Pressure PECVD Research Articles

Multidimensional jagged SnSb/C/DLC nanofibers fabricated by AP-PECVD method for Li-ion battery anode

The atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) method has been shown to have dramatic effects on the morphology and structure of nanomaterials. For the sake of solving the capacity decline caused by alloy expansion and improving the electrode performance of SnSb/C nanofiber anodes in Li-ion batteries, the self-designed AP-PECVD device was first used to deposit large numbers of diamond-like carbon (DLC) nanoparticles on nanofibers to construct a special 3D structure. Interestingly, after the AP-PECVD and carbonization treatment, we found that most DLC nanoparticles had a single crystal structure and nanofibers reacted with a high energy hydrogen plasma to generate a special jagged morphology. The special jagged grooves provided an excellent channel for the Li ions’ insertion/extraction, and the 3D structure provided a buffer space for the volume expansion of SnSb alloy during the electrochemical cycle. Compared with the SnSb/C nanofibers, SnSb/C/DLC nanofibers exhibited a much better electrochemical performance with a high reversible capacity of 583.54 mAh g−1 at the 100th cycle, and excellent rate capability. This paper proved that the AP-PECVD device can successfully deposit a DLC nanoparticle layer and the construction of nanofiber morphology was a valid method to improve the electrochemical properties of the nanofiber anode in Li-ion batteries.

Maskless atmospheric pressure PECVD of SiOx films on both planar and nonplanar surfaces using a flexible atmospheric microplasma generation device

AbstractThis paper presents the use of a simple‐arranged, low‐cost, and flexible atmospheric pressure microplasma generation device (μPGD) with controlled gas discharge to achieve maskless atmospheric plasma‐enhanced chemical vapor deposition (PECVD) of SiOx films on both planar and nonplanar surfaces. The μPGD is mainly composed of a copper–polyimide–copper sandwich structure with predefined microfluidic channels. Uniform microplasmas of different shapes and dimensions were generated in the open air. SiOx films were masklessly deposited with well‐defined edges and good feature transfer fidelity. The SEM, EDS, XPS, and FTIR spectra of the deposited film confirm the SiOx structure. These results indicate that μPGD is able to achieve maskless PECVD of SiOx films in the open air, especially micropatterning on nonplanar surfaces.

Highly efficient formation process for functional silicon oxide layers at low temperatures (≤ 120 °C) using very high-frequency plasma under atmospheric pressure

SiO2-like films are deposited with high rates at substrate temperatures in the range of ≤120 °C by means of the developed atmospheric-pressure (AP) plasma-enhanced chemical vapor deposition (PECVD) technology. The AP plasma is excited by using a novel parallel-plate-type electrode system under supplying a 150 MHz very high frequency (VHF) electric power. As the process gases, oxygen (O2) and hexamethyldisiloxane (HMDSO) diluted with helium (He) are used. The electrode system is capable of forming one-dimensional flow of the process gases without any turbulence both inside and outside the plasma zone, which achieves the deposition conditions with no contamination of substrate surface with dust particles. The microstructure and surface roughness of the films are discussed by controlling O2 flow rate (O2/HMDSO source ratio) and VHF power density (PVHF), aiming at the use of the films as the gate insulators of low-temperature thin film transistors (TFTs). Irrespective of the substrate materials (Si wafers or polyethylene naphthalate (PEN) sheets), the films deposited with an appropriate O2 flow rate condition show smooth surface and cross sectional morphologies with no particles being incorporated during the deposition, which lead to the sufficiently good quality to be used as the gate insulator of low-temperature Si TFTs. The capability of forming functional thin films on temperature sensitive substrates will also lead to various applications of AP-VHF plasma as an efficient coating tool for polymer substrates.

