Synthesis of Ge nanocrystals grown by ion implantation and subsequent annealing

Ge Nanocrystallites (nc-Ge) have been formed by 250 keV Ge+74 implantation at fluences of [0.5; 0.8; 1; 2; 3; 4]x10(16) atoms/cm(2) into 300-nm-thick SiO2 layer thermally grown on p-type Si (100) substrate, followed by thermal treatment at 1000 C in forming gas atmosphere for 1 hour. All the samples show a broad Raman spectrum with fluences variation as function of the shift Raman. Ge+-dose dependence of the Raman intensity at w approximate to 304 cm(-1) for SiO2 with nc-Ge was observed. The photoluminescence spectra exhibit a maximum intensity around 3.2 eV for the sample implanted at room temperature with a dose of 2x10(16) cm(-2). Infrared spectroscopy shows that the SiO2 film moved off stoichiometry due to Ge+74 ion implantation, and that Ge oxides are formed in it. This result is shown as a reduction of GeOx at exactly the dose corresponding to the maximum PL peak (3.2 eV) and the largest Raman emission at 304 cm(-1). This method is fully compatible with silicon microelectronic technology.