Getting high-efficiency photoluminescence from Si nanocrystals in SiO2 matrix

Silicon nanocrystals in ${\mathrm{SiO}}_2$ matrix are fabricated by plasma enhanced chemical vapor deposition followed by thermal annealing. The structure and photoluminescence (PL) of the resulting films is investigated as a function of deposition temperature. Drastic improvement of PL efficiency up to 12% is achieved when the deposition temperature is reduced from 250 °C to room temperature. Low-temperature deposition is found to result in a high quality final structure of the films in which the silicon nanocrystals are nearly strain-free, and the ${\mathrm{Si/SiO}}_2$ interface sharp. The demonstration of the superior structural and optical properties of the films represents an important step towards the development of silicon-based light emitters.