LASER-INDUCED CRYSTALLIZATION PHENOMENA IN GETE-BASED ALLOYS .2. COMPOSITION DEPENDENCE OF NUCLEATION AND GROWTH

The laser-induced crystallization behavior of GeTe-based amorphous alloys has been measured with a novel multipulse laser technique. This enables the composition dependence of the nucleation rate and crystal growth speed to be independently followed. Two types of crystallization are investigated. The first involves single-phase crystallization of quaternary alloys based on Ge39Sb9Te52, in which the composition dependence of nucleation and growth is followed as Se, S, Sn, and Si are included. Both the nucleation rate and crystal-growth speed vary exponentially with the composition, and a correlation is found between crystallization behavior and bond strengths. The second involves multiphase crystallization in the GeSbTe ternary system. It is shown that the observed variations in crystallization behavior primarily arise from the composition dependence of nucleation rather than crystal growth. The implications of this finding for the importance of long range diffusion during crystallization in the GeSbTe system are discussed. (C) 1995 American Institute of Physics.