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Emission of the silicon oxide films grown on Si by wet thermal oxidation at 900 °С and by plasma-enhanced chemical vapor deposition from the SiH4 + N2O mixture at 350 °С has been compared using electroluminescence. The electroluminescence spectra were recorded in electrolyte – insulator – semiconductor system. The intense band in the red range with a maximum at 1.9 eV dominates the electroluminescence spectrum of the thermal oxide film. It was concluded that this band is related with the existence of silanol groups (Si — OH) in the oxide matrix. Multiband emission in the UV range is observed in the electroluminescence spectrum of the oxide film formed by plasma-enhanced chemical vapor deposition. Additional investigations using IR and RS spectroscopy revealed that observed spectrum modulation is of an oscillatory nature and is not the result of interference. Presumably, the luminescence in the UV region is due to the presence of oxygen deficiency centers containing bonds with hydrogen atoms.

Selective, nanometer-thin organosilica layers created by plasma-enhanced chemical vapor deposition (PECVD) exhibit selective gas permeation behavior. Despite their promising pure gas performance, published data with regard to mixed gas behavior are still severely lacking. This study endeavors to close this gap by investigating the pure and mixed gas behavior depending on temperatures from 0 °C to 60 °C for four gases (helium, methane, carbon dioxide, and nitrogen) and water vapor. For the two permanent gases, helium and methane, the studied organosilica membrane shows a substantial increase in selectivity from αHe/CH4 = 9 at 0 °C to αHe/CH4 = 40 at 60 °C for pure as well as mixed gases with helium permeance of up to 300 GPU. In contrast, a condensable gas such as CO2 leads to a decrease in selectivity and an increase in permeance compared to its pure gas performance. When water vapor is present in the feed gas, the organosilica membrane shows even stronger deviations from pure gas behavior with a permeance loss of about 60 % accompanied by an increase in ideal selectivity αHe/CO2 from 8 to 13. All in all, the studied organosilica membrane shows very promising results for mixed gases. Especially for elevated temperatures, there is a high potential for separation by size exclusion.

In semiconductor industry, low-dielectric-constant SiCOH films are widely used as inter-metal dielectric (IMD) material to reduce a resistance-capacitance delay, which could degrade performances of semiconductor chips. Plasma enhanced chemical vapor deposition (PECVD) system has been employed to fabricate the low-dielectric-constant SiCOH films. In this work, among various parameters (plasma power, deposition pressure, substrate temperature, precursor injection flow rate, etc.), helium carrier gas flow rate was used to modulate the properties of the low-dielectric-constant SiCOH films. Octamethylcyclotetrasiloxane (OMCTS) precursor and helium were injected into the process chamber of PECVD. And then SiCOH films were deposited varying helium carrier gas flow rate. As helium carrier gas flow rate increased from 1500 to 5000 sccm, refractive indices were increased from 1.389 to 1.428 with enhancement of mechanical strength, i.e., increased hardness and elastic modulus from 1.7 and 9.1 GPa to 3.3 and 19.8 GPa, respectively. However, the relative dielectric constant (k) value was slightly increased from 2.72 to 2.97. Through analysis of Fourier transform infrared (FTIR) spectroscopy, the effects of the helium carrier gas flow rate on chemical structure, were investigated. It was thought that the increase in helium carrier gas flow rate could affect the density with changes of chemical structure and composition. In conclusion, regulation of helium carrier gas flow rate can effectively modulate k values and mechanical strength, which is needed for IMD material in semiconductor fabrication possess.

SiCOH thin films were deposited on rigid silicon (Si) wafers and flexible ITO/PEN substrates via plasma-enhanced chemical vapor deposition at room temperature using a tetrakis(trimethylsilyloxy)silane (TTMSS) precursor. Different chemical compositions of hydrocarbon and Si–O bondings were obtained depending on substrate types and deposition conditions. The main chemical compositions of the as-deposited films were observed as C–Hx (x = 2, 3) stretching, Si–CH3 bending, Si–O–Si stretching, and H–Si–O bending/Si–CH3 stretching modes. With regard to the as-deposited films, the dielectric constant increased from 1.83 to 3.45 when the plasma power increased from 20 to 80 W and the lowest leakage current of 1.76×10-4 A/cm2 was obtained at the plasma power of 80 W. After bending tests with 1000, 5000, and 10000 bending cycles, the dielectric constants of the SiCOH films increased and leakage currents decreased. The structures of the SiCOH films after the bending tests were highly complicated with a variety of chemical bonding combinations. Higher peak intensity and peak area of main chemical bonding were obtained with the increased bending cycles, resulting in the increase in dielectric constants. It should be noted that the film with small changes in peak area fractions of the bending and stretching modes showed good electrical and mechanical stabilities after bending tests.

For dielectric elastomers, the high loading of high k ceramic fillers can increase the dielectric constant of elastomers, but their Young’s modulus can also be greatly increased and the high loading of filler increases the complex viscosity of composites during manufacturing process. In this study, graphene platelets (GE) fabricated by plasma-enhanced chemical vapor deposition (PECVD) is used to improve the dielectric constant of ethylene propylene diene monomer (EPDM)-based elastomer. The dependence of the cure, electrical, rheological, dielectric and mechanical properties of EPDM-based elastomers on amount of GE is analyzed. It is found that the addition of 0.5% graphene platelets can increase the dielectric constant of EPDM control from 2.0 to 6.6 (230% increase) at 103 Hz, with little change of electric resistivity. Moreover, the addition of 0.5% graphene platelets decreases the complex viscosity of EPDM control from 48,000 to 16,500 Pa S (1.9 times decrease) at 1.7 Hz. Compared to EPDM control, the 0.5% graphene increase the relative ratio of dielectric constant to Young’s modulus by 180%.

