• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.11
• /
• pp.1483-1491
• /
• 2001

Enhancement of pulsed-laser ablation by an artificially deposited liquid film is presented. Measurements of ablation rate, ablation threshold, and surface topography arc performed. Correlation between material ablation and photoacoustic effect is examined by the optical beam deflection method. The dependence of ablation rate on liquid-film thickness and chemical composition is also examined. The results indicate that photomechanical effect in the phase explosion of liquid is responsible for the enhanced ablation. The low critical temperature of liquid induces explosive vaporization with localized photoacoustic excitation in the superheat limit and increases the ablation efficiency. Experiments were carried out utilizing a Q-swiched Nd:YAG laser at near-threshold laser fluences with negligible plasma effect (up to ∼100 MW/cm$^2$).

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.451-455
• /
• 1995

The composition and thickness dependence and the ferromagnetic under- and overlayer effect on the magnetoresistance ratio and saturation field of the Co-Ag nano-granular films were investigated. The maximum magnetoresistance (23% at R.T.) in the as-deposited state was obtained in the $3000{\AA}$ $Co_{30} Ag_{70}$ bare alloy film. As the thickness of the alloy films decreased below $500{\AA}$, the MR ratio decreased because of the resistivity increase and the non-uniform film formation. We showed that the ferromagnetic over- and underlayer could reduce the saturation field of the nano-granular films via exchange coupling effect. The magnetoresistance and the saturation field of the $100{\AA}$ alloy film were 3.65 % and 2.85 kOe respectively and those of the under- and overlayered alloy films with $200{\AA}$ Fe were 3.3 % and 1.23 kOe respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.8 no.3
• /
• pp.125-130
• /
• 2007

DLC coating on ceramics is very useful for manufacturing the materials with hardness and low friction. Adhesion of DLC thin film on ceramics, on the other hand, is usually very weak. Adhesion of DLC film depends on many parameters such as contamination and chemical bonding between thin film and substrate. In this study, adhesion of DLC film on ceramics was improved by the intermediate layer when the plasma immersion ion deposition (PIID) technique was applied. It is found that the chemical composition and the thickness of intermediate layer have significantly an effect on the adhesion of DLC thin film on $Al_2O_3$.

• Journal of the Korean institute of surface engineering
• /
• v.50 no.3
• /
• pp.177-182
• /
• 2017

The properties of electroless Ni-B thin film on diamond powder with different parameters (temperature, pH, surfactant etc.) were studied. The surface morphology, structure and composition distribution of the Ni-B film were observed by field effect scanning electron microscope (FE-SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The growth rate of Ni-B film was increased with increase of bath temperature. The B content in Ni-B film was reduced with increase of bath pH. As a result the structure of Ni-B film was changed from amorphous to crystalline structure. The PVP in solution plays multi-functional roles as a dispersant and a stabilizer. The Ni-B film deposited with adding 0.1 mM-PVP was strongly introduced an amorphous structure with higher B content (25 at.%). Also the crystallite size of Ni-B film was reduced from 12.7 nm to 5.4 nm.

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.1
• /
• pp.33-36
• /
• 2010

$MgF_2$ is a current material used for optical applications in the ultraviolet and deep ultraviolet range. Process variables for manufacturing $MgF_2$ thin film were established in order to clarify the optimum conditions for the growth of the thin film, dependant upon the process conditions, and then by changing a number of the vapor deposition conditions, substrate temperatures, and heat treatment conditions, the structural and optical characteristics were measured. Then, optimum process variables were thus derived. Nevertheless, modern applications still require improvement in the optical and structural quality of the deposited layers. In the present work, in order to understand the composition and microstructure of $MgF_2$, single layers grown on a slide glass substrate using an Electron beam Evaporator (KV-660), were analyzed and compared. The surface substrate temperature, having an effect on the quality of the thin film, was changed from $200^{\circ}C$ to $350^{\circ}C$ at intervals of $50^{\circ}C$. The heat treatment temperature, which also has an effect on the thin film, was changed from $200^{\circ}C$ to $400^{\circ}C$ at intervals of $50^{\circ}C$. The physical properties of the thin film were investigated at various fabrication conditions, such as the substrate temperature, the heat treatment temperature, and the heat treatment time, by X-ray diffraction, and field emission-scanning electron microscopy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.251-251
• /
• 2010

Organic-inorganic hybrid materials have attracted because of its combined properties, such as flexibility and high electrical performance. In addition, the hybrid materials are expected to have synergic effect which are not shown in just one component. Here, we fabricated organic-inorganic hybrid thin film. Organic-inorganic hybrid thin film have been deposited from diethyl zinc and 1, 2, 4-trihydroxybenzene (THB) by molecular layer deposition (MLD). UV-VIS, Using Infrared spectrum and X-ray photoelectron spectroscopy confirm that Zinc and THB hybrid film (ZnTHB) consist of Zn-O and THB - oxide units and the micro structure and composition of hybrid film. hat the sequential surface reactions of diethyl zinc and ethylene glycol are sufficiently self-limiting and saturating to enable well-controlled MLD growth. Transmission electron microscopy image shows lamination growth of ZnTHB film according to cycle.

