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 t he work function may be used to investigate the growth of thin epitaxi al metal films. A special setup of a basically old technique-a redesig n of a Kelvin probe-is applied to monitor work function changes not on ly during gas adsorption but also during metal deposition with high pr ecision. Such dynamical work function change measurements clearly demo nstrate the layer-wise growth of thin Cu films on an oxygen precovered Ru(0001) surface. This is revealed by the observation of multiple DEL TAPHI-oscillations with a period corresponding to the deposition of a single Cu(111) layer. Furthermore the role of the oxygen as a surfacta nt for layer-by-layer growth is concluded from the fact that under sim ilar conditions such oscillations have never been observed during Cu e vaporation on the clean Ru(0001).