Fabrication and Optical Properties of Erbium-Doped Silicon-Rich Silicon Oxide Nanofibers

Abstract

Synthesis of Er-doped silicon-rich silicon oxide (SRSO) nanofibers bundled into yarns was successfully achieved. Photoluminescence (PL) studies of the yarns detected a strong and sharp band at 1.530 μm at room temperature, which is attributed to Er ions excited by energy transfer from photogenerated carriers in Si nanoclusters (nc-Si). The effective absorption cross-section of the first excited state of the Er ions is estimated to be 1.86 x 10 -16 cm -2 , higher by several orders of magnitude than that in an Er-doped SiO 2 host, due to the presence of nc-Si that serves as a sensitizer in the SRSO nanofibers. In order to investigate the luminescence mechanism of the Er ions, PL spectra excited by incident light of different wavelengths were measured. We found that both the peak position and line shape of the Er ion emissions are unaffected by the incident wavelength. The results indicate that the Er ion luminescence in the SRSO nanofibers is completely dominated by ions located at sites that are strongly coupled to the carriers in the nc-Si. We also found that the intensity of luminescence decreases by less than 30% as the temperature is raised from 10 K to room temperature, indicating that thermal quenching is significantly reduced.