Radiation induced defects in SiO₂

The main luminescent centers in SiO₂ films are the red luminescence R (650 nm; 1.85 eV) of the non-bridging oxygen hole center (NBOHC) and the twofold-coordinated (divalent) silicon with a blue B (460 nm; 2.7 eV) and a UV band (285 nm; 4.4 eV). Especially the latter ones are produced under irradiation, but from existing precursors assumed as silicon related oxygen deficient centers (SiODC). Therefore, in order to prove these models we compare a direct oxygen implantation with a direct silicon implantation into SiO ₂ layers. The main result is: implanting oxygen increases the red band R but does not affect the blue band B. Silicon surplus increases the amplitude of the blue (B) luminescence, but reduces the amplitude of the red (R) one. Studying the cathodoluminescence dose dependence of these blue and red bands we have established defect transformation kinetics in SiO₂ including six main defects and precursors as well as the mobile oxygen as the main transmitter between precursors and the radiation induced defects. The kinetics is described by eight rate equations which predict the dose dependence of the red (R) and blue (B) luminescence intensities and their temperature dependences very well.