The formation of Er-oxide nanoclusters in SiO$_2$ thin films with excess   Si
  The nucleation, distribution and composition of erbium embedded in a SiO$_2$-Si layer were studied with High Resolution Transmission Electron Microscopy (HRTEM), Electron Energy Loss Spectroscopy (EELS), Energy Filtered TEM (EFTEM), Scanning Transmission Electron Microscopy (STEM) and X-ray Photoelectron Spectroscopy (XPS). When the SiO$_2$ layer contains small amounts of Si and Er, nanoclusters of Er-oxide are formed throughout the whole layer. Exposure of the oxide to an electron beam with 1.56*10$^6$ electrons/nm$^2$/sec. causes nanocluster growth. Initially this growth matches the Ostwald ripening model, but eventually it stagnates at a constant nanocluster radius of 2.39 nm. 
Annett Th{\o}gersen, Jeyanthinath Mayandi, Terje Finstad, Arne Olsen,   Spyros Diplas, Masanori Mitome, Yoshio Bando
cond-mat.mtrl-sci cond-mat.mes-hall