• Korean Journal of Materials Research
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• v.16 no.6
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• pp.351-354
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• 2006

[ $Co_{1-x}Fe_xSb_3$ ] skutterudites were synthesized by encapsulated induction melting and their thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by the subsequent heat treatment at 773 K for 24 hours in vacuum. However, ${\delta}-CoSb_3$ was decomposed to FeSb2 and Sb when $x{\leq}0.3$, which means that the solubility limit of Fe to Co is x<0.3. The positive signs of Seebeck coefficients for all Fe-doped specimens revealed that Fe atoms acted as p-type dopants by substituting Co atoms. Thermoelectric properties were remarkably enhanced by Fe doping and optimum composition was found to be $Co_{0.7}Fe_{0.3}Sb_3$ in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.369-372
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• 2004

The characteristics of antimony implants are relatively well-known. Antimony has lower diffusion coefficient, shorter implantation range, and smaller scattering as compared with conventional dopants such as phosphorous and arsenic. It has been commonly used in the doping of buried layer in Bi-CMOS process. In this paper, characteristics and appropriate condition of monitoring in antimony implant beam tuning using $Sb_2O_3$ were investigated to get a reliable process. TW(Thema Wave) and Rs(Sheet Resistance) test were carried out to set up condition of monitoring for stable operation through the periodic inspection of instruction condition. The monitoring was progressed at the point that the slant of Rs varied significantly to investigate the variation of instruction accurately.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.331-337
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• 2015

$LaBO_3$ (B = Cr, Mn, Fe, Co, and Ni) perovskites, the most common perovskite-type mixed ionic-electronic conductors (MIECs), are promising candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The catalytic activity on MIEC-based cathodes is closely related to the bulk ionic conductivity. Doping B-site cations with other metals may be one way to enhance the ionic conductivity, which would also be sensitively influenced by the chemical composition of the dopants. Here, using density functional theory (DFT) calculations, we quantitatively assess the activation energies of bulk oxide ion diffusion in $LaBO_3$ perovskites with a wide range of combinations of B-site cations by calculating the oxygen vacancy formation and migration energies. Our results show that bulk oxide ion diffusion dominantly depends on oxygen vacancy formation energy rather than on the migration energy. As a result, we suggest that the late transition metal-based perovskites have relatively low oxygen vacancy formation energies, and thereby exhibit low activation energy barriers. Our results will provide useful insight into the design of new cathode materials with better performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.7
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• pp.557-563
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• 2003

SiC has been an useful material for the high voltage, high temperature, and high frequency devices, however, the required high process temperature to activate the implanted p-type dopants has hindered further developments. In this study, we report, for the first time, on the laser activation of implanted Al and non-alloyed Mo ohmic contacts and its application to MOSFET fabrication. The contact and sheet resistance measured from CTLM patterns have decreased by increasing laser power, and the lowest values are 3.9 $K\Omega$/$\square$ and 1.3 $\times$ 10$^{-3}$ $\Omega$-cm$^2$, respectively, at the power density of 1.45 J/cm$^2$ The n-MOSFETs fabricated on laser activated p-well exhibit well-behaved I-V characteristics and threshold voltage reduction by reverse body voltage. These results prove that the laser process for implant activation is an alternative low temperature technology applicable to SiC devices.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1432-1433
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• 2006

$Li_{2}CO_3$ doped $Ba_{0.5}Sr_{0.5}TiO_3$ ceramics were fabrication by sol-gel method. Sintering temperature must be suited to the LTCC technology. Structure and dielectric properties were investigated for effect of $Li_{2}CO_3$ dopants at BST. Structure of $Li_{2}CO_3$ doped $Ba_{0.5}Sr_{0.5}TiO_3$ ceramics were dense and homogeneous with almost no pore. Relative permittivity was decreased and dielectric loss was increased with increasing $Li_{2}CO_3$ doping rations. In the case of the 3wt% $Li_{2}CO_3$ doped $Ba_{0.5}Sr_{0.5}TiO_3$ ceramics sintered at $900^{\circ}C$, relative permittivity and dielectric loss were 907 and 0.003 at 100 kHz.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.234-238
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• 2009

