Document Type


Journal/Book Title/Conference

American Physical Society Four Corner Section Meeting

Publication Date

Fall 2014


Electron bombardment measurements have shown that disordered SiO2 exhibits cathodoluminescence, with an overall intensity that varies with incident electron beam energy and current density, sample temperature, exposure time, and wavelength. A simple model based on the defect density of states—used to explain electron transport in highly disordered insulating materials—has been extended to predict the relative cathodoluminescent intensity and spectral radiance for disordered SiO2 as a function of these variables. The spectral radiance exhibited four distinct bands, corresponding to four distinct energy distributions of defect states within the band gap; each showed different temperature dependence. These localized defect or “trap” states of disordered SiO2 are due to structural or substitutional chemical defects. The cathodoluminescence data were fit with the proposed model using mean shallow trap energy, deep trap energies, saturation dose rate, and energy-dependent penetration depth as fitting parameters. The model was able to explain all the qualitative features of the data and found good agreement with the physical parameters as measured by other methods. * Work supported through a NASA Science and Technology Research Fellowship, a Senior Research Fellowship from the National Research Council and AFRL, and funding from NASA Goddard Space Flight Center.