Role of Hydrogen in Polycrystalline Si by Excimer Laser Annealing
The role of hydrogen in the Si film during excimer laser annealing (ELA) has been successfully studied by using a novel sample structure, which is stacked by a-Si film and SiN film. Hydrogen contents in the Si films during ELA are changed by preparing samples with hydrogen content of 2.3-8.2 at.% in the SiN films with a use of catalytic (Cat)-CVD method. For the low concentration of hydrogens in the Si film, the grain size increases by decreasing hydrogen concentration in the Si film, and the internal stress of the film decreases as increasing the shot number. For the high concentration of hydrogens in the Si film, hydrogen burst was observed at 500 mJ/cm 2 and the dependence of the internal stress on the shot number becomes weak even at 318 mJ/cm 2 . These phenomena can be understood basically using the secondary grain growth mechanism, which we have proposed.
Crystal Growth of Low-Temperature Processed Poly-Si by Excimer Laser Annealing - Dependences of Poly-Si Grain on Energy Density and Shot Number -
This paper examines the characteristics of the poly-Si grains formed by ELA with the energy density from 75 mJ/cm2 to 400 mJ/cm2, and discusses the change of the crystal growth mechanism of the recrystallized poly-Si dependent on the energy density. For the energy density from 250 mJ/cm2 to 350 mJ/cm2, the disk-shaped grains are observed. The dependences of the area ratio of disk-shaped grain both on the energy density and on the shot number are examined. From these results, the role of the disk-shaped grains for the change of the crystal growth mechanism dependent on the energy density is clarified.
Surface energy and the secondary recrystallisation of platinum sheet
Abstract The secondary recrystallisation of thin platinum sheet at 1500°C was observed and the growth rates of the secondary crystals were measured. Only crystals with orientations close to {111} were observed to grow. The relative variation of surface energy with crystallographic orientation was measured by the twin boundary groove technique and the grain boundary energy relative to the average surface energy was evaluated from grain boundary groove angles, so that the applied driving pressure for secondary recrystallisation could be calculated. The drag force opposing grain boundary migration was estimated from the variation of grain boundary velocity with applied driving pressure and the grain boundary mobility was evaluated. The results are compared with other mobility measurements and grain boundary anchoring and drag effects are discussed.