• Journal of Surface Science and Engineering
• /
• v.35 no.2
• /
• pp.122-128
• /
• 2002

This study was conducted to synthesize the diamond like carbon films by plasma enhanced chemical vapor deposition (PECVD). The effects of gas composition on growth and mechanical properties of the films were investigated. A little amount of hydrogen or oxygen were added to base gas mixture of methane and argon. Methane dissociation and diamond like carbon nucleation were enhanced by installing negatively bias grid near substrate. The deposited films were indentified as hard diamond like carbon films by micro-Raman spectroscopy. The surface and fractured cross section of the films which were observed by scanning electron microscopy showed that film growth is very slow as about 0.3$\mu\textrm{m}$/hour, and relatively uniform with hydrogen addition. Vickers hardness of tungsten carbide (WC) cutting tool increased from about 1000 to 1600~1800 by deposition of DLC film, that of commercial TiN coated tool was about 1270. In cutting test of aluminum 6061 alloy, DLC coated cutting tool showed 1/3 or lower crater and flank wear than TiN coated or non-coated WC cutting tools.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.4
• /
• pp.63-69
• /
• 1994

The Ultrahigh Vacuum Electron Cyclotron Resonance Chemical Vapor Deposition(UHV-ECRCVD) system whose base pressure is 1${\times}10^{9}$ torr has been constructed. In-situ cleaning prior to the epitaxial growth was carried out at 56$0^{\circ}C$ by ECR generated uniform hydrogen plasma whose density is $10^{10}/cm{3}$. The natural oxide was effectively removed without damage by applying positive DC bias(+10V) to the substrate. RHEED(Reflection High Energy Electron Diffraction) analysis has been used to confirm the removal of the surgace oxide and the streaky 2$\times$1 reconstruction of the Si surface, and the suppression of the substrate damage is anaylized by X-TEM(cross-sectional Transmission Electron Microscopy). Surface cleaning technique by ECR hydrogen plasma confirmed good quality epitaxial growth at low temperature.

• Proceedings of the KIEE Conference
• /
• 1987.07a
• /
• pp.513-516
• /
• 1987

Hydrogenated amorphous silicon (a-Si:H) films have been deposited, for thye first time, by a remote plasma chemical vapor deposition. The hydrogen radical play a important role to control the deposition rate, The bonded hydrogen content to silicon is independent of hydrogen partial pressure in the plasma. Optical gap of deposited a-Si:H lies between 1.7eV and 1.8eV and all samples have sharp absorption edge. B-doped a-Si:H films by a RPECVD has a high doping efficiency compared with plasma CVD. The Fermi level of 100ppm B-doped film lies at 0.5eV above valence band edge.

• Journal of Surface Science and Engineering
• /
• v.42 no.5
• /
• pp.232-239
• /
• 2009

This study presented the effect of membrane thickness on hydrogen permeability. Microvoids on the surface of the membrane should not exist for the exact values of hydrogen permeability. Pd-Cu-Ni hydrogen alloy membranes were fabricated by Ni powder sintering, substrate plasma pretreatment, sputtering and Cu reflow process. And this leaded to void-free surface and dense film of Pd-Cu-Ni hydrogen alloy membrane. Hydrogen permeation test showed that hydrogen permeability increased from 2.7 to $15.2ml/cm^2{\cdot}min{\cdot}atm^{0.5}$ as membrane thickness decreased from 12 to $4{\mu}m$. This represented the similar trend as a hydrogen permeability of pure palladium membrane based on solution-diffusion mechanism.

• Journal of Energy Engineering
• /
• v.18 no.2
• /
• pp.141-146
• /
• 2009

In present work, we study the hydrogen storage of MWNT decorated with bimetallic Pt and Pd nanosize catalysts by Thermal Vapor Deposition [TVD]. The size of Pt and Pd particles is controlled as 5nm, 3nm, respectively by TVD. Before hydrogen storage measurement, the sample was heated for 1hr at $200^{\circ}C$ in H2 atmosphere. The Hydrogen sto rage of the sample was performed at room temperature and 33~34atm. The hydrogen storage of this composite showed 3.2wt% at 298K and 34atm, for three times. At 4th cycle, hydrogen storage is decreased to 1.5wt%, owing to the aggregation of bimetallic Pt and Pd nano particles.

