Simultaneous formation of Si and Ge nanocrystals in SiO 2 by one step ion implantation

Abstract

Germanium (Ge) and silicon nanocrystals (NCs) are synthesized by one step Ge ion implantation into thermally grown SiO 2 layers and subsequent annealing. X-ray diffraction and Raman scattering studies on implanted samples reveal that Ge nanocrystals of sizes 4–13 nm are formed embedded in SiO 2 for Ge fluence in the range 3 × 10 16 to 2 × 10 17 cm −2. At high fluence (≥1 × 10 17 cm −2) and annealing temperature of 950 °C, in addition to these Ge NCs, Si NCs are formed at the interface between Si and SiO 2 layer as a result of ion impact. Optical Raman spectra show a distinct peak at ∼503 cm −1 corresponding to the Si NCs. The average size of the Si NCs are smaller than the average size of the Ge NCs. Implications of our results are discussed in the light of the versatility of the ion-beam technique for the synthesis of varieties of embedded NCs.