Light-emitting silicon-rich nitride systems and photonic structures

In this paper we report recent results on the optoelectronic properties of silicon-rich nitride (SRN), a novel material for microphotonics applications compatible with silicon technology. We have investigated optical emission, energy transfer phenomena to erbium ions and PbS colloidal quantum dots in SRN films and grown active photonic SRN structures. The optical properties of the films were studied by micro-Raman and photoluminescence spectroscopy and, as confirmed by transmission electron microscopy analysis, indicate the presence of small (1-2 nm) Si clusters characterized by efficient (7% quantum efficiency at room temperature), broad-band and near-infrared emission with very large absorption/emission Stokes shift. Time and temperature resolved photoluminescence measurements demonstrate nanosecond-fast, wavelength-dependent recombination dynamics with negligible light emission thermal quenching from 4 to 330 K. First-principles simulations of 1 nm size crystalline and amorphous silicon dots show that nitrogen atoms bonded to the surface of nanometre silicon clusters play a crucial role in the emission mechanism of SRN films. In addition, we show that SRN is a suitable material for the fabrication of light-emitting complex photonic crystals and novel waveguide structures based on resonant transmission of localized light states in aperiodic dielectrics. The versatility of light-emitting SRN systems can provide alternative routes towards the fabrication of optically active CMOS devices.