Twin formation in micro-chevron laser beam scanning induced one directional crystal growth in Si film on SiO2

Twin formation in one directional crystal growth of Si strip were investigated. By comparing all {111} planes of Si before and after twinning, {111} twin plane was identified. From synthesizing all twin planes in a Si strip over 1 mm, it was found most {111} twin planes were downward with respect to substrate, and have a low inclined angle with Si/SiO2 interface. This result indicate Si/SiO2 interface is the origin of twinning, so both good interface quality and avoiding crystal orientation having {111} approximately parallel to film plane are essential for reducing twinning. Si film by chemical vapor deposition have drastically lower twin density than that by sputtering because of a better interface quality. In the ND{001} strip, there is no {111} approximately parallel to Si/SiO2 interface for triggering twinning, instead, twinning was triggered by particles.