Red emission from nano-silicon nitride multilayer films prepared using hot-wire chemical vapor deposition

Ultrathin silicon nitride multilayer films were prepared by varying silane/ammonia flow ratios 1/10 and 1/20 alternately in a silicon nitride hot-wire chemical vapor deposition chamber. Some films were annealed at 1000 °C for 1 h in an argon environment. Cross-sectional transmission electron microscopy shows ~6 nm silicon clusters formed in the annealed film. Strong visible red emission in the wavelength range 810–820 nm was detected from the films when excited with the 325 nm He–Cd laser excitation. A blueshift in the photoluminescence of the annealed film with respect to the as-deposited film is attributed to the silicon quantum confinement due to the presence of silicon clusters. Disappearance of the photoluminescence peak at 521 nm related to silicon dangling bonds in the annealed film in comparison with the as-deposited film was confirmed by the photoluminescence measurements.