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pISSN : 1225-1429 / eISSN : 2234-5078

2020 KCI Impact Factor : 0.17
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2020, Vol.30, No.5

  • 1.

    Crystal growth of ring-shaped SiC polycrystal via physical vapor transport method

    Jin Yong Park | Jeong-Hui Kim | Woo-Yeon Kim and 5other persons | 2020, 30(5) | pp.163~167 | number of Cited : 0
    Abstract PDF
    Ring-shaped SiC (Silicon carbide) polycrystals used as an inner material in semiconductor etching equipmentwas manufactured using the PVT (Physical Vapor Transport) method. A graphite cylinder structure was placed inside thegraphite crucible to grow a ring-shaped SiC polycrystal by the PVT method. The crystal polytype of grown crystal wereanalyzed using a Raman and an UVF (Ultra Violet Fluorescence) analysis. And the microstructure and components of SiCcrystal were identified by a SEM (Scanning Electron Microscope) and EDS (Energy Disruptive Spectroscopy) analyses. Thegrain size and growth rate of SiC polycrystals fabricated by this method was varied with temperature variation in the initialstage of growth process.
  • 2.

    A study on the thermal oxidation process of bulk AlN single crystal grown by PVT

    Hyo Sang Kang | Kang, Seung-Min | 2020, 30(5) | pp.168~173 | number of Cited : 0
    Abstract PDF
    To analyze and describe the behavior and mechanisms occurring in the thermal oxidation process of AlN, bulkAlN single crystals were thermally treated with different temperatures. As a result, it was confirmed that full-scaleoxidation of bulk AlN and growth of Al-oxide occurred from the temperature of 800oC, which confirmed that the weight%of O elements tended to increase while the N elements decreased with increasing the temperature. In the case of thermaltreatment at 900oC, the grown Al-oxides were merged with neighboring Al-oxides and began to form -Al2O3 poly-crystals. During thermal treatment at the temperature of 1000oC, hexagonal pyramidal shaped poly-crystalline -Al2O3 was clearlyobserved. Through the X-ray diffraction pattern analysis, the changes of surface crystal structure according to thetemperature of bulk AlN were investigated in detail.
  • 3.

    Rheological behavior and IPL sintering properties of conductive nano copper ink using ink-jet printing

    Jae Young Lee | Do Kyeong Lee | Nahm, Sahn and 3other persons | 2020, 30(5) | pp.174~182 | number of Cited : 0
    Abstract PDF
    The printed electronics field using ink-jet printing technology is in the spotlight as a next-generation technology,especially ink-jet 3D printing, which can simultaneously discharge and precisely control various ink materials, has beenactively researched in recent years. In this study, complex structure of an insulating layer and a conductive layer wasfabricated with photo-curable silica ink and PVP-added Cu nano ink using ink-jet 3D printing technology. A precise photocuredsilica insulating layer was designed by optimizing the printing conditions and the rheological properties of the ink,and the resistance of the insulating layer was 2.43 × 1013·cm. On the photo-cured silica insulating layer, a Cu conductivelayer was printed by controlling droplet distance. The sintering of the PVP-added nano Cu ink was performed using anIPL flash sintering process, and electrical and mechanical properties were confirmed according to the annealing temperatureand applied voltage. Finally, it was confirmed that the resistance of the PVP-added Cu conductive layer was very low as29 ·cm under 100oC annealing temperature and 700 V of IPL applied voltage, and the adhesion to the photo-cured silicainsulating layer was very good.
  • 4.

    Electrical properties of PZN-PZT thick films formed by aerosol deposition process

    Ochirkhuyag Tungalaltamir | Joo-Hee Jang | Yoon-Soo Park and 2other persons | 2020, 30(5) | pp.183~188 | number of Cited : 0
    Abstract PDF
    Lead zinc niobate (PZN)-added lead zirconate titanate (PZT) thick films with thickness of 5~10 m werefabricated on silicon and sapphire substrates using aerosol deposition method. The contents of PZN were varied from 0 %,20 % and to 40 %. The PZN-added PZT film showed poorer electrical properties than pure PZT film when the films werecoated on silicon substrate and annealed at 700oC. On the other hand, the PZN-added PZT film showed higher remanentpolarization and dielectric constant values than pure PZT film when the films were coated on sapphire and annealed at900oC. The ferroelectric and dielectric characteristics of 20 % PZN-added PZT films annealed at 900oC were comparedwith the result values obtained from bulk ceramic specimen with same composition sintered at 1200oC. As annealingtemperature increased, dielectric constant increased. These came from enhanced crystallization and grain growth by postheat treatment.
  • 5.

