Two-dimensional semiconductor alloys: Monolayer Mo1−xWxSe2

Monolayer Mo1−xWxSe2 (x = 0, 0.14, 0.75, and 1) alloys were experimentally realized from synthesized crystals. Mo1−xWxSe2 monolayers are direct bandgap semiconductors displaying high luminescence and are stable in ambient. The bandgap values can be tuned by varying the W composition. Interestingly, the bandgap values do not scale linearly with composition. Such non-linearity is attributed to localization of conduction band minimum states around Mo d orbitals, whereas the valence band maximum states are uniformly distributed among W and Mo d orbitals. Results introduce monolayer Mo1−xWxSe2 alloys with different gap values, and open a venue for broadening the materials library and applications of two-dimensional semiconductors.