Аннотация:The multimode nonlinear theory of formation of surface periodic point defect-defonnational (DD) structures is developed. The general set of coupled nonlinear kinetic equations for DD-gratings Fourie amplitudes is derived and reduced to
rate equation with allowance for diffusion and drift in q-space. The conditions of generation of either multimode or single mode DD-structures are cleared out and periods, times offormation and stationary amplitudes of DD-grating are determined. The theoretical results are used for interpretation of previously obtained experimental results on DD-gratings generation in Si under millisecond laser irradiation and under ion implantation.