Role of O2 negative-ion formation in low-energy electron-induced oxidation of InP(110)

Fabrication of nanocrystalline SnO₂ using electron stimulated oxidation

Fabrication of nanocrystalline SnO₂ using electron stimulated oxidation was investigated by in situ transmission electron microscopy. SnO₂ nanocrystals ranging from several to dozens of nanometers were transformed from single crystalline tin under 200 keV electron irradiation. This process includes crystallization of the surface amorphous SnO₂ layer and oxidation of the inner tin crystal substrate. On stimulation by electron irradiation, newly formed SnO₂ is supposed to act as a catalyst to oxidize the tin atoms underneath with lattice oxygen, and then be re-oxidized by absorbed oxygen from the residual gas of the microscope. This provides a new method to fabricate nanocrystalline SnO₂ materials and structures.

In situ observation of the formation of Fe3O4 in Fe4N (001) due to electron irradiation

gamma(')-Fe4N was subjected to electron irradiation with the dose rate of 6.8 x 10(23)e m(-2) s(-1) in a 400 kV transmission electron microscope. The first in situ observation of the formation of Fe3O4 (O) on Fe4N (gamma(')) with the orientation relationship of [100](O) parallel [100](gamma(')) and <001>(O) parallel <001>(gamma(')) has been made inside the microscope with the basic column vacuum of (5-6) x 10(-5) Pa. A mechanism is proposed involving the electron-stimulated dissociation of Fe-N chemical bonds, desorption of nitrogen from the surface, adsorption of oxygen to the surface, and the oxidization of excessive metallic iron on the surface.