Cathodoluminescence studies of swift heavy ion irradiated Au/SiO2/p-Si structures

Cathodoluminescence measurements were performed on swift heavy ion irradiated and annealed Au/SiO2/p-Si structures. 5nm thick Au film was deposited on 500nm SiO2 thermally grown on [100] oriented p-type Si wafers. The Au/SiO2/p-Si structures were irradiated using 350MeV Au ions at fluences of 1-4X1013cm-2 and annealed in vacuum at 1050K for 8h. The structures were characterised via Rutherford backscattering spectrometry and CL before and after annealing. The CL spectra mainly consist of an ultraviolet peak (4.3eV) arising from Neutral Oxygen Vacancies (NOVs) and a blue-violet peak (2.7eV) due to E' centres as well as NOVs, both of which are oxygen-deficient centres. It is concluded that swift heavy ion irradiations create E' centres in SiO2 and annealing transforms E' centres into NOVs. As NOVs are thought to be precursors to the formation of Si-nanoclusters (Si-nc), the present study leads to the knowledge of a possible synthesis route to form Si-nc.