HYDROGEN-INDUCED DEFECTS IN POLY-SILICON THIN FILMS OBSERVED BY RAMAN SPECTROSCOPY

摘要

Effects of hydrogenation on excimer-laser annealed polycrystalline silicon (poly-Si) for thin film transistors were investigated by using Hall effect and Raman spectroscopy. Down-stream plasma was used for hydrogenation. It was shown that the termination of dangling bonds at grain boundaries was almost completed in short time (1 min in this work) leading to the improvement of mobility and appearance of 2000 cm~(-1) band in Raman spectra. It was also shown that excess hydrogenation generates defects in grains resulting in the degradation of mobility and monotonous increase in 2100 cm~(-1) band intensity. Light exposure during hydrogenation enhances the 2100 cm~(-1) band intensity due to attacking of weak Si-Si bonds leading to the defects generation.