Jong Wan Park

Chonbuk National University, Tsiuentcheou, Jeollabuk-do, South Korea

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Publications (22)49.36 Total impact

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    ABSTRACT: Electrical transport properties of individual double-wall carbon nanotube (DWNT) are studied. Negative differential conductance (NDC) was observed for the DWNT with a defected outer shell. Such NDC was explained in terms of the resonant tunneling through multiple quantum dots. Also observed is the Fano resonance for the low-resistance samples. The Fano resonance was manifested by asymmetric peaks in the gate modulation and also by the zero-bias peak in the differential conductance curve. Both NDC and Fano resonance in DWNT demonstrates the interplay of inner and outer shells via the inter-shell hopping of electrons.
    01/2006; DOI:10.1063/1.2355260
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    ABSTRACT: Molecule-based electronic devices, utilizing self-assembled monolayer of chemically synthesized organic molecules and Au nanoparticle, were fabricated and their electrical transport properties were investigated. The current–voltage characteristics of the sample was nonlinear at temperatures below and the gate modulation curve exhibited periodic current oscillation, attributed to the Coulomb oscillation, up to . The peak position in the differential conductance curve shifts with the increase of magnetic field, due to the Zeeman splitting of the electronic energy states of the Au nanoparticle.
    Physica E Low-dimensional Systems and Nanostructures 05/2003; 18(1-18):243-244. DOI:10.1016/S1386-9477(02)00996-7 · 1.86 Impact Factor
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    ABSTRACT: We report the observation of the resonant transport in multiwall carbon nanotubes in a crossed geometry. The resonant transport is manifested by an asymmetric peak in the differential conductance curve. The observed asymmetric conductance peak is well explained by the Fano resonance originating from the scattering at the contact region of the two nanotubes. The conductance peak depends sensitively on the external magnetic field and exhibits Aharonov-Bohm-type oscillation.
    Physical Review Letters 05/2003; 90(16):166403. DOI:10.1103/PhysRevLett.90.166403 · 7.51 Impact Factor
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    ABSTRACT: Electrical transport properties of individual multi-walled carbon nanotubes in contact with the ferromagnetic electrodes, Ni78Fe22, were studied at low temperatures. The magnetoresistance curve was non-hysteretic and exhibited pronounced dip structure at the external field of 160mT. The magnetoresistance ratio depends strongly both on bias current and temperature.
    Physica E Low-dimensional Systems and Nanostructures 05/2003; 18(1):208-209. DOI:10.1016/S1386-9477(02)00968-2 · 1.86 Impact Factor
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    ABSTRACT: We have studied the effect of local gates on the electrical transport properties of single-walled carbon nanotubes (SWNT). The local gate have been incorporated into individual SWNT by depositing Al top gate in between Au/Ti electrodes. Noticeable increase of resistance was observed after the deposition of the Al top gates, implying that the Al top gate acted as a barrier for electrical conduction.
    Physica E Low-dimensional Systems and Nanostructures 05/2003; 18(1):216-217. DOI:10.1016/S1386-9477(02)00972-4 · 1.86 Impact Factor
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    ABSTRACT: We have demonstrated that W-based catalysts can produce carbon nanotubes (CNTs) effectively. Well-aligned, high-purity CNTs were synthesized using the catalytic reaction of C2H2 and W(CO)6 mixtures. The CNTs had a multiwalled structure with a hollow inside. The graphite sheets of CNTs were highly crystalline but the outmost graphite sheets were defective.
    Chemical Physics Letters 08/2002; 361(5-361):469-472. DOI:10.1016/S0009-2614(02)00982-X · 1.99 Impact Factor
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    ABSTRACT: We have synthesized high-quality gallium nitride (GaN) nanowires by a chemical-vapor-deposition method and studied the electrical transport properties. The electrical measurements on individual GaN nanowires show a pronounced n-type field effect due to nitrogen vacancies in the whole measured temperature ranges. The n-type gate response and the temperature dependence of the current–voltage characteristics could be understood by the band bending at the interface of the metal electrode and GaN wire. The estimated electron mobility from the gate modulation characteristics is about 2.15 cm2/V s at room temperature, suggesting the diffusive nature of electron transport in the nanowires. © 2002 American Institute of Physics.
