Evaporation of silver thin films on mica

We have studied the effect of evaporation parameters on the growth of epitaxial silver films on mica. Our object was to grow films with large flat areas to be used as substrates in STM studies. We have found optimum parameters which result in extremely flat films which in the scale of several micrometers consist only of terraces several hundred nanometers wide and separated by monatomic steps; and a few deep pinholes averaging an areal density of roughly one pinhole per every square micrometer of film surface. Certain other parameter values produced exceedingly rough surfaces.