Amorphous carbon films (ACFs) have recently emerged as one of the best candidates for etching-resistant hardmask materials in advanced semiconductor manufacturing processes. Etching resistivity of ACFs is known to be improved by controlling the relative abundance between sp2 and sp3 bonds. We have investigated the relative abundance between sp2 and sp3 bonds in several ACFs, fabricated by plasma-enhanced chemical vapor deposition at different temperatures, which were analyzed by using X-ray photoemission spectroscopy, Raman spectroscopy, and transmission electron microscopy. We found that the relative abundance of sp2 bond increased as the growth temperature was raised. Furthermore, the ACFs eventually evolved into nano-crystalline graphite with increasing growth temperature.

Low-dielectric-constant SiCOH films were deposited by plasma-enhanced chemical vapor deposition using 1,1,1,3,5,7,7,7-octamethyl-3,5-bis(trimethylsiloxy)tetrasiloxane (OMBTSTS) as a single precursor, and the characteristics were investigated. The relative dielectric constant (k) of the SiCOH films declined gradually from 3.57 to 1.90 with decreasing plasma power. The film with the lowest k, deposited at the lowest power of 10 W, showed the lowest leakage current density, with adequate mechanical strength (hardness: 0.98 GPa and elastic modulus: 8.56 GPa) for application in multilevel semiconductor interconnects. The chemistry of the OMBTSTS films was characterized by Fourier transform infrared spectroscopy to study the relation between the chemical and dielectric properties. The dielectric properties, such as the k value and leakage current density, could be explained by a quantitative relation between the Si-O stretching bond and hydrocarbon-related bonds, such as CH₃ and Si-CH₃ bonds, with lower polarizability in the SiCOH film. The refractive index, which is directly linked to the density of the film, was also investigated by ellipsometry. We consider OMBTSTS a promising candidate as a single precursor for fabricating low-k SiCOH films in the plasma-enhanced chemical vapor deposition system.

The n-type hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) layers were prepared by 13.56 MHz radio frequency (RF) plasma-enhanced chemical vapor deposition (PECVD). The effects of CO2 and PH3 gas flow variation on the layer performance were investigated in advance. The increase of CO2 flow rate could enhance the oxygen content (CO) in nc-SiOx:H, leading to a decrease of crystallinity (XC), which would induce a nanocrystalline to amorphous phase transition. When a small amount of PH3 was added, XC increased surprisingly. The analysis demonstrated that the incorporation of phosphorous suppressed CO in the layer although it could also induce the nanocrystalline to amorphous phase transition. It was the CO reduction that made the layer crystallize more easily. As a result, the maximum XC could be obtained with a moderate PH3 flow rate. Nevertheless, the PH3 flow rate could still be increased further in order to get the highest dark conductivity (σd). Over this point, excessive PH3 would make σd decrease gradually, which could be attributed to that the increase of the amorphous phase reduced the effective doping efficiency of phosphorus. Both the CO reduction and the phase transition from nanocrystalline to amorphous could result in the decrease of the optical bandgap (E04). The synergistic effect of CO2 and PH3 indicated that it was important to adjust CO2 and PH3 flow rates together for preparing the nc-SiOx:H layer with both high transparency and high conductivity.

Carbon coatings hold great promise for next-generation non-conductive energy storage nanomaterials. However, simplicity, stable, uniformity and high-performance remain unresolved issues. Here, unique synergy of the fluidized bed reactor with plasmas enables highly-effective, single-step fluidized-bed plasma-enhanced chemical vapor deposition (FB-PECVD) of uniform, low-temperature carbon coatings on TiO2 nano-powder (TiO2@C). Plasma-specific effects induce the formation of new phases that are beneficial for energy storage. The 6 nm carbon layer is grown within only 10 min, while the TiO2 maintains its anatase phase. The unique plasma conditions make it possible to form Ti–C bonds at the Ti/C interface at much lower temperatures than achievable otherwise. The electronic transport at the interface and structural stability are thus greatly improved. Consequently, TiO2@C shows excellent electrochemical performances as a negative electrode of sodium ion battery, such as specific discharge capacity of 290.2 mA h g−1 at 50 mA g−1 and very stable long-term cyclability (101.2% capacity retention over 300 cycles at 4000 mA g−1). Our results show that FB-PECVD is not only a versatile method for bond-reinforced interface nanoparticle coating with carbon, but also provide a new strategy for designing hybrid-phase electrochemically active nanocomposite materials.

In this work, the growth process of self-sustained vertically aligned carbon nanotubes (VA-CNTs) is investigated in full: from bare Si wafers to fully grown VA-CNTs on 4″ wafers. Each developmental step, from supporting and catalyst layers’ depositions to CNT growth, is analyzed through X-ray diffraction, X-ray reflectivity, and scanning electron microscopy, respectively. The crystalline structure of the titanium nitride supporting layer is investigated through grazing incidence X-ray diffraction, while X-ray reflectivity provides information regarding the density, thickness, and roughness of the titanium nitride layer via extended Fourier analysis. Further, the nickel layers’ and CNTs’ morphologies are investigated by scanning electron microscopy.

The Plasma Enhanced Chemical Vapor Deposition synthesis of graphene-like vertical structures from the plasma state of CO2 gas on various catalyst-free substrates is experimentally studied. A peculiarity of the synthesis conditions is the ability to control a plasma density in the synthesis region to very low values. The physical processes taking place on substrates, as well as models for the nucleation of primary aromatic rings and further growth of the formed graphene structures are considered.

