The surface structures growth’s features caused by Ge adsorption on the Au(111) surface

The initial stage of the adsorption of Ge on an Au(111) surface was investigated. The growth and stability of the structures formed at the surface were studied by ultrahigh-vacuum low-temperature scanning tunneling microscopy and analyzed using density functional theory. It was established that the adsorption of single Ge atoms at the Au(111) surface at room temperature leads to the substitution of Au atoms by Ge atoms in the first surface layer. An increasing of surface coverage up to $0.2$–$0.4$ monolayers results in the growth of an amorphous binary layer composed of intermixed Au and Ge atoms. It was shown that the annealing of the binary layer at a temperature of $T_{\text{s}}\simeq 500\,$K, as well as the adsorption of Ge on the Au(111) surface heated to $T_{\text{s}}\simeq 500\,$K for coverages up to $1$ monolayer lead to a structural transition and the formation of an Au-Ge alloy at least in the first two surface layers. Based on experimental and theoretical data, it was shown that the formation of single-layer germanene on the Au(111) surface for coverages $\leq 1$ monolayer in the temperature range of $T_{\text{s}}=297 {-} 500\,$K is impossible.