The metallic TiO single crystal film formed epitaxially on MgO is reported.
II was found that the simultaneous supply of Ti vapor and O-2 gas on the M
gO(001) surface resulted in the TiO(001) film formation. The surface struct
ure of the TiO(001) film was investigated using Li+ impact-collision ion sc
attering spectroscopy and reflection high energy electron diffraction. The
surface of TiO formed on MgO was very close to an ideal truncation of the T
iO bulk structure, while the O vacancies, whose concentration was estimated
to be 28%, exist on the outermost surface. When the TiO film was exposed t
o the O-2 atmosphere of 1 x 10(-8) Torr partial pressure with maintaining t
he substrate temperature at 1070 K, the TiO-2 x 2-O superstructure was foun
d to be formed. In the 2 x 2-O structure, the adsorbed O atoms were located
on the top sites of Ti of the outermost TiO surface, where the distance be
tween O and Ti was equal to that in the bulk, which was 2.09 Angstrom. (C)
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