Formation of ultrathin segregated-Ge crystal on Al/Ge(111) surface

Abstract We have investigated the formation of an ultrathin Ge crystal layer by vacuum annealing of the Al/Ge(111) structure. An hetero-epitaxial Al layer was found to be grown on a Ge(111) substrate by control of Al thickness and deposition rate during thermal evaporation, which the Al surface becomes the template of crystallographic structure of a segregated Ge layer. Then, surface flattening and Ge segregation of the Al/Ge(111) structure by vacuum annealing were evaluated, and the formation of ultrathin segregated-Ge crystals with a thickness below 1 nm on the hetero-epitaxial Al surface have been demonstrated.