Printed Devices Research Team

Yuseong gu, South Korea

Printed Devices Research Team

Yuseong gu, South Korea
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Bang J.,Pusan National University | Lee D.,Pusan National University | Kim S.,Inha University | Cheong W.,Printed Devices Research Team | Song P.,Pusan National University
Journal of Nanoelectronics and Optoelectronics | Year: 2011

This study examined the effect of the Zn concentration on the electrical and mechanical properties of ITO films on glass and PET substrates. Amorphous In-Sn-Zn-O (ITZO) films were successfully prepared on glass and polyethylene terephthalate (PET) substrates at room temperature. Deposition was carried out by magnetron co-sputtering system using two cathodes equipped with ITO targets (doped with 5, 7, 10 wt% SnO 2) and ZnO target as the In-Sn source and Zn source, respectively. The concentration of Zn in In-Sn-Zn-O films was controlled by adjusting the RF power supplied to the ZnO target while maintaining a constant DC power supply to the ITO target. It was confirmed that electrical properties, surface uniformity and mechanical durability were improved by the introduction of Zn atoms. The lowest resistivity (2.95×10 ?4ωcm) was obtained for the ITZO films deposited on PET substrate using an ITO target doped with 7 wt% SnO 2. © 2011 American Scientific Publishers All rights reserved.

Park H.W.,Pusan National University | Bang J.H.,Pusan National University | Hui K.N.,Pusan National University | Song P.K.,Pusan National University | And 2 more authors.
Materials Letters | Year: 2012

NiO-AZO thin films were prepared by DC and RF magnetron co-sputtering (MCS) system in an O 2 atmosphere. The lowest resistivity of 1.75 × 10 - 1 Ω cm was obtained in the film containing 1.94 mol% Al. The I-V measurements of the p-n junction ((NiO-AZO)/ITO) revealed rectifying characteristics, demonstrating that the film possess p-type conductivity. These results showed good agreement with the X-ray photoelectron spectroscopy (XPS) data by the higher bond enthalpy of Ni-O (382 ± 16.7 kJ/mol) than Zn-O (159 ± 4 kJ/mol). Moreover, the NiO-AZO films had a higher work function than NiO, highlighting the potential applications of transparent contact electrodes in Gallium nitride LEDs. © 2012 Elsevier B.V. All rights reserved.

Kim J.H.,Pusan National University | Kang C.G.,Pusan National University | Kim Y.T.,Pusan National University | Cheong W.S.,Printed Devices Research Team | Song P.K.,Pusan National University
Journal of Nanoscience and Nanotechnology | Year: 2013

Nanocytalline TiN films were deposited on non-alkali glass and Al substrates by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMF). The microstructure and corrosion resistance of the TiN-coated Al substrates were estimated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. All the TiN films shows that they have a (111) preferred orientation at room temperature. TiN films deposited on Al substrate using only DCMS 400 W showed a sheet resistance of 3.22×10-1 Ω/ (resistivity, 3.22×10-5 Ωcm). On the other hand, a relatively low sheet resistance of 1.91×10-1 Ω/ (1.91×10-5 Ωcm) was obtained for the dense nanocrystalline TiN film deposited on Al substrate using DCMS 375 W+EMF 25 W, indicating that the introduction of an EMF system enhanced the electrical properties of the TiN film. TiN films deposited on Al substrate at 400 °C had a (200) preferred orientation with the lowest sheet resistance of 1.28×10-1 Ω/(1.28×10-5 Ωcm) which was attributed to reduced nano size defects and an improvement of the crystallinity. Potentiostatic and Potentiodynamic tests with a TiN-coated Al showed good corrosion resistance (Icorr = 2.03 μA/cm2, Ecorr =-348 mV) compared to the uncoated Al substrate (Icorr = 4.45 μA/cm2, Ecorr = -650 mV). Furthermore, EMF system showed that corrosion resistance of the TiN film also was enhanced compared to DCMS only. For the TiN film deposited on Al substrate at 400 °C, corrosion current and potential was 0.63 μA/cm2 and -1.5 mV, respectively. This improved corrosion resistance of the TiN film could be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals. Copyright © 2013 American Scientific Publishers All rights reserved.

Oh S.H.,Pusan National University | Cho S.H.,Pusan National University | Cho S.H.,Daegu Technopark Nano Convergence Practical Application Center | Jung J.H.,Pusan National University | And 4 more authors.
Journal of Ceramic Processing Research | Year: 2012

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 °C at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10 -3Ωcm to 5.5 × 10 -1Ωcm, when GZO was post-annealed at 400 °C in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10 -3Ωcm (RT) to 1.2 × 10 -2Ωcm (400 °C), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

Chung A.,Pusan National University | Cho S.,Pusan National University | Cho S.,Daegu Technopark Nano Convergence Practical Application Center | Cheong W.,Printed Devices Research Team | And 3 more authors.
Journal of Ceramic Processing Research | Year: 2012

GZO/ITO double-layered films were deposited on non-alkali glass substrates by RF magnetron sputtering with various thicknesses at different deposition temperatures. The total thickness of the double layer was constant (~400 nm), and ITO thin films were prepared at various thicknesses (50, 150 and 250 nm) as function of the GZO film thickness (350, 250, 150 nm) at RT (or 200 °C). The resistivity of the double layer was found to be dependent on the thickness ratio between the two layers. The resistivity of the double-layered films decreased with increasing ITO film thickness according to the rules of parallel DC circuits of the two single layers. X-ray diffraction showed that the enhancement of the GZO (002) preferred orientation increased with increasing ITO thickness. The crystallinity of the GZO films was strongly affected by the microstructure of the buffer layer, which improved the Hall mobility and decreased the electrical resistivity. On the other hand, the crystallinity of the double layer decreased when the GZO films were deposited on the unstable buffer layer which was under post-annealed circumstances. In the case of the GZO(as-deposited at 200 °C)/ITO(RT) films, the diffusion of elements occurred between the upper and buffer layers, which caused microstructural changes in the films. This result was observed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The transmittance of the double layer was > 85% in the visible region, which suggests that these films will be suitable for photovoltaic devices.

Cheong W.-S.,Printed Devices Research Team | Sung M.C.,Printed Devices Research Team | Shin J.-H.,Printed Devices Research Team | Hwang C.-S.,Printed Devices Research Team
Journal of Crystal Growth | Year: 2011

Using ZnO, and three compositional In 2O 3-Ga 2O 3-ZnO (IGZO, In:Ga:Zn=1:1:1, 2:1:2, 2:2:1, atomic ratio) semiconductors, we have made and evaluated several double layered oxide thin-film transistors (TFTs). The drain current was mainly affected by the nearer channel material to a gate insulator. From the positive bias stress (PBS) tests, however, the electrical stability showed a complicated result, depending on both channel structures and post-heat treatments. © 2011 Elsevier B.V. All rights reserved.

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