SiGe thin films, such as hydrogenated amorphous silicon germanium (a-SiGe:H) and hydrogenated microcrystalline silicon germanium (μc-SiGe:H), are formed by plasma enhanced chemical vapor deposition (PECVD) methods from SiH4, GeH4, and H2. Thin film properties such as surface morphology, hydrogen content, and crystal structure are greatly affected by process parameters such as a substrate temperature, gas pressure, and gas composition. For example, SiH3 and GeH3 are dominant species when the SiGe thin film with low defect is deposited under low power density conditions. However, the structural defects are formed by SiH and SiH2 that are highly reactive species under high power density conditions. Although the density and flux of these highly reactive species are much lower than those of the dominant species, the electrical properties of the device are greatly affected by a few structural defects. Therefore, to understand the influence of the composition of each precursor on the thin film properties is important. The purpose of the present study is to clarify the influence of the composition of multiple precursors such as SiH3, GeH3, and H under different substrate temperatures on the surface morphology, hydrogen content, and crystal structure. We performed reactive force-field molecular dynamics (ReaxFF MD) simulations. An existing parameter set was modified to match the dissociation energies in gaseous species because bond formation and breaking are particularly important in this study. The substrate was Si (100)– (2×1), and the size of the simulation box was 30.72 Å× 26.88 Å× 45.00 Å. A periodic boundary condition was applied in the x and y directions, and a fixed boundary condition was applied in the z direction. The first bottom layer of the substrate was fixed to prevent vibrations of the substrate up and down. The second and third layers were controlled constantly at desired temperature by the Berendsen thermostat. The temperature was not controlled on the fourth and subsequent layers to prevent direct influences of changing the velocity of atom due to the temperature control on the surface reaction. The substrate temperature was set at 800 K, 1000 K, 1300 K, and 1600 K. 2000 SiH3 molecules with the velocity corresponding to 1300 K in the direction towards the substrate were deposited one by one onto the substrate surface every 7.5 ps. The initial position of the gaseous species was set at 10 Å above the top of substrate Si atoms, and the in-plane (x-y) position were set randomly. The Velocity-Verlet algorithm was used for time integrations corresponding to 0.25 fs time step. A pre-thermal annealing for 7.5 ps and a post-thermal annealing for 60 ps were performed before and after the deposition to fully equilibrate the substrate and deposited thin films. Figure shows front views of the final configurations and results of analysis when the substrate temperature is 800 K, 1000 K, 1300 K, and 1600 K. The yellow, blue, and red represent substrate Si atoms, added Si atoms, and added H atoms, respectively. Gray shown in the figure are gas-solid surfaces. The surface construction algorithm was used to calculate a surface area that is closely related to the surface morphology. The hydrogen content was calculated using the select type algorithm. The structure identification algorithm for the crystal structure was used to characterize the structure of simulated films. These analyses were carried out by the Open visualization tool (OVITO). The surface area decreases as the substrate temperature increases, indicating that the formation of smoother surface at high temperature. The diffusivity of a SiH3 molecule that reached to the surface increases as the substrate temperature increases, and the atomic scale valleys are filled. This tendency is in good agreement with relevant studies. The hydrogen content was calculated by dividing the number of added H atoms by the total number of atoms existing in the system. The hydrogen content decreases as the substrate temperature increases because a hydrogen desorption is promoted as the substrate temperature increases. Figure 1

To enhance the corrosion and wear resistance of biological titanium alloy Ti6Al4V in the human body, plasma nitriding + plasma enhanced chemical vapor deposition (PN + PECVD), laser remelting (LR) process were employed to modify the titanium alloy, respectively. The microhardness of LR and PN + PECVD samples was reported to increase by 117% and 165%, respectively, in contrast to that before the samples were modified. The thickness of LR modified layer was reported as 10 μm, and the nitrided film on the surface of PN + PECVD sample exhibited the thickness of 2 μm. The wear and corrosion performances of three samples were analyzed by friction and corrosion experiments in the simulated body fluid. As revealed from the experimental results, the wear rates of LR and PN + PECVD samples were 74.1% and 94.5% lower than that of Ti6Al4V. It can be seen that the surface modification layer can play a good role in protecting Ti6Al4V substrate from wear. By the electrochemical corrosion experiment, the corrosion resistance of Ti6Al4V, LR and PN + PECVD samples was ranked as PN + PECVD > LR > Ti6Al4V. It is therefore speculated that the PN + PECVD and LR modification processes could noticeably enhance the corrosion and wear resistance of Ti6Al4V in the human body.

Carbon nanowalls (CNWs) are vertically standing, interconnecting flake- or wall-like collections of graphene sheets. In the present work, this material was synthesized by applying precisely controlled high-voltage nanosecond pulses to a substrate using an inductor energy storage circuit in a radical-injection plasma-enhanced chemical vapor deposition system, employing a CH4/H2 plasma. The resulting interconnected networks had a low density of CNWs with large average wall-to-wall distances. During the application of short-period pulses, the entire substrate surface was uniformly activated, thus enhancing the adsorption of carbon precursors and preventing CNW nucleation. As a result, an amorphous carbon film covered the surface of the substrate and a low CNW density was obtained with average wall-to-wall distances greater than 700 nm. On the basis of these results, the growth mechanism of CNWs was modeled.

We study the characteristics of graphene grown through low power capacitive coupled radio frequency plasma enhanced chemical vapor deposition (PECVD) and explore its application. Fully-covered, mostly single-layered, and highly defective graphene films were grown on Cu substrates through plasma composed of various argon/methane/hydrogen gas ratio with low RF power within a minute under a moderate substrate temperature at 850 °C . The structural, chemical, and electrical properties of the graphene films were measured through Raman spectroscopy, X-ray photoelectron spectroscopy, and Hall measurement, respectively. The Raman signatures were strongly affected by the argon/hydrogen flow rates and the subsequent thermal annealing, and is strongly correlated to carrier mobility of the film. Through analysis of the defect related Raman bands within the theoretical framework of activated defect model, it is concluded that the defects found in the graphene films are originated from ion bombardment during the growth processes. The vacancy defects on the graphene film provides adsorption sites for gaseous molecules and induces changes of charge transfer in the graphene film. The response of the graphene-based sensor fabricated with the PECVD grown graphene is 6% under 100 ppb of N O 2 , which can be a candidate of potential N O 2 gas sensing material in the future.

