The surface of ultrathin silicon on insulator (SOI) material has been
characterized with surface science analysis techniques including atomi
c-resolution scanning tunneling microscopy. It is shown that the (100)
SOI surface can be fabricated with a comparable degree of structural
perfection as the (100) surface of bulk Si. Fermi level pinning by ''t
ype C'' dimer defects results in a fully depleted and thus effectively
insulating Si film. (C) 1998 American Institute of Physics.