We have investigated the effects of dopant on the thermoelectric properties that $La_{(1-x)}M_xCoO_3$(M=Sr, Ca;x=0, 0.1) bulk ceramics fabricated by the conventional solid state reaction method. The Seebeck coefficient of $La_{(1-x)}M_xCoO_3$(M=Sr, Ca;x=0, 0.1) bulk ceramics was measured at wide temperature range from 300 K to 673 K. The thermoelectric properties(Seebeck coefficient and electrical resistivity) depend strongly on the kinds of dopants. Sr and Ca dopant decrease the Seebeck coefficient. Density of sintered $La_{0.9}Sr_{0.1}CoO_3$ ceramic at 1523 K was 7.12 $g/cm^2$ and Seebeck coefficient was 35 ${\mu}V/K$ at 663 K. However, the electrical resistivity of the Sr doped sample was low and stable.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.74-82
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• 2004

Planar laser-induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Acetone PLIF is chosen because fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone PLIF is applied to measure quantitative air excess ratio distribution in an engine fueled with LPG. Acetone is excited by KrF excimer laser (248nm) and its fluorescence image is acquired by ICCD camera with a cut-off filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile is suggested. Raw images are divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which is taken by a calibration process, are converted to air excess ratio distribution. This investigation shows instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.81-82
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• 2006

Doping is a well-known method for improving electroluminescent (EL) efficiency of organic light emitting diodes. In our study, doping with 2 materials simultaneously, we could achieve improved EL efficiency. The emission layer was tris-(8-hydroxyquinoline)aluminum, and the 2 dopants were N,N'-dimethyl-quinacridone (DMQA) and 10-(2-Benzothiazolyl)-2, 3, 6, 7-tetrahydro-1,1,7,7,-tetramethyl 1-1H, 5H, 11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one (C-545T). The EL intensity of co-doped device was nearly flat, it shows that co-doping technique could be a effective way to improve the EL efficiency. EL efficiency of Single-doped device based on DMQA and C-S45T were ~6.47Cd/A and ~7.45Cd/A, respectively. Co-doped device showed higher EL efficiency of ~8.30Cd/A.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.517-520
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• 2010

Lead-free $0.9(Na_{0.52}K_{0.48})NbO_3$ - $0.1LiTaO_3$ piezoelectric ceramics doped with $Ag_2O$ (0-4 mol%) have been prepared by the conventional mixed oxide method. The structural and electrical properties were analyzed in order to find its potential applications. The crystal structure of 1-4 mol% Ag doped $0.9(Na_{0.52}K_{0.48})NbO_3$-$0.1LiTaO_3$ lead free piezoelectric ceramics were investigated for several sintering temperatures ($1100^{\circ}C$) by the use of X-ray diffraction analysis. In order to analyze the effect of Ag dopants on the $0.9(Na_{0.52}K_{0.48})NbO_3$-$0.1LiTaO_3$ ceramic, the diffraction intensity ratio of the (002) to (200) planes were calculated from the X-ray diffraction patterns of the ceramic samples.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.105-111
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• 2019

The TADF (Thermally Activated Delayed Fluorescence)-based OLED patents were analyzed and 4410 of patents were selected at the first step. And 975 patents were screened at second step. Finally, 39 key patents were selected. Patent qualitative analysis was performed in these patents to find which of the four property (lifetime, efficiency, color purity, driving voltage) of TADF was improved. Also, the variation of the hosts and dopants in patented TADF material were surveyed and their combination was analyzed. According to the analysis of the variation and the combination, some of TADF compounds were used as an assistant dopant to transfer energy. In addition, it tended to transfer energy by forming exciplex that shows TADF characteristics. These were similar to the mechanism of the introduced hyper fluorescence and could solve the inherent TADF problems. Finally, patent citation network was illustrated to visualize the patent citations and citations relationship of the major applicants in the current TADF-based OLED technology. The leading patent applicant organization was revealed as Idemitsu Kosan, Semiconductor Energy Laboratory, UDC, Princeton University, Merck and Nippon Steel & Sumikin Chemical, which had lots of reference patents 559, 524, 477, 310, 258, and 167, respectively.