Evolution of a periodic structure on the surface of a semiconductor interacting with laser radiation

A theoretical study is made of the evolution of the shape of corrugations that form on the surface of germanium and silicon as a result of interaction with laser radiation. It is shown that an allowance for the electrodynamic nonlinearity results in a change from an exponential growth of a periodic structure and establishes limits on the depth of surface corrugations. An increase in the energy carried by laser pulses and in the number of pulses broadens the spectrum of the periodic structure and the period corresponding to the maximum corrugation depth changes compared with the value corresponding to a surface plasmon resonance. The profile of the periodic structure becomes distorted by a structure with half the initial period. The small difference between the predicted maximum corrugation depth and that found experimentally is a demonstration of the dominant role of the electrodynamic nonlinearity in the formation of periodic structures on germanium and silicon surfaces as a result of interaction with laser radiation.