  Tin-containing nanocrystals, embedded in silicon, have been fabricated by
growing an epitaxial layer of Si_{1-x-y}Sn_{x}C_{y}, where x = 1.6 % and y =
0.04 %, followed by annealing at various temperatures ranging from 650 to 900
degrees C. The nanocrystal density and average diameters are determined by
scanning transmission-electron microscopy to ~ 10^{17} cm^{-3} and ~ 5 nm,
respectively. Photoluminescence spectroscopy demonstrates that the light
emission is very pronounced for samples annealed at 725 degrees C, and
Rutherford back-scattering spectrometry shows that the nanocrystals are
predominantly in the diamond-structured phase at this particular annealing
temperature. The origin of the light emission is discussed.
