Showing papers on "Plasma-enhanced chemical vapor deposition published in 2018"
TL;DR: The results from ALD sidewall passivation revealed that the size-dependent influences on peak EQE can be minimized by proper sidewall treatment, and the importance of sidewall passedivation was demonstrated by comparing leakage current and external quantum efficiency (EQE).
Abstract: Optoelectronic effects of sidewall passivation on micro-sized light-emitting diodes (µLEDs) using atomic-layer deposition (ALD) were investigated. Moreover, significant enhancements of the optical and electrical effects by using ALD were compared with conventional sidewall passivation method, namely plasma-enhanced chemical vapor deposition (PECVD). ALD yielded uniform light emission and the lowest amount of leakage current for all µLED sizes. The importance of sidewall passivation was also demonstrated by comparing leakage current and external quantum efficiency (EQE). The peak EQEs of 20 × 20 µm2 µLEDs with ALD sidewall passivation and without sidewall passivation were 33% and 24%, respectively. The results from ALD sidewall passivation revealed that the size-dependent influences on peak EQE can be minimized by proper sidewall treatment.
182 citations
TL;DR: It is found that both the precursor and certain core materials have an influence on the coating composition, while other parameters, such as the precursor concentration, aerosol residence time and temperature, influence the morphology, but hardly the chemical composition.
Abstract: Nanoparticles are coated in-flight with a plasma-enhanced chemical vapor deposition (PECVD) process at ambient or elevated temperatures (up to 300 °C). Two silicon precursors, tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are used to produce inorganic silica or silica-organic shells on Pt, Au and TiO₂ particles. The morphology of the coated particles is examined with transmission electron microscopy (TEM) and the chemical composition is studied with Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). It is found that both the precursor and certain core materials have an influence on the coating composition, while other parameters, such as the precursor concentration, aerosol residence time and temperature, influence the morphology, but hardly the chemical composition. The coated particles are used to demonstrate simple applications, such as the modification of the surface wettability of powders and the improvement or hampering of the photocatalytic activity of titania particles.
126 citations
TL;DR: A quasi-equilibrium plasma-enhanced chemical vapor deposition method is developed to produce high-quality ultra-clean GQDs with sizes down to 2 nm directly on SiO2/Si, which are used as SERS substrates, demonstrating a sensitive SERS substrate.
Abstract: Graphene is regarded as a potential surface-enhanced Raman spectroscopy (SERS) substrate. However, the application of graphene quantum dots (GQDs) has had limited success due to material quality. Here, we develop a quasi-equilibrium plasma-enhanced chemical vapor deposition method to produce high-quality ultra-clean GQDs with sizes down to 2 nm directly on SiO2/Si, which are used as SERS substrates. The enhancement factor, which depends on the GQD size, is higher than conventional graphene sheets with sensitivity down to 1 × 10−9 mol L−1 rhodamine. This is attributed to the high-quality GQDs with atomically clean surfaces and large number of edges, as well as the enhanced charge transfer between molecules and GQDs with appropriate diameters due to the existence of Van Hove singularities in the electronic density of states. This work demonstrates a sensitive SERS substrate, and is valuable for applications of GQDs in graphene-based photonics and optoelectronics. Surface-enhanced Raman spectroscopy (SERS) is a promising technology for sensitive optical sensors, generally using rough metal films. Here, Liu et al. synthesize high-quality graphene quantum dot films which offer a large SERS enhancement due to a strong light-matter interaction with Van Hove singularities.
115 citations
TL;DR: In this article, the high-k dielectric layer of Al2O3 acts as an electron blocking layer which minimizes the surface recombination at the interface, and the barrier width is optimized by controlling the thickness of the Al 2O3 interlayer to achieve the highest efficiency of 8.4%.
70 citations
TL;DR: In this paper, the combined techniques of PECVD and the growth of graphene underneath the catalyst layer were proposed, and transfer-free single-layer graphene films with 2.5 inch in diameter on quartz substrate can be obtained with the growth temperature of 700°C, which is 250°C lower than that for graphene synthesis using thermal CVD.
