We report the first pulse width study of the various morphological changes and bulk phase transitions of single crystal silicon irradiated by 1‐&mgr;m pulses of 4–260‐ps duration. In particular, we find that amorphous silicon is formed from the melt contrary to published expectations, but only for pulse widths less than 10 ps. We also find that the single shot melting threshold is pulse width dependent. Additionally, we observe the growth of multishot damage and of periodic ripple patterns with pulses as short as 4 ps.