Multiple scattering causes the low energy-low angle constant wavelength topographical instability of argon ion bombarded silicon surfaces

► Phase diagram of Ar+ bombarded Si surfaces in the linear regime of surface dynamics. ► Holes and perpendicular mode ripples are caused by multiple scattering events. ► Only ultra-smooth stable silicon surfaces are for incidence angles < 50° from normal. ► Phase diagram characterized by diverging wavelength phase transition.