Atomic structure of twins in GaAs

Abstract
Two types of twins with different atomic structure may exist in GaAs: rotation type and reflection type. A selective chemical etching technique was employed to clarify which of these two twin types occurs in practical GaAs crystals. Twins in an As-rich horizontal Bridgman (HB) GaAs, a Ga-rich HB GaAs, and a liquid-encapsulated Czochralski GaAs were studied, and the results showed that all of the studied twins were rotation type. This suggests that the bonding configuration at the twin plane is a more important factor than stoichiometry of the crystal, in determining the type of twins in GaAs.