Explosive Crystallization of Amorphous Germanium Films

Laser processing of amorphous thin films of amorphous Ge often results in an explosive or self-sustaining crystallization reaction. The reaction is sustained by the heat liberated during crystallization. In a theoretical analysis of the process that was presented at this symposium last year, Gilmer and Leamy postulated the existence of a thin layer of liquid at the propagating interface. The liquid layer forms at temperatures above Ta, the melting point of amorphous Ge, and is predicted to be ~ 0.02 – 0.1 of the film thickness in width. We have obtained experimental confirmation of the presence of this liquid layer.