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

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–H2 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.