Anisotropy of optical absorption in layered single crystals

The optical energy gap of Re doped MoSe2 single crystal Mo0.995Re0.005Se2 has been measured at room temperature near the fundamental absorption edge. The incident light was kept normal to the basal plane i.e. along the c-axis of the grown crystals. Results have been given 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 three dimensional model and not the two dimensional could be used to describe the optical properties of Re doped MoSe2 single crystal. Also, the optical energy gaps depend upon the amount of the intercalating Re material. (C) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.