Amorphous silicon thin films on glass substrates were crystallized by a 4‐&mgr;s light pulse from a plasma arc. Explosive crystal growth from nucleation centers was observed at 4.6 J/cm2. Large silver‐shaped streaks (0.7 mm×50 &mgr;m) were produced. Conductivity changed by six orders of magnitude and the flashed samples gave high photoconductivity. Growth patterns were different near the threshold value of 3.1 J/cm2.