Si-nanocrystals/SiO2 thin films obtained by pyrolysis of sol–gel precursors

Polymer pyrolysis to nanoceramics is employed for the production of photo-luminescent thin film samples, consisting of Si-nanocrystals dispersed in silica matrix. Thin films were deposited on Si wafer by spin-coating technique from a triethoxysilane-derived sol–gel solution. This is a fast process and a low cost technique. Samples were annealed at different temperatures between 600 °C and 1300 °C, under N2 gas atmosphere. Structural evolution and luminescence from Si-ncs vs. temperature were investigated by FT-IR absorption spectroscopy and photo-luminescence. Absorption spectrum of As-Prep sample shows several vibrational bands due to Si–H, C–Hx, and Si–O–Si structural units, without any appreciable luminescence. Silica phase segregation and intense PL (790 nm) due to Si-ncs were observed on annealing at T > 1000 °C.