Large Oscillator Strength Excitons in PbGa2S4 Crystals

Abstract

In PbGa2S4 crystals the exciton states with the energy of about 290 meV and high oscillator strength (longitudinal – transversal dissipation of 75 meV) were observed. The ground states of the excitons are not dissociated at the room temperature. At the temperature of 77 K and 8.6 K the ground (n=1) and excited (n=2,3) states of two excitons series A and B are observed. The Bor radius for A excitons is about 70 Å and for B excitons is about 10Å.