Explosive Crystallization in Amorphous Silicon Induced by Picosecond High-Power Laser Pulses

Ring-shaped crystallization was observed in ion-implanted amorphous silicon by using picosecond extremely high-power laser pulses. A poly-crystalline region is formed circularly around the laser-induced damage region even at an oblique incidence. Additionally, ripple structures are formed concentrically, and the ripple spacing decreases with increasing distance from the spot center. The results are well understood with a picture that crystallization is caused explosively by laser-driven shock.