Modulation of photocarrier relaxation dynamics in two-dimensional semiconductors

摘要

a Real-space representation of electrons and holes bound into excitons for a 3D bulk and a quasi-2D monolayer. b Evolution of photocarriers after instantaneous interband excitation. c (Left) Schematic of the type-II band alignment of a MoS2/WS2 heterostructure and the charge transfer process. (Right) Band profile of a MoS2/WSe2 heterostructure illustrating the mechanisms of interfacial recombination: the Shockley–Read–Hall (SRH) mechanism (red dashed arrow) and the Langevin mechanism (blue arrow). d Valley-contrasting optical selection rules in a 2D hexagonal lattice with broken inversion symmetry. Figure reproduced with permission from a ref. 24, © 2014 American Physical Society; b ref. 22, © 2016 WILEY‐VCH Verlag GmbH & Co., KGaA, Weinheim; c ref. 29, © 2014 Springer Nature and ref. 31, © 2014 Springer Nature; d ref. 34, © 2014 Springer Nature