Electron beam charge injection and modification of electronical and optical properties of SiO₂

Ionizing radiation in the dielectric and optically transparent material SiO₂ produces defect luminescence as well as exoelectron emission. Under cathodo-excitation, e.g. the main blue luminescence band at 460 nm (2.7 eV) is appearing and then strongly growing with an exponential saturation. The luminescence center is correlated with oxygen deficiency and twofold-coordinated silicon = Si:. A simple oxygen vacancy presents the precursor for this kind of defect transformation. A comparison of different excitation-relaxation processes like cathodoluminescence (CL), charge injection (IV) and trapping, secondary electron field emission (SEFE), and exoelectron emission (EEE) leads to a generally similar excitation-dose behaviour with an electron beam saturation dose of about 0.01-0.1 As/cm². This suggests itself a correlation of these four excitation mechanisms likely related to the same kind of defect in glassy SiO₂.