Ellipsometric measurements of quantum confinement effects on higher interband transitions of Ge nanocrystals

We studied the dielectric functions of Ge nanocrystals obtained by crystallization of amorphous Ge thin films embedded in SiO ₂. Partial crystallization of films was induced by thermal annealing. Crystalline regions gave rise to clear spectral features due to interband transitions whose critical point parameters correlated with the initial a-Ge thickness. These changes were clearly attributed to quantum confinement effects. Second derivative of derivative function spectra and their fit showing the blueshift in E ₁, and E ₁ + δ ₁, transitions. Energies obtained in bulk Ge are labeled "B" and given for reference.