Impact of substrate heating during Al deposition and post annealing on surface morphology, Al crystallinity, and Ge segregation in Al/Ge(111) structure

We have studied the impact of Ge substrate heating during ∼25 nm thick Al deposition and post annealing in N 2 ambient on the surface flatness of an Al/Ge(111) structure, the crystallographic structure of the deposited Al layer, and formation of a Ge segregated layer. Surface segregation of Ge atoms on a flat metal surface is an effective means of growing two-dimensional Ge crystals as well as an ultrathin Ge crystalline layer. The surface morphology of the Al/Ge(111) structure becomes flat by substrate heating during Al deposition. The crystallinity of the Al layer on Ge(111) can be improved by both substrate heating and post annealing. Ge segregation on a flat Al(111) surface also occurred by post annealing.