• Journal of Surface Science and Engineering
• /
• v.49 no.3
• /
• pp.286-300
• /
• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.476-479
• /
• 2000

In this study, mesh-type PECVD system was suggested to minimize the hydrogen concentration. The main structural difference between the triode system and a conventional system is that a mesh was attached to the substrate holding electrode. We investigated several conditions to compare with conventional PECVD. The main effect of mesh was to minimize the substrate damage by ion bombardment and to enhance the surface reaction to induce hydrogen desorption. It was also found that hydrogen concentration decreased but deposition rate increased as increasing applied dias. Applied DC bias enhanced sputtering process. Intense ion bombardment causes the weakly bonded hydrogen or hydrogen-containing species to leave the growing film and increased adatom mobility. Furthermore, addition of hydrogen gas enhance the surface diffusion of adatom. The structural properties of poly-Si films were analyzed by scanning electron microscopy(SEM).

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.45-48
• /
• 2007

Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syn-gas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums and $WO_{3}/ZrO_{2}$. Thermochemical 2-step methane reforming were accomplished at 900 $^{\circ}C$(syn-gas production step) and 800 $^{\circ}C$(water-splitting step). In syn-gas production step, it appeared carbon deposition on metal oxides with increasing react ion time. Various mediums showed the different starting point of carbon deposition each other. To minimize the carbon deposition, the reaction time was controlled before the starting point of carbon deposition. As a result, $CO_{x}$ were not evolved in water-splitting step, Among the various metal oxides, $Mn-ferrite/ZrO_{2}$ showed high reactivity, proper $H_{2}/CO$ ratio, high selectivity of undesired $CO_{2}$ and high evolution of $H_{2}$.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.339.1-339.1
• /
• 2014

In this paper we studied the application of inter-poly dielectric as silicon dioxide-like film was deposited by the higher energy assisting deposition (HEAD) process the modified CCP process, which enables low temperature (LT) process and improving film density. In these experiments the relative hydrogen concentration of $SiO_2$-like films deposited on silicon substrate were analyzed by the secondary ion mass spectroscopy (SIMS) and it was shown that our lower hydrogenated oxide (LHO) film prepared by HEAD process with the precursor contained the siloxane species had lower hydrogen concentration, $8{\times}10{\cdot}^{22}cm{\cdot}^3$ than that of the commercial undoped silicon glass (USG) film ($1{\times}10{\cdot}^{21}cm{\cdot}^3$) prepared by the high density plasma-chemical vapor deposition (HDP-CVD). We consider that the LHO film deposited by HEAD process used as high performance material into Flash memory devices.

• Korean Journal of Materials Research
• /
• v.19 no.2
• /
• pp.102-107
• /
• 2009

The effect of annealing under argon atmosphere on hydrogenated amorphous silicon (a-Si:H) thin films deposited at room temperature and $300^{\circ}C$ using Radio Frequency (RF) magnetron sputtering has been investigated. For the films deposited at room temperature, there was not any increase in hydrogen content and optical band gap of the films, and as a result, quality of the films was not improved under any annealing conditions. For the films deposited at $300^{\circ}C$, on the other hand, significant increases in hydrogen content and optical band gap were observed, whereas values of microstructure parameter and dark conductivity were decreased upon annealing below $300^{\circ}C$. In this study, it was proposed that the Si-HX bonding strength is closely related to deposition temperature. Also, the improvement in optical, electrical and structural properties of the films deposited at $300^{\circ}C$ was originated from thermally activated hydrogen bubbles, which were initially trapped at microvoids in the films.