Epitaxial growth of AlAs/CoAl/AlAs(001) heterostructures by controlling the metal surface

Epitaxial growth of CoAl films on AlAs(001) films was examined for films with Co contents of 47–58 at. %. The surface terminations of CoAl films were characterized, and the dependance of surface terminations and surface reconstructions on the Co/Al composition was examined. When AlAs/CoAl/AlAs heterostructures were fabricated by growing AlAs overlayers on CoAl films whose surface terminations were well defined, a mixture of AlAs(001) and AlAs(111) phases grew on the Al‐terminated surface, whereas only the AlAs(001) phase grew on the Co‐terminated surface. The Co‐terminated CoAl surface thus is suitable for the overgrowth of AlAs. A high‐quality epitaxial GaAs/AlAs/CoAl/AlAs/GaAs heterostructure was grown by combining the control of metal surface terminations with low‐temperature migration‐enhanced epitaxial growth of AlAs overlayers.