• 한국초전도학회:학술대회논문집
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• v.9
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• pp.392-396
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• 1999

Superconducting YBa$_2Cu_3O_{7-{\delta}}$(YBCO) thin films were grown on Hastelloy(Ni-Cr-Mo alloys) with CeO$_2$ buffer layer in-situ by pulsed laser deposition in a multi-target processing chamber. To apply superconducting property on power transmission line, we have deposited YBCO thin film on flexible metallic substrate. However, it is difficult to grow the YBCO films on flexible metallic substrates due to both interdiffusion problem between metallic substrate and superconducting overlayers and non-crystallization of YBCO on amorphous substrate. It is necessary to use a buffer layer to overcome the difficulties. We have chosen CeO$_2$ as a buffer layer which has cubic structure of 5.41 ${\AA}$ lattice parameter and only 0.2% of lattice mismatch with 3.82 ${\AA}$ of a-axis lattice parameter of YBCO on [110] direction of CeO$_2$ In order to enhance the crystallization of YBCO films on metallic substrates, we deposited CeO$_2$ buffer layers with varying temperature and 02 pressure. By XRD, it is observed that dominated film orientation is strongly depending on the deposition temperature of CeO$_2$ layer. The dominated orientation of CeO$_2$ buffer layer is changed from (200) to(111) by increasing the deposition temperature and this transition affects the crystallization of YBCO superconducting film on CeO$_2$ buffered Hastelloy.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.61-66
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• 1998

High quality c-axis oriented $YBa_{2}Cu_{3}O_{7}$ films were prepared using the pulsed laser deposition on $SrTiO_{3}$(100) substrate. The atomically smooth $SrTiO_{3}$surface with terraces one unit cell in height could be obtained by a high temperature annealing. $YBa_{2}Cu_{3}O_{7}$ thin films deposited on the substrates exhibited layer-by-layer growth with a c-axis unit cell height. $YBa_{2}Cu_{3}O_{7}$ thin films thus prepared showed critical temperature ${\ge}90$ K with transition width ${\le}0.6$ K, room temperature resistivity of ${\sim}300{\mu}{\Omega}cm$, and critical current density ${\sim}4.6{\times}10^{6}A/cm^{2}$ at 77 K.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.341-341
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• 2012

Recently, oxide semi-conductor materials have been investigated as promising candidates replacing a-Si:H and poly-Si semiconductor because they have some advantages of a room-temperature process, low-cost, high performance and various applications in flexible and transparent electronics. Particularly, amorphous indium-gallium-zinc-oxide (a-IGZO) is an interesting semiconductor material for use in flexible thin film transistor (TFT) fabrication due to the high carrier mobility and low deposition temperatures. In this work, we demonstrated improvement of flexibility in IGZO TFTs, which were fabricated on polyimide (PI) substrate. At first, a thin poly-4vinyl phenol (PVP) layer was spin coated on PI substrate for making a smooth surface up to 0.3 nm, which was required to form high quality active layer. Then, Ni gate electrode of 100 nm was deposited on the bare PVP layer by e-beam evaporator using a shadow mask. The PVP and $Al_2O_3$ layers with different thicknesses were used for organic/inorganic multi gate dielectric, which were formed by spin coater and atomic layer deposition (ALD), respectively, at $200^{\circ}C$. 70 nm IGZO semiconductor layer and 70 nm Al source/drain electrodes were respectively deposited by RF magnetron sputter and thermal evaporator using shadow masks. Then, IGZO layer was annealed on a hotplate at $200^{\circ}C$ for 1 hour. Standard electrical characteristics of transistors were measured by a semiconductor parameter analyzer at room temperature in the dark and performance of devices then was also evaluated under static and dynamic mechanical deformation. The IGZO TFTs incorporating hybrid gate dielectrics showed a high flexibility compared to the device with single structural gate dielectrics. The effects of mechanical deformation on the TFT characteristics will be discussed in detail.

• Current Photovoltaic Research
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• v.3 no.3
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• pp.80-84
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• 2015

We suggest new emitter formation method using solid-phase epitaxy (SPE); solid-phase epitaxy emitter (SEE). This method expect simplification and cost reduction of process compared with furnace process (POCl3 or BBr3). The solid-phase epitaxy emitter (SEE) deposited a-Si:H layer by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) on substrate (c-Si), then thin layer growth solid-phase epitaxy (SPE) using rapid thermal process (RTP). This is possible in various emitter profile formation through dopant gas ($PH_3$) control at deposited a-Si:H layer. We fabricated solar cell to apply solid-phase epitaxy emitter (SEE). Its performance have an effect on crystallinity of phase transition layer (a-Si to c-Si). We confirmed crystallinity of this with a-Si:H layer thickness and annealing temperature by using raman spectroscopy, spectroscopic ellipsometry and transmission electron microscope. The crystallinity is excellent as the thickness of a-Si layer is thin (~50 nm) and annealing temperature is high (<$900^{\circ}C$). We fabricated a 16.7% solid-phase epitaxy emitter (SEE) cell. We anticipate its performance improvement applying thin tunnel oxide (<2nm).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.292-292
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• 2007

