Properties of ultrathin silver films on the Ni(001) face

Abstract

Adsorption and isothermal desorption of silver on the Ni(001) face were investigated using AES, LEED, directional elastic peak (DEPES), and directional Auger (DAES) electron spectroscopies. At room temperature the first silver layer was found to grow up to the coverage θ≈0.74−0.78 where silver islands start to grow on it. At higher temperatures (620 K, for instance) the first layer grows alone up to θ≈0.86−0.89. Next, the first and second layers grow simultaneously up to θ≈1.7 where the first layer is completed and a 3D growth begins. Silver layer consists of close packed Ag(111) islands. Among two possible epitaxial orientations and two stacking sequences possible for each orientation, only one orientation and one sequence are preferable because the silver islands start to grow from the steps at the substrate. The dependence of silver Auger peak height on time, obtained during isothermal desorption consist of a linear part and an exponential one corresponding to the desorption of the second and the first silver layer, respectively. From such dependences for different desorption temperatures binding energies of silver atoms in the second and the first silver layer (3.04 and 3.59 eV/atom, respectively) are calculated.