In situ crystallization of amorphous silicon in the transmission electron microscope

Amorphous Si thin films have been crystallized by in situ annealing in the transmission electron microscope. Crystallization occurred at about 700°C in electron-beam-deposited Si films, 400 Å thick, on amorphous Si₃N₄ substrates. Dendritic Si crystallites were observed with ⟨110⟩ and ⟨111⟩ orientations. The fast growth direction was parallel to ⟨112⟩. All crystallites were internally twinned with Σ = 3, (111) twin boundaries providing nucleation sites for atom attachment. The amorphous-crystal interface propagation was recorded on videotape to study the mechanism of crystallization. Interface velocities were measured at several temperatures and an activation energy of 3·36±0·23 eV was obtained for crystal growth.