Optical band gap in tungsten diselenide single crystals intercalated by indium

Optical absorption in single crystals of InxWSe2 (x = 0, 0.33, 0.50) has been measured at room temperature near the fundamental absorption edge. Results have been analyzed on the basis of two- and three-dimensional models. Both direct and indirect transitions are involved in the absorption process. The indirect transition was found to be allowed with two phonons involved in the process. The direct and indirect energy gaps and phonon energies for all the crystals have been estimated. The three-dimensional model and not the two-dimensional model could be used to describe the optical properties of InxWSe2 single crystals. (C) 2000 Elsevier Science B.V. All rights reserved.