Optical properties of excitons in CdS semiconductor-insulator quantum wires

The characteristic features of the luminescence spectra of CdS semiconductor nanocrystals, crystallized in hollow channels in a dielectric template, are explained in terms of excitonic transitions in semiconductor-insulator quantum wires. The excitonic transition energies agree with the values calculated taking into account the effects of size quantization and the “dielectric enhancement of excitons” — the large increase in the electron-hole attraction as a result of the difference between the permittivities of the semiconductor and insulator. The theoretically computed binding energies of excitons in CdS quantum wires with a diameter of 10 nm reach 170 meV. It is shown that the excitonic transition energy is constant for a wide range of wire diameters.