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

Abstract
In recent years, many investigators have reported visible photoluminescence from structures that consist of Ge or Si nanocrystals embedded in a SiO 2 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 Si 1−x Ge x O 2 ( x =0.15) at 450–500 °C and subsequent chemical reduction in forming gas (85/15: N 2 /H 2 ; 800 °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.