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Kim K.H.,Korea Advanced Institute of Science and Technology | Hong S.H.,Korea Advanced Institute of Science and Technology | Cha S.I.,Korea Electrotechnology Research Institute | Lim S.C.,Korea Institute of Industrial Technology | And 2 more authors.
Materials Transactions | Year: 2010

The effects of surface roughness and heat treatment on the bonding quality of surface-activated bonding (SAB)-treated copper-nickel fine clad metals were investigated. An increase in the surface roughness of the copper layer decreased the peel strength after cladding, indicating that increases in the surface roughness decreased the contact area between the clad materials in the SAB cladding process, unlike conventional cold rolling that induces high deformation. In addition, the peel strength of the clad metals increased up to 7.3 N/mm wim decreasing surface roughness of the copper layer after heat treatment. The change in the total sheet resistance of the copper-nickel clad metal with the heat treatment depended on the balance between a decrease in the sheet resistance due to the reduction of dislocation and the increase in the heat treatment temperature, and an increase in the sheet resistance due to the diffusion of nickel in the copper direction. ©2010 The Japan Institute of Metals.

Lee Y.-S.,Inha University | Lee Y.-S.,Korea Institute of Materials Science | Yeon B.-H.,Inha University | Yeon B.-H.,Heesung Metal Ltd. | And 2 more authors.
Materials Letters | Year: 2012

A new type of periodic cellular metal called wire-woven bulk Kagome (WBK) was used as a precursor for creating the composite materials with improved dispersibility. Preheated and non-preheated preforms were placed into molds, and then molten aluminum was poured into them to fabricate composites. The effects of preheating on the wettability and interfacial reaction between the aluminum matrix and the WBK preform were then investigated. The preheated preform composite had good wettability compared to the non-preheated preform composite. Interfacial phenomena between the aluminum matrix and the WBK preform were observed. Our research offers a new avenue for solving the problem of composite material dispersibility. © 2012 Elsevier B.V. All rights reserved.

Cho S.H.,Electronics and Telecommunications Research Institute | Ko J.B.,Korea Advanced Institute of Science and Technology | Ryu M.K.,Electronics and Telecommunications Research Institute | Yang J.-H.,Electronics and Telecommunications Research Institute | And 4 more authors.
IEEE Transactions on Electron Devices | Year: 2015

We report the electrical characteristics of backchannel etch (BCE) metal-oxide-semiconductor thin-film transistor (TFT) comprised of aluminum-doped tin-zinc-indium oxide (ATZIO). It has high etch selectivity in wet chemical etchants, which consist of H3PO4, CH3COOH, and HNO3. This is contrary to the conventional metal-oxide-semiconductors of indium-gallium-zinc oxides, which are highly soluble in the acidic chemicals. As a result, no etch stop layer is needed to protect the backchannel from the wet etchant damage during the source and drain patterning in the bottom-gate-staggered TFT structure. This provides the possibility of oxide TFT fabrication process made as simple as that of the current amorphous silicon TFT using three or four photomasks with short channel length and less parasitic capacitance. The electrical characteristics of our ATZIO BCE-TFTs have the mobility of 21.4 cm2/Vs , subthreshold swing (S.S) of 0.11 V/decade, and threshold voltage of 0.8 V. In spite of the BCE structure, they have excellent stability against bias temperature stress, which shows the threshold voltage shifts of +0.75 V and-0.51 V under the prolonged positive (+20 V) and negative (-20 V) gate bias stresses for 10 000 s at 60 °C, respectively. © 2015 IEEE.

Lee S.-P.,Andong National University | Hwang B.,Andong National University | Paek Y.-K.,Andong National University | Chung T.-J.,Andong National University | And 4 more authors.
Journal of the European Ceramic Society | Year: 2013

The application of a two-step sintering route successfully decreased the sintering temperature of Al-doped ZnO transparent conducting oxide target. The two-step sintering consisted of initial heat treatment (IHT) at 800-1000 °C under mild (<2. MPa) external pressure, and pressureless final sintering at 1250-1350 °C in a separate furnace. The optimum IHTs for effective densification depended on the Al doping. The 800 °C IHT was effective for 1. wt.% Al doping, and the 1000 °C IHT, for 3. wt.% Al doping. As a result of the effective IHT, the volume of the micron sized pore decreased with the fragmentation into submicron pores. This suggests that cohesion of the secondary particles occurred during the effective IHT. The IHT temperature for achieving cohesion increased in the 3. wt.% Al doping. The criterion for determining the IHT in the two-step sintering was identified as the minimum temperature at which the cohesion of secondary particles can be achieved. © 2012 Elsevier Ltd.

Lee G.-E.,Korea National University of Transportation | Kim I.-H.,Korea National University of Transportation | Choi S.-M.,Korea University of Technology and Education | Lim Y.S.,Korea Institute of Ceramic Engineering And Technology | And 3 more authors.
Journal of the Korean Physical Society | Year: 2014

p-Type Bi2Te3-Sb2Te3 solid solutions were prepared by mechanical alloying (MA) and hot pressing (HP) under different process conditions, after which the transport and the thermoelectric properties were evaluated. The relative densities of all hot-pressed specimens were over 98%, and the microstructure and crystal orientation were independent of the HP direction. All specimens exhibited p-type conduction, and the electrical resistivity was observed to increase slightly with increasing temperature, indicating a degenerate semiconductor behavior. The carrier concentration decreased with increasing HP temperature while the mobility increased. The maximum figure of merit obtained was 0.86 at 323 K for Bi0.5Sb1.5Te3 hot-pressed at 648 K. © 2014, The Korean Physical Society.

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