The Relevance of Point Defects in Studying Silica-Based Materials from Bulk to Nanosystems

Abstract

The macroscopic properties of silica can be modified by the presence of local microscopic modifications at the scale of the basic molecular units (point defects). Such defects can be generated during the production of glass, devices, or by the environments where the latter have to operate, impacting on the devices’ performance. For these reasons, the identification of defects, their generation processes, and the knowledge of their electrical and optical features are relevant for microelectronics and optoelectronics. The aim of this manuscript is to report some examples of how defects can be generated, how they can impact device performance, and how a defect species or a physical phenomenon that is a disadvantage in some fields can be used as an advantage in others.

Trapping Mechanisms and Delayed Recombination Processes in Scintillating Ce-Doped Sol–Gel Silica Fibers

“…The in-depth analysis of the role of point defects and of their close interplay with luminescent activators in the recombination processes governing the scintillation emission is not commonly encountered in amorphous materials because the inhomogeneous disorder of glass leads to broadening of electronic levels related to defects . In previous studies, thermally stimulated luminescence (TSL) has been used both to estimate the characteristic parameters of trapping levels and for application-oriented purposes. − We chose Ce-doped sol–gel silica as a model material to study the correlation between TSL active traps and slow tails in time-resolved scintillation.…”

The void side of silica: surveying optical properties and applications of mesoporous silica

“…Also, the emission features, related to the natural passivation of the silica surface, are quite sensitive to the environment, thus fostering the research on the optical features of void MS. The natural benchmark was bulk silica and the plethora of point defects producing optical absorption and emission fingerprints [89,90], eventually related to laser or high energy irradiation [91,92]. Another obviously occurring reference is nanosized silicon [93,94] since silicon nanocrystals and porous silicon have their surface layer typically oxidized.…”