This paper investigated the potential use of argon (Ar) as an alternative carrier gas to helium (He) during the tetraethyl orthosilicate–silicon dioxide (TEOS–SiO2) process using a plasma-enhanced chemical vapor deposition (PECVD) system. Due to the shortage or depletion of conventional He gas, it is important to find alternative gases. This study investigated the effects of the Ar carrier gas on the vaporization efficiency and properties of SiO2 film in the PECVD TEOS–SiO2 process for different process conditions, such as flow rate and plasma power. Ar showed a much higher vaporization efficiency and faster deposition rate than He due to its higher molecular weight and plasma density, indicating that SiO2 film can be deposited considerably faster with less Ar gas. While changes in the film density and residual film stress were also noted depending on the types of carrier gas and amounts or types of plasma power, these changes were insignificant and within the controllable process range during the PECVD process. Therefore, the use of Ar gas can reduce costs and contribute to improvements in productivity without affecting the quality of SiO2 film.

The growth of TiO₂ and ZnO thin films is studied by means of coarse-grained kinetic Monte Carlo simulations under conditions typically encountered in plasma-enhanced chemical vapor deposition experiments. The basis of our approach is known to work well to simulate the growth of amorphous materials using cubic grids and is extended here to reproduce not only the morphological characteristics and scaling properties of amorphous TiO₂ but also the growth of polycrystalline ZnO with a good approximation, including the evolution of the film texture during growth and its dependence on experimental conditions. The results of the simulations have been compared with available experimental data obtained by X-ray diffraction, analysis of the texture coefficients, atomic force microscopy, and scanning electron microscopy.

Vertically oriented graphene (VG) has attracted attention for years, but the growth mechanism is still not fully revealed. The electric field may play a role, but the direct evidence and exactly what role it plays remains unclear. Here, we conduct a systematic study and find that in plasma-enhanced chemical vapor deposition, the VG growth preferably occurs at spots where the local field is stronger, for example, at GaN nanowire tips. On almost round-shaped nanoparticles, instead of being perpendicular to the substrate, the VG grows along the field direction, that is, perpendicular to the particles' local surfaces. Even more convincingly, the sheath field is screened to different degrees, and a direct correlation between the field strength and the VG growth is observed. Numerical calculation suggests that during the growth, the field helps accumulate charges on graphene, which eventually changes the cohesive graphene layers into separate three-dimensional VG flakes. Furthermore, the field helps attract charged precursors to places sticking out from the substrate and makes them even sharper and turn into VG. Finally, we demonstrate that the VG-covered nanoparticles are benign to human blood leukocytes and could be considered for drug delivery. Our research may serve as a starting point for further vertical two-dimensional material growth mechanism studies.

We have investigated the structure and electrical conductivity of carbon nanographite layers grown by chemical vapor deposition, enhanced by microwave plasma (PECVD) on an setup by IPLAS Innovative Plasma Systems GmbH (Germany). The samples were grown on fused silica substrates with deposition times of 20 and 40 min, respectively. The study of the formed layers of nanographite by the method of Raman light scattering and scanning electron microscopy showed that the surface of the nanographite sample deposited for 20 min is covered with a large number of unconnected vertical graphene nuclei with an average size of less than 10 nm. An increase in the growth time to 40 min led to an increase in the size of the nuclei to 20 –30 nm; however, their overlap does not occur. This confirmed that the samples corresponded to the initial stages of the formation of vertical graphene in the grown nanographite layers and there is no percolative structure in them. The obtained samples were used to study the temperature dependences of the sheet electrical resistance at direct current in the range of 4 –300 K and the effect on them of the number of cycles N cooling – heating (300 K – 2 K – 300 K) in an atmosphere of gaseous helium, as well as the change in the atmosphere storage of samples (by placing them in the air after warming up to room temperature). It was found that the electrical resistance of the sample deposited for 20 min is very sensitive to two technological parameters of measurement – the number of cycles N and the change in the storage atmosphere after heating. This manifested itself in the fact that after four cooling – heating cycles and one change of the atmosphere (helium – air – helium) after warming up, the resistance increased by more than 20 %, reaching saturation. The resistance of the sample, deposited for 40 min, showed less sensitivity during thermal cycling, increasing by no more than 10 %. The effect of thermal cycling we attribute to the rearrangement of defects formed at the boundaries of grains in the nanographite layer, and in the case of a change in the atmosphere, with the passivation of dangling bonds with atmospheric gases.

Amorphous InGaZnO (a-IGZO) Thin Film Transistors (TFTs) has been studied extensively for their perspective applications in next generation active-matrix displays such as liquid crystal displays and flat-panel displays, due to its better field-effect mobility (>10 cm2/V · S), larger Ion/Ioff ratio (>106), and better stability electrical. Hydrogen is known as shallow donors for n-type (channel) oxide semiconductors (Dong, J.J., et al. 2010. Effects of hydrogen plasma treatment on the electrical and optical properties of Zno films: Identification of hydrogen donors in ZnO. ACS Appl. Mater. Interfaces, 2, pp.1780–1784), and it is also effective passivator for traps (Tsao, S.W., et al., 2010. Hydrogen-induced improvements in electrical characteristics of a-IGZO thin-film transistors. Solid-State Electron, 54, pp.1497–1499). In this study, In-Situ hydrogen plasma is applied to deposit IGZO channel. With atmospheric-pressure PECVD (AP-PECVD), IGZO thin film can be deposited without vacuum system, large area manufacturing, and cost reducing (Chang, K.M., et al., 2011. Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet. Thin Solid Films, 519, pp.5114–5117). The results show that with appropriate flow ratio of Ar/H2 plasma treatment, the a-IGZO TFT device exhibits better performance with mobility (μFE) 19.7 cm2/V · S, threshold voltage (VT) 1.18 V, subthreshold swing (SS) 81 mV/decade, and Ion/Ioff ratio 5.35×107.

