Hydrogen bonding in laser-crystallized poly-Si

Abstract Hydrogen bonding and diffusion during laser dehydrogenation and crystallization of hydrogenated amorphous silicon (a-Si:H) are investigated. The samples were crystallized at room temperature. After each crystallization step the specimens were characterized by hydrogen effusion measurements and Raman spectroscopy. The as-deposited a-Si:H films contain a hydrogen concentration of approximately 13 at.%. Initially, step-by-step laser crystallization produces a stratified structure. The poly-Si surface layer acts as a diffusion barrier for hydrogen. Completely crystallized poly-Si films contain a residual H concentration of approximately 1×10 21 cm −3 .