Tomokuni Mitsuishi

On the Phase Transformation of VO2

Phase transformation of VO2 was studied by the optical microscopy, the X-ray difraction and the electrical resistance. Growth of transformed regions from sites of nucleation was observed in micrographs. The critical temperature of the transition and the rate of the growth were dependent on the mechanical strain. Apparent growth velocities were 0.01~1 mm./sec. at heating rates of 0.1~6°C/min. The intermediate phase suggested by Umeda et al with NMR was identified with a phase observed by our experiment. The lattice constants are a=5.80 AA, b=4.52 AA. c=5.38 AA, α=91.55°, β=122.78°, γ\doteqdot90°. Both the impurities of Al, Fe, and Cr and the reduction were effective for the creation of the triclinic phase. The low temperature phase which is normally monoclinic was found to be triclinic for those crystals which have the wider temperature range of the intermediate phase. The intermediate phase was explained assuming a metastable structure stabilized by the Magneli defect.

A new experimental determination of the relationship between the Hall mobility and the hole concentration in heavily doped p-type silicon

Abstract The relationship between the Hall mobility and the hole concentration in p-type silicon were experimentally investigated. Boron and gallium were used as dopants; their doping was done by either the ion implantation or the diffusion technique. It was found that the relationships for boron-doped specimens and for gallium-doped specimens for the heavily doped range are considerably different from each other. Both of these relationships are also different from the so-called Irvin curve which is well known as a standard relationship between the mobility of carriers and the impurity concentration, but the relationship for boron doping is almost consistent with that of Thurber et al., if the Hall mobility factor is reasonably taken into account.

Correlation between lattice damage and electrical activation of phosphorus-implanted silicon

Quantitative comparision between the profiles of damage density before annealing and carrier concentration after annealing were examined for a wide range of phosphorus‐implantation dose (1013–1016 cm−2). Electrical‐activation mechanisms during low‐temperature (around 500 °C) annealing before epitaxial regrowth occurs were found to be different in the different damaged regions (very low, ∼20%, 20–75%, 75%∼damage density).

Thermal Behavior of B, P and As Atoms in Supersaturated Si Produced by Ion Implantation and Pulsed-Laser Annealing

The heat treatment effect on supersaturated Si crystals with B, P, or As produced by high-dose ion implantation (8×1015 cm-2) and Q-switched ruby laser annealing (2.0 J/cm2) is investigated. The deactivation of excess B atoms becomes appreciable with a high-temperature heat treatment above 800°C, while deactivations of excess P and As atoms take place even at low temperatures of 300–400°C. The deactivation process of B atoms at such high temperatures was found to be a precipitation of B atoms with an activation energy of 3.2 eV using Hall effect measurements and transmission electron microscopy observation.

Damage-dependent electrical activation of ion-implanted silicon. I. Experiments on phosphorus implants

The electrical activation mechanism of phosphorus ions implanted into a silicon substrate is studied during low‐temperature (?550 °C) annealing. Apparently anomalous behavior where the electrically active fraction versus dose curve shows a peak in a limited dose range is analyzed by measuring the distribution profiles of damage and carrier concentration. Carrier generation was found to be strongly influenced by the extent of damage in the layer. Phosphorus atoms in layers with less than 20% damage were not electrically activated. However, in layers with more than 20% damage, electrical activation abruptly increased with the change of damage. This correlation existed at each depth in the substrate for all samples with various doses. The anomalous dose dependence of the electrically active fraction was recognized to be an integral result of the phenomenon. Analysis of the damage formation showed that overlapping of amorphous clusters produced in each ion trajectory is essential for the electrical activation...

Laser sintering of VO2 film

The conventional preparation process of VO2 temperature sensors requires the precise control of ambient atmosphere. This is one of the difficulties in their application to integrated devices. Laser sintering proved to be useful in overcoming this difficulty. Specimens of VO2 film (1.4×1.4×0.04 mm3 in size) printed on alumina substrates changed in electrical resistance by a factor of 102 at about 68 °C with increasing temperature, after exposing them, in open air, to a 2‐ms pulse beam from a ruby laser on relaxation oscillation, whose energy density was 6.5 J/cm2.

Mobility and carrier‐concentration profiles of P+ ion‐implanted, isothermally annealed silicon crystals

Experimental data of carrier mobility and carrier concentration profiles in depth from the surface of silicon wafers implanted with 50 keV P+ ions of various doses, isothermally annealed at 480 °C, are reported. Generation and annihilation of mobility controlling defects and carrier trapping centers are discussed with these data. A comment on the carrier recovery of heavily dosed specimens is given.