Electronic structure of MoSe2, MoS2, and WSe2. II. The nature of the optical band gaps

R. Coehoorn, C. Haas, and R. A. de Groot
Phys. Rev. B 35, 6203 – Published 15 April 1987
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Abstract

From band-structure calculations it is shown that MoSe2, MoS2, and WSe2 are indirect-gap semiconductors. The top of the valence band is at the Γ point and the bottom of the conduction band is along the line T of the hexagonal Brillouin zone, halfway between the points Γ and K. The A and B excitons correspond to the smallest direct gap at the K point. This assignment of the exciton peaks is shown to be consistent with the polarization dependence of their intensities, their effective masses, and the observed dependence of their splitting on the spin-orbit splittings of the constituent elements. The wave function at the top of the valence band is shown to be a metal-nonmetal antibonding state, which explains the observed high stability of these materials in photoelectrochemical cells against photocorrosion.

  • Received 20 October 1986

DOI:https://doi.org/10.1103/PhysRevB.35.6203

©1987 American Physical Society

Authors & Affiliations

R. Coehoorn and C. Haas

  • Laboratories of Physical and Inorganic Chemistry, Materials Science Centre of the University of Groningen, Nijenborgh 16, 9747 AG Groningen, The Netherlands

R. A. de Groot

  • Research Institute for Materials, Faculty of Science, University of Nijmegen, Toernooiveld, 6515 ED Nijmegen, The Netherlands

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Vol. 35, Iss. 12 — 15 April 1987

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