Tanuj Kumar, D. C. Agarwal, N. P. Lalla, D. Kanjilal
We show that the ion beam induced incompressible amorphous solid flow in terms of advection mass transport mechanism leads to the erosion and deposition of atoms at the amorphous/crystalline (a/c) interface resulting in the formation of pattern at the a/c interface as well as at the free surface. The ion beam impact generated erosion and mass redistribution at the free surface [proposed by Bradley-Harper (BH) and its extended theories] are found to be irrelevant in patterning of surface. By varying the location of a/c interface, it has been established that a/c interface plays the prominent role in surface patterning. The morphological variation of Si surface after 50 keV Ar+ ion bombardment has been investigated by atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (X-TEM) as a function of ion fluence. We propose a new approach that Navier-Stokes flow inside the amorphous layer coupled with the Exner equation successfully explains the growth mechanism of surface patterning.
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http://arxiv.org/abs/1207.5426
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