Dynamic mode optimization for the deposition of homogeneous TiO2 thin film by atmospheric pressure PECVD using a microwave plasma torch

An atmospheric pressure plasma-enhanced chemical vapor deposition process using a microwave plasma torch has been used for titania thin film synthesis. A dynamic deposition mode was set up to cover a square centimeter surface with a nanostructured TiO2 film. The process parameters were studied and optimized to control the coating crystallinity and morphology and limit the formation of powder in the plasma phase. Contrary to static deposition, the substrate movement promotes a film growth by particles agglomeration in the reference conditions, leading to a cauliflower-like morphology. Then, the precursor proportion in the plasma appears to be determinant in the TiO2 film microstructure. For a precursor flow rate beyond 0.2 slpm, the titania nanoparticles formation in the gas phase is promoted and the thin film is growing by particles agglomeration, leading to a columnar cauliflower-like morphology. At a flow rate of 0.2 slpm, the growth by surface reaction is promoted and the TiO2 film is columnar, where each column is an anatase crystal. After the optimization of the substrate holder movement, it was possible to deposit this last microstructure homogeneously on a square centimeter surface.

Efficient silicon nitride SiNx:H antireflective and passivation layers deposited by atmospheric pressure PECVD for silicon solar cells

AbstractThis work demonstrates the efficient optical and passivation properties provided by hydrogenated silicon nitride (SiNx:H) layers deposited in a lab‐scale atmospheric pressure plasma enhanced chemical vapor deposition (AP‐PECVD) reactor. By applying modulated low‐frequency plasma (200 kHz), homogeneous SiNx:H layers, with small variances in thickness w and refractive index n (Δw ≤ 2 nm; Δn ≤ 0.02), were achieved on a surface area of 45 × 55 mm2. The use of voltage amplitude modulation enabled discharge optimization and led to greatly enhanced SiNx:H film homogeneity and conformity in comparison with continuous plasma discharge conditions. Additionally, AP‐PECVD SiNx:H showed good thermal stability (Δw ≤ 1 nm; Δn ≤ −0.02) with low absorption coefficients (k ≤ 0.1 at 275 nm), demonstrating that such layers could act as efficient antireflective coatings. Furthermore, outstanding surface passivation properties were achieved after firing, both on n‐type FZ c‐Si substrates of standard 2.8 Ω.cm doping (τeff = 1.45 ms) and on highly doped 85 Ω/sq n+ emitters (j0e = 74 ± 2 fA.cm−2). Finally, AP‐PECVD SiNx:H thin films were tested on industrial passivated emitter and rear solar cell (PERC) architectures, where the potential of applying these layers both as efficient rear‐side capping layer and front‐side antireflective coating was demonstrated. The first lab‐scale 40 × 40 mm2 PERC solar cells featuring AP‐PECVD SiNx:H layers led to conversion efficiencies of up to 20.6%. These results pave the way for upscaling the dielectric barrier discharge lab‐scale reactor in an industrial in‐line process, which could provide low‐cost and high‐throughput SiNx:H capping and antireflective layers.

Study of In-Situ Hydrogen Plasma Treatment on InGaZnO with Atmospheric Pressure-Plasma Enhanced Chemical Vapor Deposition.

In the past few years, thin film transistors have a wide range of applications on display technology, material selection and quality for its active layer is critical for device performance. Traditional amorphous silicon (a-Si) silicon has a lot of advantages such as good productivity, short process and low-cost. It also has a lot of shortcomings on these applications on TFTs such as photosensitivity, light degradation, and opacity, etc. The dispute of the material based on a-Si:H as an active layer in TFT is low field effect mobility (~1 cm²/V·S) (M. Shur and M. Hack, J. Appl. Phys. 55, 3831 (1984)), photo sensitivity (low band gap about 1.7 V) and high deposition temperature (~400 °C) (M. Shur, et al., J. Appl. Phys. 66, 3371 (1989); K. Khakzar and E. H. Lueder, IEEE Trans. Electron Devices 39, 1438 (1992)). Amorphous In-Ga-Zn-O (IGZO) had attracted attention that compared with the conventional a-Si:H, due to its good properties of simultaneously high/low conductivity with high visual transparency via doping level. Oxide-based semiconductors, such as ZnO (G. Adamopoulos, et al., Appl. Phys. Lett. 95, 133507-3 (2009); H.-C. Cheng, et al., Appl. Phys. Lett. 90, 012113-3 (2007)) and IGZO (C. J. Chiu, et al., Electron Device Letters, IEEE 31, 1245 (2010); L. Linfeng and P. Junbiao, IEEE Transactions on Electron Devices 58, 1452 (2011)) have been reported for the active channel layer. These oxide-based materials offer good electrical properties and high transparency for thin film transistors, its high transmittance can be applied to fabricate the full transparent TFT on flexible substrate. With In-Situ hydrogen plasma treatment on a-IGZO produced by atmospheric pressure-plasma enhanced chemical vapor deposition (AP-PECVD), the material characteristics of a-IGZO is studied.

