Correlation between photo response and nanostructures of silicon quantum dots in annealed Si-rich nitride films

Synthesis and characterization of silicon quantum dots (Si QDs) materials are carried out. The Si QDs were prepared from a hydrogenated silicon rich nitride film that is deposited by the plasma enhanced chemical vapor deposition process with a gas mixture of SiH4 and NH3 at flow ratios from 0.5 to 2. The Si QDs can be precipitated from the hydrogenated silicon rich nitride film by a high temperature annealing. The optimum density of the Si QDs precipitated amounts to 6.4 × 1012 cm− 2, as calculated from transmission electron microscope images, for flow ratio of SiH4 versus NH3 at 2, and particle sizes less than 6 nm. The dots density within the film becomes concentrated when the flow ratio of SiH4 versus NH3 increases. The intensity of photo response increases drastically when the dots density becomes large.

► Silicon quantum dots (Si QDs) precipitated from deposited films were identified.
► All Si QDs obtained exhibit similar sizes but different densities.
► Correlation between photo response and amount of Si QDs was established.
► The photo response increases with increasing density of Si QDs in the film.