58 citations
TL;DR: Laid-down graphene glass has higher transparency, lower sheet resistance, and much improved macroscopic uniformity when compare to its vertical graphene counterpart and it performs better in transparent heating devices.
Abstract: Plasma-enhanced chemical vapor deposition (PECVD) is an applicable route to achieve low-temperature growth of graphene, typically shaped like vertical nanowalls. However, for transparent electronic applications, the rich exposed edges and high specific surface area of vertical graphene (VG) nanowalls can enhance the carrier scattering and light absorption, resulting in high sheet resistance and low transmittance. Thus, the synthesis of laid-down graphene (LG) is imperative. Here, a Faraday cage is designed to switch graphene growth in PECVD from the vertical to the horizontal direction by weakening ion bombardment and shielding electric field. Consequently, laid-down graphene is synthesized on low-softening-point soda-lime glass (6 cm × 10 cm) at ≈580 °C. This is hardly realized through the conventional PECVD or the thermal chemical vapor deposition methods with the necessity of high growth temperature (1000 °C-1600 °C). Laid-down graphene glass has higher transparency, lower sheet resistance, and much improved macroscopic uniformity when compare to its vertical graphene counterpart and it performs better in transparent heating devices. This will inspire the next-generation applications in low-cost transparent electronics.
57 citations
TL;DR: A nonlinear silicon nitride waveguide fabricated by readily available PECVD, conventional contact UV-lithography and high-temperature annealing techniques, thus dramatically reducing the processing complexity and cost is presented.
Abstract: In this work, we present a nonlinear silicon nitride waveguide. These waveguide are fabricated by readily available PECVD, conventional contact UV-lithography and high-temperature annealing techniques, thus dramatically reducing the processing complexity and cost. By patterning the waveguide structures firstly and then carrying out a high-temperature annealing process, not only sufficient waveguide thickness can be achieved, which gives more freedom to waveguide dispersion control, but also the material absorption loss in the waveguides be greatly reduced. The linear optical loss of the fabricated waveguide with a cross-section of 2.0 × 0.58 µm2 was measured to be as low as 0.58 dB/cm. The same loss level is demonstrated over a broad wavelength range from 1500 nm to 1630 nm. Moreover, the nonlinear refractive index of the waveguide was determined to be ~6.94 × 10−19 m2/W, indicating that comparable nonlinear performance with their LPCVD counterparts is expected. These silicon nitride waveguides based on a PECVD deposition platform can be useful for the development of more complicated on-chip nonlinear optical devices or circuits.
47 citations
TL;DR: In this paper, the characteristics of silicon nitride films deposited by low pressure chemical vapor deposition (LPCVD) and PECVD, with special attention to the hydrogenation and chemical composition of silicon Nitride films, were compared.
Abstract: This paper analyzes and compares the characteristics of silicon nitride films deposited by low pressure chemical vapor deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD), with special attention to the hydrogenation and chemical composition of silicon nitride films. Three different LPCVD processes at various DCS and NH3 gas flow rates and deposition temperatures, together with PECVD using SiH4 and NH3 and ICP CVD using SiH4 and N2, were compared. The silicon nitride film deposition rate decreases with an increasing NH3/DCS ratio in LPCVD, which also leads to an increase in the refractive index and a decrease in the residual stress in the film. There is nearly no hydrogen incorporated in the LPCVD films, which differs from PECVD and ICP CVD that show significant Si-H and N-H bonds. The chemical composition of silicon nitride films is mostly Si-rich, except for the LPCVD process at high NH3/DCS ratio with near stoichiometric chemistry.
47 citations
TL;DR: A simple, efficient, and economical process is reported for the direct synthesis of carbon nanotube (CNT) field emitters on metal alloy and an X-ray generated image of an integrated circuit was taken using the compact field emission device developed herein.
