The generation of rotational twins in the growth of GaAs and GaSb on Ge(111) substrates by molecular beam epitaxy has been characterized by X-ray diffraction. Rotational twins are shown to be less generated in GaSb than in GaAs. It has been demonstrated that the generation of rotational twins in GaAs can be suppressed by inserting GaSb as a buffer layer. It has also been demonstrated that the use of the As-2 beam and vicinal surfaces is effective for suppressing twin generation in GaAs. (C) 2016 Elsevier B.V. All rights reserved.