Seed-Induced Crystallization of Amorphous Silicon for the Formation of Large-Grain Poly-Crystalline Silicon

A new method for reducing crystallization time of hydrogenated amorphous silicon thin films and more successfully controlling grain structure has been studied through seeding of the bulk matrix with nanocrystallites during film deposition. Films were deposited by a system in which crystallites and amorphous film were synthesized in separate RF-powered plasmas. Average crystallite size was confirmed to be 20 to 50 nm via TEM imaging. Several films with various initial crystallite population densities were produced, and their crystallization kinetics were studied via Raman spectroscopy throughout a staged annealing process. Seeded films consistently displayed a characteristic crystallization time less than the incubation time of unseeded control films. Furthermore, films with larger initial seed densities exhibited earlier crystallization onset. A separate study also was performed in which the dark conductivity was compared between films re-crystallized from various initial seed densities.