    Applied Physics Letters 05/2002; 80(19):3548-3550. DOI:10.1063/1.1478158 · 3.52 Impact Factor
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    ABSTRACT: The electrical transport properties of two multiwall carbon nanotubes in a crossed geometry were studied. Each carbon nanotube exhibited differential conductance vanishing with the power of bias voltage. The power-law dependence of the differential conductance was attributed to the Tomonaga-Luttinger liquid behavior of the carbon nanotube, which is considered to be a one-dimensional conductor. The differential conductance curve of one of the two carbon nanotubes was affected significantly by constant bias voltage applied to the other carbon nanotube. The characteristic features of the change of the differential conductance curve we have observed are in good agreement with the theoretical predictions for the two crossed Tomonaga-Luttinger liquids which are expected to exhibit correlated electron transport.
    Journal of the Physical Society of Japan 06/2001; 70(6):1464-1467. DOI:10.1143/JPSJ.70.1464 · 1.48 Impact Factor
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    ABSTRACT: The growth behavior of carbon nanotubes (CNT) deposited from C2H2 by thermal CVD method was investigated. Nickel particles of diameter ranging from 15 to 90 nm were used as the catalyst. CNTs were deposited in various environments of N2, H2, Ar, NH3 and their mixtures to investigate the effect of the environment on the CNT growth behavior. The deposition was performed at 850°C in atmospheric pressure. In pure N2 environment, thick carbon layer deposition occurred on the substrate without CNT growth. The Ni particles encapsulated by the carbon deposition could not work as the catalyst in this condition. However, the growth of CNT was enhanced as the H2 concentration increased in the mixture of N2 and H2 environment. In pure H2 environment, randomly tangled CNTs could be obtained. The growth of CNT was much enhanced when using NH3 as the environment gas. Vertically aligned CNTs could be deposited in NH3 environment, whereas the CNT growth could not be obtained in the mixture of N2 and H2 environment of the same ratio of N/H. These results were discussed in terms of the passivation of the catalyst caused by the excessive deposition of carbon on the catalyst surface. For the deposition of the CNT, the decomposition rate of C2H2 should be controlled to supply carbon for nanotube growth without passivation of the catalyst surface by excessive carbon deposition. The present work showed that the composition of environment gas significantly affects the reaction kinetics in the CNT growth. It is also noted that nitride surface layer formation on Ni catalyst in NH3 environment can affect the CNT growth behavior.
    Diamond and Related Materials 03/2001; 10(3-7-10):1235-1240. DOI:10.1016/S0925-9635(00)00446-5 · 1.57 Impact Factor
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    ABSTRACT: Non-local electric transport phenomena were observed for a multi-wall carbon nanotube. The magnetic field dependence of non-local resistance was out of phase with respect to the conventional four-probe resistance, which could be explained in terms of the Landauer-Büttiker formula. Our observations indicate that the phase coherence length of multi-wall carbon nanotube exceeds the voltage probe length of about 1.1 µm at the measured temperatures.
    Journal of the Physical Society of Japan 01/2001; 70(3):789-792. DOI:10.1143/JPSJ.70.789 · 1.48 Impact Factor
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    ABSTRACT: We have observed a memory effect in an aluminum single-electron memory cell with a floating node. Electrons were injected to or emitted from the floating node by field emission, which was evidenced by the sudden change in the Coulomb oscillation of a single-electron transistor. With the compensating voltage applied to the back gate, the Coulomb oscillation could be completely suppressed if the gate voltage sweep direction was reversed. We found that the Coulomb-oscillation period changed with the ratio of control-gate to back-gate voltage, being fitted well to the expected formula.