Recently resistive random access memory (RRAM) is considered to be the most promising one to become the next generation memory since its simple Metal/Insulator/Metal (MIM) structure, lower power consumption and fabrication cost (Meena, J.S., et al., 2014. Overview of emerging nonvolatile memory technologies. Nanoscale Research Letters, 9(1), p.526). Due to some bottlenecks for current flash memory, such as high operation voltage, low operation speed, poor retention time and endurance, RRAM device is regarded as an alternative solution (Fuh, C.S., et al., 2011. Role of environmental and annealing conditions on the passivation-free In–Ga–Zn–O TFT. Thin Solid Films, 520, pp.1489–1494). In this investigation, the memory layer of RRAM device is IGZO, and it is deposited with AP-PECVD technique which can operate under atmosphere, reduce cost of the process. Microwave annealing (MWA) is used to enhance the RRAM device reliability (Fuh, C.S., et al., 2011. Role of environmental and annealing conditions on the passivation-free In–Ga–Zn–O TFT. Thin Solid Films, 520, pp.1489–1494). Experiment shows that with appropriate MWA treatment, the IGZO RRAM device exhibits better electrical characteristics, reliability issues such as numbers of switching cycle and data retention time are also improved (Teng, L.F., et al., 2012. Effects of microwave annealing on electrical enhancement of amorphous oxide semiconductor thin film transistor. Applied Physics Letters, 101, p.132901).

A self-consistent fluid simulation of inductively coupled plasma-enhanced chemical vapour deposition (ICP-CVD) using silane, argon, and hydrogen mixture is presented. The model solves the continuity equations for charged species, the drift-diffusion equations to describe their transport and the electron energy balance equation, coupled with Maxwell’s and Poisson’s equations, using COMSOL Multiphysics software. In order to obtain a better comprehending of the discharge parameters, a discharge in a Gaseous Electronics Conference cell (GEC) reactor is simulated. In this study, the GEC reactor with five-turn inductive coils is driven at a radio frequency of 13.56 MHz in order to sustain the plasma discharge at low temperature for a mixture of SiH4/Ar/H2, with an intial gas pressure fixed at 20 mTorr. The simulations yield the profile of plasma components such as electron density and temperature as well as the electrical potential in the centre of the discharge during silicon films deposition. The effects of external settings, such as chamber pressure, applied power and hydrogen dilution, on the growth rate of the silicon films deposited by ICP-CVD are then investigated. It is shown that the increase of the applied power from 1000 to 3000 W and the gas pressure from 10 to 40 mTorr results in a moderate increase in the deposition rate of the silicon films, whereas the increase in the dilution of the hydrogen in the mixture produces its decrease.

Thickness control of a semiconductor thin film in the multistack layer (MSL) deposition process is important for improving the reliability and the performance of devices based on 3-dimensional stacked layers. The “first wafer effect” refers to the phenomenon where the thickness and the map profile of the first prepared wafer differ from those of the wafer prepared via the continuous process when deposition is started after the plasma deposition process has not been conducted for a certain time. We adopted stack seasoning to eliminate the first wafer effect for the MSL thickness and substantially reduced the effect; we also propose a mechanism based on stable improvement of the environment inside the chamber. Another interesting result is that, in addition to ensuring the reproducibility of the variations in stack layer thickness among wafers, the individual thicknesses of stack layers in the first wafer are reliably improved.

Low temperature poly-crystalline silicon thin-film transistors (LTPS-TFTs) and indium-gallium-zinc-oxide TFTs (IGZO-TFTs) are potential candidates for future technology of various displays. Due to its simple manufacturing process, low cost and good uniformity, IGZO-TFTs have been developed as main stream display technology. From the viewpoint of device electrical characteristics, a-IGZO TFTs have better field-effect mobility (>10 cm2/V * s), larger Ion/Ioff ratio (>106), smaller subthreshold swing (S.S) and good stability. In this study, atmospheric-pressure PECVD (AP-PECVD) is used to deposit a-IGZO active layer, during the deposition process In-Situ hydrogenation is applied to enhance the layer characteristics. Also, the layer is then surface oxidation treated by neutral beam system (NBS). The optimal TFTs device characteristics is reached with In-Situ hydrogenation of H2 90 sccm, and surface oxidation of 400 W NBS treatment. The field-effect mobility is 34.05 cm2/V * s, threshold voltage is 1.74 V, subthreshold swing is 62 mV/decade, and current ratio Ion/Ioff is 2.04×107. Compared with conventional plasma, NBS used in this study provides charge-free plasma which could enhance device electric characteristics.

In this paper, the environmental stability of silicon nitride (SiNx) films deposited at 80 °C by plasma-enhanced chemical vapor deposition was studied systematically. X-ray photoelectron spectroscopy and Fourier transform infrared reflection were used to analyze the element content and atomic bond structure of the amorphous SiNx films. Variation of mechanical and optical properties were also evaluated. It is found that SiNx deposited at low temperature is easily oxidized, especially at elevated temperature and moisture. The hardness and elastic modulus did not change significantly with the increase of oxidation. The changes of the surface morphology, transmittance, and fracture extensibility are negligible. Finally, it is determined that SiNx films deposited at low-temperature with proper processing parameters are suitable for thin-film encapsulation of flexible devices.

