The distribution of electrically active B concentration in single SiNWs (nanowires) grown by a vapor-liquid-solid (VLS) process was studied by analyzing Fano resonance in Raman spectra. We found a gradient of active B concentration along the growth direction; the B concentration was the largest at the substrate side and the smallest at the catalyst side. The observed concentration gradient suggests the conformal growth of a high B concentration layer during a VLS process. To confirm this effect, we grew SiNWs with controlled impurity profiles, that is, p-type/intrinsic ( p-i) and intrinsic/ p-type ( i-p) SiNWs, by controlling the supply of B source during SiNWs growth. We found that p-i SiNWs can be grown by just stopping the supply of B source in the middle of the growth, while i-p SiNWs were not realized; that is, the whole region of nominal " i-p" SiNWs was B-doped even if we started the supply of B source in the middle of the growth. These results confirm the above doping model. We also found that the distribution of active B concentration was significantly modified by high temperature annealing. By annealing at 1,100 degrees C for 1 min, B concentration became almost uniform along 10 microm long SiNWs irrespective of initial B profiles. This suggests very efficient diffusion of B atoms in a defective high B concentration surface layer of SiNWs.

No abstract

Previous studies comparing prospective memory between the elderly and young adults have shown that elderly adults perform better in naturalistic settings, while young adults perform better in laboratory settings. The purpose of this study was to examine what factors influence prospective memory in naturalistic settings, and we specifically focused on age, the complexity of the prospective memory task, self-evaluation and knowledge of memory function, retrospective memory, external memory aids, and internal memory strategies as potential influential factors. Eightysix healthy, elderly participants were enrolled (44 women and 42 men, mean age = 68.56 years, SD = 4.53). The results showed that the use of external memory aids increased in complex prospective memory tasks that depended on output monitoring, while other factors did not influence prospective memory performance. These results suggest that elderly adults can perform tasks adequately by using external memory aids that compensate for age-related memory declines in naturalistic settings.j pr_453 30..41

No abstract