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 be en measured at room temperature near the fundamental absorption edge. Resul ts have been analyzed on the basis of two- and three-dimensional models. Bo th direct and indirect transitions are involved in the absorption process. The indirect transition was found to be allowed with two phonons involved i n the process. The direct and indirect energy gaps and phonon energies for all the crystals have been estimated. The three-dimensional model and not t he two-dimensional model could be used to describe the optical properties o f InxWSe2 single crystals. (C) 2000 Elsevier Science B.V. All rights reserv ed.