• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.661-666
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• 1995

The surface structure of the adsorption site for the identification of active sites involved in the Ziegler-Natta catalyst was studied by surface science techniques. As an example of a real catalyst, TiCl3 single crystals were prepared in a gradient furnace designed for this study and characterized by Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED) under ultrahigh vacuum condition. The chlorine covered Ti (0001) surface was employed as a model catalyst for the study of Ziegler-Natta catalyst. The diffuse LEED (DLEED) technique for the surface structural determination was applied to this disordered chlorine adsorbed on Ti (0001) surface. The diffuse scattering intensities were measured by a TV-computer method using a low light level video camera. From an analysis of two catalyst systems, the informations for the surface structure of the model catalyst surfaces were derived.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.494-497
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• 1996

The effect of implanted nitrogen and carbon ion into SUS 304 on the absorption of hydrogen by cathodic chaging were studied. Implantations of $N^+$, $C^+$ were performed with doses of $3\times10^{17}$ ions $\textrm{cm}^2$ and $5\times10^{17}N^+cm^2$, and $5\times10^{17}C^+cm^2$, at an energy of 90 keV. Nitrides and carbide were investigatedby X-ray diffraction, Auger electron spectroscopy (AES) and scanning electron microscope (SEM). Formation of hydrides during cathodic charging were depressed by a modified surface layer. It is concluded that the both nitrides and carbides act as the barrier of hydrogen migration and the catalyst of desorption of cathodically charged hydrogen.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.14-19
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• 2011

We have fabricated GaN Schottky barrier diode (SBD) for high-voltage applications on Si substrate. The leakage current and the electrical characteristics of GaN SBD are investigated by annealing metal-semiconductor junctions. Ohmic junctions of Ti/Al/Mo/Au and Schottky junctions of Ni/Au are used in the fabrication. A test structure is proposed to measured buffer leakage current through a mesa structure. When annealing temperature is increased from $700^{\circ}C$ to $800^{\circ}C$, measured buffer leakage current is also increased from 87 nA to 780 nA at the width of 100 ${\mu}m$. The diffusion of Au, Ti, Mo, O into GaN buffer layer increases the leakage current and that is verified by Auger electron spectroscopy. Experimental results show that the low leakage current and the high breakdown voltage of GaN SBD are achieved by annealing metal-semiconductor junctions.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.79-80
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• 1994

A systematic study on isoelectronic impurities in thin-film eletroluminescent devices (TFELD) has been made on the basis of the experimental analysis aimed at a survey for the blue-emitting materials. Codoping effects of isoelectronic impurities, such as oxygen(O), tellurium(Te), and lithium(Li), on the emissive characteristics of ZnS:Ce$^{3+}$ and ZnS:Tm$^{3+}$TFELD have been investigated by means of the X-ray diffraction studies, the Auger electron spectroscopy, the cathodoluminescent spectra, and the electroluminescent spectra. Experiment results reveal that oxygen codoping gives rise to an increase of the luminance, due to a suppression of the nonradiative energy transfer via sulfur vacancies Te codoping in ZnS:Ce$^{3+}$ TFELD result in a large change in the crystal field around Ce$^{3+}$ ions. Li codoping in ZnS:Tm$^{3+}$ TFELD causes the luminance to increase slightly, due to a lowering in the symmetry of Tm$^{3+}$ions. Likewise, the experimental results suggest strongly that an Auger-type enegy loss via lattece defects such an sulfur vacancies acts as a non-emissive in TFELD.ve in TFELD.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.7-12
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• 1995

When a $Ta_O_5$ dielectric film is deposited on a bare silicon, the growth of $SiO_2$ at the $Ta_O_5$/Si interface cannot be avoided. Even though the $SiO_2$ layer is ultrathin (a few nm), it has great effects on the electrical properties of the capacitor. The concentration depth profiles of the ultrathin interfacial $SiO_2$ and $SiO_2/Si_3N_4$ layers were obtained using an Auger electron spectroscopy (AES) equipped with a cylindrical mirror analyzer (CMA). These AES depth profiles were quantitatively analyzed by comparing with the theoretical depth profiles which were obtained by considering the inelastic mean free path of Auger electrons and the angular acceptance function of CMA. The direct measurement of the interfacial layer thicknesses by using a high resolution cross-sectional TEM confirmed the accuracy of the AES depth analysis. The $SiO_2/Si_3N_4$ double layers, which were not distinguishable from each other under the TEM observation, could be effectively analyzed by the AES depth profiling technique.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.212-215
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• 2010

