Size dependence of electron—LO-phonon coupling in semiconductor nanocrystals

An increase in the Fröhlich-electron-LO-phonon interaction strength with decreasing nanocrystal size in the strong confinement limited is reported. This results from the size dependence of resonant Raman scattering by $\mathrm{Cd}{\mathrm{S}}_x{\mathrm{Se}}_{1-x}$ nanocrystals embedded in a glass slab. The mean particle radius $20<\mathrm{}\overline{R}<30\mathrm{}$ Å increases monotonically with the position along the slab so that, for each laser line, the resonance has been tuned by scanning the sample with a microprobe. The relative strength between Fröhlich and deformation-potential contributions is determined by analyzing the polarization properties of the scattering.