Novel Si nanocrystal formation technique as applied to fabrication of Si nanostructure

The fabrication of nanometer sized structure (nanostructure) has been attractive in the field of material science because the appearance of novel physical and optical properties is expected in low-dimensional and size-reduced materials. We have discovered that Si nanocrystals can be formed in a SiO/sub 2/ thin film under irradiation of an electron beam at high temperature. The specimen in the present work was prepared from a SiO/sub 2/ single crystal (quartz). The acceleration voltage of an electron beam was 100 kV in order to reduce sputtering for Si atoms. The thin area of the SiO/sub 2/ film was easily amorphized by irradiation of the electron beam even if the current density was less than 10/sup 5/ A/m/sup 2/. When the high intensity electron beam was focused on the amorphized SiO/sub 2/ thin film at 850 K inside an UHV-FE-TEM, crystalline Si nanoparticles emerged at the irradiated area, the diameter of which was as large as the beam diameter (several nm).