Optical Properties of Germanium Quantum Dots

Abstract

We report a combined theoretical and experimental investigation of quantum confinement effects on the E1 interband structures in the optical spectra of Ge quantum dots. The experimental average radius goes from ≈12 to ≈60 Å. A blueshift of the E1 absorption peak (up to 0.1 eV) and a strong reduction in the oscillator strength, are measured effects of the quantum confinement. The theoretical analysis is performed for nanocrystals up to 15 Å through a semi-empirical tight-binding approach. We overcome the single-particle scheme including, in a perturbative approach, the Coulomb electron–hole interaction which induces a red-shift of the E1 peak with respect to the one-electron calculation.