Abstract: In this study, a simple, efficient, and economical process is reported for the direct synthesis of carbon nanotube (CNT) field emitters on metal alloy. Given that CNT field emitters can be customized with ease for compact and cold field emission devices, they are promising replacements for thermionic emitters in widely accessible X-ray source electron guns. High performance CNT emitter samples were prepared in optimized plasma conditions through the plasma-enhanced chemical vapor deposition (PECVD) process and subsequently characterized by using a scanning electron microscope, tunneling electron microscope, and Raman spectroscopy. For the cathode current, field emission (FE) characteristics with respective turn on (1 μA/cm²) and threshold (1 mA/cm²) field of 2.84 and 4.05 V/μm were obtained. For a field of 5.24 V/μm, maximum current density of 7 mA/cm² was achieved and a field enhancement factor β of 2838 was calculated. In addition, the CNT emitters sustained a current density of 6.7 mA/cm² for 420 min under a field of 5.2 V/μm, confirming good operational stability. Finally, an X-ray generated image of an integrated circuit was taken using the compact field emission device developed herein.
45 citations
TL;DR: In this paper, a novel strategy of growing carbon nanotubes vertically and uniformly on the surface of carbon nanofibers via plasma enhanced chemical vapor deposition (PECVD) was proposed to prepare a kind of CNFs-CNTs adsorption materials.
34 citations
TL;DR: Onion-like carbon films were prepared by constant current high-frequency dual-pulsed plasma enhanced chemical vapor deposition technique as discussed by the authors, which achieved a super high elastic recovery up to 92%, but also obtained a super-low friction coefficient below 0.01 and wear rate about 6.41×10−18m3/Nm in ambient atmosphere.
TL;DR: Reversible and irreversible changes in the phase composition of the As-Te films under annealing of the surface by laser irradiation have been demonstrated and studied to establish the correlation between optical and structural properties of the materials developed.
30 Aug 2018
TL;DR: In this paper, the fracture toughness of PECVD silicon nitride and silicon oxynitride thin films was investigated under different silane flow rates, and the results showed that the hardness, Young modulus, and fracture toughness increased with increasing flow rate.
Abstract: Silicon nitride and silicon oxynitride thin films are widely used in microelectronic fabrication and microelectromechanical systems (MEMS). Their mechanical properties are important for MEMS structures; however, these properties are rarely reported, particularly the fracture toughness of these films. In this study, silicon nitride and silicon oxynitride thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) under different silane flow rates. The silicon nitride films consisted of mixed amorphous and crystalline Si3N4 phases under the range of silane flow rates investigated in the current study, while the crystallinity increased with silane flow rate in the silicon oxynitride films. The Young’s modulus and hardness of silicon nitride films decreased with increasing silane flow rate. However, for silicon oxynitride films, Young’s modulus decreased slightly with increasing silane flow rate, and the hardness increased considerably due to the formation of a crystalline silicon nitride phase at the high flow rate. Overall, the hardness, Young modulus, and fracture toughness of the silicon nitride films were greater than the ones of silicon oxynitride films, and the main reason lies with the phase composition: the SiNx films were composed of a crystalline Si3N4 phase, while the SiOxNy films were dominated by amorphous Si–O phases. Based on the overall mechanical properties, PECVD silicon nitride films are preferred for structural applications in MEMS devices.
TL;DR: In this paper, the growth of chemical vapor deposited TiN from a reaction gas mixture of TiCl4, N2 and H2 was investigated on three different transition metal substrates: Fe, Co and Ni at deposition temperatures ranging from 850°C to 950°C.