    Japanese Journal of Applied Physics 08/2000; 39(8):4826-4829. DOI:10.1143/JJAP.39.4826 · 1.06 Impact Factor
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    ABSTRACT: The contact resistance between a carbon nanotube and metal electrodes decreases by several orders of magnitude and becomes long-term stable when the nanotube contacted by Ti-Au electrodes was annealed by a rapid thermal annealing method at 600-800 °C for 30 s. The contact resistances of the annealed samples are in the range 0.5-50 kΩ at room temperature, depending on the electrical properties of the nanotube. The short and relatively low-temperature annealing process enables us to make a surface Ti-nanotube contact suitable for electrical measurements. For the samples with relatively low contact resistances (0.5-5 kΩ) at room temperature, the contact resistance remained constant or decreased slightly as the temperature was lowered. Those with a relatively high contact resistance (5-50 kΩ), on the other hand, showed increasing contact resistance with a lowering of the temperature.
    Journal of Physics D Applied Physics 08/2000; 33(16):1953. DOI:10.1088/0022-3727/33/16/303 · 2.72 Impact Factor
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    ABSTRACT: The electric transport properties of an Al/Al2O3/Ni/Al2O3/Al single-electron transistor were studied. Compared to the all-normal-metal single-electron transistors, our sample showed enhanced tunnel current inside the Coulomb gap both in the superconducting and the normal state of the Al. The tunnel current showed sharp increase for the magnetic field H~+/-1.57T, which also was evidenced by the change of current-voltage (/I-/V) characteristics with the magnetic field.
    Physica B Condensed Matter 07/2000; 284(2002):1794-1795. DOI:10.1016/S0921-4526(99)02983-X · 1.28 Impact Factor
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    ABSTRACT: Two di!erent kinds of mesoscopic N}S}N junctions were fabricated by sandwiching Al or Pb "lm between two closely separated Au wires. d</dI versus < curves for an Au}Pb}Au junction show a sharp zero-bias dip, while those for an Au}Al}Au show a reentrant zero-bias maximum. Interference between conjugate electrons and holes at an interface with di!erent degree of transparency is responsible for the contrasting behavior. 2000 Elsevier Science B.V. All rights reserved.
    Physica B Condensed Matter 07/2000; DOI:10.1016/S0921-4526(99)02900-2 · 1.28 Impact Factor
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    ABSTRACT: Luttinger liquid behavior was observed in a crossed junction formed with two metallic multi-wall carbon nanotubes whose differential conductance vanished with the power of bias voltage and temperature. With applying constant voltage or current to one of the two carbon nanotubes in a crossed geometry, the electrical transport properties of the other carbon nanotube were affected significantly, implying there exists strong correlation between the carbon nanotubes. Such characteristic features are in good agreement with the theoretical predictions for the crossed two Luttinger liquids.
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    ABSTRACT: We have measured both the magnetoresistance and differential conductance of multiwalled carbon nanotubes as a function of magnetic field perpendicular to the tube axis. The measured differential conductance showed a large depletion of the density of states near the Fermi level and its magnitude was changed with a magnetic field. It was found that the aperiodic fluctuations and negative magnetoresistance mainly originate from the change of density of the states near the Fermi level with the magnetic field, rather than a quantum interference effect. At a particular magnetic field, the true metallic conduction along the outermost shell was observed, and the conductance approached the theoretical value, 2G0=4e2/h, as the temperature was lowered.
    Physical Review B 06/2000; 611(24). DOI:10.1103/PhysRevB.61.R16362 · 3.74 Impact Factor
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    ABSTRACT: The transport properties of an Al/Al2O3/Al three-junction single-electron transistor in the superconducting state were studied. Electrostatic coupling between different islands leads to a splitting of the peak in the Coulomb oscillations of the quasiparticle tunneling current. Also observed is a clear beating of the Coulomb oscillations, which is attributed to the cross capacitance between a gate electrode and neighboring island. Numerical calculations based on the orthodox theory with inclusion of cross capacitance reproduce well most of the features seen in our data.
