Formation of Si Nanocrystallites in Al-Added Amorphous Si Films by Electron Beam Irradiation

Si nanocrystallites were formed in Al-added amorphous Si films (Al/a-Si, a-Al x Si 1-x ) by the irradiation of a focused electron beam. In-situ heating of the a-Al 0.025 Si 0.975 films was performed at temperatures up to 400 \mbox{ \circ C}. The size, shape, and concentration of the Si crystallites varied significantly with the film temperature and electron beam irradiation time. Si nanocrystallites with a mean size of ${\sim}10$ nm were formed when the films were kept at 200 \mbox{ \circ C}, and irradiated using an electron beam with a current density of 15.7 pA/cm 2 . The total crystallite volume fraction in the films increased from ${\sim}9.2$ to ${\sim}94.8$% with increasing temperature from 100 to 400 \mbox{ \circ C}. The estimated activation energy for the crystallization in the a-Al 0.025 Si 0.975 film under the electron beam irradiation was $0.78\pm 0.05$ eV.