Published online by Cambridge University Press: 11 July 2012
We present a femtosecond pump-probe ellipsometer operating over a spectral range of 1.4 – 1.7 eV with a ∼50fs time resolution. The calibration and preliminary findings of the setup are discussed. We tested the apparatus on bulk crystalline silicon (not shown here) and on silicon nanocrystals embedded in an amorphous silicon phase. The ellipsometric angles (ψ, Δ) were determined as a function of time and wavelength. The results suggest that a simple Drude model of free carrier absorption is not sufficient to explain the findings.