as silicon precursor, varying the argon flow of the hollow cathode; and ii) carbonitriding the substrate. Profilometry, Raman, and Secondary Ion Mass Spectrometry (SIMS), as well as nanohardness, micro-scratch, scratch, and VDI 3198 indentation tests were used to evaluate the characteristics of the films and their adhesion on the substrates. The results demonstrated that the argon flow can be used for tuning the Ag-DLC film’s hardness, toughness, and adherence on silicon interlayers. The carbonitriding process, in turn, provided an improvement in the film toughness compared with non-carbonitrided samples. Considering the lower cost and easier handling of N2 compared to the silicon precursors commonly available (TMS, HDMSO, SiH4, etc.), the carbonitriding process proved more appropriate to improve the adhesion of the Ag-DLC films on the Ti6Al4V alloy.

Nanocrystalline silicon oxide (nc-SiOx:H) is a multipurpose material with varied applications in solar cells as a transparent front contact, intermediate reflector, back reflector layer, and even tunnel layer for passivating contacts, owing to the easy tailoring of its optical properties. In this work, we systematically investigate the influence of the gas mixture (SiH4, CO2, PH3, and H2), RF power, and process pressure on the optical, structural, and passivation properties of thin n-type nc-SiOx:H films prepared in an industrial, high-throughput, plasma-enhanced chemical vapor deposition (PECVD) reactor. We provide a detailed description of the n-type nc-SiOx:H material development using various structural and optical characterization techniques (scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Raman spectroscopy, and spectroscopic ellipsometry) with a focus on the relationship between the material properties and the passivation they provide to n-type c-Si wafers characterized by their effective carrier lifetime (τeff). Furthermore, we also outline the parameters to be kept in mind while developing different n-type nc-SiOx:H layers for different solar cell applications. We report a tunable optical gap (1.8–2.3 eV) for our n-type nc-SiOx:H films as well as excellent passivation properties with a τeff of up to 4.1 ms (implied open-circuit voltage (iVoc)~715 mV) before annealing. Oxygen content plays an important role in determining the crystallinity and hence passivation quality of the deposited nanocrystalline silicon oxide films.

Using plasma-enhanced chemical vapor deposition (PECVD), a mixed gas of silane (SiH4) and methane (CH4) was diluted with hydrogen (H2) to produce thin films of silicon nanocrystals embedded in a silicon carbide (SiC) matrix. This method prevents the co-deposition of SiH and SiC from high-temperature annealing procedures. This study experimentally explores the improvement of the electronic structure by adjusting two processing parameters according to classical nucleation theory (ratio of SiH4 to CH4 and working gas pressure). The deposited films were examined using ellipsometry spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and photoluminescence to determine grain size, crystal volume fraction, topography, and bond configurations. The results show that increasing the working gas pressure can increase the density of SiC, while increasing the ratio of SiH4 to CH4 can only produce larger grain sizes. This is consistent with how SiC works and grows. Without using a high-temperature annealing procedure, this technique can improve the electrical structure of SiC contained in the SiC matrix formed by PECVD.

Hexamethyldisiloxane (HMDSO) is an organosilicon compound with a modifiable bandgap, depending on the deposition conditions. This material has many unique properties due to its stability, low toxicity, and strong adhesion, making it useful as a protective barrier against corrosion, moisture, and oxidation. In this work, HMDSO films were deposited on glass substrates by the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique at different deposition times. The optical properties of HMDSO films, such as dielectric permittivity, refractive index, extinction and absorption coefficients, and band gap energy, are inferred from transmission and reflection spectra. As the deposition time increased, the real part of the dielectric constant, the refractive index, and the bandgap energy showed a decrease, dropping from 4.24 to 3.40, from 2.06 to 1.84, and from 2.85 eV to 2.03 eV, respectively. The latter result is determined using classical models such as the O’Leary-Johnson-Lim (‘OJL’) interband transition and the harmonic oscillator model. HMDSO and Silver are used in this study for the fabrication of optical filters using two types of structures, a multiple cavity metal–dielectric (MCMD) and the Fabry–Perot structure. The silver layers are deposited by a sputtering process. The MCMD optical filter shows a higher transmittance of about 30%, but a wide range of wavelengths is transmitted. In contrast, the Fabry–Perot filter showed high contrast but a lower transmittance of about 20%.

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.

Amorphous silicon carbide (a-SiC) is a wide-bandgap semiconductor with high robustness and biocompatibility, making it a promising material for applications in biomedical device passivation. a-SiC thin film deposition has been a subject of research for several decades with a variety of approaches investigated to achieve optimal properties for multiple applications, with an emphasis on properties relevant to biomedical devices in the past decade. This review summarizes the results of many optimization studies, identifying strategies that have been used to achieve desirable film properties and discussing the proposed physical interpretations. In addition, divergent results from studies are contrasted, with attempts to reconcile the results, while areas of uncertainty are highlighted. [ABSTRACT FROM AUTHOR]

In order to stop reaction between silicon carbide particle and transition metals in high temperature, this research introduces a new core shell material consisting of 180 ptm SiC particle and uniform alumina insulation layer, which is made by fluidized bed plasma enhanced chemical vapor deposition (FB PECVD) method. The morphology, composition and phase structure of the coating were characterized by scanning electron microscope and X ray diffractometer. The mixed sintering method was conducted to simulate the state of SiC particles mixed with transition metals at high temperatures* The alumina layer is 4 ptm thick and made of amorphous alumina with little carbonaceous impurities. After 12 hours calcination at 700 °C/I 060 °C in air, the amorphous alumina layer transform to y A120$/q Al2 O3 layer. After high temperature vacuum calcination, this insulation layer effectively prevents SiC particle from reaction with Ni alloy metal material, resulting in better performance of SiC in high temperature. [ABSTRACT FROM AUTHOR]

