984 resultados para EXFOLIATED GRAPHITE OXIDE


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The promising theoretical properties of diamond, together with the recent advances in producing high-quality single crystal diamond substrates, have increased the interest in using diamond in power electronic devices. This paper presents numerical and experimental off-state results for a diamond Schottky barrier diode (SBD), one of most studied unipolar devices in diamond. Finding a suitable termination structure is an essential step towards designing a high voltage diamond device. The ramp oxide structure shows very encouraging electronic performance when used to terminate diamond SBDs. High-k dielectrics are also considered in order to further improve the reliability and electrical performance of the structure. © 2007 Elsevier B.V. All rights reserved.

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The paper's goal is the first demonstration of the fabrication of high power Schottky diodes on synthetic diamond using oxide ramp termination. In order to allow full activated impurities at room temperature and a high hole mobility a low boron doping of the drift layer is employed. Several aspects of the manufacturing technology are presented. A termination with a small ramp angle can be obtained using only RIE technique due to diamond wafer nonuniformity (roughness). Experimental forward and reverse characteristics measured on diamond diodes are also included. © 2007 IEEE.

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Tubular graphite cones (TGCs) with a single-crystal nanotip have been achieved by means of microwave plasma-assisted chemical vapor deposition using in-situ-evaporated Fe catalysts. The absence of the disorder-induced D band in Raman spectra revealed the single-crystalline feature of the nanotip. TGCs were found to stem from Fe catalytic carbon spherules on the order of 100 mum diameter, whose critical role in promoting both nucleation and plasma annealing in the formation of highly crystalline TGCs is discussed. The crystalline quality of such TGCs can be further verified by the investigation of their oxidative stability in air. All TGCs can survive up to 600 degrees C without any structural variations, and a few TGCs still survive with an anisotropic etched and stepped nanotip at temperatures up to 800 degrees C, much better than CNTs. Thus, TGCs with single crystalline nanotips are potential candidates for scanning probes in high-temperature oxygen-containing environments.