Emitting modification in Si-rich-SiNx films versus silicon nitride compositions

SiN x films were grown by plasma-enhanced chemical vapor deposition on Si substrates with the composition controlled by the flow ratio R : ammonia to silane in the range R = 0.45–1.0. Then SiN x films were annealed at 1100 °C for 30 min to form Si-quantum dots (QDs). Fourier transform infrared spectroscopy study permits estimating SiN x compositions. Photoluminescence (PL) spectra of SiN x films included bands peaked at: 2.87–2.99, 2.42–2.54, 2.10–2.25, and 1.47–1.90 eV. Former three PL bands are attributed to emission via defects in SiN x films. Fourth PL band is assigned to exciton emission in Si QDs, detected by transmission electron microscopy study in films grown at R ≤ 0.67. The nature of non-radiative defects in SiN x films is discussed as well.