Articles you may be interested inA methodology to identify and quantify mobility-reducing defects in 4H-silicon carbide power metal-oxidesemiconductor field-effect transistors Influence of the surface morphology on the channel mobility of lateral implanted 4H-SiC (0001) metal-oxidesemiconductor field-effect transistors J. Appl. Phys. 112, 084501 (2012); 10.1063/1.4759354 Effect of nitric oxide annealing on the interface trap density near the conduction bandedge of 4H-SiC at the oxide /(1120) 4H-SiC interface Effects of anneals in ammonia on the interface trap density near the band edges in 4H-silicon carbide metaloxide-semiconductor capacitors

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Solar-to-hydrogen conversion efficiencies of water-splitting photochathodes using epitaxially grown p-type 4H-, 6H-and 3C-SiC were estimated in a two-electrode system without applying any external bias. By using electrode materials with small oxygen overpotentials as counter electrodes, the photocurrent became comparable to that observed in a three-electrode system with a suitable bias. Estimated efficiencies seem to depend on the bandgap of the SiC polytypes. For the 3C-SiC, the obtained efficiency was 0.38%, which is so far the highest value reported for SiC. We confirmed that the hydrogen volumes estimated from the photocurrent were almost the same as actual volumes observed by gas chromatography.

SUMMARYThis paper proposes a high speech quality noise suppression method based on weighted noise estimation and MMSE STSA. The proposed method continuously updates the noise estimate, using weighted noisy speech according to the estimated speech-to-noise ratio. In order to fully utilize the improvement offered by noise estimation, the spectral gain is corrected according to the estimated speech-to-noise ratio. By using accurate noise estimation, more accurate SNR than in the conventional method is obtained, which helps to reduce distortion in the enhanced speech. In subjective speech quality evaluations, the five-stage MOS was improved by 0.35 and 0.40 at the maximum, respectively, for the cases in which the speech was encoded and was not encoded after noise suppression. The improved version, which was developed on the basis of the proposed noise suppressor, satisfies all 3GPP minimum requirements for speech quality and has been installed in a commercially available model.

We report on spectral-domain and time-domain measurements and numerical calculations of group velocities in a photonic crystal coupled waveguide, where the unique guided mode band structure has a flat band region within the photonic band gap allowing for slow light observation. The spectral dependence of group velocity, which is measured by interference method, indicates the existence of slow light modes around the inflection point of the unique flat band, rather than at the band edge. Time-domain observation of optical pulses propagating along two-dimension slab photonic crystal coupled waveguides is also demonstrated by using a high speed oscilloscope. By adjusting the wavelength of the input pulses toward the flat band of the coupled defect modes, an increasing duration time between reference and output pulses are clearly observed. An extremely small group velocity of 0.017c is thus obtained. Calculated group velocities show good agreement with our measured results.

The expansion behavior of a single Shockley stacking fault (SSSF) originating from a basal plane dislocation in a 4H-SiC epitaxial layer on the (112¯0) a-plane under electron beam (EB) (//[112¯0]) irradiation was observed. The width of the SSSF was proportional to the EB current. EB irradiation at a fixed spot outside an SSSF can expand the SSSF as effectively as direct SSSF irradiation. It was found that the selective excitation of an SSSF and/or a Si-core partial dislocation (PD) is possible by appropriately setting the EB irradiation position because the cathodoluminescence spectrum varies with the irradiation position around an SSSF. The rate of SSSF expansion upon the indirect excitation of a Si-core PD is much larger than that upon direct SSSF excitation. However, the expansion rate under both indirect SSSF excitation and indirect Si-core PD excitation is smaller than that under indirect Si-core excitation. The C-core PD became mobile after supplying a threshold number of electron-hole pairs.

Synopsis Behaviors of oxygen and sulfur during DC ESR were investigated to treat their transfer on wide operating scales. On oxygen transfer, a carbon steel was remelted in CaF2 A1203 slag under the atmosphere. It was confirmed that ingots remelted as electrodes of negative polarity give higher oxygen content than those as positive. Those differences would be resulted from the differences of the current density and the interfacial area between the metal and the slag. The oxygen contents in the ingots remelted in a large scale furnace could be estimated from the present results on the oxygen transfer through the molten metal/slag interface, assuming that the mass transfer coefficient o f oxygen depends on the current density of the interface. On sulfur transfer, a resulfurized carbon steel was remelted in ANF-6 and ANF-7 slaps under the atmospheres of varied oxygen partial pressure. Assuming the electrochemical reactions at the reacting interfaces, the accumulating rate of sulfur in the slag pool was determined. And then the sulfur in the ingot was calculated on the mass balance of sulfur. The calculated results were compared with the experimental ones. On DCSP, the calculated results show the good agreement with the experimental ones, but not on DCRP.