Microscopic model of the doping dependence of linewidths in monolayer transition metal dichalcogenides

Abstract

A fully microscopic model of the doping-dependent exciton and trion linewidths in the absorption spectra of monolayer transition metal dichalcogenides in the low temperature and low-doping regime is explored. The approach is based on perturbation theory and avoids the use of phenomenological parameters. In the low-doping regime, we find that the trion linewidth is relatively insensitive to doping levels, while the exciton linewidth increases monotonically with doping. On the other hand, we argue that the trion linewidth shows a somewhat stronger temperature dependence. The magnitudes of the linewidths are likely to be masked by phonon scattering for T ≥ 20 K in encapsulated samples in the low-doping regime. We discuss the breakdown of perturbation theory, which should occur at relatively low-doping levels and low temperatures. Our work also paves the way toward understanding a variety of related scattering processes, including impact ionization and Auger scattering in clean 2D samples.

Two-Dimensional Spectroscopy of Two-Dimensional Materials

“…where r 0 is the screening length. We note that this form of the potential is microscopically derived in the limit of infinite exciton effective mass, which is the correct limit for the MND model [31]. If, however, we endeavor to more realistically treat the nearly equal electron and hole masses as found in TMDCs, a different effective potential should be employed [32].…”

Electron recoil effect in electrically tunable MoSe2 monolayers

“…While at the lowest doping density the spectral asymmetry from recoil effect is rather pronounced, the spectra acquire a more symmetric lineshape at higher doping densities. This observation is partially related to a slightly increased symmetric broadening due to additional densityinduced scattering [7,25,49] as well as potential contributions from direct recombination discussed in the context of Eqs. ( 15) and ( 16).…”

Doping-induced non-Markovian interference causes excitonic linewidth broadening in monolayer WSe$_2$

“…Predicted exciton-trion energy separations already spanned from values comparable to experiments [33,35,[37][38][39] to overestimates [36]. However, no description could quantitatively explain the interplay of measured exciton-trion energy separation and simultaneously occurring exciton linewidth broadening, which was underestimated in previous theories [36][37][38]40] compared to experiments [19][20][21]. Our description manifests that the interplay and description of simultaneous energy shifts and linewidth broadenings requires a consistent many-body treatment of not only excitons and trions but also the associated scattering continua obtained by exact diagonalization.…”