When energetic ions impinge on a solid surface, they can cause a variety of effects such as removal of atoms, amorphization, defect creation, and surface morphology modifications. One of these modifications involves the formation of nanopatterns such as ripples, dots, and holes on a nanoscale. This seminar will focus on the overview theories of the self-organized ripple formation on the surface by ion bombardment. Moreover, the experimental spontaneous nanometre-scale quasi-periodic structures which are formed at the two surfaces of polycrystalline Ni films and Si(111) single crystal wafers by irradiation with a broad Ar+ ion beam at room temperature will be presented. The development of these structures can be reproduced by the numerical solutions of the MCB continuum equation describing the evolution of surface morphology under ion irradiation, using realistic coefficients derived from material properties. In particular, the demonstration differences will be observed in pattern formation on the two surfaces under the conditions studied, such as wavelength stability and exponential growth of interface width for the Ni surfaces compared with wavelength coarsening and interface width saturation on Si(111), can be understood in terms of a crossover between linear and nonlinear behaviors of them.

Mogtaba B. Mekki is a lecturer in the Physics Department. His current primary research focuses on the morphological characterizations experimentally/numerically of ion-induced modifications and the self-organized nanostructures on non-equilibrium solid surfaces. In addition, his research interest includes fractal analyses of the dynamic surface growth.

. 

________________________________________

All faculty, researchers, and students are invited to attend.