Laser Pulse Triggering of the Explosive Crystallization in Amorphous Si and Ge Thin Films

ABSTRACTThe structure and morphologies of the thin amorphous a-Si and oc-Ge films crystallized “in situ” in an electronic microscope by pulsed YAG laser have been studied using conventional and high-resolution transmission electronic microscopy observations. It is found that the laser induced nucleation rate (I) is laser pulse length dependent. I is about 1021-1022 cm−3 s−1 (α-Si) and 1023-1025 cm−3 s−1 (α-Ge) near the melting point. Explosive dendritic formation is the result of competition between solid state light induced nucleation and melting mediated explosive growth.