In this study, tungsten (W) was coated on a copper (Cu) substrate by using double-glow discharge technique using a pure W panel as the target and argon (Ar) as the discharge and sputtering gas. The crystal structure of the W coating was examined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed with cross-section images to investigate the penetration depth of W into the Cu body. Additionally, the properties of wearability resistance, corrosion resistance and mechanical strength of the W coated Cu matrix were also measured. It is concluded that in double-glow plasma, W coated Cu can be facilely prepared. It is noticed that the treatment temperature heavily dominates the properties of the W-Cu composite.
In this study, argon and nitrogen were used as the discharge gases in radio-frequency (RF: 13.56 MHz) powered dielectric barrier atmospheric plasma. It was noticed that in single dielectric barrier discharge (DBD) with nitrogen as the discharge gas, or in argon plasma with a high applied power, micro-filament channels were easily formed. The channels in these two kinds of discharge were both constrictive on the bare metallic electrode and expansive on the opposite electrode covered with a quartz layer. The number of micro-channels was increased along with the input power, which caused the change in the I-V curve shape, i.e., the current kept increasing and the voltage fluctuated within a confined range. With double dielectric layers, however, no micro-channels appeared in the ICCD images, and the I-V curve demonstrated a totally different shape. It was assumed that micro-filaments exhibited a restraining effect on the discharge voltage. The mechanism of this restraining effect was explored in this work.
Atomic layer deposition(ALD) technique is used in the preparation of organic/inorganic layers,which requires uniform surfaces with their thickness down to several nanometers.For film with such thickness,the growth mode defined as the arrangement of clusters on the surface during the growth is of significance.In this work,Al 2 O 3 thin film was deposited on various interfacial species of pre-treated polyethylene terephthalate(PET,12 μm) by plasma assisted atomic layer deposition(PA-ALD),where trimethyl aluminium was used as the Al precursor and O 2 as the oxygen source.The interfacial species,-NH 3,-OH,and-COOH as well as SiCHO(derived from monomer of HMDSO plasma),were grafted previously by plasma and chemical treatments.The growth mode of PA-ALD Al 2 O 3 was then investigated in detail by combining results from in-situ diagnosis of spectroscopic ellipsometry(SE) and ex-situ characterization of as-deposited layers from the morphologies scanned by atomic force microscopy(AFM).In addition,the oxygen transmission rates(OTR) of the original and treated plastic films were measured.The possible reasons for the dependence of the OTR values on the surface species were explored.
Plasticizers that are generally used in plastics to produce flexible food packaging materials have proved to cause reproductive system problems and women's infertility.A longterm consumption may even cause cancer diseases.Hence a nano-scale layer,named as functional barrier layer,was deposited on the plastic surface to prevent plasticizer diethylhexyl phthalate's(DEHP) migration from plastics to foods.The feasibility of functional barrier layer i.e.SiO x coating through plasma enhanced chemical vapor deposition(PECVD) process was then described in this paper.We used Fourier transform infrared spectroscopy(FTIR) to analyze the chemical composition of coatings,scanning electron microscope(SEM) to explore the topography of the coating surfaces,surface profilemeter to measure thickness of coatings,and high-performance liquid chromatography(HPLC) to evaluate the barrier properties of coatings.The results have clearly shown that the coatings can perfectly block the migration of the DEHP from plastics to their containers.It is also concluded that process parameters significantly influence the block efficiency of the coatings.When the deposition conditions of SiO x coatings were optimized,i.e.50 W of the discharge power,4:1 of ratio of O 2:HMDSO,and ca.100 nm thickness of SiO x,71.2% of the DEHP was effectively blocked.
Without extra heating, Al2O3 thin films were deposited on a hydrogen-terminated Si substrate etched in hydrofluoric acid by using a self-built electron cyclotron resonance (ECR) plasma-assisted atomic layer deposition (ALD) device with Al(CH3)3 (trimethylaluminum; TMA) and O2 used as precursor and oxidant, respectively. During the deposition process, Ar was introduced as a carrier and purging gas. The chemical composition and microstructure of the as-deposited Al2O3 films were characterized by using X-ray diffraction (XRD), an X-ray photoelectric spectroscope (XPS), a scanning electron microscope (SEM), an atomic force microscope (AFM) and a high-resolution transmission electron microscope (HRTEM). It achieved a growth rate of 0.24 nm/cycle, which is much higher than that deposited by thermal ALD. It was found that the smooth surface thin film was amorphous alumina, and an interfacial layer formed with a thickness of ca. 2 nm was observed between the Al2O3 film and substrate Si by HRTEM. We conclude that ECR plasma-assisted ALD can grow Al2O3 films with an excellent quality at a high growth rate at ambient temperature.
This work reports the experimental results on the characteristics of radio frequency dielectric barrier N2 /Ar discharges.Depending on the nitrogen content in the feed gas and the input power,the discharge can operate in two diferent modes: a homogeneous glow discharge and a constricted discharge.With increasing input power,the number of discharge columns increases.The discharge columns have starlike structures and exhibit symmetric self-organized arrangement.Optical emission spectroscopy was performed to estimate the plasma temperature.Spatially resolved gas temperature measurements,determined from NO emission rotational spectroscopy were taken across the 4.4 mm gap filled by the discharge.Gas temperature in the middle of the gas gap is lower than that close to the electrodes.
In this paper, we report silicon oxide coatings deposited by plasma enhanced chemical vapor deposition technology(PECVD) on 125 μm polyethyleneterephthalate(PET) surfaces for the purpose of the shelf lifetime extension of sealed polymer solar cells. After optimization of the processing parameters, we achieved a water vapor transmission rate(WVTR) of ca. 10-3g/m2/day with the oxygen transmission rate(OTR) less than 0.05 cc/m2/day, and succeeded in extending the shelf lifetime to about 400 h in encapsulated solar cells. And then the chemical structure of coatings related to the properties of encapsulated cell was investigated in detail.