    Physical Review B 01/1999; 59(3). DOI:10.1103/PhysRevB.59.1629 · 3.74 Impact Factor
  • Jae Suk Lee, Jong Wan Park, Sang Mo Shin
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    ABSTRACT: A new micro catalytic gas sensor for detecting inflammable gases was fabricated on a Si wafer by thin film deposition and Si anisotropic etching. The size of the fabricated sensor was 3.25×2.20 mm2. The sensor was designed to consist of a catalyst with high surface area and a heater with high temperature coefficient of resistance (TCR) in order to acquire high sensitivity to gases of interest. The TCR of the sensor was found to be 3844 ppm °C−1. Sensitivities to methane and butane gases were 2.2 mV 1000 ppm−1 and 8.9 mV 1000 ppm−1, respectively. The optimum applied Wheatstone bridge power was varied in the range from 350 to 400 mW, being much smaller than those of commercial pellistors. It was also found that sensitivities to methane and butane gas were decreased by increasing humidity.
    Sensors and Actuators B Chemical 12/1997; 45(3):265-269. DOI:10.1016/S0925-4005(97)00322-5 · 4.29 Impact Factor
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    ABSTRACT: Although the use of sheep in total artificial heart (TAH) implantation has many advantages, they are known to show a significant morbidity rate on cardiopulmonary bypass (CPB); this has been considered to be a major limiting factor in using them for TAH experiments. We conducted a series of ovine CPB experiments to evaluate the sheep's pathophysiological response to CPB. CPB-related hemolysis, bleeding, and lung dysfunction were analyzed in 5 sheep, which had undergone CPB, used at our hospital for TAH implantation. Four of the 5 sheep survived the experimental procedures, and 3 of them survived on a long-term basis. Unacceptable degrees of hemolysis related to CPB were not observed. Postoperative bleeding was not remarkable, and coagulation test results did not show significant abnormal findings. Acute lung injuries of a mild to moderate degree were found mainly at the microscopic level, but rarely had clinical significance. In conclusion, this experiment suggests that sheep can be used for the animal model for TAH implantation with acceptable risk on CPB circuits and techniques are used.
    Artificial Organs 03/1997; 21(2):154-9. DOI:10.1111/j.1525-1594.1997.tb00353.x · 1.87 Impact Factor
  • Seoghyeong Lee, Jong‐Wan Park
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    ABSTRACT: The effect of fluorine addition on silicon oxide film properties as a function of SiF 4 /O 2 gas flow ratio was investigated. The films were deposited by using electron cyclotron resonance plasma chemical vapor deposition with SiF 4 and O 2 as source gases diluted in Ar. Characterization of films was carried out in terms of various gas flow ratios (SiF 4 /O 2 =0.2–1.0). The microwave power and substrate temperature during deposition were fixed at 700 W and 300 °C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by x‐ray photoelectron spectroscopy, and refractive index by ellipsometry. The dielectric constant was determined from C–V measurements at 1 MHz. FTIR spectra show that as the fluorine concentration increased, the intensities of the Si–F bonding peak and the shoulder peak (at around 1160 cm<sup>-1</sup>) of the Si–O stretching mode both increased. Refractive index and deposited film density decreased with increasing SiF 4 /O 2 gas flow ratio. The SiOF film deposited at a SiF 4 /O 2 gas flow ratio of 1.0 exhibited a fluorine content of 11.8 at. % and a dielectric constant of 3.14. © 1996 American Institute of Physics.
    Journal of Applied Physics 12/1996; 80(9-80):5260 - 5263. DOI:10.1063/1.363512 · 2.19 Impact Factor

Publication Stats

552 Citations
49.36 Total Impact Points

Institutions

  • 2001–2003
    • Chonbuk National University
      • Department of Physics
      Tsiuentcheou, Jeollabuk-do, South Korea
  • 2000–2003
    • Korea Research Institute of Standards and Science
      Daiden, Daejeon, South Korea
  • 1995–2002
    • Hanyang University
      • Division of Materials Science and Engineering (MSE)
      Sŏul, Seoul, South Korea
  • 1999
    • Chungbuk National University
      • Department of Physics
      Chinsen, North Chungcheong, South Korea
  • 1997
    • Seoul National University Hospital
      Sŏul, Seoul, South Korea