A cross-sectional atomic force microscopy study of nanocrystalline Ge precipitates in SiO2 formed from metastable Si1-xGexO2

In recent years, many investigators have reported visible photoluminescence from structures that consist of Ge or Si nanocrystals embedded in a SiO2 matrix deposited or grown on various substrates. We have developed a rapid technique for studying the through-thickness microstructure of this class of materials via atomic force microscopy (AFM) and, using this technique, we report on the precipitation and growth of Ge crystallites formed via a two-step process of hydrothermal oxidation of Si1-xGexO2(x=0.15) at 450-500 degrees C and subsequent chemical reduction in forming (85/15: N-2/H-2; 800 degrees C). The Ge-particle distributions obtained with this AFM cross-sectional technique are consistent with those previously reported using other techniques. The utility of cross-sectional AFM for the evaluation of nanoscale features in the thickness of a thin film is evaluated. (C) 1997 American Institute of Physics.