An investigation was made of the electronic activity of defects in polycrystalline silicon thin films grown via excimer-laser annealing, solid-phase crystallization and continuous-wave laser lateral crystallization. The activity of defects was deduced from the erosion by Secco etching, which was based upon the enhancement of etching due to electronically active states in the band-gap. Hydrogenation protected the grain boundaries and sub-grain boundaries from etching; indicating that those defects were originally active and were inactivated by hydrogen. The in-grain defect density was characterized by the variation of stress in the films with etching, where the stress was estimated using Raman spectroscopy. It was shown that excimer-laser annealed polycrystalline Si contained a high density of active defects in the grains, while solid-phase crystallized and continuous-wave laser lateral crystallized polycrystalline Si films contained a lower density. This feature of excimer-laser annealing was attributed to the freezing of defects in grains during rapid cooling after laser irradiation. This was consistent with the elimination of defects by post-annealing of the excimer-laser annealed film at 1000C. In the case of continuous-wave laser lateral crystallization, it was deduced that laterally directed growth was effective in decreasing defects.

Electrochemical and Raman-Scattering Characterizations of Defects in Polycrystalline Silicon Thin Films Formed by Excimer-Laser Annealing, Solid-Phase Crystallization, and Continuous-Wave Laser Lateral Crystallization. K.Kitahara, Y.Ohashi, K.Yamamoto, N.Sasaki: Japanese Journal of Applied Physics, 2009, 48[2], 021205