Cathodoluminescence of electron irradiated opal-based nanocomposites

Abstract

Synthetic opals infilled with silicon (opal-Si) and with Si and Pt (opal-Pt-Si) have been irradiated in a scanning electron microscope under high excitation conditions. Electron irradiation-induced changes in the morphology and luminescent defect structure of both types of nanocomposites were assessed by scanning electron microscopy and by cathodoluminescence (CL) microscopy and spectroscopy. Irradiation causes strong morphological changes in the ordered structure of the matrix and quenching of the nanocrystals-related CL emission in the opal-Si samples. On the contrary, such effects are not observed in the opal-Pt-Si nanocomposites. In both types of samples, electron irradiation induces the appearance of a CL band centered at 2.95 eV, attributed to complex centers involving oxygen vacancies in the silica spheres forming the matrix.