Spin polarized tunneling studies were carried out with Al-Ga bilayer as a spin detector, by Meservey-Tedrow technique. The superconductor (SC)/Insulator (I)/Ferromagnet (FM) tunnel junctions were provided by ultra high vacuum molecular beam epitaxy (UHV-MBE) technique. The analysis of interfacial properties in the Al-Ga bilayer was also carried out by Auger electron spectroscopy. It was observed that the superconducting transition temperature and energy gap were raised in comparison with that of bulk Ga and pure ultrathin Al films. Current studies clearly show how one can modify the material properties at the interface just with a few monolayers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.247-250
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• 2001

We studied optical properties of SiON thin-film in the applications of optical waveguide. SiON thin-film was grown in $300^{\circ}C$ by PECVD(plasma enhanced chemical vapor deposition) system. The change of SiON thin-film composition and refractive Index was studied as a function of varying $NH_3$ gas flow rate. As $NH_3$ gas flow rate was increased, Quantity of N and refractive index were increased at the same time. By the results, we could form the SiON thin-film to use of a waveguide with refractive index of 1.6. We analyzed the conditions of the thin-film with FTIR(fourier transform infrared) and OES (optical emission spectroscopy). N-H bonding($3390cm^{-1}$ ) can be removed by thermal annealing. And we could observe the SiH bonding state and quantity by OES analysis in $SiH_4$

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.38-45
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• 1999

Electrochemical lithium intercalation into a PECVD (plasma enhanced chemical vapour deposited) carbon film electrode was investigated in 1 M $LiPF_6-EC$ (ethylene carbonate) and DEC (diethyl carbonate) solution during lithium intercalation and deintercalation, by using cyclic voltammetry supplemented with ac-impedance spectroscopy. The size of the graphitic crystallite in the a- and c-axis directions obtained from the carbon film electrode was much smaller than those of the graphite one, indicating less-developed crystalline structure with hydrogen bonded to carbon, from the results of AES (Auger electron spectroscopy), powder XRD (X-ray diffraction) method, and FTIR(Fourier transform infra-red) spectroscopy. It was shown from the cyclic voltammograms and ac-impedance spectra of carbon film electrode that a threshold overpotential was needed to overcome an activation barrier to entrance of lithium into the carbon film electrode, such as the poor crystalline structure of the carbon film electrode showing disordered carbon and the presence of residual hydrogen in its structure. The experimental results were discussed in terms of the effect of host carbon structure on the lithium intercalation capability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.247-250
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• 2001

We studied optical properties of SiON thin-film in the applications of optical waveguide. SiON thin-film was grown in 300$^{\circ}C$ by PECVD(plasma enhanced chemical vapor deposition) system. The change of SiON thin-film composition and refractive Index was studied as a function of varying NH$_3$ gas flow rate. As NH$_3$ gas flow rate was increased, Quantity of N and refractive index were increased at the same time. By the results, we could form the SiON thin-film to use of a waveguide with refractive index of 1.6. We analyzed the conditions of the thin-film with FTIR(fourier transform infrared) and OES(optical emission spectroscopy). N-H bonding(3390cm$\^$-1/) can be removed by thermal annealing. And we could observe the SiH bonding state and quantity by OES analysis in SiH$_4$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.58-61
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• 1995

Instead of using CCl$_4$CCl$_2$F$_2$ gases, we used a alternative reaction gas of CFCs which we have developed, for the experiment of laser induced dry etching of laser induced dry etching of GaAs, and compared with the etch profile of a usual reation gas. Laser powers(power density) on the sample surface were varied from 100 mW(12.7 MW/$\textrm{cm}^2$) to 210mW(27 MW/$\textrm{cm}^2$) The laser beam was scanned over the sample by moving the cell with a speed raging from 8.3$\mu\textrm{m}$/sec and the gas pressure also was varied form 260 Torr to 760 Torr, High etching rates up to 136 $\mu\textrm{m}$/sec and an aspect ratio of 2.6 have been achieved by single scan of laser beam. The chemical compositions of the reaction products deposited on the etched groove were measured by Auger electron spectroscopy(AES) Etch profiles, including depth and width were observed by scanning electron microscopy(SEM)