Crystallization of amorphous Ge films induced by semiconductor diode laser annealing

Crystallization of amorphous Ge (a-Ge) films induced by semiconductor diode laser (SDL) irradiation has been investigated. 500-nm-thick a-Ge films are crystallized by scanning 807 nm CW SDL light focused to 4.0 × 0.1 mm2 with the scanning speed (v) ranging from 100 to 350 mm/s. From X-ray diffraction and Raman scattering spectra, it is confirmed that the films crystallized at v = 100 mm/s show [220] preferential orientation with no residual amorphous component. On the basis of in-situ monitoring, it has been confirmed that a-Ge films annealed at a v higher than 200 mm/s are transformed to crystalline phase via solid phase crystallization, while films annealed with v lower than 170 mm/s are melted and recrystallized.