Effect of surface-height derivative processes on ion-bombardment-induced ripple formation

Oblique-incidence ion bombardment of solids is known to produce ripples with wave vectors parallel or orthogonal to the projection of the ion flux onto the surface. The present paper evaluates the contributions from the second- and higher-order derivative components inherent in the spatial distribution of the energy deposited by ions and from the first-derivative component resulting from radiation-induced viscous how. It is shown that higher than fourth-order processes only weakly modify ripple parameters, but that the latter process, while also generally of weak influence, can attain a critical value that inhibits any ripple formation. [S0163-1829(99)00103-4].