Orientational ordering and domain-wall formation in Sb overlayers on GaAs(110)

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Abstract
Real-space scanning tunneling microscope images of Sb thin films on GaAs(110) show disordered surface structures at 300 K, but an ordered overlayer occurs when annealed. The annealed incommensurate Sb thin film shows grains with distinct superstructure orientations. Within each Sb grain, the superstructure exhibits 25-Å periodicity and alignment either 40° or 140° with respect to [11¯0] of the GaAs substrate. Striped domain walls with a mean separation of 110±7 Å are formed in each grain. The superstructure can be explained in terms of a Moiré effect in which the Sb overlayer is rotated by ±7° with respect to the substrate [11¯0] direction.