Si nanocrystals with an average size Ø = 2.31 ± 0.35 nm are prepared by chemical etching of Si powder. After being mixed with SiO2 sol-gel (SOG) and thermally annealed, a broadband photoluminescence from the thin film of Si nanocrystals in SOG is observed. The RGB ratio of the PL (1.00/3.26/4.59 for the pure white light emission) can be tuned by changing the annealing temperature or atmosphere.

Optical gains

The optical gains of Si nanocrystals in SOG are measured by variable stripe length (VSL) and shifting excitation spot (SES) methods for the four components (λ = 400, 490, 560, 620 nm) of PL. Positive optical gains are obtained, which are 117.49, 123.20, 94.57, 89.93 cm-1 respectively.

Potential applications

It is established that the light emission from Si nanocrystals is related to their interfacial states whilst theoretical calculations suggest that the number of Si and O bond determines the wavelength of light emission. With white light emission and positive optical gains for the RGB components under ultraviolet excitation, Si nanocrystals in SOG have potential in white-light Si lasing and Si lighting.

More information about this research can be found in the journal Nanotechnology 26 475203.

Further reading

Colloidal quantum dots: solar applications (Jan 2015)
Nanographene broadens memory prospects (Nov 2015)
Developing visible light-active titanium dioxide photocatalysts (Mar 2015)