Thin Film Instability and Nanostructure Formation: a Molecular Dynamics Study
M. Han, J.S. Lee, S. Park and Y.K. Choi
Seoul National University, KR
Keywords: molecular dynamics simulation, nanostructure, thin film, instability
One of the recent studies showed that the structures can be self-constructed by controlling the instability of thin fluid film of a nano-scale [S.Y. Chou and L. Zhuang, J. Vac. Sci. and Technol. B, 17, 3197-3202 (1999)]. Several physical elements involved in the process determine the characteristics of the structure formation. The Molecular dynamics simulation is used to probe the phenomena. Two sources of instability are investigated: the normal temperature gradient and the long-range attractive potential by the wall. In the first case, the wall temperature is controlled so that the film maintains its temperature gradient of about 150.4 degrees per nanometer. Contrary to the continuum theory which predicts a parabolic behavior with a peak with respect to the wave number squared, the growth rate decreases in a monotonic fashion. The effect of the surface tension gradient, rather than evaporation, may drive the growth. Another source of instability is considered that is the interaction between the upper wall and the fluid film through a potential originating from the interaction between ion and non-polar molecule. The solid potential induces the formation of one or more vertical structures. This may result from the distortion of the pressure by the solid potential.
Nanotech 2004 Conference Technical Program Abstract