Homogeneously size distributed Ge nanoclusters embedded in SiO2 layers produced by ion beam synthesis

500 nm SiO2 layers were implanted with 450 keV (F = 3 x 10(16) at./cm(2)) and 230 keV (F = 1.8 x 10(16) at./cm(2)) Ge ions at room temperature to obtain an almost constant Ge concentration of about 2.5 at.% in the insulating layer. Subsequently, the specimens were annealed at temperatures between 500 degrees C and 1200 degrees C for 30 min in a dry N-2 ambient atmosphere. Cross-sectional TEM analysis reveal homogeneously distributed Ge nanoclusters arranged in a broad band within the SiO2 layer. Their mean cluster size varies between 2.0 and 6.5 nm depending on the annealing conditions. Cluster-free regions are always observed close to the surface of the specimens independent of the annealing process, whereas a narrow Ge nanocluster band appears at the SiO2/Si interface at high annealing temperatures, e.g. greater than or equal to 1000 degrees C. The atomic Ge redistribution due to the annealing treatment was investigated with a scanning TEM energy dispersive X-ray system and Rutherford back scattering(RBS). (C) 1999 Elsevier Science B.V. All rights reserved.