Ion beam synthesis and characterization of Ge nanoparticles in SiO2

Ge quantum dots embedded in SiO 2 have been obtained by implantation of Ge ions in the 10 16 –10 17 cm −2 dose range, followed by post-implantation annealing in the temperature range T a = 300−1000 °C. Using Rutherford back-scattering, grazing incidence X-ray diffraction and grazing incidence small angle X-ray scattering it was found that Ge-QDs are synthesized as discrete, spherical QDs, with radius ranging from 1.7 to 10 nm, depending on dose and T a . For T a above 800 °C the Ge atom diffusion becomes considerable, leading to a strong increase of both size and size distribution of Ge QDs, but still without sizeable loss of Ge atoms from the implanted layer.