Investigation of Electrical Characteristics on AP-PECVD Fabricated Amorphous IGZO TFTs with Hydrogen Plasma Treatment.

TFT panel production process can be divided into three kinds of technology. There have amorphous silicon (a-Si), low-temperature polysilicon (LTPS) and amorphous IGZO (a-IGZO) oxide. Traditional amorphous silicon (a-Si) silicon has a lot of advantages such as good productivity, short process and low-cost. It also has a lot of shortcomings on these applications on TFTs such as photosensitivity, light degradation, and opacity, etc. The dispute of the material based on a-Si:H as an active layer in TFT is low field effect mobility (~1 cm²/V·S) (M. Shur and M. Hack, J. Appl. Phys. 55, 3831 (1984)), photo sensitivity (low band gap about 1.7 V) and high deposition temperature (~400 °C) (M. Shur, et al., J. Appl. Phys. 66, 3371 (1989); K. khakzar and E. H. Lueder, IEEE Trans. Electron Devices 39, 1438 (1992)). Amorphous In-Ga-Zn-O (IGZO) had attracted attention that compared with the conventional a-Si:H, in the past three years, a-IGZO thin film transistors is more popular which compared with the other oxide semiconductors, because of its larger Ion/Ioff ratio (>106, smaller subthreshold swing (SS), better field-effect mobility and better stability against electrical stress. Hydrogen plasma treatment is applied in improving a-IGZO TFTs active layer, which is fabricated by atmospheric pressure-plasma enhanced chemical vapor deposition (AP-PECVD), the electrical characteristics of a-IGZO TFTs is investigated.

Low-temperature deposition of TiO2by atmospheric pressure PECVD towards photoanode elaboration for perovskite and solid-state dye-sensitized solar cells

An original low-temperature atmospheric pressure plasma-enhanced chemical vapor deposition process was used to deposit titanium dioxide thin films. The parametric study in dynamic mode deposition aimed at growing an ideal columnar film composed of aligned anatase monocrystals as solar cell photoanode, previously obtained on silicon wafers in static mode deposition. A process parameters optimization was necessary to deposit onto thermally sensitive glass/FTO substrates. In this paper, the morphology, crystallinity and optical transmission of the coatings have been studied. The coatings display a columnar cauliflower-like structure, composed of TiO2amorphous particles assembly. After deposition, the light transmission properties of the substrate were reduced. As a solution, an ultrasound bath cleaning was set up to enhance the transmitted light through the photoanode.

Polymer Dielectrics: A Scalable, High‐Throughput, and Environmentally Benign Approach to Polymer Dielectrics Exhibiting Significantly Improved Capacitive Performance at High Temperatures (Adv. Mater. 49/2018)

High-throughput production of high-temperature capacitor films is realized by Qi Li, Jinliang He, Qing Wang, and co-workers in article number 1805672 through fast and continuous deposition of a nanoscale thin layer of an insulating barrier using atmospheric-pressure plasma-enhanced chemical vapor deposition. This approach should be adaptable to the industrial extrusion method for highly productive manufacturing of capacitor films.

Insights into the Role of Plasma in Atmospheric Pressure Chemical Vapor Deposition of Titanium Dioxide Thin Films

In this work, the effect of plasma on the chemistry and morphology of coatings deposited by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition (AP-PECVD) is investigated. To do so, plasma deposited amorphous titanium dioxide (TiO2) thin films are compared to thin films deposited using Atmospheric Pressure Chemical Vapor Deposition (AP-CVD) not involving the use of plasma. We focus here on the effect and the interest of plasma in the AP-PECVD process over AP-CVD for low substrate temperature deposition. The advantages of AP-PECVD over AP-CVD are often suggested in many articles however no direct evidence of the role of the plasma for TiO2 deposition at atmospheric pressure was reported. Hence, herein, the deposition via both methods is directly compared by depositing coatings with and without plasma using the same CVD reactor. Through the control of the plasma parameters, we are able to form low carbon coatings at low temperature with a deposition rate twice faster than AP-CVD, clearly showing the interest of plasma. Plasma enhanced methods are promising for the deposition of coatings at industrial scale over large surface and at high rate.

