Strong photoluminescence at 1540 nm from Er-doped amorphous silicon oxycarbide: A novel silicon material for photonic applications

The present investigators have previously reported on strong room-temperature luminescence at 1540 nm from erbium-doped amorphous silicon oxycarbide (a-SiCxOy) thin films. An enhancement of ∼20 times was found for asgrown SiC0.5O1.0 compared to SiO2 control samples under continuous wavelength (cw) pumping at 496.5 nm. Here, we report the effects of post-deposition annealing on the photoluminescence (PL) properties of Er-doped silicon oxycarbide. The amorphous SiCxOy films were grown by thermal chemical vapor deposition (TCVD) at 800°C and postdeposition annealing was conducted in the temperature range 500-1100°C. The thin films were then implanted with 260keV Er ions and subsequently annealed at 900°C. Strong room-temperature photoluminescence around 1540 nm was observed, with efficient Er+3 ion excitation occurring for pumping wavelengths ranging from 460 nm to 600 nm. Modeling of the power dependence of Er luminescence yielded an effective Er excitation cross-section about four orders of magnitude larger than that for a direct optical excitation of Er+3 ions. Additionally, Fourier transform infrared spectroscopy (FTIR) studies of post-deposition annealed samples revealed a strong correlation between the Er PL intensity and the C-O bond concentration in the materials. The work suggests a novel method for achieving efficient Er luminescence in Si-based materials through controlled engineering of the Si-C-O system.