Formation of metal nanoparticles on electron-irradiated silicon surfaces

鳥越 和尚

Abstract

This dissertation presents the formation of metal nanoparticles on electron-irradiated silicon (Si) surfaces. Gold (Au) nanoparticles of about 10 nm in diameter have been selectively grown in the electron-irradiated areas of about 100 nm in diameter. The growth process has been elucidated by in-situ observations with an ultra-high vacuum transmission electron microscope (UHV-TEM) at temperatures up to 700 ℃ and the structure was characterized by means of transmission electron diffraction (TED), high-angular annular dark-field (HAADF) and energy dispersive x-ray (EDX), etc. The size and spatial distributions of Au nanoparticles have been systematically investigated as functions of electron dose and temperature. The growth position of nanoparticles in the irradiated areas was successfully controlled by changing the experimental parameters. A conventional theory of formation of nanoparticles was extended to the model on surfaces in which surface roughness is induced by electron irradiation. The extended model has reproduced the experimental results qualitatively.
As for applications, silicon nanowires (SiNWs) have been successfully grown from the Au nanoparticles in the irradiated areas by chemical
vapor deposition (CVD). The growth process and mechanism have been studied using the advantage that the identical irradiated areas can be identified by TEM before and after the CVD process.