Spot laser melting of monocrystalline silicon leads to characteristic surface structures that are defined by a peak and a quasi-periodic ripple structure. The structures are created by a 50-100 mu s pulsed infrared fiber laser and are approximately 30-100 mu m in size. We present an analytical model explaining the creation of the peak by the density anomaly of silicon. Additionally, we show that the quasi-periodic ripple structure stems from a frozen capillary wave, which allows us to determine the resolidification velocity from the ripple radii. For a structure of molten radius R-melt = 41.5 mu m, we determine a resolidification velocity v(re) = (56.6 +/- 9.2) cm/s. A numerical model for the same structure yields v(re) = 49.2 cm/s, which agrees with the value determined from the ripple pattern. The capillary wave is excited in the melt pool due to thermocapillary convection. Published by AIP Publishing.
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