Work‐function oscillations during Cu film growth on an oxygen precovered Ru(0001) surface: A basically old technique as a powerful film growth monitor

In the present work it is demonstrated how dynamical measurements of the work function may be used to investigate the growth of thin epitaxial metal films. A special setup of a basically old technique—a redesign of a Kelvin probe—is applied to monitor work function changes not only during gas adsorption but also during metal deposition with high precision. Such dynamical work function change measurements clearly demonstrate the layer‐wise growth of thin Cu films on an oxygen precovered Ru(0001) surface. This is revealed by the observation of multiple ΔΦ‐oscillations with a period corresponding to the deposition of a single Cu(111) layer. Furthermore the role of the oxygen as a surfactant for layer‐by‐layer growth is concluded from the fact that under similar conditions such oscillations have never been observed during Cu evaporation on the clean Ru(0001).