Are thin film physical structures fractals?

The columnar physical structures commonly found in vapor-deposited thin films have been classified by several variations of what have been termed structure zone models. Perhaps the most interesting feature of these various models is their universal application to apparently all film materials and deposition processes. A structural self-similarity over a wide range of film thicknesses, preparation conditions, and materials types appear to be pointing toward a common origin. Reasons will be presented as to why thin films may be fractals and the consequence of this suggestion to understanding the origin and evolution of thin film physical structure. In particular, recent ballistic aggregation computer models provide a promising avenue of research.