Formation and evolution of epitaxial Co5Ge7 on Ge(001) surface by reactive deposition inside an ultrahigh-vacuum transmission electron microscope

Abstract

Cobalt was deposited on single-crystal Ge(001) surface at ∼350°C by electron-beam evaporation in an ultrahigh-vacuum transmission electron microscope. The deposited Co reacts with Ge to form nanosized islands with the cobalt germanide Co5Ge7 phase. The Co5Ge7 islands show square and rectangular shapes. Two epitaxial orientation relationships between Co5Ge7 and Ge were observed: Co5Ge7 ⟨110⟩(001)‖Ge⟨100⟩(001) and Co5Ge7⟨001⟩(110)‖Ge⟨100⟩(001).