In-situ dynamic observation on cluster formation in amorphous oxide films

Abstract

Morphologies of small metal particles and arrangements of their internal atoms became unstable under electron beam irradiation. Such structural instability cannot be explained simply by temperature effect but additional effects such as charging up effect . In the study, instability of the particle-support films of amorphous carbon and SiO2 themselves, which were exposed inevitably to the electron beam, was noticed by observing intensity fluctuations in granular images of the films. Our preliminary work showed that fluctuation occurs with a frequency of several tens of Hertz and diminishes with a decrease in the electron beam intensity (below 10amp.). Migratory motion of atoms in small particles and the amorphous films was thought to be responsible for the image intensity fluctuation. Such an intensity fluctuation, therefore, is important for understanding small particle stability and crystallization. The present work deals with in-situ observation on amorphous oxide films using the TV recording technique. The observation was conducted on an ABT- 002B microscope at 200kV.