Nitrogen-doped vertical graphene (NVG) nanosheets have attracted enormous attention as promising metal-free electrochemical catalysts for the oxygen reduction reaction (ORR). However, the conventional synthesis of NVG nanosheets by plasma enhanced chemical vapor deposition (PECVD) suffers from high costs caused by high temperature and a complex process. Herein, we introduce a one-step strategy to fabricate NVG nanosheets in a lab-built high-flux plasma enhanced chemical vapor deposition (H-PECVD) system at low temperature. The obtained NVG nanosheets possess a vertically interconnected structure with moderate defects. The beneficial morphology and structure endow the optimal catalyst (NVG-30) with a comparable ORR activity and much superior stability to the commercial Pt/C catalyst. Ultraviolet photoelectron spectroscopy (UPS) measurements suggest a low work function of NVG-30 with an excellent electron-donating capability. Moreover, the NVG-30 catalyst shows a superior discharge performance with high energy density and discharge durability in an assembled Zn–air battery. This work not only proposes a feasible strategy to fabricate NVG nanosheets but also demonstrates effective metal-free catalysts for the ORR and metal–air batteries.

Flexible hybrid electronics and fan-out redistribution layers rely on electroplating Cu on polymers. In this work, direct low-temperature plasma-enhanced chemical vapor deposition (PECVD) of graphene on electroplated Cu over polyimide substrates is demonstrated, and the deposition of graphene is found to passivate and strengthen the electroplated Cu circuit. The effect of the H2/CH4 ratio on the PECVD graphene growth is also investigated, which is shown to affect not only the quality of graphene but also the durability of Cu. 100,000 cycles of folding with a bending radius of 2.5 mm and the corresponding resistance tests are carried out, revealing that Cu circuits covered by graphene grown with a higher H2/CH4 ratio can sustain many more bending cycles. Additionally, graphene coverage is shown to suppress the formation of copper oxides in ambient environment for at least 8 weeks after the PECVD process.

Being the second-generation semiconductor material, GaAs is widely used in high-power devices. In this paper, a new method of multi-temperature points linear fitting for the light intensity values of the surface of GaAs collected at different temperatures, which range from 40 °C to 100 °C and the temperature rise interval is 20 °C, was used in order to obtain the thermoreflectance property. Meanwhile, the thermoreflectance property of the passivated GaAs was analyzed because the surface of GaAs is very easy to be oxidized, which will affect the performance and stability of GaAs devices. Finally, we obtained the thermoreflectance coefficient of GaAs and the passivated GaAs in visible spectrum and near-ultraviolet illumination wavelengths. The result shows that the optical response of GaAs was changed by the presence of the passivation layer significantly because of the interference effects. The study solves the problem of selecting the appropriate illumination wavelength in the study of the thermoreflectance property of GaAs. Therefore, the research is of great significance for accurate temperature measurement of GaAs semiconductor power devices.

Diamond-like carbon (DLC) coatings offer versatile applications in surface engineering due to high hardness and strength, chemical and radiation resistance, biocompatibility and low friction coefficient. When doped with Si, such coatings demonstrate even more beneficial properties, such as lower friction coefficient and higher thermal stability. We demonstrate the instrumental developments of a plasma-enhanced chemical vapor deposition (PECVD) method and the use of an original low-cost set-up aimed to synthesize Si-doped DLC films using polyphenylmethylsiloxane (PFMS) precursors. These films on the surface of glass substrate were characterized by means of XPS, AFM, Raman spectroscopy, and nanoindentation. Dry fiction coefficient was found to be reduced for Si-doped DLC for 4–6 times in comparison with glass substrate.

A new route for the preparation of tantalum nitride (Ta3N5) thin films for photoelectrochemical (PEC) applications was demonstrated, based on plasma-enhanced chemical vapor deposition (PCVD). Ta3N5 was produced on a Ta foil substrate using PCVD with a Ta precursor, followed by NH3 nitridation at high temperatures. Various characterization techniques were used to assess the properties of the resulting films, including X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, cross-sectional scanning transmission electron microscopy with elemental mapping, cross-sectional high resolution transmission electron spectroscopy, and X-ray photoelectron spectroscopy. This PCVD technique formed an amorphous phase that was converted into a multilayer structure having the composition TaOx/Ta3N5/Ta3N5 + Ta2N/Ta during nitridation. Photoelectrochemical (PEC) trials assessing the progress of the oxygen evolution reaction showed a high photocurrent density of 8.1 mA cm−2 at 1.23 V vs. RHE under simulated solar radiation. This represents one of the highest values ever reported for Ta3N5 without further modification or the addition of a surface layer. The incident photon-to-current efficiency of this specimen reached a maximum of 67% at 500 nm and the device was stable for up to 60 min. The superior PEC performance obtained in this work is attributed to the formation of a highly crystalline, compact and uniform Ta3N5 + Ta2N layer.

We present the study on graphene growth on Cu substrate through low power capacitive coupled radio frequency (RF) plasma enhanced chemical vapor deposition. Fully-covered graphene was grown on Cu substrate through a plasma composed of various argon/methane/hydrogen gas ratio with a 50 W RF power source within a minute under a relatively low substrate temperature at 850 ∘C. The nucleation and growth dynamics is further investigated through processing and analysis of the images acquired through scanning electron microscopy, and interpreted with a modified Johnson-Mehl-Avrami-Kolmogorov model. The roles of hydrogen in limiting the nucleation density and stabilization of the graphene grain edges are discussed in light of the analysis, and a time dependent grain expansion rate in which the graphene grains grow fast at the early stage and saturated at later stage is implemented into the model to achieve good fitting of the coverage evolution.

