Yoshio Murakami

Calculation of Diffusion Component of Leakage Current in pn Junctions Formed in Various Types of Silicon Wafers (Intrinsic Gettering, Epitaxial, Silicon on Insulator)

We derived a general analytical formula for the diffusion component of leakage current in pn junctions formed in various types of silicon wafers such as intrinsic gettering (IG), epitaxial (EPI), and silicon on insulator (SOI) wafers. From this analysis, it can be understood quantitatively that defect regions in IG wafers increase the diffusion current, although heavily doped regions in epitaxial wafers decrease the diffusion current, and in SOI wafers the diffusion current can be considerably reduced when there is a low recombination velocity at the Si/SiO2 interface.

Measurement of Energy Reflection from Metals Bombarded by 10–30 keV Hydrogen Ion Beam

Measurement has been made on the energy reflection from Mo, Cu, stainless steel and Al targets bombarded by hydrogen ions in the energy range of 10–30 keV. A broad beam from a duoPIGatron ion source is applied on a large target plate and the reflected energy flux is received by a small thermocouple. The results are compared with theoretical calculations and experimental data reported in literature.

N+p Junction Leakage Current in p/p+ Epitaxial Wafers

The reverse-bias leakage current of silicon pn junctions formed in the p/p+ epitaxial structure have been investigated for the case in which a high density of oxygen precipitates exist in the p+ substrates. It is confirmed experimentally that the p/p+ structure has an advantage of the decrease of diffusion current even in the case of high oxygen precipitates in the p+ substrate. By calculating the minority carrier profile near the depletion region, the differences in diffusion current are well explained by the difference in the gradient of minority carrier profile at the edge of depletion region.

Some Considerations on Large-Sized Catalytic Pumps for Nuclear Fusion Apparatus

Studies have been made of the problems encountered in the development of a large-sized catalytic pump for the pumping of hydrogen in nuclear fusion apparatus. An experimental pump having a speed of about 5000 liter/sec is assumed to use at partial pressures between 10-7 and 10-5 Torr. The influence of water vapor on the atomization of hydrogen at the rhenium filament is one of the problems, and is discussed from the structural point of view. The lifetime of the cuprous oxide layer is another important problem. A convenient method of oxidation of copper plates by atomic oxygen produced at an incandescent rhenium filament is proposed for the generation and regeneration of the oxide. The optimum temperatures of the cuprous oxide layer are also determined for the rapid desorption of water vapor from the oxide and for the effective reaction with hydrogen atoms.