Papers by Author: Ichiro Yonenaga

Abstract: Deformation Characteristics in High-Purity Si Crystals Subjected to Bending Tests Were Studied. Specimens Were Deformed at the Temperatures Higher than 800°C without Brittle Fracture under Application of a High Stress up to 350 Mpa. Stress-Strain Behavior and the Yield Stresses Depend on the Temperature and the Strain Rate. The Results Were Discussed in Terms of the Dislocation Dynamics and Dislocation Mobility to Provide Fundamental Knowledge for Wafer Manufacturing.

Abstract: Czochralski Growth of Si Crystals Heavily Doped with in Impurity and Co-Doped with Electrically Neutral Impurity C or Ge Was Conducted in Order to Investigate the Solubility and Ionization Ratio of in in Si for Utilizing in Advanced ULSI and PV Devices. The Carrier Concentrations in the Grown in-Doped and (In+C) and (In+Ge) Co-Doped Crystals Were in a Range of 3.5~6.5 × 10¹⁶ Cm^-3, much Lower than the Total Concentration of in Impurity due to the Low Ionization Ratio. Sufficient Increase of Carrier Concentrations by Co-Doping of C or Ge Impurity Was Not Detected for their Low Concentrations in the Grown Crystals Investigated.

Abstract: The atomistic structure of Czochralski-grown SixGe1-x binary mixed semiconductor was studied experimentally and theoretically. By extended X-ray absorption fine structure (XAFS) studies it was found that bulk SiGe semiconductor is a random mixture and that the Ge-Ge, Ge-Si and Si-Si bond lengths maintain distinctly different lengths and vary in a linear fashion against the alloy composition across the whole composition range 0 < x < 1, in good agreement with expectations derived from the ab-inito electronic structure calculations. The result indicates that SiGe is a suitable model for a disorder mixed material and that the bond lengths and bond angles are distorted with the composition.