To apply PDP panel, Soda lime glass(SLG) is cheeper than Non-alkali glass and PD-200 glass but has problems such as low strain temperature and ion diffusion by alkali metal oxide. In this paper suggest the methode that prohibits ion diffusion by deposing barrier layer on SLG. Indium thin oxide(ITO) thin films and barrier layers were prepared on SLG substrate by Rf-magnetron sputtering. These films show a high electrical resistivity and rough uniformity as compared with PD-200 glass due to the alkali ion from the SLG on diffuse to the ITO film by the heat treatment. However these properties can be improved by introducing a barrier layer of $SiO_2\;or\;Al_2O_3$ between ITO film and SLG substrate. The characteristics of films were examined by the 4-point probe, SEM, UV-VIS spectrometer, and X-ray diffraction. GDS analysis confirmed that barrier layer inhibited Na and Ka ion diffusion from SLG. Especially ITO films deposited on the $Al_2O_3$ barrier layer had higher properties than those deposited on the $SiO_2$ barrier layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.8-9
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• 2006

Hafnium oxide ($HfO_2$) thin films were deposited on p-type (100) silicon wafers by atomic layer deposition (ALD) using TEMAHf and $O_3$. Prior to the deposition of $HfO_2$ films, a thin Hf ($10\;{\AA}$) metal layer was deposited. Deposition temperature of $HfO_2$ thin film was $350^{\circ}C$ and its thickness was $150\;{\AA}$. Samples were then annealed using furnace heating to temperature ranges from 500 to $900^{\circ}C$. The MOS capacitor of round-type was fabricated on Si substrates. Thermally evaporated $3000\;{\AA}$-thick AI was used as top electrode. In this work, We study the interface characterization of $HfO_2$/Hf/Si MOS capacitor depending on annealing temperature. Through AES(Auger Electron Spectroscopy), capacitance-voltage (C-V) and current-voltage (I-V) analysis, the role of Hf layer for the better $HfO_2$/Si interface property was investigated. We found that Hf meta1 layer in our structure effective1y suppressed the generation of interfacial $SiO_2$ layer between $HfO_2$ film and silicon substrate.

• Current Photovoltaic Research
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• v.2 no.1
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• pp.36-39
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• 2014

Formation mechanism of residual carbon layer, frequently observed in the $CuInSe_2$ (CIS) thin film prepared by direct solution coating routes, was investigated in order to find a way to eliminate it. As a model system, a methanol solution with dissolved Cu and In salts, whose viscosity was adjusted by adding ethylcellulose (EC), was chosen. It was found that a double layer, a top metal ion-derived film and bottom EC-derived layer, formed during an air drying step presumably due to different solubility between metal salts and EC in methanol. Consequently, the top metal ion-derived film acts as a barrier layer inhibiting further thermal decomposition of underlying EC, resulting a formation of bottom carbon residue layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.521-524
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• 2012

We report on variations of electrical properties with different active layer thickness and post-annealing temperature in amorphous In-Ga-Zn-O (IGZO) thin-film transistors (TFTs). In particular, subthreshold swing (SS) of the IGZO-TFTs was improved as increasing the active layer thickness at an given post-annealing temperature, accompanying the negative shift in turn-off voltage. However, as increasing post-annealing temperature, only turn-off voltage was shifted negatively with almost constant SS value. The effect of the active layer thickness and post-annealing temperature on electrical properties, such as SS, field effect mobility and turn-off voltage in IGZO-TFTs has been explained in terms of the variation of trap density in IGZO channel layer and at gate dielectric/IGZO interface.

• Applied Science and Convergence Technology
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• v.26 no.1
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• pp.11-15
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• 2017

To improve the adhesion of Mo thin film as a back contact material, a DC magnetron sputtering system was used to deposit in the form of a bi-layer on soda-lime glass. Films with low resistivity and good adhesion were obtained from this deposition, even though the two qualities were found be hard to obtain at the same time. The best Mo bi-layer showed a resistivity of $8.13{\times}10^{-4}{\Omega}{\cdot}cm$ at $500^{\circ}C$ and $3.0{\times}10^{-3}\;Torr$. The XRD measurements showed that the crystallites of the films were mainly oriented in the (110) direction, the FE-SEM images revealed that the resistivity of the Mo films decreased with increasing substrate temperature, which temperature reduction is accompanied by an increase of the grain size. These experimental results were analyzed using the Fuchs-Sondheimer theory. Our Mo bi-layer film with better crystallinity and lower resistivity can be suitably used as a back-contact layer for CIGS solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.267-268
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• 2005

In this paper, the inorganic-organic thin film encapsulation layer was newly adopted to protect the organic layer from moisture and oxygen. Using the electron beam, Sputter and Spin-Coater system, the various kinds of inorganic and organic thin-films were deposited onto the Ethylene Terephthalate(PET) and their interface properties between organic and inorganic layer were investigated. In this investigation, the SiON and Polyimide(PI) layer showed the most suitable properties. Under these conditions, the WVTR(water vapour transition rate) for PET can be reduced from level of 0.57 g/$m^2$/day (bare subtrate) to $1{\times}10^{-5}$ /$m^2$/day after application of a SiON and Polyimide layer. These results indicates that the SiON/PI/SiON/PI/PET barrier coatings have high potential for flexible organic light-emitting diode(OLED) applications.