• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.550-552
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• 2003

We prepared $Co_{77}Cr_{20}Ta_3$ Magnetic layer for perpendicular magnetic recording media with introduce Two-step methode and Amorphous Si Underlayer on slide glass substrate. The thickness of magnetic layer were 100nm, and Underlayer were varied from 5 to 100 nm. The multi layer Properties of crystal structure were examined with XRD. Prepared thin films showed improvement of dispersion angle of c-axis orientation ${\Delta}{\theta}_{50}$ caused by inserting Buffer-layer and amorphous Si underlayer.

• Journal of Magnetics
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• v.21 no.1
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• pp.35-39
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• 2016

$Cr_{100-x}Ti_x$ amorphous texture-inducing layers (TIL) were investigated to realize highly (002) oriented $L1_0$ FePt-C granular films through hetero-epitaxial growth on the (002) textured bcc-$Cr_{80}Mn_{20}$ seed layer (bcc-SL). As-deposited TILs showed the amorphous phase in Ti content of $30{\leq}x(at%){\leq}75$. Particularly, films with $40{\leq}x{\leq}60$ kept the amorphous phase against the heat treatment over $600^{\circ}C$. It was found that preference of the crystallographic texture for bcc-SLs is directly affected by the structural phase of TILs. (002) crystallographic texture was realized in bcc-SLs deposited on the amorphous TILs ($40{\leq}x{\leq}70$), whereas (110) texture was formed in bcc-SLs overlying on crystalline TILs (x < 30 and x > 70). Correlation between the angular distribution of (002) crystal orientation of bcc-SL evaluated by full width at half maximum of (002) diffraction (FWHM) and a grain diameter of bcc-SL indicated that while the development of the lateral growth for bcc-SL grain reduces FWHM, crystallization of amorphous TILs hinders FWHM. $L1_0$ FePt-C granular films were fabricated under the substrate heating process over $600^{\circ}C$ with having different FWHM of bcc-SL. Hysteresis loops showed that squareness ($M_r/M_s$) of the films increased from 0.87 to 0.95 when FWHM of bcc-SL decreased from $13.7^{\circ}$ to $3.8^{\circ}$. It is suggested that the reduction of (002) FWHM affects to the overlying MgO film as well as FePt-C granular film by means of the hetero-epitaxial growth.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1071-1074
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• 2006

Ca/Ag double layer which is fabricated by thermal evaporation exists as the double layer of (Ca+O)/(Ag+Ca). In Ca layer, are crystalline Ca(OH)2 and amorphous Ca and in Ag layer, are crystalline Ag and amorphous Ca. And for the certain thickness of Ag, in the Ca/Ag double layer, the thicker Ca is, the higher transmittance is.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.849-852
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• 2002

Recently, amorphous selenium is used as x-ray conversion material for flat-panel x-ray detector. In this paper, we investigated the effect of breakdown under high voltage and leakage current in PN-type multi-layer structure based on p-type a-Se and n-type conductive thin film. Experimental results show that the multi-layer based detector reduced leakage current because n-type CeO2 conductive layer prevent from hole injection into a-Se layer from collection electrode, Also, the breakdown voltage was improved by dielectric layer between a-Se and top electrode.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.91-99
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• 1994

Damage induced by Si ion implantation and its annealing behavior during rapid thermal annealing were investigated by cross-sectional TEM (transmission electron microscopy) and RB ( Rutherford backscattering) spectrum. 150keV and 50keV Si ions were implanted in Si (100) at room temperature with doses of 2${\times}10^{15}cm^{-2}$. And 100keV Si ions were implanted in Si with doses from 1${\times}10^{14}cm^{-2}$. A variety of damage structures were generated by Si ion implantation such as continuous amorphous layer extending to the surface buried amorphous layer and damage clusters. Damage clusters are annealed out at the lower annealing temperature of 550 $^{\circ}C$. However, event at the temperature of 110$0^{\circ}C$ end of range loops remain in the original lower amorphous/crystal interface in the case of continuous and buried amorphous layer formation. Extended defects in the shape of zipper dislocations are also observed at the middle of the recrystallized region in the buried amorphous layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.403-404
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• 2012

