Observation of tightly bound trions in monolayer MoS2

摘要: Two-dimensional (2D) atomic crystals, such as graphene and transition-metal dichalcogenides, have emerged a new class of materials with remarkable physical properties. In contrast to graphene, monolayer MoS2 is non-centrosymmetric material direct energy gap. Strong photoluminescence, current on-off ratio exceeding 10^8 in field-effect transistors, efficient valley spin control by optical helicity recently been demonstrated this material. Here we report the spectroscopic identification doped tightly bound negative trions, quasi-particle composed two electrons hole. These quasi-particles, which can be created polarized holes, no analogue other semiconducting materials. They also possess large binding (~ 20 meV), rendering them significant even at room temperature. Our results open up avenues both for fundamental studies many-body interactions opto-electronic valleytronic applications 2D crystals.