Atomic resolution imaging on Si(100)2x1 and Si(100)2x1:H surfaces with noncontact atomic force microscopy

We investigate the difference in atomic resolution images between the Si(100)2 x 1 reconstructed surface with a dangling bond and the Si(100)2 x 1:H monohydride surface without a dangling bond using noncontact atomic force microscopy. On the Si(100)2 x I surface, the distance between bright spots is 3.2 +/- 0.1 Angstrom, which is larger than that between silicon atoms. On the Si(100)2 x 1:H surface, the distance between bright spots is 3.5 +/- 0.1 Angstrom, which is in good agreement with that between hydrogen atoms. For the first time, individual hydrogen atoms are resolved. This means that the distance between measured bright spots forming dimers is increased by the hydrogen termination.