• Journal of the Semiconductor & Display Technology
• /
• v.10 no.3
• /
• pp.29-33
• /
• 2011

Film growth rate and composition variation are numerically analyzed during the selective area growth of InGaN on the GaN triangular stripe microfacet in this study. Both the vapor phase diffusion and the surface diffusion are considered to determine the In composition on the InGaN surface. To obtain the In composition on the surface, flux of In atoms due to the surface diffusion is added to the concentration determined from the Laplace equation which is governing the gas phase diffusion. The solution model is validated by comparing the growth rates from the analyses to the experimental results of GaN and InN films. The In composition and resulting wave length are increased when the surface diffusion is considered. The In content is also increased according to the increasing mask width. The effect of mask width to the In content and wave length is increasing in the case of a small open region.

• Journal of Sensor Science and Technology
• /
• v.21 no.4
• /
• pp.263-269
• /
• 2012

Al doped ZnO(AZO) thin films were deposited at different substrate temperatures by a continuous composition spread(CCS) method. Various compositions of Al doped ZnO thin films deposited at substrate temperatures between 0 and $250^{\circ}C$ were explored to find excellent electrical and optical properties. The AZO thin film deposited at $100^{\circ}C$ had the lowest resistivity, $9{\times}10^{-4}{\Omega}$ cm and its average transmittance at the 400 to 700 nm wavelength region was 92 %. Optimized composition of the AZO thin film which had the lowest resistivity and high transmittance was 3.13 wt% Al doped ZnO.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.2
• /
• pp.93-99
• /
• 1996

In this work BN thin films were deposited on Si substrate by R. F. sputtering method at $200^{\circ}C$ and in Ar + $N_2$ mixed gas atmosphere. In order to investigate the effect of ion bombardment on substrate for c-BN bonding, substrate bias voltage was applied. The optimum substrate bias voltage for c-BN bonding was determined by FTIR analysis on specimens which were deposited with various bias voltages. Then BN thin film was deposited with this optimum condition and its phase, morphology, chemical composition, and refractive index were compared with those of BN film which was deposited without bias voltage. FTIR results showed that BN films deposited with substrate bias voltage were composed of mixed phases of c-BN and h-BN, while those deposited without bias voltage were h-BN only. When pure Ar gas was used for sputtering gas, BN films were delaminated easily from substrate in air, while when 10% $N_2$ gas was added to the sputtering gas, although c-BN specific infrared peak was reduced, delamination did not occur. GXRD and TEM results showed that BN films were amorphous phases regardless of substrate bias voltage, and AES results showed that the chemical compositions of B/N were about 1.7~1.8. The refractive index of BN film deposited with bias voltage was higher than that without bias voltage. The reason is believed to be the existence of c-BN bonding in BN film and the higher density of film that deposited with the substrate bias voltage.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.378-380
• /
• 2009

$MgF_2$ is a current material for the optical applications in the UV and deep UV range. Process variables for manufacturing the $MgF_2$ thin film were established in order to clarify optimum conditions for growth of the thin film depending upon process conditions, and then by changing a number of vapor deposition conditions and substrate temperature, Annealing conditions variously, structural and Optical characteristics were measured. Thereby, optimum process variables were derived. Nevertheless, modern applications still require improvement of the optical and structural quality of the deposited layers. In the present work, the composition and microstructure of $MgF_2$ single layers grown on slide glass substrate by Electro beam Evaporator(KV-660) processes, were analyzed and compared. The surface Substrate temperature having an effect on the quality of the thin film was changed from $200[^{\circ}C]$ to $350[^{\circ}C]$ at intervals of $50[^{\circ}C]$. and annealing temperature an effect on the thin film was changed from $200[^{\circ}C]$ to $400[^{\circ}C]$ at intervals of $50[^{\circ}C]$. Physical properties of the thin film were investigated at various fabrication conditions substrate temperature, annealing and temperature, annealing time by XRD, FE-SEM.