Formation of a single interface-near, δ-like Ge nanocluster band in thin SiO2 films using ion-beam synthesis

Abstract

The possibility to create a δ-like, interface-near Ge nanocluster band in a 20 nm thin SiO2 layer by ion-beam synthesis is demonstrated. The role of the post-implantation annealing conditions for the formation of Ge nanoclusters in the center of the layer, near the interface, or in both regions is discussed. The presence of hydrogen in the annealing atmosphere accelerates the redistribution of Ge in SiO2. By applying a two-step annealing process, preannealing in hydrogen containing atmosphere at low temperature followed by a rapid thermal annealing at high temperature, the controlled fabrication of a single δ-like, interface-near Ge nanocluster band was achieved. In some clusters 〈100〉 lattice planes of Ge were observed. From this and the similar contrast situation for amorphous clusters it is concluded that the interface-near clusters consist of elementary germanium.