Abstract: The growth of chemical vapor deposited TiN from a reaction gas mixture of TiCl4, N2 and H2 was investigated on three different transition metal substrates: Fe, Co and Ni at deposition temperatures ranging from 850 °C to 950 °C. The interactions between the substrate metals and the gas phase were investigated using thermodynamic calculations. The TiN coatings were characterized by scanning electron microscopy, scanning transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and transmission Kikuchi diffraction. Chemical vapor deposition (CVD) of TiN on Co substrates resulted in dense, columnar coatings of single phase TiN. The activation energy for TiN deposition on Co was determined to be 90 kJ/mol. CVD of TiN on Fe substrates caused severe substrate corrosion by the formation of gaseous FeClx. Due to the substrate corrosion, the activation energy could not be determined. Furthermore, it was found that CVD of TiN on Ni substrates produced a phase mixture of TiN and Ni3Ti. Formation of Ni3Ti could be minimized by decreasing the H2 partial pressure and increasing the N2 partial pressure. Deposition on Ni yielded two different activation energies, 40 kJ/mol in the temperature interval 850 °C to 900 °C and 165 kJ/mol in the interval 900 °C to 950 °C. This is an indication of two different types of process control, which were identified as Ni diffusion into the growing film and a gas phase processes. The results of the present study showed that CVD of TiN on a cemented carbide using Fe and Ni in the binder phase, must be optimized in order to avoid corrosion or unwanted phases. Methods to achieve this are presented in this paper.
TL;DR: Control of film thickness and roughness is focused on to improve the ultraviolet (UV)-protective performance of TiO2 films prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition using titanium(IV) isopropoxide as the precursor and argon as the plasma working gas.
Abstract: This article focuses on control of film thickness and roughness to improve the ultraviolet (UV)-protective performance of TiO2 films prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition using titanium(IV) isopropoxide (TTIP) as the precursor and argon as the plasma working gas. The relationship between the film morphology and UV-protective performance suggested that a decrease in roughness is the key factor to achieve performance improvement. The effects of substrate temperature and precursor concentration were investigated, and the results showed that an increase in both substrate temperature and precursor concentration reduced the roughness and improved the transparency to visible light without reducing the ability to block UV light. Finally, a TiO2 film with greater than 99% UV light blockage and greater than 95% transmittance of visible light was obtained.
TL;DR: In this article, the structural, optoelectronic and mechanical properties of amorphous silicon carbon nitride (Si-C-N) thin films produced by plasma enhanced chemical vapor deposition (PECVD) at different negative substrate biases (Ud) are studied.
TL;DR: In this article, the effect of multi-interlayers on the adhesion and durability of diamond-like carbon (DLC) films on Al substrates was investigated, and it was shown that improving the wear resistance required high plastic index parameter (H/E) values rather than high H values.
Abstract: Aluminum (Al) alloys are light and have good workability; however their low hardness and poor wear resistance are drawbacks limiting their wide application in the automotive industry Deposition of diamond-like carbon (DLC) films, which exhibit high hardness and good wear resistance, onto the surface of Al alloy substrates can overcome these drawbacks Because Al alloys and DLC films have low affinity for each other, adhesion between the two is poor However, the use of an interlayer can improve adhesion To investigate the effect of multi-interlayers on the adhesion and durability of DLC films on Al substrates, DLC films with Ti, Si-DLC, or Ti/Si-DLC interlayers were deposited onto A2024 substrates using plasma-enhanced chemical vapor deposition (PECVD) Prior to PECVD, an Ar-bombardment treatment was conducted to clean the surface of the substrate Subsequently, a Ti interlayer was deposited by sputtering for 15 min, a Si-DLC interlayer was deposited using a tetramethylsilane (TMS) and methane gas mixture for 15 min, and DLC was deposited using methane gas for 90 min The nanohardness of the Ti/Si-DLC multi-interlayered sample reached 33 GPa more than 8 GPa higher than that of the single-interlayered samples In addition, the Ti/Si-DLC multi-interlayered sample exhibited higher hardness/Young's modulus (H/E) ratios than the single-interlayered samples Wear tests showed that the wear volumes for the balls and the multi-interlayered samples were smaller than those for the single-interlayered samples In addition, the delamination distance of the Ti/Si-DLC multi-interlayer sample was 3300 m, more than 1500 m longer than that of single-interlayered samples This study demonstrates that improving the wear resistance required high plastic index parameter (H/E) values rather than high H values
TL;DR: In this paper, the antifriction properties of coatings in the form of a nanocomposite of a silica layer with molybdenum disulfide nanoparticles distributed in it, whose average sizes are 70, 64, 61, and 53 nm and concentrations are 80, 73, 68, and 62 wt %, respectively, grown via plasma-chemical deposition at atmospheric pressure on a 12Cr18Ni10Ti steel, are studied.
