Scanning tunneling microscopy on concave-shaped Si(100) substrates

Abstract

The surface structure, step- and terrace-width distribution of mechano-chemically prepared, concave-shaped Si(100) substrates, have been determined by scanning tunneling microscopy (STM). The as-prepared surfaces present a continuous range of local polar miscut angles Θ = 0° – 12° and the full range of azimuthal directions. Under UHV treatment the surface breaks up into stepped surfaces with 2× 1 and 1 × 2 reconstructed terraces. Depending on the local miscut angle Θ, three topographically different regions can be distinguished. A double-domain structure with single-layer steps is observed for Θ around 1°. In [001]-like directions scaly arrangements of small terraces with both reconstructions were found. In [011]-like directions and for Θ exceeding 6°, this phase is transformed into a single-domain structure where terraces are connected by double-layer steps. For intermediate Θ, 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 Θ exceeding 9°.