Raman scattering and optical properties of InSb quantum dots embedded in a glassy matrix

Well-dispersed InSb quantum dots (QDs) of the average diameter: d = 4, 6, 9, 12, and 20 am were grown in a GeO2 glassy matrix by melt-quenching and annealing under various conditions. The formation and growth of the InSb QDs were evaluated by analyzing the first order Raman lineshapes of TO and LO modes by an optical phonon confinement model, and it was confirmed that the growth obeyed the Lifshitz and Slyozov's mechanism. The InSb QDs of d = 4 nm exhibit an optical transition band at 3.6 eV as the lowest excitation transition, which is considerably lower than the value estimated by an effective mass approximation. In analyzing the confined TO and LO phonons, we found that a resonant Raman effect of InSb QDs and a dielectric effect of the glassy matrix should be taken into account besides the phonon confinement model by Campbell and Fauchet.