    Fabrication of flexible sponge electrodes using Ag nanowires

    Kyoung Ryeol Park | Sehoon Yoo | Ryu, Jeong-ho and 1other persons | 2020, 30(5) | pp.189~193 | number of Cited : 0
    Abstract PDF
    Recently, various methods for preparing a flexible electrode for implementing a wearable sensor have beenintroduced. Wearable sensors show similar tendency to use various polymer substrates, which provides elasticity suitable tothe motion of human body. In this paper, a highly elastic silver nanowire based electrode was prepared on a sponge-basedstretchable substrate, and electrical properties were evaluated. Silver nanowires were grown using a wet chemical synthesis,impregnated into a plasma-treated sponge, and then heat treated at a low temperature. In particular, the plasma surface treatmentof the sponge enables uniform coating of silver nanowires. The flexible sponge electrode showed reliable electrical resistancechanges over 160 repeated tensile-compression cycles.
  • 6.

    The synthesis of ultrathin Nb-doped TiOx nanosheets

    Sang Eun Lee | Seo Jun | Park, Hee Jung | 2020, 30(5) | pp.194~199 | number of Cited : 0
    Abstract PDF
    By controlling the composition of the metal-oxide nanosheet having a two-dimensional layered crystal structure,material properties and application can be extended. In this study, the composition of the nanosheet could be expanded frompure composition to doping composition by successfully synthesizing the TiO2 nanosheet doped with Nb. Specifically, thedoping composition was designed when synthesizing the layered metal oxide as a starting material (K0.8Ti1.73xNbxLi0.27O4,x = 0, 0.03, 0.07) and chemical exfoliation was performed. By doing this, it was possible to obtain the Nb-doped TiOyultrathin nanosheet. The size of the nano sheet was 2 m or less based on the long length in the x-y direction, and thethickness was about 1 nm. Nb-doping was confirmed by XRD and SEM-EDS analysis.
  • 7.

    Oxidation behavior of (Mo1xWx)Si2 high-temperature heating elements

    Sung-Chul Lee | Jaeha Myung | Yongnam Kim and 4other persons | 2020, 30(5) | pp.200~207 | number of Cited : 0
    Abstract PDF
    MoSi2, (Mo1/2W1/2)Si2, and WSi2 powders were synthesized by self-propagating high-temperature synthesis (SHS)method. The synthesized powders were heat-treated at 500, 1,000, 1,200, 1,300, 1,400, 1,500 and 1,600oC in ambientatmosphere. Oxidation of Mo-W silicide powder was found at low temperature of 500oC. XRD structure analysis and DTA/TG data showed that MoO3 w as f ormed w ith 5 00oC heat treatment for 1 hour, and that it was -cristobalite phase that wasformed with 1200oC heat treatment, not -quartz phase which is commonly found and stable at room temperature. Existence of W accelerated decomposition at both low and high temperature. Fully sintered MoSi2 and (Mo1/2W1/2)Si2specimen did not show decomposition or weight loss by oxidation, with 1 hour heat treatment at either low or hightemperature. Notably, it was difficult to sinter WSi2 because of oxidation reaction at low temperature.
  • 8.

    Thermal displacement minimization of an oxide target for bonding process by finite element analysis and optimal design

    Hanyoung Cha | Chan-Yeup Chung | 2020, 30(5) | pp.208~213 | number of Cited : 0
    Abstract PDF
    In this research, design optimization was investigated using the finite element analysis and the optimal designtechnique based on the PQRSM algorithm to minimize the thermal deformation of IGZO oxide in a target module inwhich IGZO oxide and a copper backplate are bonded to each other. In order to apply the optimal design technique inconjunction with finite element analysis, the x-coordinate of lower supports and upper fixed boards used as designvaluables, and the optimal design was performed to minimize the thermal displacement of IGZO materials as the objectivefunction. After the optimization process, the thermal displacement within IGZO oxide could be reduced to 42 % comparingwith the initial model. The result is thought to be useful in the industry as it can reduce the thermal deformation of targetoxides materials only by changing the position of the subsidiary materials during the bonding process.