This work was devoted to studying the atomic structure and electron spectrum of a-SiOx : H films created on silicon and glass substrates by means of plasma-enhanced chemical vapor deposition (PECVD). Depending on the conditions of oxygen supply into the reactor, the stoichiometric parameter x of the films was varied from 0.57 to 2. The structure of the films and the specific features of their electron structure were characterized depending on the parameter x with a complex of structural and optical methods and ab initio quantum-chemical simulation for the model SiOx structure. The studied SiOx : H films were established to consist predominantly of silicon suboxides SiOy, SiO2 clusters, and amorphous silicon. Based on the spatial fluctuations of their chemical composition, the model of bandgap width and potential fluctuations was proposed for SiOx electrons and holes. The obtained data would provide the charge transport in a-SiOx : H films with more precise modeling important for the creation of nonvolatile random-access memory (RAM) elements and memristors on their basis.

In this study, an intrinsic hydrogenated amorphous silicon (a-Si:H) thin film was deposited using the plasma-enhanced chemical vapor deposition technique. The samples were annealed at 700 °C and 900 °C for 1 h. Optical measurements indicated the formation of nanocrystallites embedded in an amorphous a-Si:H matrix and the density increased with the annealing temperature. The electrical properties of the Schottky diodes Au/a-Si:H were investigated using admittance spectroscopy over a temperature range of 300–500 K. The conductivity at room temperature in the dark increased by several orders of magnitude after the transition from an amorphous to nanocrystalline structure. The activation energy was deduced based on the variations in the conductivity with temperature. The responses of the amorphous and nanocrystalline phases were identified by complex impedance analysis. The amorphous phase was dominant at low frequencies and high temperatures, whereas the response of the nanocrystalline phase was observed at high frequencies and low temperatures. Semicircular arcs were observed in the impedance plot at different temperatures and an electrical equivalent circuit was proposed. Complex impedance analysis demonstrated that the relaxation phenomenon was a thermally activated process. Moreover, we deduced the temperature at which the available density of the trapped charge states vanished based on the temperature dependence of the average normalized change.

In this study, it was aimed to obtain vertically-oriented graphene nano-sheets (VGNs) on copper foils using CH4 gas as the precursor material by means of plasma enhanced chemical vapor deposition (PECVD) technique. VGNs were obtained at 50 W, 75 W and 100 W Radio Frequency (RF) powers by this technique and the effect of RF power on the morphological structure of graphene layers was investigated. VGNs were also analyzed by Raman spectroscopy, scanning electron microscopy (SEM) and water contact angle (WCA) measurements. The SEM images showed that the VGNs became more tightly packed with the increase of RF power and thus these coating parameters had a significant effect on the morphological structure. WCA analyzes for VGNs were also performed and it was found that VGNs obtained at 100 W RF power had higher contact angle value than the other RF powers. These VGNs, which have both large surface area and optically transparent, are thought to be materials that have the potential to be used in supercapacitors and solar cells.

Large-area silicon-nitride thin films deposited from silane and ammonia by plasma-enhanced chemical vapor deposition are investigated experimentally in a 300 mm apparatus with a vertical showerhead. The responses of deposition rate and refractive index to the process parameters are found and discussed. The effects of showerhead configuration on the full-wafer deposition rate and refractive index are further examined, and the inherent non-uniformity is improved by using a proper convex showerhead. The residual gases are analyzed online, and a good correlation between the partial pressure of hydrogen and the deposition rate is found.

Both intrinsic and doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films were prepared by plasma-enhanced chemical vapor deposition (PECVD) with various process parameters, such as a hydrogen dilution ratio, power, substrate temperature, and doping ratios of phosphorus or boron. The crystallization characteristics of nc-Si:H thin films grown with various process parameters were carefully and systematically investigated by Raman spectroscopy. Generally speaking, the results show that the higher the hydrogen dilution ratio and power or the lower the doping ratio, the higher the average grain size and the crystalline volume fraction of both thin films prepared and investigated here. In addition, a p-i-n type nc-Si:H thin film solar cell, which has an open circuit voltage of 660 mV and a short circuit current intensity of 13.06 mA/cm2, was directly prepared on a flat transparent conductive glass substrate.

This work demonstrates the electrochemical activation of graphene nanowalls (GNWs) for both negative and positive electrodes of high-voltage (≥3.7 V), organic electrical double-layered capacitors (EDLCs). A plasma-enhanced chemical vapor deposition (PECVD) method is employed to vertically grow graphene nanowalls. The crystallinity and layer number of GNWs can be controlled by the synthesis variables such as precursor flow rate and pressure. The material characterization includes Raman spectra, scanning electron microscopy, and X-ray diffraction analysis. Cyclic voltammetry (CV) is employed to promote the charge storage capacity of GNWs in 1 M tetraethylammonium tetrafluoroborate/propylene carbonate (TEABF4/PC) between 2 and -3 V (vs. Ag/AgNO3). Anions and cations in the electrolyte are respectively intercalated into the layered structure of GNWs at sufficiently positive and negative potentials, raising the space of graphene layers. Several parameters of cyclic voltammetry (e.g., potential window, cycle number, activation time, etc.) are investigated to achieve the highest specific capacitance. The results reveal that after the electrochemical activation at 25 mV s−1 from 0 to +2 V and from 0 to −3 V for 10 cycles, the specific capacitance of most few-layer graphene nanowalls is doubled.

