Concentration profile distortion under ion beam mixing: an example of Levy flight.

In order to model the evolution of concentration profiles induced by ion beam mixing in thick layers, Monte Carlo simulations were performed to study in detail the transition probability controlling the evolution of this profile within the binary collision approximation. We demonstrate that this transition probability can be factorized in two distinct functions. The first one can be understood as a scale factor. The second one controls the dynamics of ion beam mixing which can be analyzed as a Levy flight. The power law form of the tail of this function closely linked to the cross section of a collision event is responsible for long tails of concentration profiles. We demonstrate that the Levy flight nature of ion beam mixing induces an enhancement of the evolution of the initial concentration profile.