Formation and annealing effect for close-packed Ge/Cu(111) layers

Growth and annealing effects of Ge/Cu(111) ultrathin films as deposited at ambient temperature have been studied using Auger electron spectroscopy and low-energy electron diffraction techniques. Ge/Cu(111) system shows a $1×1$ structure up to 5 monolayers as deposited at 300 K. The kinetic energy of Cu $L3M45M45$ Auger electrons shifts to a lower value upon deposition of Ge overlayers. This could be explained by the electric charge transfer between Ge and Cu atoms. From the intensity ratio change of Auger signals $(IGe/ICu),$ significant interdiffusion of Ge/Cu(111) films occurs around 375 K. Owing to the formation of a Cu-rich surface layer, the Cu $L3M45M45$ peak restores to the initial kinetic energy of a clean Cu(111) surface at 500 K.