Real-time 3D visualization of the formation of micrograting structures upon direct laser interference patterning of Si and Ge

We present a real-time study of the formation processes of microgratings in Si and Ge fabricated by single pulse Direct Laser Interference Patterning (λ = 193 nm, τ = 23 ns). To this end, we have performed time-resolved optical reflectivity and diffraction measurements with ns temporal resolution, enabling us to follow in real-time the dynamics of the melting and solidification process as well as the evolution of the surface topography. The results will be compared with results of grating structures fabricated with fs laser pulses, featuring strong differences in the surface topography profiles due to the different excitation conditions.