UV-Protective TiO2 Thin Films with High Transparency in Visible Light Region Fabricated via Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition.

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.

Deposition of polysiloxane coatings by runaway electrons preionized diffuse discharge in nitrogen flow

A deposition of polysiloxane coating on titanium substrate by means of atmospheric pressure plasma enhanced chemical vapor deposition (PECVD) in a runaway electron preionized diffuse discharge (REP DD) has been investigated. The coating was produced from vapor of hexomethyldisiloxane (HMDSO) diluted in nitrogen at a flow rate of 1 nl/min. After deposition, the mechanical properties of the coatings have been measured by means of a nanoidentation. The maximum nanohardness of the coating with 3 μm thickness was 4.7 GPa. Energy dispersive analysis has shown that the coatings contain a significant content of carbon and titanium (about 52 at. %, 32 at. %, respectively) and a low content of silicon (about 16 at. %). In the FTIR spectrum, high intensity bands corresponding to stretching vibrations of the Si-O-Si, the Si(CH3)x and CH3 groups are observed, that indicates the organic and inorganic coating structure. Carbon free coating can be produced by REP DD plasma treatment of the deposited SiOxCyHz film, when REP DD operated only in nitrogen.

Facile Fabrication of a Two-Dimensional TMD/Si Heterojunction Photodiode by Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition.

A growth technique to directly prepare two-dimensional (2D) materials onto conventional semiconductor substrates, enabling low-temperature, high-throughput, and large-area capability, is needed to realize competitive 2D transition-metal dichalcogenide (TMD)/three-dimensional (3D) semiconductor heterojunction devices. Therefore, we herein successfully developed an atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique, which could grow MoS2 and WS2 multilayers directly onto PET flexible substrate as well as 4-in. Si substrates at temperatures of <200 °C. The as-fabricated MoS2/Si and WS2/Si heterojunctions exhibited large and fast photocurrent responses under illumination of a green light. The measured photocurrent was linearly proportional to the laser power, indicating that trapping and detrapping of the photogenerated carriers at defect states could not significantly suppress the collection of photocarriers. All the results demonstrated that our AP-PECVD method could produce high-quality TMD/Si 2D-3D heterojunctions for optoelectronic applications.

Variable roughness development in statically deposited SiO2 thin films: a spatially resolved surface morphology analysis

For the first time a systematic analysis of the growth front evolution of statically deposited silica films in an atmospheric pressure-plasma enhanced chemical vapour deposition (AP-PECVD) reactor was carried out. The growth front evolution was studied as a function of time and position in the reactor. Focussed beam spectroscopic ellipsometry was used to assess the local film growth rate and atomic force microscopy (AFM) to analyse the surface roughness development. Spatially resolved AFM analysis showed a strong dependence of the rms roughness on the position, and consequently on the thickness and local deposition rate (LDR), in the reactor. Time resolved surface morphology analysis at two specific positions at high and low LDR indicated different growth exponents β = 0.33 and β = 0.11, respectively. From the analysis of the static roughness development in the AP-PECVD reactor certain limitations on the deposition time and the maximum LDR for dynamic or web rolled deposition conditions have been elucidated. Moreover, the system is characterized by a set of roughness exponents = 0.9, = 1.6 and global roughness exponent = 2.3. The different values of α indicate an anomalous scaling behaviour of the system whereas different growth exponents β suggest a breakdown of the anti-shadowing mechanism.

Atmospheric-pressure plasma-enhanced chemical vapor deposition of UV-shielding TiO2 coatings on transparent plastics

UV-shielding TiO2 coatings for the protection of the UV-degradable transparent plastic polymethylmethacrylate (PMMA) were prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD). The structure and morphology of AP-PECVD-derived TiO2 films and TiO2-coated PMMA were characterized by XRD, FTIR, SEM, and water contact angle measurements, and their optical properties were investigated by UV–vis spectroscopy. The results showed that AP-PECVD-derived TiO2 had an amorphous structure, and a TiO2 layer with a compact columnar structure without any visible cracks was successfully formed on PMMA without damaging the structure of the polymer. The film deposited on PMMA exhibited excellent UV-shielding performance with 99% absorption of UV light in the wavelength range of 200–280 nm and with visible light transmittance above 90%.

