We investigated two types of V-shaped extended defects on the basal plane in epitaxial 4H-SiC by synchrotron X-ray topography, photoluminescence imaging/spectroscopy and transmission electron microscopy (TEM). One is the (2, 5) stacking fault (in Zhdanov notation) bounded by two partial dislocations with the Burgers vector b ± 1/4[0 0 0 1]; the other is the (2, 3, 3, 5) stacking fault bounded by partial dislocations with b = ±1/4[0 0 0 1]. The core of the partial dislocations associated with the (2, 3, 3, 5) fault has an out-of-plane component (Frank component) and three in-plane components (Shockley components); the three Shockley components are cancelled out in total. The electronic structures of the (2, 5) and (2, 3, 3, 5) stacking faults were further examined by photoluminescence spectroscopy and first-principles calculations. It is suggested that the (2, 5) and (2, 3, 3, 5) stacking faults both have an interband state at a similar energy level, although they differ structurally.

A mobile electronic device includes: a housing; an image projector provided on the housing for projecting a portion of an original image to a projection area; and a processing unit. The processing unit causes the image projector to change an image projected to the projection area from a first image corresponding to a first portion of the original image to a second image corresponding to a second portion of the original image according to change information for changing the image projected by the image projector.

An epitaxial crystal for a field effect transistor which has a nitride-based III-V group semiconductor epitaxial crystal grown on a SiC single crystal base substrate having micropipes by use of an epitaxial growth method, wherein at least a part of the micropipes spreading from the SiC single crystal base substrate into the epitaxial crystal terminate between an active layer of the transistor and the SiC single crystal base substrate.

An epitaxial SiC single crystal substrate including a SiC single crystal wafer whose main surface is a c-plane or a surface that inclines a c-plane with an angle of inclination that is more than 0 degree but less than 10 degrees, and SiC epitaxial film that is formed on the main surface of the SiC single crystal wafer, wherein the dislocation array density of threading edge dislocation arrays that are formed in the SiC epitaxial film is 10 arrays/cm2 or less.

Highlights • Highly p-type doped 4H-SiC crystals were grown by physical vapor transport. • Al-N co-doping is useful to stabilize the 4H-SiC polytype on highly p-type growth. • 4H-SiC crystals grown with using Al-N co-doping show low resistivity of 86 mΩ cm. • 3″ highly p-type 4H-SiC crystal growth was performed with using Al-N co-doping. Abstract P-type 4H–silicon carbide (SiC) crystal growth has been achieved by physical vapor transport using aluminum and nitrogen co-doping. Aluminum carbide with a two-zone heating furnace was used for p-type doping, and yielded homogenous aluminum doping during SiC crystal growth by physical vapor transport. The 4H–SiC polytype with high-aluminum doping was unstable, but aluminum–nitrogen co-doping improved its stability. We grew p-type 4H–SiC bulk crystals of less than 90 mΩ cm by using co-doping. Secondary-ion mass spectrometry and Raman spectroscopy showed that the crystal growth of highly doped p-type SiC can be achieved by using the physical vapor transport method.

Provided is a silicon carbide epitaxial wafer which is formed on a substrate that is less than 1° off from the {0001} surface of silicon carbide having an α-type crystal structure, wherein the crystal defects in the SiC epitaxial wafer are reduced while the flatness of the surface thereof is improved.

The β-isopropylmalate dehydrogenase (β-IPMDH) gene of Acetobacter aceti No. 1023, which complemented the leuB mutation of Escherichia coli, was cloned and expressed in E. coll. Plasmids pCAL1 and pCAL4, carrying a 5.44 kilobase pairs (kb) HindIII-fragment in the opposite orientation, conferred the same β-IPMDH activity as that of the wild type strain of E. coli. Restriction mapping and deletion analysis indicated that the β-IPMDH gene was located on a 1.65kb AatII-HindIII fragment. Plasmids pMVL1 and pMVL2, composing the cloned β-IPMDH gene and plasmid pMV102, a plasmid indigenous to Acetobacter, were constructed as plasmid cloning vectors which allow selection of leu+ transformants in an A. aceti leu- host. The A. aceti leu- host was obtained through the insertional inactivation occurring as a result of homologous recombination between the chromosome of A. aceti and the cloned β-IPMDH gene, which was disrupted by insertion of the kanamycin resistance gene from pACYC177 into the BamHI site in the AatII-HindIII fragment. This system constitutes a relatively simple technique for gene disruption or replacement in Acetobacter that requires a single transformation.

In real environments, the presence of ambient noise and room reverberations seriously degrades the accuracy in sound source localization. In addition, conventional sound source localization methods cannot localize multiple sound sources accurately in real noisy environments. This paper proposes a new method of multiple sound source localization using a distributed microphone system that is a recording system with multiple microphones dispersed to a wide area. The proposed method localizes a sound source by finding the position that maximizes the accumulated correlation coefficient between multiple channel pairs. After the estimation of the first sound source, a typical pattern of the accumulated correlation for a single sound source is subtracted from the observed distribution of the accumulated correlation. Subsequently, the second sound source is searched again. To evaluate the effectiveness of the proposed method, experiments of two sound source localization were carried out in an office room. The result shows that sound source localization accuracy is about 99.7%. The proposed method could realize the multiple sound source localization robustly and stably. key words: real environment, multiple sound sources, sound source localization, distributed microphone system, inter-channel correlation, TDOA

Recently the importance of hands-free speech interfaces is increasingly recognized. However； in real environments； the presence of ambient noises and room reverberations seriously degrades the performance of the hands-free speech recognition. Reliable sound source localization is necessary to maximize the effect of noise reduction. This paper proposes a new method of multiple sound source localization using a distributed microphone system that is a recording system with multiple microphones dispersed to a wide space. The proposed method localizes a sound source by finding the position that maximizes the accumulated correlation coefficient between multiple channel pairs. After the estimation of the first sound source； a model of the accumulated correlation for a single sound source is subtracted from the observed distribution of the accumulated correlation. Subsequently； the second sound source is searched again. To evaluate the effectiveness of the proposed method； experiments of multiple sound source localization were carried out in an actual office room. The result shows that multiple sound source localization accuracy is about 96.0%. The proposed method could realize the multiple sound source localization robustly and stably.

An equivalent circuit model for gallium nitride-based high electron mobility transistors (GaN-HEMTs) in an exact circuit simulation is proposed. The equivalent circuit contains inherent GaN device properties； such as current-collapse and shot-channel effects. Base on the equivalent model； an power loss simulator was developed. The simulation accuracy was more than 93%. A converter optimum design method is discussed using the power loss simulator.