TY - JOUR

T1 - Colloquium

T2 - Excitons in atomically thin transition metal dichalcogenides

AU - Wang, Gang

AU - Chernikov, Alexey

AU - Glazov, Mikhail M.

AU - Heinz, Tony F.

AU - Marie, Xavier

AU - Amand, Thierry

AU - Urbaszek, Bernhard

PY - 2018/4/4

Y1 - 2018/4/4

N2 - Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. Here recent progress in understanding of the excitonic properties in monolayer TMDs is reviewed and future challenges are laid out. Discussed are the consequences of the strong direct and exchange Coulomb interaction, exciton light-matter coupling, and influence of finite carrier and electron-hole pair densities on the exciton properties in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observed in applied electric and magnetic fields is summarized.

AB - Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. Here recent progress in understanding of the excitonic properties in monolayer TMDs is reviewed and future challenges are laid out. Discussed are the consequences of the strong direct and exchange Coulomb interaction, exciton light-matter coupling, and influence of finite carrier and electron-hole pair densities on the exciton properties in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observed in applied electric and magnetic fields is summarized.

KW - SINGLE-LAYER MOS2

KW - HIGH MAGNETIC-FIELDS

KW - GAAS QUANTUM-WELLS

KW - MONOLAYER MOLYBDENUM-DISULFIDE

KW - GIANT BANDGAP RENORMALIZATION

KW - DER-WAALS HETEROSTRUCTURE

KW - VAPOR-PHASE GROWTH

KW - MONO LAYER

KW - VALLEY POLARIZATION

KW - ROOM-TEMPERATURE

UR - http://www.scopus.com/inward/record.url?scp=85045574534&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/colloquium-excitons-atomically-thin-transition-metal-dichalcogenides

U2 - 10.1103/RevModPhys.90.021001

DO - 10.1103/RevModPhys.90.021001

M3 - Article

AN - SCOPUS:85045574534

VL - 90

JO - Reviews of Modern Physics

JF - Reviews of Modern Physics

SN - 0034-6861

IS - 2

M1 - 021001

ER -