50 mm diameter Sn-doped (001) beta-Ga2O3 crystal growth using the vertical Bridgeman technique in ambient air

Available online 3 July 202050 mm-diameter Sn-doped beta-Ga2O3 crystals with growth orientation perpendicular to (001) plane were grown with the newly-developed resistance heating vertical Bridgeman furnace using platinum-rhodium alloy crucibles in ambient air. Weak low angle grain boundaries and several small grains were detected on the both-side mirror polished 50 mm-diameter (001) wafer, using high resolution refraction x-ray topography. However, no imperfections were observed over the whole wafer area when using crossed polarizer analysis. Measured values of both the full width at half maximum and the dislocation densities were widely distributed in the wafer, ranging from 10 to 50 arcsec and 100 to 2000/cm(2) respectively with no distinctive correlations among them. The Sndoped crystals with concentrations ranging from 5 x 10(17) to 5 x 10(18) atom/cm(3) could be grown by Sn-doping in a range from 0.05 to 0.1 mol%, and (001) oriented, 50 mm-diameter n-type oxide semiconductor wafers with a carrier density of 3.6 x 10(18)/cm(3), a mobility of 60 cm(2)/Vsec and a resistivity of 0.03 Omega.cm, were obtained from a 0.1 mol% Sn-doped crystal.ArticleJOURNAL OF CRYSTAL GROWTH.546:125778(2020)journal articl

Estimation of Buttiker-Landauer traversal time based on the visibility of transmission current

We present a proposal for the estimation of B\"uttiker-Landauer traversal time based on the visibility of transmission current. We analyze the tunneling phenomena with a time-dependent potential and obtain the time-dependent transmission current. We found that the visibility is directly connected to the traversal time. Furthermore, this result is valid not only for rectangular potential barrier but also for general form of potential to which the WKB approximation is applicable . We compared these results with the numerical values obtained from the simulation of Nelson's quantum mechanics. Both of them fit together and it shows our method is very effective to measure experimentally the traversal time.Comment: 12 pages, REVTeX, including 7 eps figure

2-inch diameter (100) β-Ga2O3 crystal growth by the vertical Bridgman technique in a resistance heating furnace in ambient air

Available online 20 May 2020ArticleJOURNAL OF CRYSTAL GROWTH.545:125724(2020)journal articl

Lateral Effects in Fermion Antibunching

Lateral effects are analyzed in the antibunching of a beam of free non-interacting fermions. The emission of particles from a source is dynamically described in a 3D full quantum field-theoretical framework. The size of the source and the detectors, as well as the temperature of the source are taken into account and the behavior of the visibility is scrutinized as a function of these parameters.Comment: 22 pages, 4 figure

Development of the Shinshu University Online System of General Academic Resources (SOAR)

This paper discusses the development of the Shinshu University Online System of General Academic Resources (SOAR). As a participant in the 2006-2007 Cyber Science Infrastructure (CSI) development project of the National Institute of Informatics (NII), Shinshu University is seeking to develop SOAR as an integrated academic resource system. In addition to developing an environment for providing accesstothe latest academic resources within the university, SOAR is intended to promulgate university research results and research activities, both within Japan and around the world, to a broad audience. Specifically, this system achieves mutual coordination by linking e-journals and the Web of Science to the researcher directory and the institutional repository—two system cornerstones. SOAR can be regarded as a potential model for future academic-resource systems. Although the Institutional Repository (SOAR-IR) was developed using existing software, the Researcher Directory (SOARRD) is a new system based on XML technology.ArticleProgress in Informatics. 5:137-151 (2008)journal articl

Morphology and formation mechanism of metallic inclusions in VB-grown sapphire crystals

Morphologies of metallic inclusions observed in sapphire crystals grown by the vertical Bridgman (VB) technique using a tungsten (W) crucible were investigated. Square- or hexagonal-shaped inclusions 2-5 mu m in size were observed in sapphire crystals around the interface between the seed and the grown crystal. It was found that such inclusions consisted of W metal used for the crucible. The morphology of some of the inclusions reflects a rhombic dodecahedron which is based on the cubic structure of W and is surrounded by {110} faces. It is probable that inclusions form in the sapphire melt during the crystal growth process, and then sink in the melt to the growth interface due to the high density of W. (C) 2013 Elsevier B.V. All rights reserved.JOURNAL OF CRYSTAL GROWTH. 401:388-391 (2014)journal articl