Atomically resolved scanning tunneling microscopy of hydrogen-terminated Si(001) surfaces after HF cleaning

Atomic structures of hydrogen-terminated Si(001) surfaces after HF cleaning are investigated by scanning tunneling microscopy. It is revealed that the surface is macroscopically rough but is composed of terraces and steps. In side a terrace, 1x1 structures are formed. This corresponds to the ideal 1x 1 dihydride structure. The step edges run along the < 110 > direction. On t he other hand, the 1x1 dihydride structure disappears when the surface is s ubsequently rinsed with ultrapure water, because every other dihydride row of the ideal 1x1 structure is preferentially etched in ultrapure water. (C) 2000 American Institute of Physics. [S0003- 6951(00)03604-4].