Abstract
Auger depth profiling of an Ag layer grown epitaxially on a Pb(111) surface shows that constant diffusion of Pb occurs and a saturated ordered monolayer of Pb is finally formed on the Ag/vacuum interface. The surface concentration of Pb is found to increase exponentially as a function of time, after the sputtering ion beam was turned off. The time constant of this phenomenon (∼15 s–2.5 min) is dependent on the length of the ion sputtering time and the thermal annealing of the sample prior to the depth profiling. The diffusivity is estimated to be in the range of 2.1×1012–2.1×1013 cm2/s at room temperature.