Si quantum dots with a high absorption coefficient: Analysis based on both intensive and extensive variables

Silicon quantum dots (Si-QDs) were produced by pulsed laser ablation in liquid. By measuring the absorption spectra and the concentration of the Si-QD solution, two extinction coefficients were obtained from UV to near IR region: the atomic molar extinction coefficient and the quantum dot molar extinction coefficient. The magnitude of the atomic molar extinction coefficient of the Si-QDs was found to be up to 30 and 270 times those of crystalline and amorphous Si, respectively, and up to 740 times that of previously fabricated Si-QDs. The Si-QDs remained stably dispersed in hydrocarbon and alcohol solvents for over 10 months.