Time-Resolved Measurements of Stimulated Surface Polariton Wave Scattering and Grating Formation in Pulsed-Laser-Annealed Germanium

摘要

Nanosecond resolution optical probe measurements of the growth of surface ripples in pulsed-laser-annealed Ge are reported. The ripples are shown to arise from stimulated scattering of the incident laser light into surface polariton waves at the air/liquid/solid interfaces which form during the optical excitation. These surface waves grow exponentially from spontaneous scattering via feedback involving modulation of the velocity of the liquid/solid interface. The final ripple structure results from the density change on melting coupled with transverse diffusional processes during the regrowth.