Investigations on the transformation of vertically aligned CNTs to intramolecular junctions by atmospheric pressure PECVD

Atmospheric pressure glow discharge plasma assisted chemical vapor deposition process is used for the growth of carbon nanotubes (CNTs) on Inconel without using any external catalyst. Four different sets of samples are prepared by varying the growth time. The grown nanostructures are then characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. Field emission measurements are also done on the grown structures. Our investigations revealed that vertically aligned CNTs transformed into intramolecular junctions of CNTs with an increase in deposition time from 4 to 10 min. This time dependence for the transformation is investigated and correlated with other characterization results. It is seen that field emission behavior is the best for the vertically aligned CNTs but it also improves when the junctions of CNTs are present in the matrix after increasing growth time to 15 min. The investigations reveal that branching brings favorable defects in the grown CNTs that can give rise to impressive field emission current density. A schematic model has been prepared based on the experimental findings to find out the reason behind the growth of these junctions and how did they help in improving field emission.

Investigation of Gate-Stacked In-Ga-Zn-O TFTs with Ga-Zn-O Source/Drain Electrodes by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition.

Atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) was employed for the fabrication of indium gallium zinc oxide thin-film transistors (IGZO TFTs) with high transparent gallium zinc oxide (GZO) source/drain electrodes. The influence of post-deposition annealing (PDA) temperature on GZO source/drain and device performance was studied. Device with a 300 °C annealing demonstrated excellent electrical characteristics with on/off current ratio of 2.13 × 108, saturation mobility of 10 cm2/V-s, and low subthreshold swing of 0.2 V/dec. The gate stacked LaAlO3/ZrO2 of AP-IGZO TFTs with highly transparent and conductive AP-GZO source/drain electrode show excellent gate control ability at a low operating voltage.

Using KrF ELA to Improve Gate-Stacked LaAlO₃/ZrO₂ Indium Gallium Zinc Oxide Thin-Film Transistors with Novel Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition Technique.

Atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique and KrF excimer laser annealing (ELA) were employed for the fabrication of indium gallium zinc oxide thin-film transistors (IGZO-TFTs). Device with a 150 mJ/cm2 laser annealing densities demonstrated excellent electrical characteristics with improved on/off current ratio of 4.7×107, high channel mobility of 10 cm2/V-s, and low subthreshold swing of 0.15 V/dec. The improvements are attributed to the adjustment of oxygen vacancies in the IGZO channel to an appropriate range of around 28.3% and the reduction of traps at the high-k/IGZO interface.

Conference Proceedingon Nanomaterials and Nanochemistry Hard Carbon and Silica based Films Synthesized under Atmospheric Pressure

Atmospheric pressure-plasma enhanced chemical vapor deposition (AP-PECVD) method using a dielectric barrier discharge (DBD)is a cost-effective process because of no need of vacuum process. In this study, we synthesized silicabased films (SiO:CH) and hydrogenated amorphous carbon films (A-C:H) by AP-PECVD method. We synthesized SiO:CH films from tetramethoxysilane (TMOS) and O2 diluted with N2 and investigated the effect of the substrate temperature and the TMOS flow rate on hardness of the films. The hardness increased from 4.0 to 6.9 GPa as the substrate temperature increased from 80 to 300°C. To synthesize a-C:H films, filamentary DBD (FDBD) was used to improve the hardness compared to the films synthesized by glow DBD (GDBD), which is generally used for APCVD.The hardness of the films increased from 3.7 to 11.9 GPa by using FDBD.

Roll to roll atmospheric pressure plasma enhanced CVD of titania as a step towards the realisation of large area perovskite solar cell technology

Highly effective TiO2−x electron transport layers produced by continuous atmospheric pressure PECVD achieve efficiency gains in mesoporous perovskite photovoltaic cells.