Fabrication of nanoscale topographies on Ge(100) surface by low energy Ar+ ion sputtering

The nanoscale pattern formation on Ge(100) surfaces is studied by exposure of uniform Ar+ ion beam of energy 500 eV for ion incidence angle 0°-85° at room temperature. Anisotropic ripple nanopatterns with wave-vector along parallel and perpendicular to the ion beam projection are found to evolve at 75° and 85° respectively for fixed ion fluence 1 × 1019 cm−2. In order to explore the ion beam induced ripple formation mechanism, their dynamics with ion fluence at each ion incidence angle of 75° and 85° are also investigated. Perpendicular mode ripples exhibit sawtooth structures and abruptly high surface roughness at larger ion fluences. The overall topographic evolution is discussed in light of existing theoretical models of ion beam nanopatterning.