Electron microscope studies of vapor deposited materials: Nucleation, epitaxial growth and surface topography

Abstract

The nucleation and epitaxial growth of deposits at both low and high temperature substrate conditions and the resulting two and three dimensional growth modes have been investigated using electron diffraction and high resolution electron microscopy. At high temperatures, the growth of small particles such as Au, Pt and Ge grown under low rate conditions similar to molecular beam epitaxy are revealed by lattice imaging. Using an intermediate buffer layer Ag film, surface growth of (100) and (310) Au thin film layers are revealed by diffraction contrast to be in a step ledge growth regime. For molecular growth, it has been possible to produce thin epitaxial C60 films on mica by controlling substrate temperature. While the above investigations were performed ex situ to the microscope vacuum environment, an in situ evaporator has been installed on a high resolution microscope. Observations can be made in real time of cluster growth from atomic diamters on up. The resulting atomic motion around cluster edges is similar in appearance to surface melting.