Role of hydrogen in excimer laser annealing of hydrogen-modulation doped a-Si film

摘要

A novel low-temperature process for the crystallization of silicon is proposed: excimer laser annealing (ELA) of amorphous silicon (a-Si) with a hydrogen-modulation-doped layer (ELHMD). The effects of hydrogen on low-energy crystallization by conventional ELA and by ELHMD were investigated. As the hydrogen concentration increases, the crystallinity of the polycrystalline silicon prepared at a low-energy density improves. Nucleation is enhanced by the energy of desorption of hydrogen from Si-H_2 bonds during melting of the Si. In addition, film exfoliation can be suppressed by using hydrogen-modulation-doped a-Si film. H modulation doping has the effect of controlling the presence of nucleation sites in the direction of the film thickness.