Abstract
The radiative recombination in the layered transition metal dichalcogenide compounds 2H-WS 2 and 2H-WSe 2 has been investigated. It is shown that the strong photoluminescence (PL) of these indirect band gap semiconductors is caused by recombination of excitons bound to neutral centers formed due to the intercalation of halogen molecules Br 2 and I 2 in the well defined sites of the van der Waals gap. These centers, located at energy E T , 0.1 v eV below the conduction band, display the same properties as the isoelectronic traps in GaP, providing the efficient radiative recombination.