Massive ground ice found in the Barrow Permafrost Tunnel at 3–7 m depths from the surface has been interpreted as an ice wedge and used to reconstruct early Holocene environmental changes. To better understand the development of this ground ice, we conducted radiocarbon dating for 34 samples of plant remains from the massive ground ice and underlying sediment layer. A significantly large gap in the measured radiocarbon ages (more than 24 ka) between massive ice and the underlying sediment layer throughout the tunnel profile suggested at least two possibilities. One is that the lower and older sediment layer had thrust upwards at the boundary between intruding ice wedge and adjacent sediment, and the growing ice had pushed the sediment sideways. Another is that erosional events had removed surface materials at about 12–36 ka BP (14–41 cal ka BP) before the overlaying sediment layer with massive ground ice developed. The overall distribution of radiocarbon ages from the massive ice supported the ice-wedge hypothesis as a formation mechanism, although our results showed several age inversions and large fluctuations. Dating of densely spaced samples revealed two ground-ice regions with similar ages around 11–11.5 and 10–10.5 ka BP divided by a relatively narrow region of transitional ages along the tunnel long-axis. This distribution may be explained by a possible misalignment between the sampling direction and the ice-wedge growth line or by intermittent ice growth with repeated cracking at more random locations than the classic ice-wedge growth model suggested.

Homoepitaxial growth on 4H-SiC Si-face substrates with sizes corresponding to 150 mm was carried out. The influence of growth conditions for uniformity and epitaxial defect density was investigated. A 150 mm size was realized by using two 76.2 mm wafers lined up in a radial direction. C/Si ratio is found to be a major parameter for controlling triangular defect density and the generation of step bunching. As a result, the surface morphology without bunched step structure and the triangular defect density with 0.5 cm−2 were obtained by decreasing C/Si ratio to 1.0 on the size corresponding to 150 mm. Under this condition, good carrier concentration and thickness uniformity of σ/mean =15.2 % and 1.7 % could be obtained.

Microbial synthesis of gold nanoparticles was achieved at 25°C and pH 7-1 using the mesophilic bacterium Shewanella algae with H2 as the electron donor. The microbial synthesis of gold nanoparticle was a fast process: 1 mM AuCl4− ions were completely reduced to insoluble gold within 30 min. At the solution pH 7, the gold nanoparticles of 10-20 nm were synthesized in the periplasmic space of S. algae cells. When the solution pH was decreased to 1, the gold nanoparticles of 50-500 nm were precipitated extracellularly. The solution pH was an important factor in controlling the morphology of biogenic gold particles and location of gold deposition.

Growth and characterization of p-type 4H-SiC epitaxial layers grown on (11-20) substrates are reported. P-type 4H-SiC epilayers with smooth surface morphology have been grown on (11-20) substrates by low-pressure, hot-wall type CVD with SiH4–C3H8–H2–TMA system. The doping concentration can be controlled in the range from about 1×1016cm−3 to 1×1019cm−3. Anisotropy of the crystalline quality is observed by x-ray diffraction measurement. P-type epilayers, in which near band-gap emissions are dominated and D-A pair peak is not observed, are obtained. Hole mobility of (11-20) epilayers is smaller than that of (0001) epilayers probably due to the lack of crystalline quality compared to (0001) epilayers. The results of both low-temperature photoluminescence and the temperature dependence of Hall effect measurements indicate that the boron concentration as undoped impurity in (11-20) epilayer is lower than that of (0001) epilayer. This may be caused by the smaller incorporation efficiency of boron into (11-20) epilayer than that of (0001) epilayer.

The differences of secondary defects between B+ and Al+ implanted layers in high-energy implantation were investigated. At the same volume concentration of implanted ion, density of secondary defects in Al+ implanted layer is higher than that in B+ implanted layer. On the contrary, mean defect size in B+ implanted layer is larger than that in Al+ implanted layer. The structure of secondary defect is thought to be a dislocation loop formed by an extra Si-C layer or localized lattice strain correlated to agglomerated interstitials. The amount of interstitials used for secondary defect formation is estimated. It almost coincides the same amount of implanted ions, and this correlation doesn't depend on ion species. B+ and Al+ implanted layers have different activation energy for secondary defect formation. This result means that they have different agglomerating mechanism of interstitials, which cause the differences of defect size and density between them.