Abstract: The antifriction properties of coatings in the form of a nanocomposite of a silica layer with molybdenum disulfide nanoparticles distributed in it, whose average sizes are 70, 64, 61, and 53 nm and concentrations are 80, 73, 68, and 62 wt %, respectively, grown via plasma-chemical deposition at atmospheric pressure on a 12Cr18Ni10Ti steel, are studied. The best tribotechnical properties are established for a SiO2 + 68% MoS2 coating (61 nm) which possesses the most stationary friction mode and a friction force two times lower as compared to a MoS2-free SiO2 coating.
TL;DR: In this paper, the effect of an amorphous hydrogenated silicon interlayer on the adherence of a-C:H coatings on four metallic surfaces (AISI M2 steel, AISI 304 stainless steel, Nitinol alloy, and Ti6Al4V alloy) was studied.
Abstract: The effect of an amorphous hydrogenated silicon (a-Si:H) interlayer on the adherence of amorphous hydrogenated carbon (a-C:H) coatings deposited on four metallic surfaces: AISI M2 steel, AISI 304 stainless steel, Nitinol alloy, and Ti6Al4V alloy was studied. The interlayers and the coatings were deposited employing an asymmetrical bipolar pulsed-DC PECVD system with an active screen. Multilayer a-C:H coatings were also deposited, with the aim of obtaining thicker films. The interlayers were synthetized by varying the applied negative pulse amplitude from −0.8 kV to −10 kV, keeping their thickness constant at 250 nm. The coatings' adhesion was evaluated using classical scratch and VDI 3198 indentation tests. Raman spectroscopy was used to analyze the films' atomic arrangements. The total compressive stress was determined through the measurement of the substrate curvature before and after the film deposition, while nanoindentation experiments allowed determining the films' hardness and elastic modulus. In order to determine the chemical bonding between a-Si:H and the metallic surfaces, X-ray photoelectron spectroscopy (XPS) was used. The obtained results showed high values of critical loads, allowing a high degree of adherence of the a-C:H coatings to all the metallic materials. The highest Lc1 critical load values (≥25 N) were determined when the a-Si:H interlayers were deposited using the highest negative applied voltage (from −6 kV to −10 kV) on the Nitinol alloy surfaces. The XPS results suggested that the high degree of adhesion of the a-C:H coatings to Nitinol could be attributed to chemical bonds of Ti Si and Ni Si formed in the interface, while for the Ti6Al4V alloy the Ti Si bonds predominated. On the other hand, on steel surfaces the adhesion was due to Fe Si bonds. A combination of a modified pulsed-DC PECVD system with an active screen and an a-Si:H interlayer allowed depositing hard, adherent, and low-stress a-C:H coatings.
TL;DR: In this article, a phenomenological-based virtual metrology (VM) technique is developed for predicting the silicon nitride film thickness in multi-layer plasmaenhanced chemical vapor deposition (PECVD).
Abstract: A phenomenological-based virtual metrology (VM) technique is developed for predicting the silicon nitride film thickness in multi-layer plasma-enhanced chemical vapor deposition (PECVD). Particularly, the analysis of optical emission spectroscopy based on the excitation kinetics in nitrogen plasma is used to develop novel variables, named plasma-information (PI) variables. One variable, PIWall, is determined by analyzing the light transmittances of the nitrogen emissions at the contaminated window, representing the drift of reactor-wall condition. The other variable, PIVolume, is determined by analyzing vibrational distribution of N2( $\text{C}^{3} {\Pi }_{\text u}$ , $
u =0-4$ ) states, representing the drift of plasma density and temperature. These PI variables are applied as part of input variables of VM to improve the prediction accuracy. The partial least squares regression is adopted as the statistical method and the contribution of PI variables on the VM are evaluated through the variable influence evaluation on projection. It demonstrates the necessity of PI variables in VM for PECVD and the reactor-wall condition is a major cause of drift in PECVD.
