If the physical properties of C(60) fullerene molecules can be controlled in C(60) products already in use in various applications, the potential for industrial development will be significant. Encapsulation of a metal atom in the C(60) fullerene molecule is a promising way to control its physical properties. However, the isolation of C(60)-based metallofullerenes has been difficult due to their insolubility. Here, we report the complete isolation and determination of the molecular and crystal structure of polar cationic Li@C(60) metallofullerene. The physical and chemical properties of Li@C(60) cation are compared with those of pristine C(60). It is found that the lithium cation is located at off-centre positions in the C(60)-I(h) cage interior and that the [Li(+)@C(60)] salt has a unique two-dimensional structure. The present method of purification and crystallization of C(60)-based metallofullerenes provides a new C(60) fullerene material that contains a metal atom.

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We have fabricated a metal–oxide–semiconductor (MOS) electron tunneling cathode with ultrathin SiO2 and examined the emission characteristics. We found that the emission occurred from an entire gate area by electron tunneling through the potential barrier in the MOS diode and the emission current was 0.7% of the total current flowing through the diode. The emission was also found to be nearly independent of pressure.

The effect of fluorine implantation on the interface radiation hardness of Sigate metaloxidesemiconductor transistors J. Appl. Phys. 66, 3909 (1989); 10.1063/1.344012Oxide breakdown reliability degradation on Sigate metaloxidesemiconductor structure by Al diffusion through polycrystalline silicon An Si-gate metal-oxide-semiconductor (MOS) electron tunneling cathode was fabricated and its emission characteristics were examined. The emission occurred at a gate voltage higher than the work function of the Si gate by electron tunneling through the potential barrier in the MOS cathode and was stable in the Si-gate cathode. The energy distribution of emitted electrons was measured and was confirmed to be mainly determined by the scattering process of hot electrons in the oxide. The emission current from the Si-gate MOS cathode was nearly independent of pressure.

An effective mean-free path of hot electrons in the conduction band of SiO2 in a Si-gate metal–oxide–semiconductor (MOS) electron tunneling cathode was measured and found to be about 0.7 nm. Following these observations, we proposed and fabricated a depletion gate MOS electron tunneling cathode. The highest transfer ratio of 13.3% was achieved in the cathode at the low emission current level, which was considerably higher than that of tunneling cathodes studied in the past. However, the ratio decreased drastically at high current due to the hole injection into the depletion region from the gate.