NANOSCALE-CRYSTALLITE NUCLEATION AND GROWTH IN AMORPHOUS SOLIDS

A model is proposed to describe the crystallization in disordered soli ds. The model is based on accounting for small statistical fluctuation s in structural parameters (valence angles, bond lengths, etc.), which are shown to affect the crystallization kinetics dramatically. As opp osed to the standard approach that neglects any effects due to disorde r, the model reveals clearly divided stages of nucleation, growth, and ripening in the crystallization of one-component disordered solids. W e show that at the nucleation stage the crystallization is nonlinear i n time and is bounded by a certain small volume fraction (approximate to 0.1). At the growth stage the radius of the crystallites depends on time logarithmically and approximately double its initial value until the ripening stage comes. The results of Raman light-scattering exper iments designed to test various predictions of the model are presented for a-Si:H subjected to crystallization. Good agreement is obtained.