  It is shown that the electronic conduction in silicon-on-insulator (SOI)
layers exhibits a metallic regime which is very similar to that in
high-mobility Si-metal oxide semiconductor structures (MOS). The peak in the
electron mobility versus density, the strong drop in resistivity and the
critical concentration for the metal-insulator transition are all consistent.
On the basis of our SOI data for the temperature and in-plane magnetic field
dependence of the resistivity, we discuss several models for the metallic state
in two dimensions. We find that the observed behavior can be well described by
the theory on the interaction corrections in the ballistic regime. For the
investigated regime, the temperature dependent screening of scattering
potentials gives also a good description of the data.
