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Energy deposition and sputtering

When an atom impacts a target, some of the atoms eject from the target and take away some energy and the rest energy is deposited in the target. Subsequently, the atoms in the target rearrange with this energy and restore to new positions. A direct consequence of this redistribution is instability of the surface affecting nanofabrication of electronic devices. Nonetheless, the precise mechanisms by which the deposited energy redistributes and governs sputtering remain unknown. Sigmund in 1969 first proposed a detailed theory to explain this behavior. He assumed a linear relation between sputtering and deposited energy ans successfully predicted a range of surface instability features. It's however incorrectly predict surface behavior for off-normal ion impacts. This research provided the first physical understanding of the relation between sputtering and deposited energy. It is found that the relation is non-linear and time-dependent [1]. The discrepancy removes the existing limitations of the theory of pattern formation and establishes a new platform to explore pattern formation in solids.
 


Fig. Angle dependent rotation the energy ellipsoid created in single impact atomic collision.
 
Further reading: [1] Ion impact energy distribution and sputtering of Si and Ge (pdf, doi)
                            M. Z. Hossain, J. B. Freund, and H. T. Johnson, Journal of Applied Physics 111, 103513 (2012)