Patterned structures of silicon nanocrystals prepared by laser annealing

Patterned structures of nanocrystalline silicon have been fabricated in the films of sandwiched structure (a-SiNx:H /a-Si:H/a-SiNx:H) on the substrate prepared by plasma-enhanced chemical vapor deposition from highly diluted silane and ammonia. The a-Si:H layer in the films are crystallized by excimer laser annealing. Phase transition takes place in the regions where the bright stripes of laser interference occur by means of a grating, whereas no phase transition appears in the dark area. The thickness of a-Si:H layer determines the sizes of the nanocrystals because they cannot extend into the a-SiNx:H confining layers. With increasing laser intensity, the stripe region looks melted and a hole-structure is formed.