This study details the creation of composite films consisting of amorphous hydrogenated diamond-like carbon (DLC) and copper on stainless steel, exploring their impact on heat transfer properties. Analysis of growth morphologies indicates the development of diamond crystals in a nanocrystalline ballas-like form on stainless steel substrates, suggesting radial growth of the crystals. Raman spectroscopy of the films reveals the presence of the T2g vibration mode of diamond crystals alongside D and G bands. The downward shift of the T2g peak to 1157 cm−1 suggests the formation of nanocrystalline diamond. Additionally, Cu–O vibration peaks are detected, attributed to atmospheric copper oxidation at the surface. Raman mapping, based on intensities corresponding to Cu–O at 450 cm−1 and the E2g phonon mode of sp2 bonded carbon at 1580 cm−1, indicates a uniform distribution of copper and DLC films. The application of a diamond-like carbon/Cu composite film significantly enhances the heat flux on the surface of stainless steel. While the uncoated surface exhibits a heat flux of 100 W/m2, the presence of DLC/Cu composite coating elevates it to 450 W/m2. [ABSTRACT FROM AUTHOR]

This feature article presents insights concerning the correlation of plasma‐enhanced chemical vapor deposition and plasma‐enhanced atomic layer deposition thin film structures with their barrier or membrane properties. While in principle similar precursor gases and processes can be applied, the adjustment of deposition parameters for different polymer substrates can lead to either an effective diffusion barrier or selective permeabilities. In both cases, the understanding of the film growth and the analysis of the pore size distribution and the pore surface chemistry is of utmost importance for the understanding of the related transport properties of small molecules. In this regard, the article presents both concepts of thin film engineering and analytical as well as theoretical approaches leading to a comprehensive description of the state of the art in this field. Perspectives of future relevant research in this area, exploiting the presented correlation of film structure and molecular transport properties, are presented. [ABSTRACT FROM AUTHOR]

Nanocrystalline silicon oxide (nc-SiOx:H) is a multipurpose material with varied applications in solar cells as a transparent front contact, intermediate reflector, back reflector layer, and even tunnel layer for passivating contacts, owing to the easy tailoring of its optical properties. In this work, we systematically investigate the influence of the gas mixture (SiH4, CO2, PH3, and H2), RF power, and process pressure on the optical, structural, and passivation properties of thin n-type nc-SiOx:H films prepared in an industrial, high-throughput, plasma-enhanced chemical vapor deposition (PECVD) reactor. We provide a detailed description of the n-type nc-SiOx:H material development using various structural and optical characterization techniques (scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Raman spectroscopy, and spectroscopic ellipsometry) with a focus on the relationship between the material properties and the passivation they provide to n-type c-Si wafers characterized by their effective carrier lifetime (τeff). Furthermore, we also outline the parameters to be kept in mind while developing different n-type nc-SiOx:H layers for different solar cell applications. We report a tunable optical gap (1.8–2.3 eV) for our n-type nc-SiOx:H films as well as excellent passivation properties with a τeff of up to 4.1 ms (implied open-circuit voltage (iVoc)~715 mV) before annealing. Oxygen content plays an important role in determining the crystallinity and hence passivation quality of the deposited nanocrystalline silicon oxide films. [ABSTRACT FROM AUTHOR]

In recent years, there has been growing interest in pH-responsive polymers. Polymers with ionizable tertiary amine groups, which have the potential to be used in many critical application areas due to their pKa values, have an important place in pH-responsive polymers. In this study, poly(2-Diisopropyl aminoethyl methacrylate) (PDPAEMA) thin films were coated on various substrates such as glass, fabric, and silicon wafer using a one-step environmentally friendly plasma enhanced chemical vapor deposition (PECVD) method. The effects of typical PECVD plasma processing parameters such as substrate temperature, plasma power, and reactor pressure on the deposition rate were studied. The highest deposition rate was obtained at a substrate temperature of 40 °C, a reactor pressure of 300 mtorr, and a plasma power of 60 W. The apparent activation energy was found to be 17.56 kJ/mol. Based on the results of this study, uniform film thickness and surface roughness were observed in a large area. The PDPAEMA thin film was exposed to successive acid/base cycles. The results showed that the pH sensitivity of the thin film produced by the PECVD method is permanent and reversible. [ABSTRACT FROM AUTHOR]

This work used plasma-enhanced chemical vapor deposition (PECVD) at low temperatures to deposit a silicon nitride layer on multicrystalline silicon (mc-Si), both with and without porous silicon, in an attempt to enhance the multicrystalline silicon's properties for solar cell applications. Silicon nitride has been successfully tested as a passivation and antireflection film in mc-Si. Consequently, reflectance is reduced from 40 to 7% in the 300–1200 nm wavelength range due to the change in the silicon's morphology, while the effective carrier lifetime value for the Si substrate rose from 8 µs to 71 µs following SiNx treatment, thus benefitting a solar cell. A laser beam-induced current (LBIC) also revealed an improvement in the diffusion length of minority carriers, with it rising from 150 µm to 432 µm following SiNx treatment. Excellent results were also observed after combining porous silicon with a SiNx thin film, it increased the effective carrier lifetime to 104 µs, the diffusion length to 676 µm, the reflectance reduced to 3%, and the surface recombination velocity reduced to 1.6 cm/s. The obtained results therefore suggest that PECVD-based silicon-nitride-covered porous silicon shows promise in terms of cost-effectiveness and efficiency, thus helping to advance solar cell technology. [ABSTRACT FROM AUTHOR]