EPITAXIAL-GROWTH OF SILVER ON MICA AS STUDIED BY AFM AND STM

The epitaxial growth of Ag(111) on mica was studied using the techniques of atomic force microscopy (AFM) and scanning tunneling microscopy (STM). We examined the morphology of these films primarily with AFM as a function of the substrate growth temperature (75 to 350-degrees-C) and film thickness (50 to 300 nm) for slow metal deposition rates of 1 to 2 angstrom/s. In the lower temperature regime near or below 75-degrees-C, a ''rolling hill'' morphology is observed for all film thicknesses. In the higher temperature regime above approximately 75-degrees-C, a number of different surface morphological phases exist which depend on both the film thickness and growth temperature. As the film thickness increases, the phases develop in the following order: (1) island, (2) channel, (3) hole and (4) network. The rate of progression through these phases with increasing film thickness is slower for higher substrate temperatures. Although a number of these films appear atomically flat in small regions, holes and other surface features often disrupt the surface flatness on a larger scale. We have found, however, that it is possible to grow films which are atomically flat on the micrometer-scale using higher deposition rates (approximately 40 angstrom/s) and high substrate temperatures.