On the correlation between surface roughness and work function in copper

Both surface roughness (SR) and work function (WF) are important characteristics of a solid surface. Understanding the relationship between SR and WF is necessary in order to apply the Kelvin probe technique to characterize surface behavior. In this study, SR and WF of copper surfaces were measured using atomic force microscopy and scanning Kelvin probe, respectively. Experimental results showed that WF decreased with increase of SR. Using sine functions, a capacitor model was proposed and a correlation between WF and SR was established. The theoretical predictions of WF were in good agreement with experimental results. The model is also useful for analyzing the effect of tip geometry on measurements of WF. (C) 2005 American Institute of Physics.