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The synthesis of metal silicide at the metal/silicon oxide interface by electronic excitation was investigated using transmission electron microscopy. A platinum silicide, α-Pt2Si, was successfully formed at the platinum/silicon oxide interface under 25-200 keV electron irradiation. This is of interest since any platinum silicide was not formed at the platinum/silicon oxide interface by simple thermal annealing under no-electron-irradiation conditions. From the electron energy dependence of the cross section for the initiation of the silicide formation, it is clarified that the silicide formation under electron irradiation was not due to a knock-on atom-displacement process, but a process induced by electronic excitation. It is suggested that a mechanism related to the Knotek and Feibelman mechanism may play an important role in silicide formation within the solid. Similar silicide formation was also observed at the palladium/silicon oxide and nickel/silicon oxide interfaces, indicating a wide generality of the silicide formation by electronic excitation. [ABSTRACT FROM AUTHOR]

Electronic-excitation-effects of phase stability in III-V binary compound nanoparticles have been studied by TEM. When GaSb particles were excited by 75 keV electrons, the compound transforms to a two-phase consisting of an antimony core and a gallium shell or an amorphous phase, or remains the original crystalline phase, depending on particle size and/or temperature. It is suggested that such nonlinear responses of the phase stability may arise from synergistic effects of bond instability under excited states, formation of high density of excited states, chemical equilibrium under excited states and temperature dependence of defects mobility. [ABSTRACT FROM AUTHOR]

We studied the effect of electron flux on phase separation induced by electronic excitation in GaSb nanoparticles, in order to see whether the phase separation is characterized as a cooperative phenomenon, in which a nonlinear relation may be found between density of excited states introduced and the efficiency of the phase separation or not. The phase separation to two phases consisting of an antimony core and a gallium shell proceeds abruptly after incubation time with increasing electron dose and does only at the flux above a threshold value. It is suggested that such nonlinear behaviors take place as a cooperative phenomenon among electronic-excitation effect, nano-size effect and temperature. [ABSTRACT FROM AUTHOR]

The synthesis of platinum silicide at a Pt/SiO x interface by photon irradiation was investigated using transmission electron microscopy. A platinum silicide, Pt 2 Si, was successfully formed at the Pt/SiO x interface by irradiation with 680 and 140 eV photons, but not by irradiation with 80 eV photons. Silicide formation was also induced by irradiation with electrons of energy 75 keV. The amount of silicide formed by photon irradiation was lower than the amount obtained by electron irradiation. Silicide formation by both photon and electron irradiation was accompanied by Si depletion in amorphous SiO x . The experimental results indicate that silicide formation is induced by electronic excitation. A possible mechanism for silicide formation is proposed on the basis of the results. [ABSTRACT FROM AUTHOR]