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ABSTRACT: When NaCl was colored with Na vapor, X-rays and Cl2 vapor, respectively, the surface became highly active catalytically. Almost without exception, the decrease in the enhanced activity upon heating occurs in the range of the annihilation temperature of the color centers. This result indicates that both F- and V-centers in NaCl may contribute to the reaction as active sites.
Berichte der Bunsengesellschaft für physikalische Chemie. 05/2010; 90(4):353 - 356.
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ABSTRACT: Direct integration of AlGaAs/GaAs HEMTs on AlN ceramic substrates has been demonstrated based on the fluidic self-assembly (FSA) technology. The FSA is a unique technology to arrange small device blocks (around a few tens of microns) onto the other substrates. With this technology the core part of the HEMT having no pad can be mounted on the ceramic substrate. The HEMT core can then be connected electrically with the circuit on a ceramic substrate using a planar wiring process. This eliminates large stray capacitance and inductance in the conventional technology. It has been demonstrated that the good FET characteristics are obtained even after FSA process.
Electronics Letters 12/2005; · 0.96 Impact Factor
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ABSTRACT: In this study, we have fabricated the CNTFETS, where the contact electrodes are covered with insulator, and studied the effects of the antibody-antigen reaction on the drain current.
Microprocesses and Nanotechnology Conference, 2005 International; 11/2005
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ABSTRACT: Carbon nanotube FETs (CNT-FETs) are very attractive because of their ideal one-dimensional structure of the channel, which would lead to the ballistic transport of the carrier and a large transconductance. Among various growth techniques, plasma-enhanced CVD (PECVD) seems to be attractive because of its advantages such as the low-temperature growth on a large-area substrate. However, there are few reports which succeeded in growing single-walled nanotubes (SWNTs) [4] and fabricating CNT-FETs using PECVD probably due to the ion bombardment damage of the plasma. We have recently reported that the insertion of a grid between the anode and cathode in the PECVD is effective in suppressing the ion bombardment damage. In this report, we grew SWNTs directly on the SiO<sub>2</sub>,/Si substrate using the PECVD and the patterned catalysts, and succeeded in fabricating CNT-FETs.
Microprocesses and Nanotechnology Conference, 2005 International; 11/2005
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ABSTRACT: Carbon nanotube field effect transistors (CNTFETs) have great advantages over the conventional Si MOSFETs because of their high transconductance and large current driving capability. However, CNTFETs exhibit a large hysteresis in the I<sub>D</sub>-V<sub>GS</sub> characteristics. W. Kim et al. have reported that the water molecules on the device surface are the origin of the large hysteresis, which can be suppressed by surface passivation using PMMA. In our experiments, however, the reproducibility was quite poor. In this study, we have statistically studied the hysteresis and the passivation process. The reproducibility of the passivation has been improved by introducing cleaning process before the PMMA passivation.
Microprocesses and Nanotechnology Conference, 2005 International; 11/2005
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Electronics Letters 01/2005; 41(23):1275-1276. · 0.96 Impact Factor
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COMPOUND SEMICONDUCTORS 2004, PROCEEDINGS; 01/2005
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ABSTRACT: The transient behavior of AlGaN-GaN MIS-HEMTs were studied by drain current deep level transient spectroscopy. Two electron traps were observed, one of which had similar activation energy to that of defect that was commonly observed in epitaxial GaN. We compared the results with those of AlGaN-GaN HEMTs. The hole-trap-like positive peaks in the DLTS, which were observed in the HEMTs, were not observed in the MIS-HEMTs. It has been pointed out that the positive peaks did not originate from change in hole trap population in the channel but reflected the change in the electron population in the surface states of the HEMT access regions. The gate insulator was effective to suppress not only the gate leakage current but also the surface-state-related signals.
IEEE Electron Device Letters 09/2004; · 2.85 Impact Factor
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Japanese Journal of Applied Physics 09/2004; 43(9A):5951-5954. · 1.06 Impact Factor
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ABSTRACT: Recently, applications of chaos, which is often observed in nonlinear systems, have attracted much attention in the field of information processing and communication systems. Using RTDs to implement such nonlinear circuits has significant advantages, such as high operation frequency. In this paper, we describe some applications of resonant tunneling chaos generator circuits.
Future of Electron Devices, 2004. International Meeting for; 08/2004
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Japanese Journal of Applied Physics 08/2004; 43(8A):5235-5238. · 1.06 Impact Factor
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ABSTRACT: The direct observation of the chaos signal patterns in a microwave frequency range was demonstrated on the resonant tunneling chaos generator circuit. It is difficult to observe such non-periodic signals because one must use a sampling oscilloscope. To overcome this problem we introduced a control circuit which resets the chaos generator circuit repeatedly to output identical signals. This permitted us to observe seemingly random patterns. We also discussed the extension of this control technique, which leads to various applications.
Indium Phosphide and Related Materials, 2004. 16th IPRM. 2004 International Conference on; 07/2004
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Advanced Engineering Materials 04/2004; 6(4):211 - 214. · 1.18 Impact Factor
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ABSTRACT: Ultra-high frequency operation at 88 GHz was demonstrated for the frequency divider based on the resonant tunnelling chaos circuit. It was also shown that the phase noise is comparable to that of the conventional circuits in spite of the novel operating principle.
Electronics Letters 11/2003; · 0.96 Impact Factor
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ABSTRACT: Drain current collapse in AlGaN/GaN HEMTs has been studied systematically by applying bias stress to the device. The collapse was suppressed by light illumination with energy smaller than the bandgap. The position dependence of the light illumination and the measurement of series source and drain resistances revealed that the collapse was caused by the surface states between the gate and drain electrodes, which captured electrons injected from the gate. The current collapse was eliminated by the passivation of the device surface with Si<sub>3</sub>N<sub>4</sub> film.
IEEE Transactions on Electron Devices 11/2003; · 2.32 Impact Factor
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ABSTRACT: We have investigated the effect of surface passivation on breakdown by electrical characterization and electroluminescence (EL) measurements of AlGaN/GaN HEMTs.
Compound Semiconductors, 2003. International Symposium on; 09/2003
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Japanese Journal of Applied Physics 06/2003; 42(6B):4116-4119. · 1.06 Impact Factor
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Japanese Journal of Applied Physics 04/2003; 42(4B):2226-2229. · 1.06 Impact Factor
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Japanese Journal of Applied Physics 04/2003; 42(4B):2278-2280. · 1.06 Impact Factor
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Japanese Journal of Applied Physics 02/2003; 42(2A):424-425. · 1.06 Impact Factor
