Power dependence of orientation in low-temperature poly-Si lateral grains crystallized by a continuous-wave laser scan

Publication date: 1 June 2017
Source:Thin Solid Films, Volume 631
Author(s): Nobuo Sasaki, Yoshiaki Nieda, Daisuke Hishitani, Yukiharu Uraoka
A low-temperature poly-Si film with 99.8% {100} texture in the surface normal direction within 10° is obtained by single-scan continuous-wave laser lateral crystallization of 60nm-thick a-Si without a seed at room temperature in air. This texture extends over the entire melted width of 105μm except for narrow edge regions and is maintained for the full scan length of 1.8mm. Highly {100}-oriented films in the surface-normal direction are obtained at the low net laser power P(1-R) of 1–1.25W above the threshold for the lateral grain growth, where P is the incident total power, and R is the reflectivity of the sample. A second power threshold exists where the degree of the {100} surface-normal texture begins to decrease above the first threshold for lateral grains. Above the second threshold, the percentage of the {100} surface-normal texture decreases linearly with the increasing P(1-R) at the same slope of 20% in 0.1W change for all the samples with different cap thicknesses.