Optical and microstructural properties of doubly Ge–Si implanted SiO2 layers

Photoluminescence (PL) properties of 500 nm thick SiO2 films on Si substrate subjected to combined Ge–Si implantations have been studied: Sequentially 400 keV Ge+ and 200 keV Si+ ions were implanted into SiO2 to concentrations of 3% and 1–10%, respectively. As calculated using the SRIM 2000 code, under these conditions depth profiles of implanted species should be contained in the region 100–400 nm below the oxide surface. After the implantation, samples were annealed at temperatures ranging from 700 to 1100 °C, in order to obtain Si and Ge nanoclusters. A weak near UV luminescence peak at a wavelength of about 315 nm, a strong blue band at 400 nm and a near-infrared 780 nm band were observed for thus prepared samples. The optical emission was stable and reproducible. Diffusion of germanium towards the Si/SiO2 interface during the annealing process is suppressed by silicon ions additionally introduced into SiO2.