Temperature dependence of the optical absorption spectra of InP/ZnS quantum dots

Abstract

The optical-absorption spectra of InP/ZnS (core/shell) quantum dots have been studied in a broad temperature range of T = 6.5–296 K. Using the second-order derivative spectrophotometry technique, the energies of optical transitions at room temperature were found to be E₁ = 2.60 ± 0.02 eV (for the first peak of excitonic absorption in the InP core) and E₂ = 4.70 ± 0.02 eV (for processes in the ZnS shell). The experimental curve of E₁(T) has been approximated for the first time in the framework of a linear model and in terms of the Fan’s formula. It is established that the temperature dependence of E₁ is determined by the interaction of excitons and longitudinal acoustic phonons with hω = 15 meV.