Crystalline nm-sized Ge colloid particles were formed in glasses, which contained 10%GeO2, by 1.5MeV proton implantation without post-thermal annealing. Although O-deficient type point defects that were associated with Ge ions were preferentially formed at fluences of up to 1017/cm2, the formation of fine Ge crystalline particles was observed at fluences of more than 5 x 1017/cm2. No formation of Ge colloids or Ge-related point defects was detected after implanting 1.5MeV He+ to a fluence of 1018/cm2. The Ge colloid-formation layers were 22 to 26 below the implanted surface. These depths agreed well with the region of peak electronic energy deposition. It was found that Ge-OH groups formed in preference to Si-OH groups upon implanting protons, and that the decay curve during isochronal annealing was close to that for optical absorption at about 3eV. This was attributed to the presence of nm-sized Ge. A red photoluminescence which peaked at about 1.9eV was observed for all of the implanted substrates.

K.Kawamura, H.Hosono, H.Kawazoe: Journal of Applied Physics, 1996, 80[3], 1357-63