Surface morphology of silicon–tin alloys grown by molecular beam epitaxy on Si and Si1−xGex substrates

Abstract

The surface morphology and bulk structure of both strained (0.01≤x≤0.053) and strain-free Si1−xSnx (x=0.055) layers grown by molecular beam epitaxy on (001) Si and Si1−yGey substrates have been investigated by atomic force and transmission electron microscopy. The surfaces of all Si1−xSnx layers were found to have a mazelike structure composed of rectangular features faceted primarily by {113} planes. Transmission electron microscopy images of the alloys revealed columnar structures originating at the interface between the alloys and the substrates. The formation of the observed surface morphologies and the columnar structure is attributed to the surface-growth processes modified by the Sn atoms as compared to the growth of pure Si.