Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Poster: Nanostructures on Surfaces I
O 49.24: Poster
Tuesday, March 13, 2018, 18:15–20:30, Poster A
Ion beam induced surface patterns - All coefficients for the equation of motion from Monte Carlo simulations — •Hans Hofsäss, Omar Bobes, and Alrik Stegmaier — II. Physikalisches Institut, Universität Göttingen, Germany
Linear theories of surface pattern formation typically consider curvature dependent effects related to the 1st order moments of the erosion, redistribution and implantation crater functions. Smoothing of a surface is described by either thermal surface diffusion or ion-induced viscous flow. The equation of motion (EOM) of the surface h(x,y,t) then consists of 1st and 2nd order spatial derivatives and a 4th order term related to smoothing. Using the Monte Carlo simulation codes SDTrimSP we calculate all crater function moments (erosion, redistribution and implantation) up to 4th order and derive all coefficients for the EOM up to 4th order, including the non-linear coefficients. The calculation is applicable to almost any ion-target combination up to ion energies of several 10 keV, any ion incidence angle, and may include dynamic changes of the target stoichiometry. Higher order crater function moments give rise to a wavelength dispersion of the ripple propagation velocity and contributions similar to a diffusion term. Non-linear coefficients related to derivatives (dh/dx)2,(dh/dx)3,(dh/dy)3, (dh/dx)(dh/dx)2 give rise to amplitude saturation and terrace formation. We calculate the complete set of coefficients using SDTrimSP for several model cases, which are then used as input for a software package that allows the simulation of dynamics for arbitrary, nonlinear EOMs.