Ultrathin epitaxial films of MgO(100) have been grown on NiO(100) film
s on a Mo(100) substrate. ISS results demonstrate that the NiO surface
is almost completely masked for MgO coverages of 2 ML, and LEED studi
es confirm that the growth of MgO is epitaxial. The electronic structu
re probed by ELS demonstrates the development of MgO surface band stru
cture through the sequential appearance of MgO transitions, but there
are no transitions apparent which involve interface states. Increasing
the thickness of the MgO overlayer on NiO induces an upward shift in
the Ni(2p3/2) XPS binding energy, with a shift of 1.0 eV for 7.5 ML of
MgO, indicating that there is transfer of negative charge from the Mg
O to the NiO. Our findings for the growth of MgO on NiO demonstrate th
e feasibility of synthesis and study of ordered, layered, mixed oxide
films only a few angstrom thick.