We fabricated TFT devices with the GeSe channel. A single device consists of a Pt source and drain, a Ti glue layer and a GeSe chalcogenide channel layer on SiO2/Si substrate which worked as the gate. We confirmed the drain current with variations of gate bias and channel size. The I-V curves of the switching device are shown in Fig. 1. The channel of the device always contains amorphous state, but can be programmed into two states with different threshold voltages (Vth). In each state, the device shows a normal Ovonic switching behavior. Below Vth (OFF state), the current is low, but once the biasing voltage is greater than Vth (ON state), the current increases dramatically and the ON-OFF ratio is high. Based on the experiments, we draw the conclusion that the gate voltage can enhance the drain current, and the electric field by the drain voltage affects the amorphous-amorphous transition. The switching device always contains the amorphous state and never exhibits the Ohmic behavior of the crystalline state.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.280-281
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• 2011

We fabricated the devices of TFT type with the amorphous chalcogenide channel. A single device consists of a Pt source and drain, a Ti glue layer and a GeSe chalcogenide channel layer on SiO2/Si substrate which worked as the gate. We confirmed the drain current with variations of gate bias and channel size. The I-V curves of the switching device are shown in Fig. 1. The channel of the device always contains amorphous state, but can be programmed into two states with different threshold voltages (Vth). In each state, the device shows a normal Ovonic switching behavior. Below Vth (OFF state), the current is low, but once the biasing voltage is greater than Vth (ON state), the current increases dramatically and the ON-OFF ratio is about 4 order. Based on the experiments, we contained the conclusion that the gate voltage can enhance the drain current, and the electric field by the drain voltage affects the amorphous-amorphous transition. The switching device always contains the amorphous state and never exhibits the Ohmic behavior of the crystalline state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.77-80
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• 2001

Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation $\Delta$$\theta$$_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 2000e. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer.t also seed layer.r.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.94-99
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• 1994

The purpose of this work is to investigate the interface characteristics of hydrogenated amorphous silicon thin films prepared by PECVD and photo-induced CVD and to examine the annealing effects of ultraviolet irradiation on hydrogenated amorphous silicon thin films which were degraded by visible light illumination. The interface layer thickness of films deposited by photo-induced CVD was about 600-900.angs. while that by PECVD was about 1000-1300.angs.. These results can show that the quality of interface layer in photo induced CVD film is better than that in PECVD sample. The electrical properties are improved by ultraviolet irradiation on visible light soaked a-Si:H films using photo-CVD light sources, probably due to the fact that UV generates phonons in a-Si:H films and anneal the meta stable defects.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1047-1055
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• 2010

The objective of this study is to investigate the ballistic properties of Zr-based amorphous alloy surface composites fabricated by high-energy electron-beam irradiation. The mixture of Zr-based amorphous powders and $LiF+MgF_2$ flux powders was deposited on a pure Ti substrate, and then an electron beam irradiated this powder mixture to fabricate a one-layer surface composite. A four-layer surface composite, in which the composite layer thickness was larger than 3 mm, was also fabricated by irradiating the deposited powder mixture by an electron beam three times on the one-layer surface composite. The microstructural analysis results indicated that a small amount of fine crystalline particles were homogeneously distributed in the amorphous matrix of the surface composite layer. According to the ballistic impact test results, the surface composite layers effectively blocked a fast traveling projectile, while many cracks were formed at the composite layers, and thus the surface composite plates were not perforated. The surface composite layer containing ductile ${\beta}$ dendritic phases showed a better ballistic performance than the one without dendrites because dendritic phases hindered the propagation of shear bands or cracks.