Oscillatory Driving of Crystal surfaces: a Route to Controlled Pattern Formation

We show that the oscillatory driving of crystal surfaces can induce pattern formation or smoothening. The driving force can be of quite different origin such as a pulsed laser beam, an electric field, or elasticity. Depending on driving conditions, step bunching and meandering, mound formation, or surface smoothening may be seen in presence of a kinetic asymmetry at the steps or kinks (the Ehrlich-Schwoebel effect). We employ a step model to calculate the induced mass flux along misoriented surfaces, which accounts for surface dynamics and stability. Flux inversion is found when varying the driving frequency. Slope selection and metastability result from the cancellation of the mass flux along special orientations. Kinetic Monte Carlo simulations illustrate these points.