STM study of the surface morphology of gold on mica.

The scanning tunneling microscope (STM) promises to be a useful tool for the study of thin film deposition processes. We have imaged the growth surface of vapor-deposited gold on mica with an STM. Monatomic steps, screw dislocations, grain boundaries and grain topographies have been mapped for various gold thicknesses and deposition temperatures. Complementary x-ray diffraction and transmission electron microscopy experiments have been used to determine the orientation, size, shape and defectiveness of the crystallites. Near room temperature, the nuclei do not fuse together into larger single crystallites as the film coalesces, and the mounded topography of the individual crystallites evolves only slightly as the film thickens. The mounds are about 500angstroms across and 75angstroms high. At higher temperatures (150C to 300C), the nuclei apparently fuse as the film coalesces, giving larger crystallites containing holes. The screw dislocations observed by STM are apparently created as these holes fill in, due to frequent misregistry of the gold lattice around the holes.