ON DYNAMICAL BEHAVIOUR OF EXCITONS IN CDS SINGLE CRYSTALS .I. CORRELATION BETWEEN INTRINSIC EXCITONIC ABSORPTION AND EMISSION

The excitonic absorption and emission are investigated on the same, extremely thin (d ≈ 3 × 10−5 cm) CdS single crystals in the range 77°K to room temperature. It is found that the zero‐phonon emission line is strongly influenced by reabsorption. After a reabsorption correction of the emission data the conclusions from the absorption and emission investigations agree with respect to the exciton‐phonon interaction. There is a contribution to the halfwidths and energetic positions of the exciton lines which is proportional to a Bose factor of LO phonons with ħω1 = 38 meV. No evidence is found for polariton effects from the reabsorption correction of the emission data. It is concluded, from the temperature dependence of the total emission intensity, that a quasi‐equilibrium exists between excitons and electron‐hole pairs. The exciton ionization energy is determined to be 31.5 meV. The dependence of the total emission intensity from the excitation intensity shows the occurrence of non‐radiative recombination processes. Band shapes and intensity rations of the one‐and two‐phonon satellites in the emission are also investigated and discussed. Copyright © 1968 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim