• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.41-44
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• 2022

In this study, we have fabricated and characterized vertical double-gate (DG) InGaAs tunnel field-effect-transistors (TFETs) with Al₂O₃/HfO₂ = 1/5 nm bi-layer gate dielectric by employing a top-down approach. The device exhibited excellent characteristics including a minimum subthreshold swing of 60 mV/decade, a maximum transconductance of 141 µS/㎛, and an on/off current ratio of over 10³ at 20℃. Although the TFETs were fabricated using a dry etch-based top-down approach, the values of DIBL and hysteresis were as low as 40 mV/V and below 10 mV, respectively. By evaluating the effects of constant voltage and hot carrier injection stress on the vertical DG InGaAs TFET, we have identified the dominant charge trapping mechanism in TFETs.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.107-117
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• 2007

Dispersion characteristics and envirounmental impactes of the stream sediments were investigated and geochemical disaster in the Namhae-Hwagye area was predicted. Stream sediments having no possibility of contamination effect and representing drainage basins were collected. Major and hazardous elements concentrations were determined by XRF, ICP-AES and NAA analysis methods. Acid decomposition for the ICP-AES have been used $HClO_4$ and HF with $200^{\circ}C$ heating at 1'st and after that $HClO_4$, HF and HCl with $200^{\circ}C$ heating at 2'nd stage. Hazardous elements concentrations for the stream sediments in the Namhae area were Cu $5.66{\sim}168\;ppm$, Pb $18.0{\sim}40.7\;ppm$, Cr $21.6{\sim}147\;ppm$, Co $4.86{\sim}25.3\;ppm$. Hazardous elements concentrations for the stream sediments in the Hwagye area were Cu $16.4{\sim}41.2\;ppm$, Pb $26.5{\sim}37.5\;ppm$ Cr $79.6{\sim}153\;ppm$, Co $15.7{\sim}29.5\;ppm$. Concentration of Cu and Co in the stream sediments show a negative correlation with $SiO_2$ in all study area. According to E.I.(Enrichment Index) of stream sediments was not enriched in study area. And average E.I. was 0.35 (Namhae) and 0.56 (Hwagye) respectively. The stream sediments were enriched as in order of Pb > Cr > Co > Cu. And the average of Enrichment Factor (E.F.) was 0.46 to 2.84, respectively. E.F. concentration of Cu and Co were nearly similar enrichment characteristic but E.F. concentration of Cr were higher enrichnent characteristic in Namhae than Hwagye area. Pb was highly enriched in all study area but the tolerable level that used to investigate the enrichment degree of hazardous elements, was not exposed to harmful hazardous elements.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.329-342
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• 2006

The purpose of this study is to determine the geochemical characteristics for the stream sediments in the Konyang area. So we can estimate the environment contamination and understand geochemical disaster. We collect the stream sediments samples by wet sieving along the primary channels and slowly dry the collected samples in the laboratory and grind to pass a 200mesh using an alumina mortar and pestle for chemical analysis. Mineralogy, major, trace and rare earth elements are determined by XRD, XRE, ICP-AES and NAA analysis methods. For geochemical characteristics on the geological groups of stream sediments, the studied area was grouped into quartz porphyry area, sedimentary rock area, anorthosite area and gneiss area. Contents of major elements for the stream sediments in the Konyang area were $SiO_2\;41.86{\sim}76.74\;wt.%,\;Al_{2}O_{3}\;9.92{\sim}30.00\;wt.%,\;Fe_{2}O_{3}\;2.74{\sim}12.68\;wt.%,\;CaO\;0.22{\sim}3.31\;wt.%,\;MgO\;0.34{\sim}3.97\;wt.%,\;K_{2}O\;0.75{\sim}0.93\;wt.%,\;Na_{2}O\;0.25{\sim}1.92\;wt.%,\;TiO_{2}\;0.40{\sim}3.00\;wt.%,\;MnO\;0.03{\sim}0.21\;wt.%,\;P_{2}O_{5}\;0.05{\sim}0.38\;wt.%$. The contents of trace and rare earth elements for the stream sediments were $Cu\;7{\sim}102\;ppm,\;Pb\;15{\sim}47\;ppm,\;Sr\;48{\sim}513\;ppm,\;V\;29{\sim}129\;ppm,\;Zr\;31{\sim}217\;ppm,\;Li\;14{\sim}94\;ppm,\;Co\;5.6{\sim}32.1\;ppm,\;Cr\;23{\sim}259\;ppm,\;Cs\;1.7{\sim}8.7\;ppm,\;Hf\;2.1{\sim}109.0\;ppm,\;Rb\;34{\sim}247\;ppm,\;Sc\;4.5{\sim}21.9\;ppm,\;Zn\;24{\sim}609\;ppm,\;Sb\;0.8{\sim}2.6\;ppm,\;Th\;3{\sim}213\;ppm,\;Ce\;22{\sim}1000\;ppm,\;Eu\;0.7{\sim}5.3\;ppm,\;Yb\;0.6{\sim}6.4\;ppm$. Generally, the contents of $Al_{2}O_{3}\;and\;SiO_2$ had a good relationships with each other in rocks but it had a bad relationships in stream sediments for this study area. The contents of $Fe_{2}O_3$, CaO, MnO and $P_{2}O_{5}$ had a good relationships with major and minor elements in stream sediments of this study area. The contents of Co and V in the stream sediments had a good relationships with other toxic elements.