Gate controlled emission from hetero-bilayer of transition metal dichalcogenides

We optically probe interlayer excitons formed between WSe2 and MoSe2 monolayers. The type II band alignment that exists between this hetero-bilayer results in electron transfer from WSe2 to MoSe2 and hole transfer in opposite directions. The spatially separated electrons and holes results in interlayer excitons with large lifetime. In our FET geometry, we control the charge carrier density in the transition metal dichalcogenide monolayers which modifies the emission of the interlayer exciton at the hetero-bilayer. By changing the charge carrier density in the WSe2 monolayer, we observe a shift from charge to neutral exciton in MoSe2 monolayer and simultaneous enhancement of interlayer exciton photoluminescence. We also report observation of localized emission from the hetero-bilayer at a low temperature of 4 K.