SCANNING-TUNNELING-MICROSCOPY ON CONCAVE-SHAPED SI(100) SUBSTRATES

The surface structure, step- and terrace-width distribution of mechano -chemically prepared, concave-shaped Si(100) substrates, have been det ermined by scanning tunneling microscopy (STM). The as-prepared surfac es present a continuous range of local polar miscut angles Theta = 0 d egrees-12 degrees and the full range of azimuthal directions. Under UH V treatment the surface breaks up into stepped surfaces with 2 X 1 and 1 X 2 reconstructed terraces. Depending on the local miscut angle The ta, three topographically different regions can be distinguished. A do uble-domain structure with single-layer steps is observed for Theta ar ound 1 degrees. In [001]-like directions scaly arrangements of small t erraces with both reconstructions were found. In [011]-like directions and for Theta exceeding 6 degrees, this phase is transformed into a s ingle-domain structure where terraces are connected by double-layer st eps. For intermediate Theta, a mixture of SL and DL steps was observed confirming a gradual and not abrupt transition between these phases. Well ordered high-index faces like (911) and (711) were observed for T heta exceeding 9 degrees.