AVS 53rd International Symposium
    Advanced Surface Engineering Wednesday Sessions
       Session SE1-WeA

Invited Paper SE1-WeA1
Atomic Chaos and Emergent Phenomena in Glancing Deposition

Wednesday, November 15, 2006, 2:00 pm, Room 2007

Session: Glancing Angle Deposition
Presenter: K. Robbie, Queen's University, Canada
Authors: K. Robbie, Queen's University, Canada
T. Brown, Queen's University, Canada
C. Elliott, Queen's University, Canada
C. Buzea, Queen's University, Canada
Correspondent: Click to Email
The atomic-scale porosity created in thin films by glancing angle deposition is the result of chaotic atomic competition. A so-called growth instability arises when atomic vapor arriving at glancing incidence condenses under conditions where the behavior of each atom strongly affects the condensation behavior of subsequent atoms - a sensitivity to initial conditions, or chaos - creating oriented dendritic structures that can be engineered on the scale of nanometers by varying the deposition geometry. The chaotic nature of this growth results in fractal morphologies, with scale-invariant self-similarity and power-law scaling in observable parameters such as the 'column' diameter. While the stochastic arrival of atoms clearly plays a role in the chaotic dynamics of this system, it appears that atomic-scale condensation dynamics also contribute - and perhaps constitute a form of quantum chaos. Examining the morphologies of films deposited at glancing incidence reveals a rich set of structures not well described by simple ballistic aggregation models. Particularly interesting are morphological rare-events that occur in some materials, and include self-organized pyramidal structures in several noble metals. These structures may be described as emergent phenomena, and suggest that there are quantum contributions to this chaotic condensation process. Experimental studies of this film growth process will be presented, including measurements of growth exponents and observations of material-dependent variation in film morphology. Existing theories of ballistic aggregation will be reviewed, followed by several proposals of directions that might be pursued to explain the formation mechanisms of the observed emergent phenomena. Finally, the potential of geometrically-controlled atomic self-assembly for technological applications will be presented.