Precipitation of semiconducting carbon nanoparticles in ion irradiated gels

Sol–gel materials are converted into glassy ceramics when subjected to ion irradiation or heat treatments. In addition, a demixing occurs in the obtained glasses when their structure is metastable. In the present work, we have irradiated silicon-based gels with 120 MeV and 2 GeV Au ions at different fluences from 8 × 109 to 2 × 1013 ions/cm2. Ion irradiation leads to formation of carbon nanoclusters, which have semiconducting properties. Photoluminescence and optical absorption spectroscopies are used to identify the semiconducting properties of carbon clusters. High resolution transmission electron microscopy (HRTEM) and energy filtered imaging of C atoms show that C particles with a size of ∼4 nm are produced and they are aligned along ion tracks. Elastic recoil detection analysis has been performed to determine the kinetics of the H evolution and to evaluate the track radius, which matches with the radius obtained from HRTEM. The obtained aligned carbon clusters (wires) would find useful applications as field emitters or nanocontacts.