nan Seiichiro

Photoluminescence evaluation of defects generated during SiGe-on-insulator virtual substrate fabrication: Temperature ramping process

Crystal qualities of Si∕SiGe∕Si-on-insulator structures with different SiGe thicknesses were evaluated by photoluminescence (PL). The wafers were annealed at different temperatures with a ramping rate of 5°C∕min. Free exciton PL peaks were clearly observed for the as-grown wafers and decreased with an increase in the annealing temperature. For the annealed wafers, defect-related PL signals were observed at around 0.82, 0.88, 0.95, and 1.0eV, which varied according to the annealing temperature and the SiGe thickness. They were also correlated to dislocation-related defects by transmission electron microscopy.

Crystallography and boundary structure of twins in Ti-Ni and Ti-Pd martensites

Morphology and crystallography of twins in the martensite in Ti-Ni and Ti-Pd shape memory alloys are reviewed on the basis of recent electron microscopy observations. It has been confirmed that there are five and three twinning modes in Ti-Ni and Ti-Pd martensites, respectively. The morphology and crystallography of newly found deformation twin in Ti-Ni martensite are briefly reported. The irrational nature of Type II twin boundary has been clarified by high resolution electron microscopy observations in edge-on state. There are neither ledge nor step structures at the irrational boundary.

Grain Boundary Structures of ARB Processed Aluminum

Grain boundary structures in the commercial purity aluminum (1100Al) highly deformed by the accumulative roll bonding (ARB) process was observed by using conventional transmission electron microscopy (CTEM) and high resolution transmission electron microscopy (HRTEM). In the low angle grain boundary with a tilt angle (2θ) of 2.1o consisted of the periodic dislocations array, the interval of those dislocations could be explained by the dislocation model for grain boundary. However, the dense dislocation region locally existed at the vicinity of the low angle boundary. On the other hand, we also observed the high angle grain boundary of which the common axis and 2θ was <110> and 125.9o, respectively. In this grain boundary, we could describe the boundary configuration in terms of the combination of the kite-shaped structure unit characterized by Σ11 coincidence boundary with the 2θ of 129.52o around <110> and the additional dislocations to compensate the difference of the actual and geometrically coincided one.

Interfacial Microstructure of Titanium Nitride – Titanium Diboride Composite Synthesized by Hot Shock Compaction

Interfacial microstructure of TiN-TiB2 composite, which was synthesized by hot shock compaction combined explosively shock condolidation and self-propagating high-temperature synthesis, was investigated by transmission electron microscopy (TEM). In the TiN-TiB2 composite included 60mol% TiN, an experimentally measured average grain size of the both TiN and TiB2 was approximately 500nm, and it decreased rather than those of the raw powders. By the conventional TEM observations, we clarified that there was a specific orientation relationship between cubic TiN and hexagonal TiB2. The high resolution electron microscopy (HREM) observations revealed that the TiN/TiB2 interphase boudnaries were atomically flat. We also observed grain boundaries of the composite and found that no secondary phases such as amorphous phase and precipitates were observed at the grain boundaries in the composite.

Advanced Materials Synthesis and Microstructural Characterization Using Explosive at Sojo University

In the research center for advances in impact engineering established in Sojo university, advanced materials have been synthesized by using shock wave and their microstructure has been investigated. An extremely high shock pressure and a dynamic hot compaction technique were developed, and the synthesis of the advanced materials and composites was succeeded. Transmission electron microscopy observations revealed unique microstructures of such materials obtained by our original advanced technique.

Photoluminescence Evaluation of Defects Generated during Temperature Ramp-up Process of SiGe-On-Insulator Virtual Substrate Fabrication

Defects generated during the temperature ramping process were evaluated by photoluminescence (PL) for Si/SiGe/Si-on-insulator structure, which is the typical structure for SiGe-on-insulator (SGOI) virtual substrate fabrication using the Ge condensation by dry oxidation. The free exciton peaks were clearly observed for the as grown wafers and decreased with the increase of annealing temperature. Defect-related PL signals at around 0.82, 0.88, 0.95 and 1.0 eV were observed and they also varied according to the annealing temperature and SiGe thickness. The defect-related PL signals were also correlated to dislocation-related defects by transmission electron microscopy (TEM)