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

The laser-induced crystallization behavior of GeTe-based amorphous all oys has been measured with a novel multipulse laser technique. This en ables the composition dependence of the nucleation rate and crystal gr owth speed to be independently followed. Two types of crystallization are investigated. The first involves single-phase crystallization of q uaternary alloys based on Ge39Sb9Te52, in which the composition depend ence of nucleation and growth is followed as Se, S, Sn, and Si are inc luded. Both the nucleation rate and crystal-growth speed vary exponent ially with the composition, and a correlation is found between crystal lization behavior and bond strengths. The second involves multiphase c rystallization in the GeSbTe ternary system. It is shown that the obse rved variations in crystallization behavior primarily arise from the c omposition dependence of nucleation rather than crystal growth. The im plications of this finding for the importance of long range diffusion during crystallization in the GeSbTe system are discussed. (C) 1995 Am erican Institute of Physics.