493 publications from this institution
A nondestructive and noncontact method for observation of microdefects in GaAs wafers has been developed with a new photo-thermal-radiation (PTR) microscope. We measured the PTR signal as a function of excitation energy (PTR spectrum) and the spatial distribution of PTR intensity (PTR image) of n-GaAs wafers at room temperature. We found that the PTR spectra have a peak due to a nonradiative state of microdefects at wavelengths ranging from 895 to 903 nm. The present PTR image shows inhomogeneities of microdefect density in GaAs wafers which cannot be observed by X-ray topography.
The mechanical behavior and fracture mechanisms of SHCC member failed in diagonal shear were evaluated both experimentally and analytically. Ultra High Performance Strain Hardening Cementitious Composite (UHP-SHCC) was applied as structural material. In the analysis, shear transfer model for SHCC was proposed based on its characteristics of cracking, that is, multiple fine cracking during strain hardening region and localization in one crack during strain softening region. As results, it was confirmed that proposed model was suitable for the mechanisms of shear transfer of SHCC and reasonable to predict the behavior of SHCC beam failed in diagonal shear.