Using a plasma enhanced chemical vapor deposition (PECVD) technique, a synchronous polymerization of 3,4-ethylenedioxythiophene (EDOT) and pyrrole monomers was investigated for the development of thin films with adjusted optoelectronic properties. Maintaining a constant amount of EDOT- and pyrrole-feed in the presence of a carrier gas, the PECVD reaction power was varied in the range of 10–100 W to give different physicochemical states of composite films composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy). The deposition rate gradually increased with the reaction power reaching the highest deposition rate at 30 nm/min (100 W) in this study. The energy bandgap of the plasma-polymerized PEDOT/PPy copolymer films increased from 2.62 to 3.27 eV as the applied power density increased from 10 to 100 W in a continuous way, that could desirably ensure a tunable control of bandgaps in thin films. The electrical conductivity and the surface roughness of the thin films continuously increased from 1.59×10-4 to 2.28×10-2 S/m and from 0.2 to 1.9 nm respectively, as the applied power density decreased. The plasma-polymerized PEDOT/PPy copolymer is expected to find its application in various optoelectronic devices including the hole injection layer (HIL) in organic light-emitting diodes (OLEDs), and organic photovoltaics (OPVs) for the improved energy match.

This study demonstrates the fabrication of thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) thin films using the initiated PECVD (i-PECVD) method, in which the initiator tert-butyl peroxide was used together with the monomer NIPAAm. The deposition rates, wettability properties, and the low critical solution temperature (LCST) of i-PECVD deposited PNIPAAM were compared with those of classical continuous wave and pulsed PECVD techniques without TBPO. The effect of plasma power, plasma operation mode, substrate temperature and the presence of initiator on the deposition rate and wettability properties of PNIPAAm thin films were investigated. The results showed that it was possible to tune the deposition rate and wettability properties of PNIPAAm thin films by changing the PECVD parameters. The highest deposition rate (47.9 nm/min) and the largest contact angle difference (18.3°) depending on the temperature were obtained using the i-PECVD method. The LCST value of i-PECVD-PNIPAAm was able to be tuned between 31 and 34 °C. Such value was dependent on the presence and amount of the initiator. On the basis of these results, the i-PECVD method can be considered as the most proper approach for producing of PNIPAAm with desired properties.

We investigated the effect of hydrogen dilution on the Si cluster volume fraction of hydrogenated amorphous films by varying the hydrogen dilution ratio at 0.5 Torr and compared it to that obtained at pure silane discharge at 0.3, 0.4, and 0.5 Torr. The correlation between the plasma emission characteristic, deposition rate, and cluster volume fraction in the hydrogen dilution plasma was described. The cluster volume fractions of films under hydrogen dilution conditions were similar to those of the pure silane but showed a higher deposition rate. The results suggest that under hydrogen dilution conditions, it is possible to maintain a higher deposition rate with a lower cluster incorporation rate.

In this study, thin films of poly(cyclohexyl methacrylate) (PCHMA) were deposited on silicon wafer using PECVD technique, in which the plasma power is inductively coupled through a quartz window using a planar-coil antenna, which was placed outside of the vacuum chamber. PCHMA is a desired sacrificial polymer for many applications because of its hydrophobicity and clean decomposition properties upon thermal annealing. During PECVD of PCHMA, the effects of plasma power and substrate temperature on the deposition rates and structural properties of as-deposited films were investigated. The highest deposition rate (46.5 nm/min) was observed at a low substrate temperature (15 °C) and at a high applied plasma power (30 W). FTIR and XPS analyses of the deposited films confirmed that the percentage of retained functional groups was increased if the intensity of applied plasma power was lowered. As-deposited PCHMA was found to decompose cleanly upon thermal annealing. The onset of thermal decomposition was 89 °C for the film deposited at 5 W applied plasma power.

We have demonstrated for the first time synthesis of amorphous As–Se films within a large compositional range (AsxSe100-x (15

To develop a synthesis technique providing enhanced control of graphene film quality and uniformity, a systematic characterization and manipulation of hydrocarbon precursors generated during plasma enhanced chemical vapor deposition of graphene is presented. Remote ionization of acetylene is observed to generate a variety of neutral and ionized hydrocarbon precursors, while in situ manipulation of the size and reactivity of carbon species permitted to interact with the growth catalyst enables control of the resultant graphene morphology. Selective screening of high energy hydrocarbon ions coupled with a multistage bias growth regime results in the production of 90% few-to-monolayer graphene on 50 nm Ni/Cu alloy catalysts at 500 &deg, C. Additionally, synthesis with low power secondary ionization processes is performed and reveals further control during the growth, enabling a 50% reduction in average defect densities throughout the film. Mass spectrometry and UV-Vis spectroscopy monitoring of the reaction environment in conjunction with Raman characterization of the synthesized graphene films facilitates correlation of the carbon species permitted to reach the catalyst surface to the ultimate quality, layer number, and uniformity of the graphene film. These findings reveal a robust technique to control graphene synthesis pathways during plasma enhanced chemical vapor deposition.

Two complementary modeling approaches (1D and 2D) are developed to explain the temperature-dependent growth kinetics of PECVD graphene formation on cobalt substrate. The gas temperature and the species concentrations are predicted for different process conditions by involving gas-phase and surface reaction mechanisms which consist of 15 gas species, 43 gas reactions, 10 surface species and 34 surface reactions. The influence of the growth temperature, the microwave power and the methane flow rate, affecting the gas species mole fractions in the reactor and the surface coverage is evaluated. The numerical results clearly indicate that the hydrogen atoms play an important role in the graphene growth in microwave plasma systems. A global sensitivity analysis is then performed in order to understand the basic mechanisms that lead to the transport of reactants by gas diffusion from the main gas stream through the boundary layer providing insight regarding the growth of graphene on the cobalt substrate.