PHOTOLUMINESCENCE STUDIES ON THE LAYER SEMICONDUCTOR IN2SE3

Photoluminescence investigations of the layered In//2Se//3 show clearly distinct results for two varieties of materials: pure alpha -In//2Se//3 and mixture of alpha and gamma -In//2Se//3. The pure alpha -In//2Se//3 exhibits, at liquid helium temperature, two photoluminescence bands: one at higher energy 1. 523 ev due to the radiative recombination of impurity bond excitons, and the other at lower energy 1. 326 ev due to recombination on luminescence centers formed by intrinsic defects due to disorder in the cation sublattice. In the mixed alpha - and gamma -In//2Se//3 only one broad band at 1. 319 ev is observed related to the additional disorder in the cation sublattice coming from the alloying of the alpha - and gamma - phases.