TL;DR: A stacked layer of ultrathin hydrogenated silicon oxide and hydrogenated amorphous silicon (a-Si:H) has been developed to passivate the crystalline silicon (c-Si) surface.
TL;DR: A novel parallel processing scheme built around a message passing interface (MPI) structure, in conjunction with a distributed collection of kinetic Monte Carlo algorithms, is applied in order to allow for transient simulations to be conducted using a mesh with greater than 1.5 million cells.
TL;DR: In this article, a single-layer silicon nitride (SiNx) film was fabricated by roll-to-roll, plasmaenhanced chemical vapor deposition (R2R-PECVD) in widths as large as 500mm.
TL;DR: In this article, residual SiH 4 molecules in H 2 plasma were used to treat silicon heterojunction (SHJ) solar cell devices, and the improved a-Si:H/c-Si interface passivation results in improvements to both the shortcircuit current density (J sc ) and open-circuit voltage (V oc ) of the SHJ solar cell in comparison to the counterpart cell treated by the traditional pure H 2 Plasma.
TL;DR: In this paper, a review of the recent applications of vapor-phase deposition methods such as initiated chemical vapor deposition (iCVD), PE-CVD, and atomic layer deposition (ALD) for the encapsulation of active pharmaceutical drugs are reported.
Abstract: Vapor-phase deposition methods allow the synthesis and engineering of organic and inorganic thin films, with high control on the chemical composition, physical properties, and conformality. In this review, the recent applications of vapor-phase deposition methods such as initiated chemical vapor deposition (iCVD), plasma enhanced chemical vapor deposition (PE-CVD), and atomic layer deposition (ALD), for the encapsulation of active pharmaceutical drugs are reported. The strategies and emergent routes for the application of vapor-deposited thin films on the drug controlled release and for the engineering of advanced release nanostructured devices are presented.
TL;DR: Diamond like carbon (DLC) films were deposited onto Ti6Al4V and Si wafer substrates by RF plasma enhanced chemical vapor deposition to investigate the influence of dopants such as fluorine (F), silicon (Si), and nitrogen (N) on composition, structure, and biocompatibility.
Abstract: Diamond like carbon (DLC) films were deposited onto Ti6Al4V and Si wafer substrates by RF plasma enhanced chemical vapor deposition. The influence of dopants such as fluorine (F), silicon (Si), and nitrogen (N) on composition, structure, and biocompatibility was investigated. Ion scattering spectroscopy analysis revealed the presence of dopant atoms in the outer-most layers of the films. Raman studies showed that the position of the G-band shifts to higher frequencies with the fluorine and nitrogen content in the DLC film, whereas the incorporation of Si into DLC induces a decrease of the position of the G peak. The corrosion behavior was studied in simulated body fluid. A higher charge transfer resistance (Rct) was observed for the doped DLC films. The indirect cytotoxicity was performed using L929 fibroblast cells. The coated surfaces were hemocompatible when tested with red blood cells. DLC films were noncytotoxic to L929 cells over a 24 h exposure. Saos-2 osteoblast cell response to the doped and undoped DLC coated surfaces was studied in adhesion, proliferation, differentiation, and mineralization assays. The production of calcium and phosphate by cells on doped DLC, particularly, nitrogen doped DLC, was higher than that on undoped DLC.
TL;DR: In this article, a repeatable preparation of large area highly conductive boron doped nano-crystalline diamond layers with low sp 2 content using microwave plasma enhanced linear antenna chemical vapour deposition apparatus was reported.
TL;DR: In this paper, the authors report on the synthesis by plasma enhanced chemical vapor deposition, morphology and catalytic activity towards oxygen reduction reaction (ORR) of hierarchical carbon nanowalls (hCNW) at different deposition times.