We have used low energy ion beams to spontaneously create patterns (sputter ripples) on Cu(001) surfaces. The evolution of the ripple amplitude and wavelength was measured in situ by using light scattering. At the temperatures $(415–455\mathrm{K})$ and ion fluxes $({10}^{14}–{10}^{15}\text{ions}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1})$ studied, the ripple formation process is found to be similar to that described by the Bradley-Harper instability theory, i.e., the wavelength does not change appreciably with time, the orientation is determined by the ion beam direction and the amplitude increases exponentially during the early stages of growth. The flux dependence of the growth rate and wavelength is measured to determine the kinetics of defect production and annihilation on the surface.

• Received 23 February 2004

DOI:https://doi.org/10.1103/PhysRevB.69.245413