Ag. Rolo et al., Structural properties of Ge nano-crystals embedded in SiO2 films from X-ray diffraction and Raman spectroscopy, THIN SOL FI, 336(1-2), 1998, pp. 58-62
SiO2 films containing small particles of Ge were grown using thr r.f.-magne
tron sputtering technique. The films were studied by means of X-ray diffrac
tion (XRD) and Raman spectroscopy. XRD studies revealed diamond structure o
f Ge particles in the films grown at temperatures higher than 500 degrees C
, The dependence of the average size of Ge nanocrystals, determined by fitt
ing the X-ray spectra (13-63 Angstrom), on the substrate temperature, r.f.-
power and the fraction of semiconductor in the target was determined. For h
igher-temperature grown films containing crystalline Ge particles, a pronou
nced peak due to confined optical phonons was observed in Raman spectra, wh
ile for those grown at lower temperature, there is just a broad band seen b
elow 300 cm(-1). A theoretical model is applied to describe the contributio
n of optical phonons confined in small Ge spheres. (C) 1998 Elsevier Scienc
e S.A. All rights reserved.