Suppression of Defects during Metal-Induced Lateral Crystallization of Polycrystalline-Silicon Thin Films by Directed Lateral Growth

Abstract

In this paper, we report that directed lateral growth is effective in reducing lattice defect density in polycrystalline-silicon (poly-Si) thin films on glass substrates. A study was conducted on metal-induced lateral crystallization (MILC) at 450–650 °C using nickel (Ni) as a catalyst and solid-phase crystallization (SPC) at 600–900 °C with no catalyst. The defect density in films was characterized by micro-Raman spectroscopy. The geometries of grains and defects were observed by scanning electron microscopy and transmission electron microscopy. It was found that the defect density in grains of poly-Si fabricated by MILC decreased with decreasing temperature, while that in grains of poly-Si fabricated by SPC increased with decreasing temperature. These results suggest that directed lateral growth becomes dominant in MILC, leading to suppression of defect formation. The growth direction was associated with the gradation of Ni density from the source region to the amorphous region.