Anomalous temperature-dependent spin-valley polarization in monolayer WS2

• DOI: 10.1038/srep18885
• Publication Date: 2016-01-05T10:07:52Z
• Authors: A.T. Hanbicki; G. Kioseoglou; M. Currie; C. Stephen Hellberg; K.M. McCreary; A.L. Friedman; B.T. Jonker
• Keywords: Trion; Auger effect

Single layers of transition metal dichalcogenides (TMDs) are direct gap semiconductors with nondegenerate valley indices. An intriguing possibility for these materials is the use their index as an alternate state variable. Several limitations to such a utility include strong, phonon-enabled intervalley scattering, well multiparticle interactions leading multiple emission channels. We prepare single-layer WS$_{2}$ that photoluminescence from either neutral or charged exciton (trion). After excitation circularly polarized light, has zero polarization, however, trion large polarization (28%) at room temperature. The also unique, non-monotonic temperature dependence we show consequence nature trion. This enables us determine coulomb assisted electron-hole radiative recombination, and 3-particle Auger process dominant mechanisms work in this system. Because involves systems, one can gate voltages modulate (or intensity) emitted TMD structures.